Changeset eef8dfb for libcfa/src/bits/locks.hfa

Timestamp:

Jan 7, 2021, 2:55:57 PM (5 years ago)

Author:

Thierry Delisle <tdelisle@…>

Branches:

ADT, arm-eh, ast-experimental, enum, forall-pointer-decay, jacob/cs343-translation, master, new-ast-unique-expr, pthread-emulation, qualifiedEnum

Children:

58fe85a

Parents:

bdfc032 (diff), 44e37ef (diff)
Note: this is a merge changeset, the changes displayed below correspond to the merge itself.
Use the (diff) links above to see all the changes relative to each parent.

Message:

Merge branch 'master' into dkobets-vector

File:

• libcfa/src/bits/locks.hfa (modified) (7 diffs)

libcfa/src/bits/locks.hfa

@@ -10 +10 @@
 // Created On       : Tue Oct 31 15:14:38 2017
 // Last Modified By : Peter A. Buhr
-// Last Modified On : Sat Aug 11 15:42:24 2018
-// Update Count     : 10
+// Last Modified On : Wed Aug 12 14:18:07 2020
+// Update Count     : 13
 //
 
@@ -27 +27 @@
 
 // pause to prevent excess processor bus usage
-#if defined( __sparc )
-        #define Pause() __asm__ __volatile__ ( "rd %ccr,%g0" )
-#elif defined( __i386 ) || defined( __x86_64 )
+#if defined( __i386 ) || defined( __x86_64 )
         #define Pause() __asm__ __volatile__ ( "pause" : : : )
 #elif defined( __ARM_ARCH )
-        #define Pause() __asm__ __volatile__ ( "nop" : : : )
+        #define Pause() __asm__ __volatile__ ( "YIELD" : : : )
 #else
         #error unsupported architecture
@@ -54 +52 @@
 
                 #ifdef __CFA_DEBUG__
-                        void __cfaabi_dbg_record(__spinlock_t & this, const char * prev_name);
+                        void __cfaabi_dbg_record_lock(__spinlock_t & this, const char prev_name[]);
                 #else
-                        #define __cfaabi_dbg_record(x, y)
+                        #define __cfaabi_dbg_record_lock(x, y)
                 #endif
         }
-
-        extern void yield( unsigned int );
 
         static inline void ?{}( __spinlock_t & this ) {
@@ -68 +64 @@
         // Lock the spinlock, return false if already acquired
         static inline bool try_lock  ( __spinlock_t & this __cfaabi_dbg_ctx_param2 ) {
+                disable_interrupts();
                 bool result = (this.lock == 0) && (__atomic_test_and_set( &this.lock, __ATOMIC_ACQUIRE ) == 0);
                 if( result ) {
-                        disable_interrupts();
-                        __cfaabi_dbg_record( this, caller );
+                        __cfaabi_dbg_record_lock( this, caller );
+                } else {
+                        enable_interrupts_noPoll();
                 }
                 return result;
@@ -83 +81 @@
                 #endif
 
+                disable_interrupts();
                 for ( unsigned int i = 1;; i += 1 ) {
                         if ( (this.lock == 0) && (__atomic_test_and_set( &this.lock, __ATOMIC_ACQUIRE ) == 0) ) break;
@@ -98 +97 @@
                         #endif
                 }
-                disable_interrupts();
-                __cfaabi_dbg_record( this, caller );
+                __cfaabi_dbg_record_lock( this, caller );
         }
 
         static inline void unlock( __spinlock_t & this ) {
+                __atomic_clear( &this.lock, __ATOMIC_RELEASE );
                 enable_interrupts_noPoll();
-                __atomic_clear( &this.lock, __ATOMIC_RELEASE );
         }
 
@@ -112 +110 @@
         #endif
 
+        extern "C" {
+                char * strerror(int);
+        }
+        #define CHECKED(x) { int err = x; if( err != 0 ) abort("KERNEL ERROR: Operation \"" #x "\" return error %d - %s\n", err, strerror(err)); }
+
         struct __bin_sem_t {
-                bool                    signaled;
                 pthread_mutex_t         lock;
                 pthread_cond_t          cond;
+                int                     val;
         };
 
