Diff [e3b24743580e0faaf833a980c334820f77cfefaf:c653b37a0a370ac84dabe4b28e825c920a425f13] for / – Cforall

doc/papers/concurrency/Paper.tex

-              re3b2474
+              rc653b37
 \articletype{RESEARCH ARTICLE}%
 \received{XXXXX}
 \revised{XXXXX}
 \accepted{XXXXX}
+\received{26 April 2016}
+\revised{6 June 2016}
+\accepted{6 June 2016}
 \raggedbottom
 …
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 \makeatother
+\newenvironment{cquote}
+               {\list{}{\lstset{resetmargins=true,aboveskip=0pt,belowskip=0pt}\topsep=3pt\parsep=0pt\leftmargin=\parindentlnth\rightmargin\leftmargin}%
+                \item\relax}
+               {\endlist}
+%\newenvironment{cquote}{%
+%\list{}{\lstset{resetmargins=true,aboveskip=0pt,belowskip=0pt}\topsep=3pt\parsep=0pt\leftmargin=\parindentlnth\rightmargin\leftmargin}%
+%\item\relax%
+%}{%
+%\endlist%
+%}% cquote
+\newenvironment{cquote}{%
+        \list{}{\lstset{resetmargins=true,aboveskip=0pt,belowskip=0pt}\topsep=3pt\parsep=0pt\leftmargin=\parindentlnth\rightmargin\leftmargin}%
+        \item\relax
+}{%
+        \endlist
+}% cquote
 % CFA programming language, based on ANSI C (with some gcc additions)
 …
 \abstract[Summary]{
 \CFA is a modern, polymorphic, \emph{non-object-oriented} extension of the C programming language.
 This paper discusses the design of the concurrency and parallelism features in \CFA, and its concurrent runtime-system.
+This paper discusses the design of the concurrency and parallelism features in \CFA, and the concurrent runtime-system.
 These features are created from scratch as ISO C lacks concurrency, relying largely on the pthreads library for concurrency.
 Coroutines and lightweight (user) threads are introduced into \CFA;
 as well, monitors are added as a high-level mechanism for mutual exclusion and synchronization.
 A unique contribution of this work is allowing multiple monitors to be safely acquired \emph{simultaneously}.
+Coroutines and lightweight (user) threads are introduced into the language.
+In addition, monitors are added as a high-level mechanism for mutual exclusion and synchronization.
+A unique contribution is allowing multiple monitors to be safely acquired simultaneously.
 All features respect the expectations of C programmers, while being fully integrate with the \CFA polymorphic type-system and other language features.
 Experimental results show comparable performance of the new features with similar mechanisms in other concurrent programming-languages.
+Finally, experimental results show comparable performance of the new features with similar mechanisms in other concurrent programming-languages.
 }%
 …
 Concurrency tools handle mutual exclusion and synchronization, while parallelism tools handle performance, cost, and resource utilization.
 The proposed concurrency API is implemented in a dialect of C, called \CFA (pronounced C-for-all).
+The proposed concurrency API is implemented in a dialect of C, called \CFA.
 The paper discusses how the language features are added to the \CFA translator with respect to parsing, semantics, and type checking, and the corresponding high-performance runtime-library to implement the concurrent features.
 …
 \CFA is a non-object-oriented extension of ISO-C, and hence, supports all C paradigms.
+%It is a non-object-oriented system-language, meaning most of the major abstractions have either no runtime overhead or can be opted out easily.
 Like C, the building blocks of \CFA are structures and routines.
 Virtually all of the code generated by the \CFA translator respects C memory layouts and calling conventions.
 While \CFA is not object oriented, lacking the concept of a receiver (\eg @this@) and nominal inheritance-relationships, C has a notion of objects: ``region of data storage in the execution environment, the contents of which can represent values''~\cite[3.15]{C11}.
 While some object-oriented features appear in \CFA, they are independent capabilities, allowing \CFA to adopt them while maintaining a procedural paradigm.
+While \CFA is not object oriented, lacking the concept of a receiver (\eg @this@) and nominal inheritance-relationships, C does have a notion of objects: ``region of data storage in the execution environment, the contents of which can represent values''~\cite[3.15]{C11}.
+While some \CFA features are common in object-oriented programming, they are independent capabilities allowing \CFA to adopt them while maintaining a procedural paradigm.
 …
 Object-oriented programming languages only provide implicit qualification for the receiver.
 In detail, the @with@-statement syntax is:
+In detail, the @with@ statement has the form:
 \begin{cfa}
 $\emph{with-statement}$:
 …
 (Enumerations are already opened.)
 The object is the implicit qualifier for the open structure-fields.
 All expressions in the expression list are opened in parallel within the compound statement, which is different from Pascal, which nests the openings from left to right.
+All expressions in the expression list are open in parallel within the compound statement, which is different from Pascal, which nests the openings from left to right.
 …
 \CFA maximizes the ability to reuse names via overloading to aggressively address the naming problem.
+Both variables and routines may be overloaded, where selection is based on number and types of returns and arguments (as in Ada~\cite{Ada}).
+\newpage
+\vspace*{-2\baselineskip}%???
+Both variables and routines may be overloaded, where selection is based on types, and number of returns (as in Ada~\cite{Ada}) and arguments.
 \begin{cquote}
+\vspace*{-\baselineskip}%???
+\lstDeleteShortInline@%
 \begin{cfa}
 // selection based on type
 \end{cfa}
-\lstDeleteShortInline@%
 \begin{tabular}{@{}l@{\hspace{2\parindentlnth}}|@{\hspace{2\parindentlnth}}l@{}}
 \begin{cfa}
 …
 Therefore, overloading eliminates long prefixes and other naming conventions to prevent name clashes.
 As seen in Section~\ref{s:Concurrency}, routine @main@ is heavily overloaded.
 As another example, variable overloading is useful in the parallel semantics of the @with@ statement for fields with the same name:
+For example, variable overloading is useful in the parallel semantics of the @with@ statement for fields with the same name:
 \begin{cfa}
 struct S { int `i`; int j; double m; } s;
 …
 \lstMakeShortInline@%
 \end{cquote}
+While concurrency does not use operator overloading directly, it provides an introduction for the syntax of constructors.
 …
 Object lifetime is a challenge in non-managed programming languages.
 \CFA responds with \CC-like constructors and destructors, using a different operator-overloading syntax.
+\CFA responds with \CC-like constructors and destructors:
 \begin{cfa}
 struct VLA { int len, * data; };                        $\C{// variable length array of integers}$
 …
 Like \CC, construction is implicit on allocation (stack/heap) and destruction is implicit on deallocation.
 The object and all their fields are constructed/destructed.
 \CFA also provides @new@ and @delete@ as library routines, which behave like @malloc@ and @free@, in addition to constructing and destructing objects:
+\CFA also provides @new@ and @delete@, which behave like @malloc@ and @free@, in addition to constructing and destructing objects:
 \begin{cfa}
+{
 …
 int i = sum( sa, 5 );                                           $\C{// use S's 0 construction and +}$
 \end{cfa}
+Type variables can be @otype@ or @dtype@.
+@otype@ refers to a \emph{complete type}, \ie, a type with size, alignment, default constructor, copy constructor, destructor, and assignment operator.
+@dtype@ refers to an \emph{incomplete type}, \eg, void or a forward-declared type.
+The builtin types @zero_t@ and @one_t@ overload constant 0 and 1 for a new types, where both 0 and 1 have special meaning in C.
+The builtin type @zero_t@ (and @one_t@) overload constant 0 (and 1) for a new types, where both 0 and 1 have special meaning in C.
 \CFA provides \newterm{traits} to name a group of type assertions, where the trait name allows specifying the same set of assertions in multiple locations, preventing repetition mistakes at each routine declaration:
 …
 \end{cfa}
+Assertions can be @otype@ or @dtype@.
+@otype@ refers to a \emph{complete} object, \ie an object has a size, alignment, default constructor, copy constructor, destructor and an assignment operator.
+@dtype@ refers to an \emph{incomplete} object, \ie, an object only has a size and alignment.
 Using the return type for overload discrimination, it is possible to write a type-safe @alloc@ based on the C @malloc@:
 \begin{cfa}
 …
 In coroutining, the single thread is self-scheduling across the stacks, so execution is deterministic, \ie the execution path from input to output is fixed and predictable.
 A \newterm{stackless} coroutine executes on the caller's stack~\cite{Python} but this approach is restrictive, \eg preventing modularization and supporting only iterator/generator-style programming;
 a \newterm{stackful} coroutine executes on its own stack, allowing full generality.
 Only stackful coroutines are a stepping stone to concurrency.
+a \newterm{stackfull} coroutine executes on its own stack, allowing full generality.
+Only stackfull coroutines are a stepping stone to concurrency.
 The transition to concurrency, even for execution with a single thread and multiple stacks, occurs when coroutines also context switch to a \newterm{scheduling oracle}, introducing non-determinism from the coroutine perspective~\cite[\S~3]{Buhr05a}.
 …
 The resulting execution system now follows a cooperative threading-model, called \newterm{non-preemptive scheduling}.
 Because the scheduler is special, it can either be a stackless or stackful coroutine.
+Because the scheduler is special, it can either be a stackless or stackfull coroutine.
 For stackless, the scheduler performs scheduling on the stack of the current coroutine and switches directly to the next coroutine, so there is one context switch.
 For stackful, the current coroutine switches to the scheduler, which performs scheduling, and it then switches to the next coroutine, so there are two context switches.
 A stackful scheduler is often used for simplicity and security.
+For stackfull, the current coroutine switches to the scheduler, which performs scheduling, and it then switches to the next coroutine, so there are two context switches.
+A stackfull scheduler is often used for simplicity and security, even through there is a slightly higher runtime-cost.
 Regardless of the approach used, a subset of concurrency related challenges start to appear.
 For the complete set of concurrency challenges to occur, the missing feature is \newterm{preemption}, where context switching occurs randomly between any two instructions, often based on a timer interrupt, called \newterm{preemptive scheduling}.
 While a scheduler introduces uncertainty in the order of execution, preemption introduces uncertainty about where context switches occur.
+While a scheduler introduces uncertainty in the order of execution, preemption introduces uncertainty where context switches occur.
 Interestingly, uncertainty is necessary for the runtime (operating) system to give the illusion of parallelism on a single processor and increase performance on multiple processors.
 The reason is that only the runtime has complete knowledge about resources and how to best utilized them.
 …
 otherwise, it is impossible to write meaningful programs.
 Optimal performance in concurrent applications is often obtained by having as much non-determinism as correctness allows.
+\subsection{\protect\CFA's Thread Building Blocks}
 An important missing feature in C is threading\footnote{While the C11 standard defines a \protect\lstinline@threads.h@ header, it is minimal and defined as optional.
 …
 While the focus of this discussion is concurrency and parallelism, it is important to address coroutines, which are a significant building block of a concurrency system (but not concurrent among themselves).
 Coroutines are generalized routines allowing execution to be temporarily suspended and later resumed.
+Coroutines are generalized routines allowing execution to be temporarily suspend and later resumed.
 Hence, unlike a normal routine, a coroutine may not terminate when it returns to its caller, allowing it to be restarted with the values and execution location present at the point of suspension.
 This capability is accomplished via the coroutine's stack, where suspend/resume context switch among stacks.
+This capability is accomplish via the coroutine's stack, where suspend/resume context switch among stacks.
 Because threading design-challenges are present in coroutines, their design effort is relevant, and this effort can be easily exposed to programmers giving them a useful new programming paradigm because a coroutine handles the class of problems that need to retain state between calls, \eg plugins, device drivers, and finite-state machines.
 Therefore, the two fundamental features of the core \CFA coroutine-API are independent call-stacks and @suspend@/@resume@ operations.
+Therefore, the core \CFA coroutine-API for has two fundamental features: independent call-stacks and @suspend@/@resume@ operations.
 For example, a problem made easier with coroutines is unbounded generators, \eg generating an infinite sequence of Fibonacci numbers
 …
 Figure~\ref{f:Coroutine3States} creates a @coroutine@ type, @`coroutine` Fib { int fn; }@, which provides communication, @fn@, for the \newterm{coroutine main}, @main@, which runs on the coroutine stack, and possibly multiple interface routines, \eg @next@.
 Like the structure in Figure~\ref{f:ExternalState}, the coroutine type allows multiple instances, where instances of this type are passed to the (overloaded) coroutine main.
 The coroutine main's stack holds the state for the next generation, @f1@ and @f2@, and the code represents the three states in the Fibonacci formula via the three suspend points, to context switch back to the caller's @resume@.
+The coroutine main's stack holds the state for the next generation, @f1@ and @f2@, and the code has the three suspend points, representing the three states in the Fibonacci formula, to context switch back to the caller's @resume@.
 The interface routine @next@, takes a Fibonacci instance and context switches to it using @resume@;
 on restart, the Fibonacci field, @fn@, contains the next value in the sequence, which is returned.
 …
 \end{quote}
 The example takes advantage of resuming a coroutine in the constructor to prime the loops so the first character sent for formatting appears inside the nested loops.
 The destructor provides a newline, if formatted text ends with a full line.
 Figure~\ref{f:CFmt} shows the C equivalent formatter, where the loops of the coroutine are flattened (linearized) and rechecked on each call because execution location is not retained between calls.
+The destruction provides a newline, if formatted text ends with a full line.
+Figure~\ref{f:CFmt} shows the C equivalent formatter, where the loops of the coroutine are flatten (linearized) and rechecked on each call because execution location is not retained between calls.
 (Linearized code is the bane of device drivers.)
 …
 };
 void main( Format & fmt ) with( fmt ) {
         for ( ;; ) {
+        for ( ;; ) {
                 for ( g = 0; g < 5; g += 1 ) {      // group
                         for ( b = 0; b < 4; b += 1 ) { // block
 …
 The previous examples are \newterm{asymmetric (semi) coroutine}s because one coroutine always calls a resuming routine for another coroutine, and the resumed coroutine always suspends back to its last resumer, similar to call/return for normal routines.
 However, @resume@ and @suspend@ context switch among existing stack-frames, rather than create new ones so there is no stack growth.
 \newterm{Symmetric (full) coroutine}s have a coroutine call to a resuming routine for another coroutine, and its coroutine main calls another resuming routine, which eventually forms a resuming-call cycle.
+\newterm{Symmetric (full) coroutine}s have a coroutine call to a resuming routine for another coroutine, and its coroutine main has a call to another resuming routine, which eventually forms a resuming-call cycle.
 (The trivial cycle is a coroutine resuming itself.)
 This control flow is similar to recursion for normal routines, but again there is no stack growth from the context switch.
 …
 The call from the consumer to @payment@ introduces the cycle between producer and consumer.
 When @payment@ is called, the consumer copies values into the producer's communication variable and a resume is executed.
 The context switch restarts the producer at the point where it last context switched, so it continues in @delivery@ after the resume.
+The context switch restarts the producer at the point where it was last context switched, so it continues in @delivery@ after the resume.
 @delivery@ returns the status value in @prod@'s coroutine main, where the status is printed.
 …
 \subsection{Coroutine Implementation}
 A significant implementation challenge for coroutines (and threads, see Section~\ref{threads}) is adding extra fields and executing code after/before the coroutine constructor/destructor and coroutine main to create/initialize/de-initialize/destroy extra fields and the stack.
+A significant implementation challenge for coroutines (and threads, see section \ref{threads}) is adding extra fields and executing code after/before the coroutine constructor/destructor and coroutine main to create/initialize/de-initialize/destroy extra fields and the stack.
 There are several solutions to this problem and the chosen option forced the \CFA coroutine design.
 …
 \end{cfa}
 and the programming language (and possibly its tool set, \eg debugger) may need to understand @baseCoroutine@ because of the stack.
 Furthermore, the execution of constructors/destructors is in the wrong order for certain operations.
+Furthermore, the execution of constructs/destructors is in the wrong order for certain operations.
 For example, for threads if the thread is implicitly started, it must start \emph{after} all constructors, because the thread relies on a completely initialized object, but the inherited constructor runs \emph{before} the derived.
 An alternative is composition:
+An alternatively is composition:
 \begin{cfa}
 struct mycoroutine {
 …
 Users wanting to extend coroutines or build their own for various reasons can only do so in ways offered by the language.