         static inline void ?{}(__bin_sem_t & this) with( this ) {
-                signaled = false;
-                pthread_mutex_init(&lock, NULL);
-                pthread_cond_init (&cond, NULL);
+                // Create the mutex with error checking
+                pthread_mutexattr_t mattr;
+                pthread_mutexattr_init( &mattr );
+                pthread_mutexattr_settype( &mattr, PTHREAD_MUTEX_ERRORCHECK_NP);
+                pthread_mutex_init(&lock, &mattr);
+
+                pthread_cond_init (&cond, (const pthread_condattr_t *)0p);  // workaround trac#208: cast should not be required
+                val = 0;
         }
 
         static inline void ^?{}(__bin_sem_t & this) with( this ) {
-                pthread_mutex_destroy(&lock);
-                pthread_cond_destroy (&cond);
+                CHECKED( pthread_mutex_destroy(&lock) );
+                CHECKED( pthread_cond_destroy (&cond) );
         }
 
         static inline void wait(__bin_sem_t & this) with( this ) {
                 verify(__cfaabi_dbg_in_kernel());
-                pthread_mutex_lock(&lock);
-                        if(!signaled) {   // this must be a loop, not if!
+                CHECKED( pthread_mutex_lock(&lock) );
+                        while(val < 1) {
                                 pthread_cond_wait(&cond, &lock);
                         }
-                        signaled = false;
-                pthread_mutex_unlock(&lock);
-        }
-
-        static inline void post(__bin_sem_t & this) with( this ) {
-                verify(__cfaabi_dbg_in_kernel());
-
-                pthread_mutex_lock(&lock);
-                        bool needs_signal = !signaled;
-                        signaled = true;
-                pthread_mutex_unlock(&lock);
-
-                if (needs_signal)
-                        pthread_cond_signal(&cond);
+                        val -= 1;
+                CHECKED( pthread_mutex_unlock(&lock) );
+        }
+
+        static inline bool post(__bin_sem_t & this) with( this ) {
+                bool needs_signal = false;
+
+                CHECKED( pthread_mutex_lock(&lock) );
+                        if(val < 1) {
+                                val += 1;
+                                pthread_cond_signal(&cond);
+                                needs_signal = true;
+                        }
+                CHECKED( pthread_mutex_unlock(&lock) );
+
+                return needs_signal;
+        }
+
+        #undef CHECKED
+
+        struct $thread;
+        extern void park( void );
+        extern void unpark( struct $thread * this );
+        static inline struct $thread * active_thread ();
+
+        // Semaphore which only supports a single thread
+        struct single_sem {
+                struct $thread * volatile ptr;
+        };
+
+        static inline {
+                void  ?{}(single_sem & this) {
+                        this.ptr = 0p;
+                }
+
+                void ^?{}(single_sem &) {}
+
+                bool wait(single_sem & this) {
+                        for() {
+                                struct $thread * expected = this.ptr;
+                                if(expected == 1p) {
+                                        if(__atomic_compare_exchange_n(&this.ptr, &expected, 0p, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST)) {
+                                                return false;
+                                        }
+                                }
+                                else {
+                                        /* paranoid */ verify( expected == 0p );
+                                        if(__atomic_compare_exchange_n(&this.ptr, &expected, active_thread(), false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST)) {
+                                                park();
+                                                return true;
+                                        }
+                                }
+
+                        }
+                }
+
+                bool post(single_sem & this) {
+                        for() {
+                                struct $thread * expected = this.ptr;
+                                if(expected == 1p) return false;
+                                if(expected == 0p) {
+                                        if(__atomic_compare_exchange_n(&this.ptr, &expected, 1p, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST)) {
+                                                return false;
+                                        }
+                                }
+                                else {
+                                        if(__atomic_compare_exchange_n(&this.ptr, &expected, 0p, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST)) {
+                                                unpark( expected );
+                                                return true;
+                                        }
+                                }
+                        }
+                }
+        }
+
+        // Synchronozation primitive which only supports a single thread and one post
+        // Similar to a binary semaphore with a 'one shot' semantic
+        // is expected to be discarded after each party call their side
+        struct oneshot {
+                // Internal state :
+                //     0p     : is initial state (wait will block)
+                //     1p     : fulfilled (wait won't block)
+                // any thread : a thread is currently waiting
+                struct $thread * volatile ptr;
+        };
+
+        static inline {
+                void  ?{}(oneshot & this) {
+                        this.ptr = 0p;
+                }
+
+                void ^?{}(oneshot &) {}
+
+                // Wait for the post, return immidiately if it already happened.
+                // return true if the thread was parked
+                bool wait(oneshot & this) {
+                        for() {