 Furthermore, implementing coroutines without language supports also displays the power of a programming language.
 While this is ultimately the option used for idiomatic \CFA code, coroutines and threads can still be constructed without language support.
 The reserved keyword simply eases use for the common case.
 Part of the mechanism to generalize coroutines is using a \CFA trait, which defines a coroutine as anything satisfying the trait @is_coroutine@, and this trait restricts the available set of coroutine-manipulation routines:
+While this is ultimately the option used for idiomatic \CFA code, coroutines and threads can still be constructed without using the language support.
+The reserved keyword simply eases use for the common cases.
+Part of the mechanism to generalize coroutines is using a \CFA trait, which defines a coroutine as anything satisfying the trait @is_coroutine@, and this trait is used to restrict coroutine-manipulation routines:
 \begin{cfa}
 trait is_coroutine( `dtype` T ) {
 …
 forall( `dtype` T | is_coroutine(T) ) void resume( T & );
 \end{cfa}
 The @dtype@ property provides no implicit copying operations and the @is_coroutine@ trait provides no explicit copying operations, so all coroutines must be passed by reference (pointer).
+The @dtype@ property of the trait ensures the coroutine descriptor is non-copyable, so all coroutines must be passed by reference (pointer).
 The routine definitions ensures there is a statically-typed @main@ routine that is the starting point (first stack frame) of a coroutine, and a mechanism to get (read) the currently executing coroutine handle.
 The @main@ routine has no return value or additional parameters because the coroutine type allows an arbitrary number of interface routines with corresponding arbitrary typed input/output values versus fixed ones.
+The generic routines @suspend@ and @resume@ can be redefined, but any object passed to them is a coroutine since it must satisfy the @is_coroutine@ trait to compile.
 The advantage of this approach is that users can easily create different types of coroutines, \eg changing the memory layout of a coroutine is trivial when implementing the @get_coroutine@ routine, and possibly redefining @suspend@ and @resume@.
 The \CFA keyword @coroutine@ implicitly implements the getter and forward declarations required for implementing the coroutine main:
 …
 \begin{cfa}
 int main() {
         MyThread * heapLive;
+        MyThread * heapLived;
+        {
                 MyThread blockLive;                                     $\C{// fork block-based thread}$
                 heapLive = `new`( MyThread );           $\C{// fork heap-based thread}$
+                MyThread blockLived;                            $\C{// fork block-based thread}$
+                heapLived = `new`( MyThread );          $\C{// fork heap-based thread}$
                 ...
         }                                                                               $\C{// join block-based thread}$
         ...
         `delete`( heapLive );                                   $\C{// join heap-based thread}$
+        `delete`( heapLived );                                  $\C{// join heap-based thread}$
+}
 \end{cfa}
 The heap-based approach allows arbitrary thread-creation topologies, with respect to fork/join-style concurrency.
 Figure~\ref{s:ConcurrentMatrixSummation} shows concurrently adding the rows of a matrix and then totalling the subtotals sequentially, after all the row threads have terminated.
+Figure~\ref{s:ConcurrentMatrixSummation} shows concurrently adding the rows of a matrix and then totalling the subtotals sequential, after all the row threads have terminated.
 The program uses heap-based threads because each thread needs different constructor values.
 (Python provides a simple iteration mechanism to initialize array elements to different values allowing stack allocation.)
 The allocation/deallocation pattern appears unusual because allocated objects are immediately deallocated without any intervening code.
 However, for threads, the deletion provides implicit synchronization, which is the intervening code.
 While the subtotals are added in linear order rather than completion order, which slightly inhibits concurrency, the computation is restricted by the critical-path thread (\ie the thread that takes the longest), and so any inhibited concurrency is very small as totalling the subtotals is trivial.
+While the subtotals are added in linear order rather than completion order, which slight inhibits concurrency, the computation is restricted by the critical-path thread (\ie the thread that takes the longest), and so any inhibited concurrency is very small as totalling the subtotals is trivial.
 \begin{figure}
 \begin{cfa}
+`thread` Adder { int * row, cols, & subtotal; } $\C{// communication variables}$
+thread Adder {
+    int * row, cols, & subtotal;                        $\C{// communication}$
+};
 void ?{}( Adder & adder, int row[], int cols, int & subtotal ) {
     adder.[ row, cols, &subtotal ] = [ row, cols, &subtotal ];
 …
     Adder * adders[rows];
     for ( int r = 0; r < rows; r += 1 ) {       $\C{// start threads to sum rows}$
                 adders[r] = `new( matrix[r], cols, &subtotals[r] );`
+                adders[r] = new( matrix[r], cols, &subtotals[r] );
+    }
     for ( int r = 0; r < rows; r += 1 ) {       $\C{// wait for threads to finish}$
                 `delete( adders[r] );`                          $\C{// termination join}$
+                delete( adders[r] );                            $\C{// termination join}$
                 total += subtotals[r];                          $\C{// total subtotal}$
+    }
 …
 To reestablish meaningful execution requires mechanisms to reintroduce determinism, \ie restrict non-determinism, called mutual exclusion and synchronization, where mutual exclusion is an access-control mechanism on data shared by threads, and synchronization is a timing relationship among threads~\cite[\S~4]{Buhr05a}.
 Since many deterministic challenges appear with the use of mutable shared state, some languages/libraries disallow it, \eg Erlang~\cite{Erlang}, Haskell~\cite{Haskell}, Akka~\cite{Akka} (Scala).
 In these paradigms, interaction among concurrent objects is performed by stateless message-passing~\cite{Thoth,Harmony,V-Kernel} or other paradigms closely related to networking concepts, \eg channels~\cite{CSP,Go}.
+In these paradigms, interaction among concurrent objects is performed by stateless message-passing~\cite{Thoth,Harmony,V-Kernel} or other paradigms closely relate to networking concepts, \eg channels~\cite{CSP,Go}.
 However, in call/return-based languages, these approaches force a clear distinction, \ie introduce a new programming paradigm between regular and concurrent computation, \eg routine call versus message passing.
 Hence, a programmer must learn and manipulate two sets of design patterns.
 While this distinction can be hidden away in library code, effective use of the library still has to take both paradigms into account.
 In contrast, approaches based on stateful models more closely resemble the standard call/return programming-model, resulting in a single programming paradigm.
+In contrast, approaches based on statefull models more closely resemble the standard call/return programming-model, resulting in a single programming paradigm.
 At the lowest level, concurrent control is implemented by atomic operations, upon which different kinds of locking mechanisms are constructed, \eg semaphores~\cite{Dijkstra68b}, barriers, and path expressions~\cite{Campbell74}.
 However, for productivity it is always desirable to use the highest-level construct that provides the necessary efficiency~\cite{Hochstein05}.
 A newer approach for restricting non-determinism is transactional memory~\cite{Herlihy93}.
 While this approach is pursued in hardware~\cite{Nakaike15} and system languages, like \CC~\cite{Cpp-Transactions}, the performance and feature set is still too restrictive to be the main concurrency paradigm for system languages, which is why it is rejected as the core paradigm for concurrency in \CFA.
+While this approach is pursued in hardware~\cite{Nakaike15} and system languages, like \CC~\cite{Cpp-Transactions}, the performance and feature set is still too restrictive to be the main concurrency paradigm for system languages, which is why it was rejected as the core paradigm for concurrency in \CFA.
 One of the most natural, elegant, and efficient mechanisms for mutual exclusion and synchronization for shared-memory systems is the \emph{monitor}.
 …
 higher-level mechanisms often simplify usage by adding better coupling between synchronization and data, \eg message passing, or offering a simpler solution to otherwise involved challenges, \eg barrier lock.
 Often synchronization is used to order access to a critical section, \eg ensuring a reader thread is the next kind of thread to enter a critical section.
 If a writer thread is scheduled for next access, but another reader thread acquires the critical section first, that reader \newterm{barged}.
+If a writer thread is scheduled for next access, but another reader thread acquires the critical section first, that reader has \newterm{barged}.
 Barging can result in staleness/freshness problems, where a reader barges ahead of a writer and reads temporally stale data, or a writer barges ahead of another writer overwriting data with a fresh value preventing the previous value from ever being read (lost computation).
 Preventing or detecting barging is an involved challenge with low-level locks, which can be made much easier by higher-level constructs.
 …
 Algorithms that allow a barger, but divert it until later using current synchronization state (flags), are avoiding the barger;
 algorithms that preclude a barger from entering during synchronization in the critical section prevent barging completely.
 Techniques like baton-passing locks~\cite{Andrews89} between threads instead of unconditionally releasing locks is an example of barging prevention.
+Techniques like baton-pass locks~\cite{Andrews89} between threads instead of unconditionally releasing locks is an example of barging prevention.
 …
 Copying a lock is insecure because it is possible to copy an open lock and then use the open copy when the original lock is closed to simultaneously access the shared data.
 Copying a monitor is secure because both the lock and shared data are copies, but copying the shared data is meaningless because it no longer represents a unique entity.
 As for coroutines/tasks, the @dtype@ property provides no implicit copying operations and the @is_monitor@ trait provides no explicit copying operations, so all locks/monitors must be passed by reference (pointer).
+As for coroutines/tasks, a non-copyable (@dtype@) trait is used to capture this requirement, so all locks/monitors must be passed by reference (pointer).
 \begin{cfa}
 trait is_monitor( `dtype` T ) {
 …
 \label{s:MutexAcquisition}
 While correctness implies a monitor's mutual exclusion is acquired and released, there are implementation options about when and where the locking/unlocking occurs.
+While correctness implicitly implies a monitor's mutual exclusion is acquired and released, there are implementation options about when and where the locking/unlocking occurs.
 (Much of this discussion also applies to basic locks.)
 For example, a monitor may need to be passed through multiple helper routines before it becomes necessary to acquire the monitor mutual-exclusion.
 …
 For maximum usability, monitors have \newterm{multi-acquire} semantics allowing a thread to acquire it multiple times without deadlock.
+\begin{cfa}
+monitor M { ... } m;
+void foo( M & mutex m ) { ... }                         $\C{// acquire mutual exclusion}$
+void bar( M & mutex m ) {                                       $\C{// acquire mutual exclusion}$
+        ... `foo( m );` ...                                             $\C{// reacquire mutual exclusion}$
+}
+`bar( m );`                                                                     $\C{// nested monitor call}$
+\end{cfa}
+The benefit of mandatory monitor qualifiers is self-documentation, but requiring both @mutex@ and \lstinline[morekeywords=nomutex]@nomutex@ for all monitor parameters is redundant.
+Instead, the semantics have one qualifier as the default, and the other required.
+For example, make the safe @mutex@ qualifier the default because assuming \lstinline[morekeywords=nomutex]@nomutex@ may cause subtle errors.
+Alternatively, make the unsafe \lstinline[morekeywords=nomutex]@nomutex@ qualifier the default because it is the \emph{normal} parameter semantics while @mutex@ parameters are rare.
+For example, atomically printing the contents of a binary tree:
+\begin{cfa}
+monitor Tree {
+        Tree * left, right;
+        // value
+};
+void print( Tree & mutex tree ) {                       $\C{// prefix traversal}$
+        // write value
+        print( tree->left );                                    $\C{// multiply acquire monitor lock on each recursion}$
+        print( tree->right );
+}
+\end{cfa}
+Mandatory monitor qualifiers have the benefit of being self-documenting, but requiring both @mutex@ and \lstinline[morekeywords=nomutex]@nomutex@ for all monitor parameter is redundant.
+Instead, one of qualifier semantics can be the default, and the other required.
+For example, assume the safe @mutex@ qualifier for all monitor parameters because assuming \lstinline[morekeywords=nomutex]@nomutex@ may cause subtle errors.
+On the other hand, assuming \lstinline[morekeywords=nomutex]@nomutex@ is the \emph{normal} parameter behaviour, stating explicitly \emph{this parameter is not special}.
 Providing a default qualifier implies knowing whether a parameter is a monitor.
 Since \CFA relies heavily on traits as an abstraction mechanism, the distinction between a type that is a monitor and a type that looks like a monitor can become blurred.
 …
 To make the issue tractable, \CFA only acquires one monitor per parameter with at most one level of indirection.
 However, there is an ambiguity in the C type-system with respects to arrays.
+However, the C type-system has an ambiguity with respects to arrays.
 Is the argument for @f2@ a single object or an array of objects?
 If it is an array, only the first element of the array is acquired, which seems unsafe;
 …
 For object-oriented monitors, calling a mutex member \emph{implicitly} acquires mutual exclusion of the receiver object, @`rec`.foo(...)@.
 \CFA has no receiver, and hence, must use an explicit mechanism to specify which object acquires mutual exclusion.
+\CFA has no receiver, and hence, must use an explicit mechanism to specify which object has mutual exclusion acquired.
 A positive consequence of this design decision is the ability to support multi-monitor routines.
 \begin{cfa}
 …
 Having language support for such a feature is therefore a significant asset for \CFA.
 The capability to acquire multiple locks before entering a critical section is called \newterm{bulk acquire} (see Section~\ref{s:Implementation} for implementation details).
+The capability to acquire multiple locks before entering a critical section is called \newterm{bulk acquire}.
 In the previous example, \CFA guarantees the order of acquisition is consistent across calls to different routines using the same monitors as arguments.
 This consistent ordering means acquiring multiple monitors is safe from deadlock.
 …
 However, such use leads to lock acquiring order problems resulting in deadlock~\cite{Lister77}, where detecting it requires dynamic tracking of monitor calls, and dealing with it requires rollback semantics~\cite{Dice10}.
 In \CFA, a safety aid is provided by using bulk acquire of all monitors to shared objects, whereas other monitor systems provide no aid.
 While \CFA provides only a partial solution, it handles many useful cases, \eg:
 \begin{cfa}
 monitor BankAccount { ... };
 void deposit( BankAccount & `mutex` b, int deposit );
 void transfer( BankAccount & `mutex` my, BankAccount & `mutex` your, int me2you ) {
         deposit( my, `-`me2you );                               $\C{// debit}$
         deposit( your, me2you );                                $\C{// credit}$
+In \CFA, safety is guaranteed by using bulk acquire of all monitors to shared objects, whereas other monitor systems provide no aid.
+While \CFA provides only a partial solution, the \CFA partial solution handles many useful cases.
+\begin{cfa}
+monitor Bank { ... };
+void deposit( Bank & `mutex` b, int deposit );
+void transfer( Bank & `mutex` mybank, Bank & `mutex` yourbank, int me2you) {
+        deposit( mybank, `-`me2you );                   $\C{// debit}$
+        deposit( yourbank, me2you );                    $\C{// credit}$
+}
 \end{cfa}
 …
+\subsection{\protect\lstinline@mutex@ statement}
+\label{mutex-stmt}
+\subsection{\protect\lstinline|mutex| statement} \label{mutex-stmt}
 The monitor call-semantics associate all locking semantics to routines.
 …
 \begin{tabular}{@{}l@{\hspace{3\parindentlnth}}l@{}}
 \begin{cfa}
 monitor M { ... };
+monitor M {};
 void foo( M & mutex m1, M & mutex m2 ) {
         // critical section
 …
 For example, Figure~\ref{f:GenericBoundedBuffer} shows a bounded buffer that may be full/empty so produce/consumer threads must block.
 Leaving the monitor and trying again (busy waiting) is impractical for high-level programming.
 Monitors eliminate busy waiting by providing synchronization to schedule threads needing access to the shared data, where threads block versus spinning.
+Monitors eliminate busy waiting by providing internal synchronization to schedule threads needing access to the shared data, where the synchronization is blocking (threads are parked) versus spinning.
 Synchronization is generally achieved with internal~\cite{Hoare74} or external~\cite[\S~2.9.2]{uC++} scheduling, where \newterm{scheduling} defines which thread acquires the critical section next.
 \newterm{Internal scheduling} is characterized by each thread entering the monitor and making an individual decision about proceeding or blocking, while \newterm{external scheduling} is characterized by an entering thread making a decision about proceeding for itself and on behalf of other threads attempting entry.
 …
 \end{figure}
 Figure~\ref{f:BBExt} shows a \CFA generic bounded-buffer with external scheduling, where producers/consumers detecting a full/empty buffer block and prevent more producers/consumers from entering the monitor until there is a free/empty slot in the buffer.
+Figure~\ref{f:BBExt} shows a \CFA generic bounded-buffer with external scheduling, where producers/consumers detecting a full/empty buffer block and prevent more producers/consumers from entering the monitor until the buffer has a free/empty slot.
 External scheduling is controlled by the @waitfor@ statement, which atomically blocks the calling thread, releases the monitor lock, and restricts the routine calls that can next acquire mutual exclusion.
 If the buffer is full, only calls to @remove@ can acquire the buffer, and if the buffer is empty, only calls to @insert@ can acquire the buffer.
+Threads making calls to routines that are currently excluded, block outside of (external to) the monitor on a calling queue, versus blocking on condition queues inside of (internal to) the monitor.
+Threads making calls to routines that are currently excluded, block outside (external) of the monitor on a calling queue, versus blocking on condition queues inside (internal) of the monitor.
+% External scheduling is more constrained and explicit, which helps programmers reduce the non-deterministic nature of concurrency.
 External scheduling allows users to wait for events from other threads without concern of unrelated events occurring.
 The mechnaism can be done in terms of control flow, \eg Ada @accept@ or \uC @_Accept@, or in terms of data, \eg Go channels.
 …
 A thread blocks until an appropriate partner arrives.
 The complexity is exchanging phone numbers in the monitor because of the mutual-exclusion property.
 For signal scheduling, the @exchange@ condition is necessary to block the thread finding the match, while the matcher unblocks to take the opposite number, post its phone number, and unblock the partner.
+For signal scheduling, the @exchange@ condition is necessary to block the thread finding the match, while the matcher unblocks to take the oppose number, post its phone number, and unblock the partner.
 For signal-block scheduling, the implicit urgent-queue replaces the explict @exchange@-condition and @signal_block@ puts the finding thread on the urgent condition and unblocks the matcher.
 …
                 wait( Girls[ccode] );
                 GirlPhNo = phNo;
                 `signal( exchange );`
+                `exchange.signal();`
         } else {
                 GirlPhNo = phNo;
                 `signal( Boys[ccode] );`
                 `wait( exchange );`
+                `exchange.wait();`
         } // if
         return BoyPhNo;
 …
+}
 \end{cfa}
 must have acquired at least the same locks as the waiting thread signalled from the condition queue.
+must have acquired monitor locks that are greater than or equal to the number of locks for the waiting thread signalled from the condition queue.
 Similarly, for @waitfor( rtn )@, the default semantics is to atomically block the acceptor and release all acquired mutex types in the parameter list, \ie @waitfor( rtn, m1, m2 )@.
 …
 @waitfor@ statically verifies the released monitors are the same as the acquired mutex-parameters of the given routine or routine pointer.
 To statically verify the released monitors match with the accepted routine's mutex parameters, the routine (pointer) prototype must be accessible.
+% When an overloaded routine appears in an @waitfor@ statement, calls to any routine with that name are accepted.
+% The rationale is that members with the same name should perform a similar function, and therefore, all should be eligible to accept a call.
+Overloaded routines can be disambiguated using a cast:
+When an overloaded routine appears in an @waitfor@ statement, calls to any routine with that name are accepted.
+The rationale is that members with the same name should perform a similar function, and therefore, all should be eligible to accept a call.
+As always, overloaded routines can be disambiguated using a cast:
 \begin{cfa}
 void rtn( M & mutex m );
 `int` rtn( M & mutex m );
 waitfor( (`int` (*)( M & mutex ))rtn, m );
 \end{cfa}
 The ability to release a subset of acquired monitors can result in a \newterm{nested monitor}~\cite{Lister77} deadlock.
+waitfor( (`int` (*)( M & mutex ))rtn, m1, m2 );
+\end{cfa}
+Given the ability to release a subset of acquired monitors can result in a \newterm{nested monitor}~\cite{Lister77} deadlock.
 \begin{cfa}
 void foo( M & mutex m1, M & mutex m2 ) {
 …
 Finally, an important aspect of monitor implementation is barging, \ie can calling threads barge ahead of signalled threads?
+If barging is allowed, synchronization between a signaller and signallee is difficult, often requiring multiple unblock/block cycles (looping around a wait rechecking if a condition is met).
+In fact, signals-as-hints is completely opposite from that proposed by Hoare in the seminal paper on monitors:
+If barging is allowed, synchronization between a singller and signallee is difficult, often requiring multiple unblock/block cycles (looping around a wait rechecking if a condition is met).
 \begin{quote}
 However, we decree that a signal operation be followed immediately by resumption of a waiting program, without possibility of an intervening procedure call from yet a third program.
 …
 \end{quote}
 \CFA scheduling \emph{precludes} barging, which simplifies synchronization among threads in the monitor and increases correctness.
-Furthermore, \CFA concurrency has no spurious wakeup~\cite[\S~9]{Buhr05a}, which eliminates an implict form of barging.
 For example, there are no loops in either bounded buffer solution in Figure~\ref{f:GenericBoundedBuffer}.
 Supporting barging prevention as well as extending internal scheduling to multiple monitors is the main source of complexity in the design and implementation of \CFA concurrency.
+Furthermore, \CFA concurrency has no superious wakeup~\cite[\S~9]{Buhr05a}, which eliminates an implict form of barging.
 …
 One scheduling solution is for the signaller to keep ownership of all locks until the last lock is ready to be transferred, because this semantics fits most closely to the behaviour of single-monitor scheduling.
 However, Figure~\ref{f:OtherWaitingThread} shows this solution is complex depending on other waiters, resulting in options when the signaller finishes the inner mutex-statement.
 The signaller can retain @m2@ until completion of the outer mutex statement and pass the locks to waiter W1, or it can pass @m2@ to waiter W2 after completing the inner mutex-statement, while continuing to hold @m1@.
+However, Figure~\ref{f:OtherWaitingThread} shows this solution is complex depending on other waiters, resulting is choices when the signaller finishes the inner mutex-statement.
+The singaller can retain @m2@ until completion of the outer mutex statement and pass the locks to waiter W1, or it can pass @m2@ to waiter W2 after completing the inner mutex-statement, while continuing to hold @m1@.
 In the latter case, waiter W2 must eventually pass @m2@ to waiter W1, which is complex because W1 may have waited before W2, so W2 is unaware of it.
 Furthermore, there is an execution sequence where the signaller always finds waiter W2, and hence, waiter W1 starves.
 …
 Signalled threads are moved to the urgent queue and the waiter at the front defines the set of monitors necessary for it to unblock.
 Partial signalling transfers ownership of monitors to the front waiter.
 When the signaller thread exits or waits in the monitor, the front waiter is unblocked if all its monitors are released.
 The benefit is encapsulating complexity into only two actions: passing monitors to the next owner when they should be released and conditionally waking threads if all conditions are met.
+When the signaller thread exits or waits in the monitor the front waiter is unblocked if all its monitors are released.
+This solution has the benefit that complexity is encapsulated into only two actions: passing monitors to the next owner when they should be released and conditionally waking threads if all conditions are met.
 …
 In an object-oriented programming-language, a class includes an exhaustive list of operations.
 However, new members can be added via static inheritance or dynamic members, \eg JavaScript~\cite{JavaScript}.
+However, new members can be added via static inheritance or dynaic members, \eg JavaScript~\cite{JavaScript}.
 Similarly, monitor routines can be added at any time in \CFA, making it less clear for programmers and more difficult to implement.
 \begin{cfa}
 monitor M { ... };
+monitor M {};
 void `f`( M & mutex m );
 void g( M & mutex m ) { waitfor( `f` ); }       $\C{// clear which f}$
 …
 void h( M & mutex m ) { waitfor( `f` ); }       $\C{// unclear which f}$
 \end{cfa}
 Hence, the cfa-code for entering a monitor looks like:
+Hence, the cfa-code for the entering a monitor looks like:
 \begin{cfa}
 if ( $\textrm{\textit{monitor is free}}$ ) $\LstCommentStyle{// \color{red}enter}$
 …
 External scheduling, like internal scheduling, becomes significantly more complex for multi-monitor semantics.
 Even in the simplest case, new semantics needs to be established.
+\newpage
+\begin{cfa}
+monitor M { ... };
+\begin{cfa}
+monitor M {};
 void f( M & mutex m1 );
 void g( M & mutex m1, M & mutex m2 ) {
 …
         waitfor( f, m2 );                                               $\C{\color{red}// wait for call to f with argument m2}$
 \end{cfa}
 Both locks are acquired by routine @g@, so when routine @f@ is called, the lock for monitor @m2@ is passed from @g@ to @f@, while @g@ still holds lock @m1@.
+Routine @g@ has acquired both locks, so when routine @f@ is called, the lock for monitor @m2@ is passed from @g@ to @f@, while @g@ still holds lock @m1@.
 This behaviour can be extended to the multi-monitor @waitfor@ statement.
 \begin{cfa}
 monitor M { ... };
+monitor M {};
 void f( M & mutex m1, M & mutex m2 );
 void g( M & mutex m1, M & mutex m2 ) {
 …
 \end{cfa}
 Again, the set of monitors passed to the @waitfor@ statement must be entirely contained in the set of monitors already acquired by the accepting routine.
+Also, the order of the monitors in a @waitfor@ statement is unimportant.
+Figure~\ref{f:UnmatchedMutexSets} shows an example where, for internal and external scheduling with multiple monitors, a signalling or accepting thread must match exactly, \ie partial matching results in waiting.
+For both examples, the set of monitors is disjoint so unblocking is impossible.
+\begin{figure}
+Note, for internal and external scheduling with multiple monitors, a signalling or accepting thread must match exactly, \ie partial matching results in waiting.
+\begin{cquote}
 \lstDeleteShortInline@%
 \begin{tabular}{@{}l@{\hspace{\parindentlnth}}|@{\hspace{\parindentlnth}}l@{}}
 …
         wait( c );
+}
 g( `m11`, m2 ); // block on wait
+g( `m11`, m2 ); // block on accept
 f( `m12`, m2 ); // cannot fulfil
 \end{cfa}
 …
 \end{tabular}
 \lstMakeShortInline@%
+\caption{Unmatched \protect\lstinline@mutex@ sets}
+\label{f:UnmatchedMutexSets}
+\end{figure}
+\end{cquote}
+For both internal and external scheduling, the set of monitors is disjoint so unblocking is impossible.
 \subsection{Extended \protect\lstinline@waitfor@}
+Figure~\ref{f:ExtendedWaitfor} show the extended form of the @waitfor@ statement to conditionally accept one of a group of mutex routines, with a specific action to be performed \emph{after} the mutex routine finishes.
+For a @waitfor@ clause to be executed, its @when@ must be true and an outstanding call to its corresponding member(s) must exist.
+The \emph{conditional-expression} of a @when@ may call a routine, but the routine must not block or context switch.
+If there are multiple acceptable mutex calls, selection occurs top-to-bottom (prioritized) in the @waitfor@ clauses, whereas some programming languages with similar mechanisms accept non-deterministically for this case, \eg Go \lstinline[morekeywords=select]@select@.
+If some accept guards are true and there are no outstanding calls to these members, the acceptor is accept-blocked until a call to one of these members is made.
+If all the accept guards are false, the statement does nothing, unless there is a terminating @else@ clause with a true guard, which is executed instead.
+Hence, the terminating @else@ clause allows a conditional attempt to accept a call without blocking.
+If there is a @timeout@ clause, it provides an upper bound on waiting.
+If both a @timeout@ clause and an @else@ clause are present, the @else@ must be conditional, or the @timeout@ is never triggered.
+In all cases, the statement following is executed \emph{after} a clause is executed to know which of the clauses executed.
+\begin{figure}
+The extended form of the @waitfor@ statement conditionally accepts one of a group of mutex routines and allows a specific action to be performed \emph{after} the mutex routine finishes.
 \begin{cfa}
 `when` ( $\emph{conditional-expression}$ )      $\C{// optional guard}$
 …
                 $\emph{statement}$                                      $\C{// action when no immediate calls}$
 \end{cfa}
+\caption{Extended \protect\lstinline@waitfor@}
+\label{f:ExtendedWaitfor}
+\end{figure}
+For a @waitfor@ clause to be executed, its @when@ must be true and an outstanding call to its corresponding member(s) must exist.
+The \emph{conditional-expression} of a @when@ may call a routine, but the routine must not block or context switch.
+If there are several mutex calls that can be accepted, selection occurs top-to-bottom in the @waitfor@ clauses versus non-deterministically.
+If some accept guards are true and there are no outstanding calls to these members, the acceptor is accept-blocked until a call to one of these members is made.
+If all the accept guards are false, the statement does nothing, unless there is a terminating @else@ clause with a true guard, which is executed instead.
+Hence, the terminating @else@ clause allows a conditional attempt to accept a call without blocking.
+If there is a @timeout@ clause, it provides an upper bound on waiting, and can only appear with a conditional @else@, otherwise the timeout cannot be triggered.
+In all cases, the statement following is executed \emph{after} a clause is executed to know which of the clauses executed.
 Note, a group of conditional @waitfor@ clauses is \emph{not} the same as a group of @if@ statements, e.g.:
 …
 \begin{cfa}
 void insert( Buffer(T) & mutex buffer, T elem ) with( buffer ) {
         if ( count == 10 )
+        if ( count == BufferSize )
                 waitfor( remove, buffer ) {
+                        // insert elem into buffer
+                        elements[back] = elem;
+                        back = ( back + 1 ) % BufferSize;
+                        count += 1;
                 } or `waitfor( ^?{}, buffer )` throw insertFail;
+}
 …
 When the buffer is deallocated, the current waiter is unblocked and informed, so it can perform an appropriate action.
 However, the basic @waitfor@ semantics do not support this functionality, since using an object after its destructor is called is undefined.
 Therefore, to make this useful capability work, the semantics for accepting the destructor is the same as @signal@, \ie the call to the destructor is placed on the urgent queue and the acceptor continues execution, which throws an exception to the acceptor and then the caller is unblocked from the urgent queue to deallocate the object.
+Therefore, to make this useful capability work, the semantics for accepting the destructor is the same as @signal@, \ie the call to the destructor is placed on the urgent queue and the acceptor continues execution, which throws an exception to the acceptor and then the caller is unbloced from the urgent queue to deallocate the object.
 Accepting the destructor is an idiomatic way to terminate a thread in \CFA.
 …
 Threads in \CFA are monitors to allow direct communication among threads, \ie threads can have mutex routines that are called by other threads.
 Hence, all monitor features are available when using threads.
+The following shows an example of two threads directly calling each other and accepting calls from each other in a cycle.
+Figure~\ref{f:pingpong} shows an example of two threads directly calling each other and accepting calls from each other in a cycle.
+Note, both ping/pong threads are globally declared, @pi@/@po@, and hence, start (and possibly complete) before the program main starts.
+\begin{figure}
+\lstDeleteShortInline@%
+\begin{cquote}
 \begin{cfa}
 thread Ping {} pi;
 …
 int main() {}
 \end{cfa}
-\vspace{-0.8\baselineskip}
-\begin{cquote}
 \begin{tabular}{@{}l@{\hspace{3\parindentlnth}}l@{}}
 \begin{cfa}
 …
 \end{cfa}
 \end{tabular}
+\lstMakeShortInline@%
 \end{cquote}
+% \lstMakeShortInline@%
+% \caption{Threads ping/pong using external scheduling}
+% \label{f:pingpong}
+% \end{figure}
+Note, the ping/pong threads are globally declared, @pi@/@po@, and hence, start (and possibly complete) before the program main starts.
+\subsection{Low-level Locks}
+For completeness and efficiency, \CFA provides a standard set of low-level locks: recursive mutex, condition, semaphore, barrier, \etc, and atomic instructions: @fetchAssign@, @fetchAdd@, @testSet@, @compareSet@, \etc.
+\caption{Threads ping/pong using external scheduling}
+\label{f:pingpong}
+\end{figure}
 \section{Parallelism}
 Historically, computer performance was about processor speeds.
 However, with heat dissipation being a direct consequence of speed increase, parallelism is the new source for increased performance~\cite{Sutter05, Sutter05b}.
+However, with heat dissipation being a direct consequence of speed increase, parallelism has become the new source for increased performance~\cite{Sutter05, Sutter05b}.
 Now, high-performance applications must care about parallelism, which requires concurrency.
 The lowest-level approach of parallelism is to use \newterm{kernel threads} in combination with semantics like @fork@, @join@, \etc.
 …
 \label{s:fibers}
 A variant of user thread is \newterm{fibers}, which removes preemption, \eg Go~\cite{Go} @goroutine@s.
 Like functional programming, which removes mutation and its associated problems, removing preemption from concurrency reduces nondeterminism, making race and deadlock errors more difficult to generate.
+A variant of user thread is \newterm{fibers}, which removes preemption, \eg Go~\cite{Go}.
+Like functional programming, which removes mutation and its associated problems, removing preemption from concurrency reduces nondeterminism, hence race and deadlock errors are more difficult to generate.
 However, preemption is necessary for concurrency that relies on spinning, so there are a class of problems that cannot be programmed without preemption.
 …
 \subsection{Thread Pools}
 In contrast to direct threading is indirect \newterm{thread pools}, where small jobs (work units) are inserted into a work pool for execution.
+In contrast to direct threading is indirect \newterm{thread pools}, where small jobs (work units) are insert into a work pool for execution.
 If the jobs are dependent, \ie interact, there is an implicit/explicit dependency graph that ties them together.
 While removing direct concurrency, and hence the amount of context switching, thread pools significantly limit the interaction that can occur among jobs.
 Indeed, jobs should not block because that also blocks the underlying thread, which effectively means the CPU utilization, and therefore throughput, suffers.
+Indeed, jobs should not block because that also block the underlying thread, which effectively means the CPU utilization, and therefore throughput, suffers.
 While it is possible to tune the thread pool with sufficient threads, it becomes difficult to obtain high throughput and good core utilization as job interaction increases.
 As well, concurrency errors return, which threads pools are suppose to mitigate.
+Intel's TBB library~\cite{TBB} is the gold standard for thread pools.
 …
 The user cluster is created to contain the application user-threads.
 Having all threads execute on the one cluster often maximizes utilization of processors, which minimizes runtime.
 However, because of limitations of the underlying operating system, heterogeneous hardware, or scheduling requirements (real-time), multiple clusters are sometimes necessary.
+However, because of limitations of the underlying operating system, heterogeneous hardware, or scheduling requirements (real-time), it is sometimes necessary to have multiple clusters.
 …
 \section{Implementation}
-\label{s:Implementation}
 Currently, \CFA has fixed-sized stacks, where the stack size can be set at coroutine/thread creation but with no subsequent growth.
 Schemes exist for dynamic stack-growth, such as stack copying and chained stacks.
 However, stack copying requires pointer adjustment to items on the stack, which is impossible without some form of garbage collection.
+However, stack copying requires pointer adjustment to items on the stack, which is impossible without some form of garage collection.
 As well, chained stacks require all modules be recompiled to use this feature, which breaks backward compatibility with existing C libraries.
 In the long term, it is likely C libraries will migrate to stack chaining to support concurrency, at only a minimal cost to sequential programs.
 …
 This storage is allocated at the base of a thread's stack before blocking, which means programmers must add a small amount of extra space for stacks.
 In \CFA, ordering of monitor acquisition relies on memory ordering to prevent deadlock~\cite{Havender68}, because all objects have distinct non-overlapping memory layouts, and mutual-exclusion for a monitor is only defined for its lifetime.
+In \CFA, ordering of monitor acquisition relies on memory ordering to prevent deadlock~\cite{Havender68}, because all objects are guaranteed to have distinct non-overlapping memory layouts, and mutual-exclusion for a monitor is only defined for its lifetime.
 When a mutex call is made, pointers to the concerned monitors are aggregated into a variable-length array and sorted.
 This array persists for the entire duration of the mutual exclusion and is used extensively for synchronization operations.
 To improve performance and simplicity, context switching occurs inside a routine call, so only callee-saved registers are copied onto the stack and then the stack register is switched;
+This array persists for the entire duration of the mutual-exclusion and its ordering reused extensively.
+To improve performance and simplicity, context switching occur inside a routine call, so only callee-saved registers are copied onto the stack and then the stack register is switched;
 the corresponding registers are then restored for the other context.
 Note, the instruction pointer is untouched since the context switch is always inside the same routine.
 …
 This method is a 2-step context-switch and provides a clear distinction between user and kernel code, where scheduling and other system operations happen.
 The alternative 1-step context-switch uses the \emph{from} thread's stack to schedule and then context-switches directly to the \emph{to} thread's stack.
 Experimental results (not presented) show the performance of these two approaches is virtually equivalent, because both approaches are dominated by locking to prevent a race condition.
+Experimental results (not presented) show the performance difference between these two approaches is virtually equivalent, because the 1-step performance is dominated by a lock instruction to prevent a race condition.
 All kernel threads (@pthreads@) created a stack.
 …
 Finally, an important aspect for a complete threading system is preemption, which introduces extra non-determinism via transparent interleaving, rather than cooperation among threads for proper scheduling and processor fairness from long-running threads.
 Because preemption frequency is usually long (1 millisecond) performance cost is negligible.
+Because preemption frequency is usually long, 1 millisecond, performance cost is negligible.
 Preemption is normally handled by setting a count-down timer on each virtual processor.
 When the timer expires, an interrupt is delivered, and the interrupt handler resets the count-down timer, and if the virtual processor is executing in user code, the signal handler performs a user-level context-switch, or if executing in the language runtime-kernel, the preemption is ignored or rolled forward to the point where the runtime kernel context switches back to user code.
 Multiple signal handlers may be pending.
 When control eventually switches back to the signal handler, it returns normally, and execution continues in the interrupted user thread, even though the return from the signal handler may be on a different kernel thread than the one where the signal is delivered.
+When control eventually switches back to the signal handler, it returns normally, and execution continues in the interrupted user thread, even though the return from the signal handler may be on a different kernel thread than the one where the signal was delivered.
 The only issue with this approach is that signal masks from one kernel thread may be restored on another as part of returning from the signal handler;
 therefore, the same signal mask is required for all virtual processors in a cluster.
+therefore, all virtual processors in a cluster need to have the same signal mask.
 However, on current UNIX systems:
 …
 \end{cfa}
 The method used to get time is @clock_gettime( CLOCK_REALTIME )@.
+Each benchmark is performed @N@ times, where @N@ varies depending on the benchmark;
+the total time is divided by @N@ to obtain the average time for a benchmark.
+Each benchmark is performed @N@ times, where @N@ varies depending on the benchmark, the total time is divided by @N@ to obtain the average time for a benchmark.
 All omitted tests for other languages are functionally identical to the shown \CFA test.
 …
 \multicolumn{1}{c|}{} & \multicolumn{1}{c|}{Median} &\multicolumn{1}{c|}{Average} & \multicolumn{1}{c|}{Std Dev} \\
 \hline
 Kernel Thread   & 333.5 & 332.96        & 4.1 \\
 \CFA Coroutine  & 49            & 48.68 & 0.47    \\
 \CFA Thread             & 105           & 105.57        & 1.37 \\
 \uC Coroutine   & 44            & 44            & 0 \\
 \uC Thread              & 100           & 99.29 & 0.96 \\
 Goroutine               & 145           & 147.25        & 4.15 \\
 Java Thread             & 373.5 & 375.14        & 8.72 \\
+Kernel Thread   & 241.5         & 243.86        & 5.08 \\
+\CFA Coroutine  & 38            & 38            & 0    \\
+\CFA Thread             & 103           & 102.96        & 2.96 \\
+\uC Coroutine   & 46            & 45.86         & 0.35 \\
+\uC Thread              & 98            & 99.11         & 1.42 \\
+Goroutine               & 150           & 149.96        & 3.16 \\
+Java Thread             & 289           & 290.68        & 8.72 \\
 \hline
 \end{tabular}
 …
 \lstset{language=CFA,moredelim=**[is][\color{red}]{@}{@},deletedelim=**[is][]{`}{`}}
 \begin{cfa}
 monitor M { ... } m1/*, m2, m3, m4*/;
+monitor M {} m1/*, m2, m3, m4*/;
 void __attribute__((noinline)) do_call( M & mutex m/*, m2, m3, m4*/ ) {}
 int main() {
 …
 \multicolumn{1}{c|}{} & \multicolumn{1}{c|}{Median} &\multicolumn{1}{c|}{Average} & \multicolumn{1}{c|}{Std Dev} \\
 \hline
 C routine                                       & 2             & 2             & 0    \\
 FetchAdd + FetchSub                     & 26            & 26            & 0    \\
 Pthreads Mutex Lock                     & 31            & 31.71 & 0.97 \\
 \uC @monitor@ member routine            & 31            & 31            & 0    \\
 \CFA @mutex@ routine, 1 argument        & 46            & 46.68 & 0.93  \\
 \CFA @mutex@ routine, 2 argument        & 84            & 85.36 & 1.99 \\
 \CFA @mutex@ routine, 4 argument        & 158           & 161           & 4.22 \\
 Java synchronized routine               & 27.5  & 29.79 & 2.93  \\
+C routine                                                       & 2                     & 2                     & 0    \\
+FetchAdd + FetchSub                                     & 26            & 26            & 0    \\
+Pthreads Mutex Lock                                     & 31            & 31.86         & 0.99 \\
+\uC @monitor@ member routine            & 30            & 30            & 0    \\
+\CFA @mutex@ routine, 1 argument        & 41            & 41.57         & 0.9  \\
+\CFA @mutex@ routine, 2 argument        & 76            & 76.96         & 1.57 \\
+\CFA @mutex@ routine, 4 argument        & 145           & 146.68        & 3.85 \\
+Java synchronized routine                       & 27            & 28.57         & 2.6  \\
 \hline
 \end{tabular}
 …
 Figure~\ref{f:int-sched} shows the code for \CFA, with results in Table~\ref{tab:int-sched}.
 Note, the incremental cost of bulk acquire for \CFA, which is largely a fixed cost for small numbers of mutex objects.
-Java scheduling is significantly greater because the benchmark explicitly creates multiple thread in order to prevent the JIT from making the program sequential, \ie removing all locking.
 \begin{figure}
 …
 volatile int go = 0;
 condition c;
 monitor M { ... } m;
+monitor M {} m;
 void __attribute__((noinline)) do_call( M & mutex a1 ) { signal( c ); }
 thread T {};
 …
+}
 \end{cfa}
 \captionof{figure}{\CFA Internal-scheduling benchmark}
+\captionof{figure}{\CFA Internal scheduling benchmark}
 \label{f:int-sched}
 \centering
 \captionof{table}{Internal-scheduling comparison (nanoseconds)}
+\captionof{table}{Internal scheduling comparison (nanoseconds)}
 \label{tab:int-sched}
 \bigskip
 …
 \multicolumn{1}{c|}{} & \multicolumn{1}{c|}{Median} &\multicolumn{1}{c|}{Average} & \multicolumn{1}{c|}{Std Dev} \\
 \hline
 Pthreads Condition Variable             & 6005  & 5681.43       & 835.45 \\
 \uC @signal@                                    & 324           & 325.54        & 3,02   \\
 \CFA @signal@, 1 @monitor@              & 368.5         & 370.61        & 4.77   \\
 \CFA @signal@, 2 @monitor@              & 467           & 470.5 & 6.79   \\
 \CFA @signal@, 4 @monitor@              & 700.5         & 702.46        & 7.23  \\
 Java @notify@                                   & 15471 & 172511        & 5689 \\
+Pthreads Condition Variable             & 5902.5        & 6093.29       & 714.78 \\
+\uC @signal@                                    & 322           & 323           & 3.36   \\
+\CFA @signal@, 1 @monitor@              & 352.5         & 353.11        & 3.66   \\
+\CFA @signal@, 2 @monitor@              & 430           & 430.29        & 8.97   \\
+\CFA @signal@, 4 @monitor@              & 594.5         & 606.57        & 18.33  \\
+Java @notify@                                   & 13831.5       & 15698.21      & 4782.3 \\
 \hline
 \end{tabular}
 …
 \begin{cfa}
 volatile int go = 0;
 monitor M { ... } m;
+monitor M {} m;
 thread T {};
 void __attribute__((noinline)) do_call( M & mutex ) {}
 …
+}
 \end{cfa}
 \captionof{figure}{\CFA external-scheduling benchmark}
+\captionof{figure}{\CFA external scheduling benchmark}
 \label{f:ext-sched}
 \centering
 \captionof{table}{External-scheduling comparison (nanoseconds)}
+\captionof{table}{External scheduling comparison (nanoseconds)}
 \label{tab:ext-sched}
 \bigskip
 …
 \multicolumn{1}{c|}{} & \multicolumn{1}{c|}{Median} &\multicolumn{1}{c|}{Average} & \multicolumn{1}{c|}{Std Dev} \\
 \hline
 \uC @_Accept@                           & 358           & 359.11        & 2.53  \\
 \CFA @waitfor@, 1 @monitor@     & 359           & 360.93        & 4.07  \\
 \CFA @waitfor@, 2 @monitor@     & 450           & 449.39        & 6.62  \\
 \CFA @waitfor@, 4 @monitor@     & 652           & 655.64        & 7.73 \\
+\uC @_Accept@                           & 350           & 350.61        & 3.11  \\
+\CFA @waitfor@, 1 @monitor@     & 358.5         & 358.36        & 3.82  \\
+\CFA @waitfor@, 2 @monitor@     & 422           & 426.79        & 7.95  \\
+\CFA @waitfor@, 4 @monitor@     & 579.5         & 585.46        & 11.25 \\
 \hline
 \end{tabular}
 …
+}
 \end{cfa}
 \captionof{figure}{\CFA object-creation benchmark}
+\captionof{figure}{\CFA object creation benchmark}
 \label{f:creation}
 …
 \multicolumn{1}{c|}{} & \multicolumn{1}{c|}{Median} & \multicolumn{1}{c|}{Average} & \multicolumn{1}{c|}{Std Dev} \\
 \hline
 Pthreads                                & 28091         & 28073.39      & 163.1  \\
 \CFA Coroutine Lazy             & 6                     & 6.07          & 0.26   \\
 \CFA Coroutine Eager    & 520           & 520.61        & 2.04   \\
 \CFA Thread                             & 2032  & 2016.29       & 112.07  \\
 \uC Coroutine                   & 106           & 107.36        & 1.47   \\
 \uC Thread                              & 536.5 & 537.07        & 4.64   \\
 Goroutine                               & 3103  & 3086.29       & 90.25  \\
 Java Thread                             & 103416.5      & 103732.29     & 1137 \\
+Pthreads                                & 26996         & 26984.71      & 156.6  \\
+\CFA Coroutine Lazy             & 6                     & 5.71          & 0.45   \\
+\CFA Coroutine Eager    & 708           & 706.68        & 4.82   \\
+\CFA Thread                             & 1173.5        & 1176.18       & 15.18  \\
+\uC Coroutine                   & 109           & 107.46        & 1.74   \\
+\uC Thread                              & 526           & 530.89        & 9.73   \\
+Goroutine                               & 2520.5        & 2530.93       & 61.56  \\
+Java Thread                             & 91114.5       & 92272.79      & 961.58 \\
 \hline
 \end{tabular}
 …
 \section{Conclusion}
 This paper demonstrates a concurrency API that is simple, efficient, and able to build higher-level concurrency features.
+This paper demonstrate a concurrency API that is simple, efficient, and able to build higher-level concurrency features.
 The approach provides concurrency based on a preemptive M:N user-level threading-system, executing in clusters, which encapsulate scheduling of work on multiple kernel threads providing parallelism.
 The M:N model is judged to be efficient and provide greater flexibility than a 1:1 threading model.
 …
 However, no single scheduler is optimal for all workloads and therefore there is value in being able to change the scheduler for given programs.
 One solution is to offer various tweaking options, allowing the scheduler to be adjusted to the requirements of the workload.
 However, to be truly flexible, a pluggable scheduler is necessary.
+However, to be truly flexible, it is necessary to have a pluggable scheduler.
 Currently, the \CFA pluggable scheduler is too simple to handle complex scheduling, \eg quality of service and real-time, where the scheduler must interact with mutex objects to deal with issues like priority inversion.
 …
 At its core, non-blocking I/O is an operating-system level feature queuing IO operations, \eg network operations, and registering for notifications instead of waiting for requests to complete.
 Current trends use asynchronous programming like callbacks, futures, and/or promises, \eg Node.js~\cite{NodeJs} for JavaScript, Spring MVC~\cite{SpringMVC} for Java, and Django~\cite{Django} for Python.
 However, these solutions lead to code that is hard to create, read and maintain.
+However, these solutions lead to code that is hard create, read and maintain.
 A better approach is to tie non-blocking I/O into the concurrency system to provide ease of use with low overhead, \eg thread-per-connection web-services.
 A non-blocking I/O library is currently under development for \CFA.
 …
 \label{futur:tools}
 While monitors offer flexible and powerful concurrency for \CFA, other concurrency tools are also necessary for a complete multi-paradigm concurrency package.
+While monitors offer a flexible and powerful concurrent for \CFA, other concurrency tools are also necessary for a complete multi-paradigm concurrency package.
 Examples of such tools can include futures and promises~\cite{promises}, executors and actors.
 These additional features are useful when monitors offer a level of abstraction that is inadequate for certain tasks.
-As well, new \CFA extensions should make it possible to create a uniform interface for virtually all mutual exclusion, including monitors and low-level locks.
 \paragraph{Implicit Threading}
 …
 The canonical example of implicit concurrency is concurrent nested @for@ loops, which are amenable to divide and conquer algorithms~\cite{uC++book}.
 The \CFA language features should make it possible to develop a reasonable number of implicit concurrency mechanism to solve basic HPC data-concurrency problems.
 However, implicit concurrency is a restrictive solution with significant limitations, so it can never replace explicit concurrent programming.
+However, implicit concurrency is a restrictive solution and has its limitations, so it can never replace explicit concurrent programming.

doc/papers/concurrency/figures/ext_monitor.fig

-              re3b2474
+              rc653b37
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 1 -1 0 0 0 12 0.0000 2 135 735 3525 3975 variables\001
 0 4 50 -1 0 11 0.0000 2 120 135 4150 1875 X\001
 0 4 50 -1 0 11 0.0000 2 120 135 4150 2175 Y\001
 0 4 50 -1 0 11 0.0000 2 120 135 4150 2475 Y\001
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+0 4 50 -1 0 11 0.0000 2 120 135 4150 1875 Y\001
+0 4 50 -1 0 11 0.0000 2 120 105 4150 2175 Z\001
+0 4 50 -1 0 11 0.0000 2 120 135 4150 2475 X\001
+0 4 50 -1 0 11 0.0000 2 120 165 4150 2775 W\001
 0 -1 0 0 3 12 0.0000 2 150 540 5025 4275 urgent\001
 1 0 50 -1 0 11 0.0000 2 165 600 3150 3150 accepted\001

src/Parser/LinkageSpec.h

-              re3b2474
+              rc653b37
 // Created On       : Sat May 16 13:24:28 2015
 // Last Modified By : Peter A. Buhr
 // Last Modified On : Mon Jul  2 07:46:49 2018
 // Update Count     : 16
+// Last Modified On : Sat Jul 22 09:32:16 2017
+// Update Count     : 14
 //
 …
 namespace LinkageSpec {
         // All linkage specs are some combination of these flags:
+        enum { Mangle = 1 << 0, Generate = 1 << 1, Overrideable = 1 << 2, Builtin = 1 << 3, GccBuiltin = 1 << 4, NoOfSpecs = 1 << 5, };
+        enum {
+                Mangle = 1 << 0,
+                Generate = 1 << 1,
+                Overrideable = 1 << 2,
+                Builtin = 1 << 3,
+                GccBuiltin = 1 << 4,
+                NoOfSpecs = 1 << 5,
+        };
         union Spec {
 …
                 };
                 constexpr Spec( unsigned int val ) : val( val ) {}
                 constexpr Spec( Spec const & other ) : val( other.val ) {}
+                constexpr Spec( Spec const &other ) : val( other.val ) {}
                 // Operators may go here.
                 // Supports == and !=
                 constexpr operator unsigned int() const { return val; }
+                constexpr operator unsigned int () const { return val; }
         };

src/Parser/parser.yy

-              re3b2474
+              rc653b37
 // Created On       : Sat Sep  1 20:22:55 2001
 // Last Modified By : Peter A. Buhr
 // Last Modified On : Mon Jul  2 20:23:14 2018
 // Update Count     : 3607
+// Last Modified On : Sun Jun 24 10:41:10 2018
+// Update Count     : 3587
 //
 …
         for ( DeclarationNode *iter = declaration; iter != nullptr; iter = (DeclarationNode *)iter->get_next() ) {
                 iter->set_extension( true );
-        } // for
-} // distExt
-void distQual( DeclarationNode * declaration, DeclarationNode * qualifiers ) {
-        // distribute qualifiers across all declarations in a distribution statemement
-        for ( DeclarationNode * iter = declaration; iter != nullptr; iter = (DeclarationNode *)iter->get_next() ) {
-                if ( isMangled( iter->linkage ) ) {             // ignore extern "C"
-                        iter->addQualifiers( qualifiers->clone() );
-                } // if
         } // for
 } // distExt
 …
 waitfor:
+        WAITFOR '(' cast_expression ')'
+                { $$ = $3; }
+        | WAITFOR '(' cast_expression ',' argument_expression_list ')'
+                { $$ = (ExpressionNode *)$3->set_last( $5 ); }
+        WAITFOR '(' identifier ')'
+                {
+                        $$ = new ExpressionNode( new NameExpr( *$3 ) );
+                        delete $3;
+                }
+        | WAITFOR '(' identifier ',' argument_expression_list ')'
+                {
+                        $$ = new ExpressionNode( new NameExpr( *$3 ) );
+                        $$->set_last( $5 );
+                        delete $3;
+                }
+        ;
 …
                 { $$ = build_waitfor_timeout( nullptr, $3, $1 ); }
                 // "else" must be conditional after timeout or timeout is never triggered (i.e., it is meaningless)
-        | when_clause_opt timeout statement WOR ELSE statement
-                { SemanticError( yylloc, "else clause must be conditional after timeout or timeout never triggered." ); $$ = nullptr; }
         | when_clause_opt timeout statement WOR when_clause ELSE statement
                 { $$ = build_waitfor_timeout( $2, $3, $1, $7, $5 ); }
 …
           '{' up external_definition_list_opt down '}'          // CFA, namespace
+                {
+                        distQual( $5, $1 );
+                        for ( DeclarationNode * iter = $5; iter != nullptr; iter = (DeclarationNode *)iter->get_next() ) {
+                                if ( isMangled( iter->linkage ) ) {             // ignore extern "C"
+                                        iter->addQualifiers( $1->clone() );
+                                } // if
+                        } // for
                         xxx = false;
                         delete $1;
 …
         | declaration_qualifier_list
+                {
                         if ( $1->type && $1->type->qualifiers.val ) { SemanticError( yylloc, "CV qualifiers cannot be distributed; only storage-class and forall qualifiers." ); }
                         if ( $1->type && $1->type->forall ) xxx = forall = true; // remember generic type
+                        if ( $1->type->qualifiers.val ) { SemanticError( yylloc, "CV qualifiers cannot be distributed; only storage-class and forall qualifiers." ); }
+                        if ( $1->type->forall ) xxx = forall = true; // remember generic type
+                }
           '{' up external_definition_list_opt down '}'          // CFA, namespace
+                {
+                        distQual( $5, $1 );
+                        for ( DeclarationNode * iter = $5; iter != nullptr; iter = (DeclarationNode *)iter->get_next() ) {
+                                if ( isMangled( iter->linkage ) ) {             // ignore extern "C"
+                                        iter->addQualifiers( $1->clone() );
+                                } // if
+                        } // for
                         xxx = false;
                         delete $1;
 …
           '{' up external_definition_list_opt down '}'          // CFA, namespace
+                {
+                        distQual( $6, $2 );
+                        distQual( $6, $1 );
+                        for ( DeclarationNode * iter = $6; iter != nullptr; iter = (DeclarationNode *)iter->get_next() ) {
+                                if ( isMangled( iter->linkage ) && isMangled( $2->linkage ) ) { // ignore extern "C"
+                                        iter->addQualifiers( $1->clone() );
+                                        iter->addQualifiers( $2->clone() );
+                                } // if
+                        } // for
                         xxx = false;
                         delete $1;

src/ResolvExpr/Resolver.cc

-              re3b2474
+              rc653b37
                                                         // Make sure we don't widen any existing bindings
                                                         resultEnv.forbidWidening();
                                                         // Find any unbound type variables
                                                         resultEnv.extractOpenVars( openVars );
 …
                                                         auto param_end = function->parameters.end();
                                                         int n_mutex_param = 0;
+                                                        int n_mutex_arg = 0;
                                                         // For every arguments of its set, check if it matches one of the parameter
 …
                                                                         // We ran out of parameters but still have arguments
                                                                         // this function doesn't match
                                                                         SemanticError( function, toString("candidate function not viable: too many mutex arguments, expected ", n_mutex_param, "\n" ));
+                                                                        SemanticError( function, toString("candidate function not viable: too many mutex arguments, expected ", n_mutex_arg, "\n" ));
+                                                                }
                                                                 n_mutex_param++;
+                                                                n_mutex_arg++;
                                                                 // Check if the argument matches the parameter type in the current scope
 …
                                                         // Check if parameters are missing
                                                         if( advance_to_mutex( param, param_end ) ) {
-                                                                do {
-                                                                        n_mutex_param++;
-                                                                        param++;
-                                                                } while( advance_to_mutex( param, param_end ) );
                                                                 // We ran out of arguments but still have parameters left
                                                                 // this function doesn't match
                                                                 SemanticError( function, toString("candidate function not viable: too few mutex arguments, expected ", n_mutex_param, "\n" ));
+                                                                SemanticError( function, toString("candidate function not viable: too few mutex arguments, expected ", n_mutex_arg, "\n" ));
+                                                        }

src/libcfa/clock

-              re3b2474
+              rc653b37
 // Created On       : Thu Apr 12 14:36:06 2018
 // Last Modified By : Peter A. Buhr
 // Last Modified On : Mon Jul  2 21:40:01 2018
 // Update Count     : 7
+// Last Modified On : Thu Apr 12 16:53:31 2018
+// Update Count     : 3
 //
 …
 };
+static inline {
+        void resetClock( Clock & clk ) with( clk ) {
+                clocktype = CLOCK_REALTIME_COARSE;
+        } // Clock::resetClock
+static inline void resetClock( Clock & clk ) with( clk ) {
+        clocktype = CLOCK_REALTIME_COARSE;
+} // Clock::resetClock
         void resetClock( Clock & clk, Duration adj ) with( clk ) {
                 clocktype = -1;
                 offset = adj + __timezone`s;                                    // timezone (global) is (UTC - local time) in seconds
         } // resetClock
+static inline void resetClock( Clock & clk, Duration adj ) with( clk ) {
+        clocktype = -1;
+        offset = adj + timezone`s;                                                      // timezone (global) is (UTC - local time) in seconds
+} // resetClock
         void ?{}( Clock & clk ) { resetClock( clk ); }
         void ?{}( Clock & clk, Duration adj ) { resetClock( clk, adj ); }
+static inline void ?{}( Clock & clk ) { resetClock( clk ); }
+static inline void ?{}( Clock & clk, Duration adj ) { resetClock( clk, adj ); }
         Duration getResNsec() {
                 struct timespec res;
                 clock_getres( CLOCK_REALTIME, &res );
                 return ((int64_t)res.tv_sec * TIMEGRAN + res.tv_nsec)`ns;
         } // getRes
+static inline Duration getRes() {
+        struct timespec res;
+        clock_getres( CLOCK_REALTIME_COARSE, &res );
+        return ((int64_t)res.tv_sec * TIMEGRAN + res.tv_nsec)`ns;
+} // getRes
+        Duration getRes() {
                 struct timespec res;
                 clock_getres( CLOCK_REALTIME_COARSE, &res );
                 return ((int64_t)res.tv_sec * TIMEGRAN + res.tv_nsec)`ns;
+        } // getRes
+static inline Time getTimeNsec() {                                              // with nanoseconds
+        timespec curr;
+        clock_gettime( CLOCK_REALTIME_COARSE, &curr );
+        return (Time){ curr };
+} // getTime
+        Time getTimeNsec() {                                                            // with nanoseconds
+                timespec curr;
+                clock_gettime( CLOCK_REALTIME, &curr );
+                return (Time){ curr };
+        } // getTime
+static inline Time getTime() {                                                  // without nanoseconds
+        timespec curr;
+        clock_gettime( CLOCK_REALTIME_COARSE, &curr );
+        curr.tv_nsec = 0;
+        return (Time){ curr };
+} // getTime
+        Time getTime() {                                                                        // without nanoseconds
+                timespec curr;
+                clock_gettime( CLOCK_REALTIME_COARSE, &curr );
+                curr.tv_nsec = 0;
+                return (Time){ curr };
+        } // getTime
+static inline Time getTime( Clock & clk ) with( clk ) {
+        return getTime() + offset;
+} // getTime
+        Time getTime( Clock & clk ) with( clk ) {
                 return getTime() + offset;
         } // getTime
+static inline Time ?()( Clock & clk ) with( clk ) {             // alternative syntax
+        return getTime() + offset;
+} // getTime
+        Time ?()( Clock & clk ) with( clk ) {                           // alternative syntax
                 return getTime() + offset;
         } // getTime
+static inline timeval getTime( Clock & clk ) {
+        return (timeval){ clk() };
+} // getTime
+        timeval getTime( Clock & clk ) {
+                return (timeval){ clk() };
+        } // getTime
+        tm getTime( Clock & clk ) with( clk ) {
+                tm ret;
+                localtime_r( getTime( clk ).tv_sec, &ret );
+                return ret;
+        } // getTime
+} // distribution
+static inline tm getTime( Clock & clk ) with( clk ) {
+        tm ret;
+        localtime_r( getTime( clk ).tv_sec, &ret );
+        return ret;
+} // getTime
 // Local Variables: //

src/libcfa/iostream

-              re3b2474
+              rc653b37
 // Created On       : Wed May 27 17:56:53 2015
 // Last Modified By : Peter A. Buhr
 // Last Modified On : Sun Jul  1 12:12:22 2018
 // Update Count     : 155
+// Last Modified On : Sat Jun  2 08:07:55 2018
+// Update Count     : 153
 //
 …
         void open( ostype & os, const char * name, const char * mode );
         void close( ostype & os );
         ostype & write( ostype &, const char *, size_t );
+        ostype & write( ostype &, const char *, unsigned long int );
         int fmt( ostype &, const char fmt[], ... );
 }; // ostream
 …
         void open( istype & is, const char * name );
         void close( istype & is );
         istype & read( istype &, char *, size_t );
+        istype & read( istype &, char *, unsigned long int );
         istype & ungetc( istype &, char );
         int fmt( istype &, const char fmt[], ... );

src/libcfa/stdlib

-              re3b2474
+              rc653b37
 // Created On       : Thu Jan 28 17:12:35 2016
 // Last Modified By : Peter A. Buhr
 // Last Modified On : Tue Jul  3 08:17:28 2018
 // Update Count     : 324
+// Last Modified On : Sat Jun  2 08:46:35 2018
+// Update Count     : 306
 //
 …
 //---------------------------------------
+extern "C" {                                                                                    // override C version
+        void srandom( unsigned int seed );
+        long int random( void );
+} // extern "C"
+static inline {
+        long int random( long int l, long int u ) { if ( u < l ) [u, l] = [l, u]; return lrand48() % (u - l) + l; } // [l,u)
+        long int random( long int u ) { if ( u < 0 ) return random( u, 0 ); else return random( 0, u ); } // [0,u)
+        unsigned long int random( void ) { return lrand48(); }
+        unsigned long int random( unsigned long int l, unsigned long int u ) { if ( u < l ) [u, l] = [l, u]; return lrand48() % (u - l) + l; } // [l,u)
+        unsigned long int random( unsigned long int u ) { return lrand48() % u; } // [0,u)
+        char random( void ) { return (unsigned long int)random(); }
+        char random( char u ) { return random( (unsigned long int)u ); } // [0,u)
+        char random( char l, char u ) { return random( (unsigned long int)l, (unsigned long int)u ); } // [l,u)
+        int random( void ) { return (long int)random(); }
+        int random( int u ) { return random( (long int)u ); } // [0,u]
+        int random( int l, int u ) { return random( (long int)l, (long int)u ); } // [l,u)
+        unsigned int random( void ) { return (unsigned long int)random(); }
+        unsigned int random( unsigned int u ) { return random( (unsigned long int)u ); } // [0,u]
+        unsigned int random( unsigned int l, unsigned int u ) { return random( (unsigned long int)l, (unsigned long int)u ); } // [l,u)
+} // distribution
+float random( void );                                                                   // [0.0, 1.0)
+double random( void );                                                                  // [0.0, 1.0)
+float _Complex random( void );                                                  // [0.0, 1.0)+[0.0, 1.0)i
+double _Complex random( void );                                                 // [0.0, 1.0)+[0.0, 1.0)i
+long double _Complex random( void );                                    // [0.0, 1.0)+[0.0, 1.0)i
+extern "C" { void srandom( unsigned int seed ); }               // override C version
+char random( void );
+char random( char u );
+char random( char l, char u );
+int random( void );
+int random( int u );
+int random( int l, int u );
+unsigned int random( void );
+unsigned int random( unsigned int u );
+unsigned int random( unsigned int l, unsigned int u );
+extern "C" { long int random( void ); }                                 // override C version
+long int random( long int u );
+long int random( long int l, long int u );
+unsigned long int random( void );
+unsigned long int random( unsigned long int u );
+unsigned long int random( unsigned long int l, unsigned long int u );
+float random( void );
+double random( void );
+float _Complex random( void );
+double _Complex random( void );
+long double _Complex random( void );
 //---------------------------------------

src/libcfa/stdlib.c

-              re3b2474
+              rc653b37
 // Created On       : Thu Jan 28 17:10:29 2016
 // Last Modified By : Peter A. Buhr
 // Last Modified On : Tue Jul  3 08:17:30 2018
 // Update Count     : 457
+// Last Modified On : Sat Jun  2 06:15:05 2018
+// Update Count     : 448
 //
 …
 //---------------------------------------
+extern "C" {                                                                                    // override C version
+        void srandom( unsigned int seed ) { srand48( (long int)seed ); }
+        long int random( void ) { return mrand48(); }
+} // extern "C"
+extern "C" { void srandom( unsigned int seed ) { srand48( (long int)seed ); } } // override C version
+char random( void ) { return (unsigned long int)random(); }
+char random( char u ) { return random( (unsigned long int)u ); }
+char random( char l, char u ) { return random( (unsigned long int)l, (unsigned long int)u ); }
+int random( void ) { return (long int)random(); }
+int random( int u ) { return random( (long int)u ); }
+int random( int l, int u ) { return random( (long int)l, (long int)u ); }
+unsigned int random( void ) { return (unsigned long int)random(); }
+unsigned int random( unsigned int u ) { return random( (unsigned long int)u ); }
+unsigned int random( unsigned int l, unsigned int u ) { return random( (unsigned long int)l, (unsigned long int)u ); }
+extern "C" { long int random( void ) { return mrand48(); } } // override C version
+long int random( long int u ) { if ( u < 0 ) return random( u, 0 ); else return random( 0, u ); }
+long int random( long int l, long int u ) { assert( l < u ); return lrand48() % (u - l) + l; }
+unsigned long int random( void ) { return lrand48(); }
+unsigned long int random( unsigned long int u ) { return lrand48() % u; }
+unsigned long int random( unsigned long int l, unsigned long int u ) { assert( l < u ); return lrand48() % (u - l) + l; }
 float random( void ) { return (float)drand48(); }               // cast otherwise float uses lrand48
 double random( void ) { return drand48(); }

src/libcfa/time

-              re3b2474
+              rc653b37
 // Created On       : Wed Mar 14 23:18:57 2018
 // Last Modified By : Peter A. Buhr
 // Last Modified On : Mon Jul  2 21:28:38 2018
 // Update Count     : 641
+// Last Modified On : Sat Apr 14 17:48:23 2018
+// Update Count     : 636
 //
 …
 enum { TIMEGRAN = 1_000_000_000LL };                                    // nanosecond granularity, except for timeval
 //######################### Duration #########################
+static inline {
+        Duration ?=?( Duration & dur, zero_t ) { return dur{ 0 }; }
+        Duration +?( Duration rhs ) with( rhs ) {       return (Duration)@{ +tv }; }
+        Duration ?+?( Duration & lhs, Duration rhs ) { return (Duration)@{ lhs.tv + rhs.tv }; }
+        Duration ?+=?( Duration & lhs, Duration rhs ) { lhs = lhs + rhs; return lhs; }
+        Duration -?( Duration rhs ) with( rhs ) { return (Duration)@{ -tv }; }
+        Duration ?-?( Duration & lhs, Duration rhs ) { return (Duration)@{ lhs.tv - rhs.tv }; }
+        Duration ?-=?( Duration & lhs, Duration rhs ) { lhs = lhs - rhs; return lhs; }
+        Duration ?*?( Duration lhs, int64_t rhs ) { return (Duration)@{ lhs.tv * rhs }; }
+        Duration ?*?( int64_t lhs, Duration rhs ) { return (Duration)@{ lhs * rhs.tv }; }
+        Duration ?*=?( Duration & lhs, int64_t rhs ) { lhs = lhs * rhs; return lhs; }
+        int64_t ?/?( Duration lhs, Duration rhs ) { return lhs.tv / rhs.tv; }
+        Duration ?/?( Duration lhs, int64_t rhs ) { return (Duration)@{ lhs.tv / rhs }; }
+        Duration ?/=?( Duration & lhs, int64_t rhs ) { lhs = lhs / rhs; return lhs; }
+        double div( Duration lhs, Duration rhs ) { return (double)lhs.tv / (double)rhs.tv; }
+        Duration ?%?( Duration lhs, Duration rhs ) { return (Duration)@{ lhs.tv % rhs.tv }; }
+        Duration ?%=?( Duration & lhs, Duration rhs ) { lhs = lhs % rhs; return lhs; }
+        _Bool ?==?( Duration lhs, Duration rhs ) { return lhs.tv == rhs.tv; }
+        _Bool ?!=?( Duration lhs, Duration rhs ) { return lhs.tv != rhs.tv; }
+        _Bool ?<? ( Duration lhs, Duration rhs ) { return lhs.tv <  rhs.tv; }
+        _Bool ?<=?( Duration lhs, Duration rhs ) { return lhs.tv <= rhs.tv; }
+        _Bool ?>? ( Duration lhs, Duration rhs ) { return lhs.tv >  rhs.tv; }
+        _Bool ?>=?( Duration lhs, Duration rhs ) { return lhs.tv >= rhs.tv; }
+        _Bool ?==?( Duration lhs, zero_t ) { return lhs.tv == 0; }
+        _Bool ?!=?( Duration lhs, zero_t ) { return lhs.tv != 0; }
+        _Bool ?<? ( Duration lhs, zero_t ) { return lhs.tv <  0; }
+        _Bool ?<=?( Duration lhs, zero_t ) { return lhs.tv <= 0; }
+        _Bool ?>? ( Duration lhs, zero_t ) { return lhs.tv >  0; }
+        _Bool ?>=?( Duration lhs, zero_t ) { return lhs.tv >= 0; }
+        Duration abs( Duration rhs ) { return rhs.tv >= 0 ? rhs : -rhs; }
+        Duration ?`ns( int64_t nsec ) { return (Duration)@{ nsec }; }
+        Duration ?`us( int64_t usec ) { return (Duration)@{ usec * (TIMEGRAN / 1_000_000LL) }; }
+        Duration ?`ms( int64_t msec ) { return (Duration)@{ msec * (TIMEGRAN / 1_000LL) }; }
+        Duration ?`s( int64_t sec ) { return (Duration)@{ sec * TIMEGRAN }; }
+        Duration ?`s( double sec ) { return (Duration)@{ sec * TIMEGRAN }; }
+        Duration ?`m( int64_t min ) { return (Duration)@{ min * (60LL * TIMEGRAN) }; }
+        Duration ?`m( double min ) { return (Duration)@{ min * (60LL * TIMEGRAN) }; }
+        Duration ?`h( int64_t hours ) { return (Duration)@{ hours * (60LL * 60LL * TIMEGRAN) }; }
+        Duration ?`h( double hours ) { return (Duration)@{ hours * (60LL * 60LL * TIMEGRAN) }; }
+        Duration ?`d( int64_t days ) { return (Duration)@{ days * (24LL * 60LL * 60LL * TIMEGRAN) }; }
+        Duration ?`d( double days ) { return (Duration)@{ days * (24LL * 60LL * 60LL * TIMEGRAN) }; }
+        Duration ?`w( int64_t weeks ) { return (Duration)@{ weeks * (7LL * 24LL * 60LL * 60LL * TIMEGRAN) }; }
+        Duration ?`w( double weeks ) { return (Duration)@{ weeks * (7LL * 24LL * 60LL * 60LL * TIMEGRAN) }; }
+        int64_t ?`ns( Duration dur ) { return dur.tv; }
+        int64_t ?`us( Duration dur ) { return dur.tv / (TIMEGRAN / 1_000_000LL); }
+        int64_t ?`ms( Duration dur ) { return dur.tv / (TIMEGRAN / 1_000LL); }
+        int64_t ?`s( Duration dur ) { return dur.tv / TIMEGRAN; }
+        int64_t ?`m( Duration dur ) { return dur.tv / (60LL * TIMEGRAN); }
+        int64_t ?`h( Duration dur ) { return dur.tv / (60LL * 60LL * TIMEGRAN); }
+        int64_t ?`d( Duration dur ) { return dur.tv / (24LL * 60LL * 60LL * TIMEGRAN); }
+        int64_t ?`w( Duration dur ) { return dur.tv / (7LL * 24LL * 60LL * 60LL * TIMEGRAN); }
+        Duration max( Duration lhs, Duration rhs ) { return  (lhs.tv < rhs.tv) ? rhs : lhs;}
+        Duration min( Duration lhs, Duration rhs ) { return !(rhs.tv < lhs.tv) ? lhs : rhs;}
+} // distribution
+static inline Duration ?=?( Duration & dur, zero_t ) { return dur{ 0 }; }
+static inline Duration +?( Duration rhs ) with( rhs ) { return (Duration)@{ +tv }; }
+static inline Duration ?+?( Duration & lhs, Duration rhs ) { return (Duration)@{ lhs.tv + rhs.tv }; }
+static inline Duration ?+=?( Duration & lhs, Duration rhs ) { lhs = lhs + rhs; return lhs; }
+static inline Duration -?( Duration rhs ) with( rhs ) { return (Duration)@{ -tv }; }
+static inline Duration ?-?( Duration & lhs, Duration rhs ) { return (Duration)@{ lhs.tv - rhs.tv }; }
+static inline Duration ?-=?( Duration & lhs, Duration rhs ) { lhs = lhs - rhs; return lhs; }
+static inline Duration ?*?( Duration lhs, int64_t rhs ) { return (Duration)@{ lhs.tv * rhs }; }
+static inline Duration ?*?( int64_t lhs, Duration rhs ) { return (Duration)@{ lhs * rhs.tv }; }
+static inline Duration ?*=?( Duration & lhs, int64_t rhs ) { lhs = lhs * rhs; return lhs; }
+static inline int64_t ?/?( Duration lhs, Duration rhs ) { return lhs.tv / rhs.tv; }
+static inline Duration ?/?( Duration lhs, int64_t rhs ) { return (Duration)@{ lhs.tv / rhs }; }
+static inline Duration ?/=?( Duration & lhs, int64_t rhs ) { lhs = lhs / rhs; return lhs; }
+static inline double div( Duration lhs, Duration rhs ) { return (double)lhs.tv / (double)rhs.tv; }
+static inline Duration ?%?( Duration lhs, Duration rhs ) { return (Duration)@{ lhs.tv % rhs.tv }; }
+static inline Duration ?%=?( Duration & lhs, Duration rhs ) { lhs = lhs % rhs; return lhs; }
+static inline _Bool ?==?( Duration lhs, Duration rhs ) { return lhs.tv == rhs.tv; }
+static inline _Bool ?!=?( Duration lhs, Duration rhs ) { return lhs.tv != rhs.tv; }
+static inline _Bool ?<? ( Duration lhs, Duration rhs ) { return lhs.tv <  rhs.tv; }
+static inline _Bool ?<=?( Duration lhs, Duration rhs ) { return lhs.tv <= rhs.tv; }
+static inline _Bool ?>? ( Duration lhs, Duration rhs ) { return lhs.tv >  rhs.tv; }
+static inline _Bool ?>=?( Duration lhs, Duration rhs ) { return lhs.tv >= rhs.tv; }
+static inline _Bool ?==?( Duration lhs, zero_t ) { return lhs.tv == 0; }
+static inline _Bool ?!=?( Duration lhs, zero_t ) { return lhs.tv != 0; }
+static inline _Bool ?<? ( Duration lhs, zero_t ) { return lhs.tv <  0; }
+static inline _Bool ?<=?( Duration lhs, zero_t ) { return lhs.tv <= 0; }
+static inline _Bool ?>? ( Duration lhs, zero_t ) { return lhs.tv >  0; }
+static inline _Bool ?>=?( Duration lhs, zero_t ) { return lhs.tv >= 0; }
+static inline Duration abs( Duration rhs ) { return rhs.tv >= 0 ? rhs : -rhs; }
+static inline Duration ?`ns( int64_t nsec ) { return (Duration)@{ nsec }; }
+static inline Duration ?`us( int64_t usec ) { return (Duration)@{ usec * (TIMEGRAN / 1_000_000LL) }; }
+static inline Duration ?`ms( int64_t msec ) { return (Duration)@{ msec * (TIMEGRAN / 1_000LL) }; }
+static inline Duration ?`s( int64_t sec ) { return (Duration)@{ sec * TIMEGRAN }; }
+static inline Duration ?`s( double sec ) { return (Duration)@{ sec * TIMEGRAN }; }
+static inline Duration ?`m( int64_t min ) { return (Duration)@{ min * (60LL * TIMEGRAN) }; }
+static inline Duration ?`m( double min ) { return (Duration)@{ min * (60LL * TIMEGRAN) }; }
+static inline Duration ?`h( int64_t hours ) { return (Duration)@{ hours * (60LL * 60LL * TIMEGRAN) }; }
+static inline Duration ?`h( double hours ) { return (Duration)@{ hours * (60LL * 60LL * TIMEGRAN) }; }
+static inline Duration ?`d( int64_t days ) { return (Duration)@{ days * (24LL * 60LL * 60LL * TIMEGRAN) }; }
+static inline Duration ?`d( double days ) { return (Duration)@{ days * (24LL * 60LL * 60LL * TIMEGRAN) }; }
+static inline Duration ?`w( int64_t weeks ) { return (Duration)@{ weeks * (7LL * 24LL * 60LL * 60LL * TIMEGRAN) }; }
+static inline Duration ?`w( double weeks ) { return (Duration)@{ weeks * (7LL * 24LL * 60LL * 60LL * TIMEGRAN) }; }
+static inline int64_t ?`ns( Duration dur ) { return dur.tv; }
+static inline int64_t ?`us( Duration dur ) { return dur.tv / (TIMEGRAN / 1_000_000LL); }
+static inline int64_t ?`ms( Duration dur ) { return dur.tv / (TIMEGRAN / 1_000LL); }
+static inline int64_t ?`s( Duration dur ) { return dur.tv / TIMEGRAN; }
+static inline int64_t ?`m( Duration dur ) { return dur.tv / (60LL * TIMEGRAN); }
+static inline int64_t ?`h( Duration dur ) { return dur.tv / (60LL * 60LL * TIMEGRAN); }
+static inline int64_t ?`d( Duration dur ) { return dur.tv / (24LL * 60LL * 60LL * TIMEGRAN); }
+static inline int64_t ?`w( Duration dur ) { return dur.tv / (7LL * 24LL * 60LL * 60LL * TIMEGRAN); }
+static inline Duration max( Duration lhs, Duration rhs ) { return  (lhs.tv < rhs.tv) ? rhs : lhs;}
+static inline Duration min( Duration lhs, Duration rhs ) { return !(rhs.tv < lhs.tv) ? lhs : rhs;}
 //######################### C timeval #########################
+static inline {
+        void ?{}( timeval & t ) {}
+        void ?{}( timeval & t, time_t sec, suseconds_t usec ) { t.tv_sec = sec; t.tv_usec = usec; }
+        void ?{}( timeval & t, time_t sec ) { t{ sec, 0 }; }
+        void ?{}( timeval & t, zero_t ) { t{ 0, 0 }; }
+        timeval ?=?( timeval & t, zero_t ) { return t{ 0 }; }
+        timeval ?+?( timeval & lhs, timeval rhs ) { return (timeval)@{ lhs.tv_sec + rhs.tv_sec, lhs.tv_usec + rhs.tv_usec }; }
+        timeval ?-?( timeval & lhs, timeval rhs ) { return (timeval)@{ lhs.tv_sec - rhs.tv_sec, lhs.tv_usec - rhs.tv_usec }; }
+        _Bool ?==?( timeval lhs, timeval rhs ) { return lhs.tv_sec == rhs.tv_sec && lhs.tv_usec == rhs.tv_usec; }
+        _Bool ?!=?( timeval lhs, timeval rhs ) { return lhs.tv_sec != rhs.tv_sec || lhs.tv_usec != rhs.tv_usec; }
+} // distribution
+static inline void ?{}( timeval & t ) {}
+static inline void ?{}( timeval & t, time_t sec, suseconds_t usec ) { t.tv_sec = sec; t.tv_usec = usec; }
+static inline void ?{}( timeval & t, time_t sec ) { t{ sec, 0 }; }
+static inline void ?{}( timeval & t, zero_t ) { t{ 0, 0 }; }
+static inline timeval ?=?( timeval & t, zero_t ) { return t{ 0 }; }
+static inline timeval ?+?( timeval & lhs, timeval rhs ) { return (timeval)@{ lhs.tv_sec + rhs.tv_sec, lhs.tv_usec + rhs.tv_usec }; }
+static inline timeval ?-?( timeval & lhs, timeval rhs ) { return (timeval)@{ lhs.tv_sec - rhs.tv_sec, lhs.tv_usec - rhs.tv_usec }; }
+static inline _Bool ?==?( timeval lhs, timeval rhs ) { return lhs.tv_sec == rhs.tv_sec && lhs.tv_usec == rhs.tv_usec; }
+static inline _Bool ?!=?( timeval lhs, timeval rhs ) { return lhs.tv_sec != rhs.tv_sec || lhs.tv_usec != rhs.tv_usec; }
 //######################### C timespec #########################
+static inline {
+        void ?{}( timespec & t ) {}
+        void ?{}( timespec & t, time_t sec, __syscall_slong_t nsec ) { t.tv_sec = sec; t.tv_nsec = nsec; }
+        void ?{}( timespec & t, time_t sec ) { t{ sec, 0}; }
+        void ?{}( timespec & t, zero_t ) { t{ 0, 0 }; }
+        timespec ?=?( timespec & t, zero_t ) { return t{ 0 }; }
+        timespec ?+?( timespec & lhs, timespec rhs ) { return (timespec)@{ lhs.tv_sec + rhs.tv_sec, lhs.tv_nsec + rhs.tv_nsec }; }
+        timespec ?-?( timespec & lhs, timespec rhs ) { return (timespec)@{ lhs.tv_sec - rhs.tv_sec, lhs.tv_nsec - rhs.tv_nsec }; }
+        _Bool ?==?( timespec lhs, timespec rhs ) { return lhs.tv_sec == rhs.tv_sec && lhs.tv_nsec == rhs.tv_nsec; }
+        _Bool ?!=?( timespec lhs, timespec rhs ) { return lhs.tv_sec != rhs.tv_sec || lhs.tv_nsec != rhs.tv_nsec; }
+} // distribution
+static inline void ?{}( timespec & t ) {}
+static inline void ?{}( timespec & t, time_t sec, __syscall_slong_t nsec ) { t.tv_sec = sec; t.tv_nsec = nsec; }
+static inline void ?{}( timespec & t, time_t sec ) { t{ sec, 0}; }
+static inline void ?{}( timespec & t, zero_t ) { t{ 0, 0 }; }
+static inline timespec ?=?( timespec & t, zero_t ) { return t{ 0 }; }
+static inline timespec ?+?( timespec & lhs, timespec rhs ) { return (timespec)@{ lhs.tv_sec + rhs.tv_sec, lhs.tv_nsec + rhs.tv_nsec }; }
+static inline timespec ?-?( timespec & lhs, timespec rhs ) { return (timespec)@{ lhs.tv_sec - rhs.tv_sec, lhs.tv_nsec - rhs.tv_nsec }; }
+static inline _Bool ?==?( timespec lhs, timespec rhs ) { return lhs.tv_sec == rhs.tv_sec && lhs.tv_nsec == rhs.tv_nsec; }
+static inline _Bool ?!=?( timespec lhs, timespec rhs ) { return lhs.tv_sec != rhs.tv_sec || lhs.tv_nsec != rhs.tv_nsec; }
 //######################### C itimerval #########################
+static inline {
+        void ?{}( itimerval & itv, Duration alarm ) with( itv ) {
+                // itimerval contains durations but but uses time data-structure timeval.
+                it_value{ alarm`s, (alarm % 1`s)`us };                  // seconds, microseconds
+                it_interval{ 0 };                                                               // 0 seconds, 0 microseconds
+        } // itimerval
+        void ?{}( itimerval & itv, Duration alarm, Duration interval ) with( itv ) {
+                // itimerval contains durations but but uses time data-structure timeval.
+                it_value{ alarm`s, (alarm % 1`s)`us };                  // seconds, microseconds
+                it_interval{ interval`s, interval`us };                 // seconds, microseconds
+        } // itimerval
+} // distribution
+static inline void ?{}( itimerval & itv, Duration alarm ) with( itv ) {
+        // itimerval contains durations but but uses time data-structure timeval.
+        it_value{ alarm`s, (alarm % 1`s)`us };                          // seconds, microseconds
+        it_interval{ 0 };                                                                       // 0 seconds, 0 microseconds
+} // itimerval
+static inline void ?{}( itimerval & itv, Duration alarm, Duration interval ) with( itv ) {
+        // itimerval contains durations but but uses time data-structure timeval.
+        it_value{ alarm`s, (alarm % 1`s)`us };                          // seconds, microseconds
+        it_interval{ interval`s, interval`us };                         // seconds, microseconds
+} // itimerval
 //######################### Time #########################
 void ?{}( Time & time, int year, int month = 0, int day = 0, int hour = 0, int min = 0, int sec = 0, int nsec = 0 );
+static inline {
+        Time ?=?( Time & time, zero_t ) { return time{ 0 }; }
+        void ?{}( Time & time, timeval t ) with( time ) { tv = (int64_t)t.tv_sec * TIMEGRAN + t.tv_usec * 1000; }
+        Time ?=?( Time & time, timeval t ) with( time ) {
+                tv = (int64_t)t.tv_sec * TIMEGRAN + t.tv_usec * (TIMEGRAN / 1_000_000LL);
+                return time;
+        } // ?=?
+        void ?{}( Time & time, timespec t ) with( time ) { tv = (int64_t)t.tv_sec * TIMEGRAN + t.tv_nsec; }
+        Time ?=?( Time & time, timespec t ) with( time ) {
+                tv = (int64_t)t.tv_sec * TIMEGRAN + t.tv_nsec;
+                return time;
+        } // ?=?
+        Time ?+?( Time & lhs, Duration rhs ) { return (Time)@{ lhs.tv + rhs.tv }; }
+        Time ?+?( Duration lhs, Time rhs ) { return rhs + lhs; }
+        Time ?+=?( Time & lhs, Duration rhs ) { lhs = lhs + rhs; return lhs; }
+        Duration ?-?( Time lhs, Time rhs ) { return (Duration)@{ lhs.tv - rhs.tv }; }
+        Time ?-?( Time lhs, Duration rhs ) { return (Time)@{ lhs.tv - rhs.tv }; }
+        Time ?-=?( Time & lhs, Duration rhs ) { lhs = lhs - rhs; return lhs; }
+        _Bool ?==?( Time lhs, Time rhs ) { return lhs.tv == rhs.tv; }
+        _Bool ?!=?( Time lhs, Time rhs ) { return lhs.tv != rhs.tv; }
+        _Bool ?<?( Time lhs, Time rhs ) { return lhs.tv < rhs.tv; }
+        _Bool ?<=?( Time lhs, Time rhs ) { return lhs.tv <= rhs.tv; }
+        _Bool ?>?( Time lhs, Time rhs ) { return lhs.tv > rhs.tv; }
+        _Bool ?>=?( Time lhs, Time rhs ) { return lhs.tv >= rhs.tv; }
+} // distribution
+static inline Time ?=?( Time & time, zero_t ) { return time{ 0 }; }
+static inline void ?{}( Time & time, timeval t ) with( time ) { tv = (int64_t)t.tv_sec * TIMEGRAN + t.tv_usec * 1000; }
+static inline Time ?=?( Time & time, timeval t ) with( time ) {
+        tv = (int64_t)t.tv_sec * TIMEGRAN + t.tv_usec * (TIMEGRAN / 1_000_000LL);
+        return time;
+} // ?=?
+static inline void ?{}( Time & time, timespec t ) with( time ) { tv = (int64_t)t.tv_sec * TIMEGRAN + t.tv_nsec; }
+static inline Time ?=?( Time & time, timespec t ) with( time ) {
+        tv = (int64_t)t.tv_sec * TIMEGRAN + t.tv_nsec;
+        return time;
+} // ?=?
+static inline Time ?+?( Time & lhs, Duration rhs ) { return (Time)@{ lhs.tv + rhs.tv }; }
+static inline Time ?+?( Duration lhs, Time rhs ) { return rhs + lhs; }
+static inline Time ?+=?( Time & lhs, Duration rhs ) { lhs = lhs + rhs; return lhs; }
+static inline Duration ?-?( Time lhs, Time rhs ) { return (Duration)@{ lhs.tv - rhs.tv }; }
+static inline Time ?-?( Time lhs, Duration rhs ) { return (Time)@{ lhs.tv - rhs.tv }; }
+static inline Time ?-=?( Time & lhs, Duration rhs ) { lhs = lhs - rhs; return lhs; }
+static inline _Bool ?==?( Time lhs, Time rhs ) { return lhs.tv == rhs.tv; }
+static inline _Bool ?!=?( Time lhs, Time rhs ) { return lhs.tv != rhs.tv; }
+static inline _Bool ?<?( Time lhs, Time rhs ) { return lhs.tv < rhs.tv; }
+static inline _Bool ?<=?( Time lhs, Time rhs ) { return lhs.tv <= rhs.tv; }
+static inline _Bool ?>?( Time lhs, Time rhs ) { return lhs.tv > rhs.tv; }
+static inline _Bool ?>=?( Time lhs, Time rhs ) { return lhs.tv >= rhs.tv; }
 char * yy_mm_dd( Time time, char * buf );

src/tests/literals.c

-              re3b2474
+              rc653b37
 // Created On       : Sat Sep  9 16:34:38 2017
 // Last Modified By : Peter A. Buhr
 // Last Modified On : Sun Jul  1 15:12:15 2018
 // Update Count     : 137
+// Last Modified On : Sun Mar  4 10:41:31 2018
+// Update Count     : 134
 //
 …
         // binary
+b01101011_l8;   0b01101011_l16;   0b01101011_l32;   0b01101011_l64;   0b01101011_l8u;   0b01101011_ul16;   0b01101011_l32u;   0b01101011_ul64;
+        +0b01101011_l8;  +0b01101011_l16;  +0b01101011_l32;  +0b01101011_l64;  +0b01101011_l8u;  +0b01101011_ul16;  +0b01101011_l32u;  +0b01101011_ul64;
+        -0b01101011_l8;  -0b01101011_l16;  -0b01101011_l32;  -0b01101011_l64;  -0b01101011_l8u;  -0b01101011_ul16;  -0b01101011_l32u;  -0b01101011_ul64;
+#ifdef __LP64__ // 64-bit processor
+b01101011_l128;   0b01101011_ul128;
+        +0b01101011_l128;  +0b01101011_ul128;
+        -0b01101011_l128;  -0b01101011_ul128;
+#endif // __LP64__
+b01101011_l8;   0b01101011_l16;   0b01101011_l32;   0b01101011_l64;   0b01101011_l128;   0b01101011_l8u;   0b01101011_ul16;   0b01101011_l32u;   0b01101011_ul64;   0b01101011_ul128;
+        +0b01101011_l8;  +0b01101011_l16;  +0b01101011_l32;  +0b01101011_l64;  +0b01101011_l128;  +0b01101011_l8u;  +0b01101011_ul16;  +0b01101011_l32u;  +0b01101011_ul64;  +0b01101011_ul128;
+        -0b01101011_l8;  -0b01101011_l16;  -0b01101011_l32;  -0b01101011_l64;  -0b01101011_l128;  -0b01101011_l8u;  -0b01101011_ul16;  -0b01101011_l32u;  -0b01101011_ul64;  -0b01101011_ul128;
         // octal
+         01234567_l8;   01234567_l16;   01234567_l32;   01234567_l64;   01234567_l8u;   01234567_ul16;   01234567_l32u;   01234567_ul64;
+        +01234567_l8;  +01234567_l16;  +01234567_l32;  +01234567_l64;  +01234567_l8u;  +01234567_ul16;  +01234567_l32u;  +01234567_ul64;
+        -01234567_l8;  -01234567_l16;  -01234567_l32;  -01234567_l64;  -01234567_l8u;  -01234567_ul16;  -01234567_l32u;  -01234567_ul64;
+#ifdef __LP64__ // 64-bit processor
+        01234567_l128;   01234567_ul128;
+        +01234567_l128;  +01234567_ul128;
+        -01234567_l128;  -01234567_ul128;
+#endif // __LP64__
+         01234567_l8;   01234567_l16;   01234567_l32;   01234567_l64;   01234567_l128;   01234567_l8u;   01234567_ul16;   01234567_l32u;   01234567_ul64;   01234567_ul128;
+        +01234567_l8;  +01234567_l16;  +01234567_l32;  +01234567_l64;  +01234567_l128;  +01234567_l8u;  +01234567_ul16;  +01234567_l32u;  +01234567_ul64;  +01234567_ul128;
+        -01234567_l8;  -01234567_l16;  -01234567_l32;  -01234567_l64;  -01234567_l128;  -01234567_l8u;  -01234567_ul16;  -01234567_l32u;  -01234567_ul64;  -01234567_ul128;
         // decimal
+         1234567890L8;   1234567890L16;   1234567890l32;   1234567890l64;   1234567890UL8;   1234567890L16U;   1234567890Ul32;   1234567890l64u;
+        +1234567890L8;  +1234567890L16;  +1234567890l32;  +1234567890l64;  +1234567890UL8;  +1234567890L16U;  +1234567890Ul32;  +1234567890l64u;
+        -1234567890L8;  -1234567890L16;  -1234567890l32;  -1234567890l64;  -1234567890UL8;  -1234567890L16U;  -1234567890Ul32;  -1234567890l64u;
+#ifdef __LP64__ // 64-bit processor
+        1234567890l128;   1234567890l128u;
+        +1234567890l128;  +1234567890l128u;
+        -1234567890l128;  -1234567890l128u;
+#endif // __LP64__
+         1234567890L8;   1234567890L16;   1234567890l32;   1234567890l64;   1234567890l128;   1234567890UL8;   1234567890L16U;   1234567890Ul32;   1234567890l64u;   1234567890l128u;
+        +1234567890L8;  +1234567890L16;  +1234567890l32;  +1234567890l64;  +1234567890l128;  +1234567890UL8;  +1234567890L16U;  +1234567890Ul32;  +1234567890l64u;  +1234567890l128u;
+        -1234567890L8;  -1234567890L16;  -1234567890l32;  -1234567890l64;  -1234567890l128;  -1234567890UL8;  -1234567890L16U;  -1234567890Ul32;  -1234567890l64u;  -1234567890l128u;
         // hexadecimal

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Changes in / [e3b2474:c653b37]

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doc/papers/concurrency/Paper.tex

doc/papers/concurrency/figures/ext_monitor.fig

src/Parser/LinkageSpec.h

src/Parser/parser.yy

src/ResolvExpr/Resolver.cc

src/libcfa/clock

src/libcfa/iostream

src/libcfa/stdlib

src/libcfa/stdlib.c

src/libcfa/time

src/tests/literals.c

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