+                                struct $thread * expected = this.ptr;
+                                if(expected == 1p) return false;
+                                /* paranoid */ verify( expected == 0p );
+                                if(__atomic_compare_exchange_n(&this.ptr, &expected, active_thread(), false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST)) {
+                                        park();
+                                        /* paranoid */ verify( this.ptr == 1p );
+                                        return true;
+                                }
+                        }
+                }
+
+                // Mark as fulfilled, wake thread if needed
+                // return true if a thread was unparked
+                bool post(oneshot & this) {
+                        struct $thread * got = __atomic_exchange_n( &this.ptr, 1p, __ATOMIC_SEQ_CST);
+                        if( got == 0p ) return false;
+                        unpark( got );
+                        return true;
+                }
+        }
+
+        // base types for future to build upon
+        // It is based on the 'oneshot' type to allow multiple futures
+        // to block on the same instance, permitting users to block a single
+        // thread on "any of" [a given set of] futures.
+        // does not support multiple threads waiting on the same future
+        struct future_t {
+                // Internal state :
+                //     0p      : is initial state (wait will block)
+                //     1p      : fulfilled (wait won't block)
+                //     2p      : in progress ()
+                //     3p      : abandoned, server should delete
+                // any oneshot : a context has been setup to wait, a thread could wait on it
+                struct oneshot * volatile ptr;
+        };
+
+        static inline {
+                void  ?{}(future_t & this) {
+                        this.ptr = 0p;
+                }
+
+                void ^?{}(future_t &) {}
+
+                void reset(future_t & this) {
+                        // needs to be in 0p or 1p
+                        __atomic_exchange_n( &this.ptr, 0p, __ATOMIC_SEQ_CST);
+                }
+
+                // check if the future is available
+                bool available( future_t & this ) {
+                        return this.ptr == 1p;
+                }
+
+                // Prepare the future to be waited on
+                // intented to be use by wait, wait_any, waitfor, etc. rather than used directly
+                bool setup( future_t & this, oneshot & wait_ctx ) {
+                        /* paranoid */ verify( wait_ctx.ptr == 0p );
+                        // The future needs to set the wait context
+                        for() {
+                                struct oneshot * expected = this.ptr;
+                                // Is the future already fulfilled?
+                                if(expected == 1p) return false; // Yes, just return false (didn't block)
+
+                                // The future is not fulfilled, try to setup the wait context
+                                /* paranoid */ verify( expected == 0p );
+                                if(__atomic_compare_exchange_n(&this.ptr, &expected, &wait_ctx, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST)) {
+                                        return true;
+                                }
+                        }
+                }
+
+                // Stop waiting on a future
+                // When multiple futures are waited for together in "any of" pattern
+                // futures that weren't fulfilled before the thread woke up
+                // should retract the wait ctx
+                // intented to be use by wait, wait_any, waitfor, etc. rather than used directly
+                void retract( future_t & this, oneshot & wait_ctx ) {
+                        // Remove the wait context
+                        struct oneshot * got = __atomic_exchange_n( &this.ptr, 0p, __ATOMIC_SEQ_CST);
+
+                        // got == 0p: future was never actually setup, just return
+                        if( got == 0p ) return;
+
+                        // got == wait_ctx: since fulfil does an atomic_swap,
+                        // if we got back the original then no one else saw context
+                        // It is safe to delete (which could happen after the return)
+                        if( got == &wait_ctx ) return;
+
+                        // got == 1p: the future is ready and the context was fully consumed
+                        // the server won't use the pointer again
+                        // It is safe to delete (which could happen after the return)
+                        if( got == 1p ) return;
+
+                        // got == 2p: the future is ready but the context hasn't fully been consumed
+                        // spin until it is safe to move on
+                        if( got == 2p ) {
+                                while( this.ptr != 1p ) Pause();
+                                return;
+                        }
+
+                        // got == any thing else, something wen't wrong here, abort
+                        abort("Future in unexpected state");
+                }
+
+                // Mark the future as abandoned, meaning it will be deleted by the server
+                bool abandon( future_t & this ) {
+                        /* paranoid */ verify( this.ptr != 3p );
+
+                        // Mark the future as abandonned
+                        struct oneshot * got = __atomic_exchange_n( &this.ptr, 3p, __ATOMIC_SEQ_CST);
+
+                        // If the future isn't already fulfilled, let the server delete it
+                        if( got == 0p ) return false;
+
+                        // got == 2p: the future is ready but the context hasn't fully been consumed
+                        // spin until it is safe to move on
+                        if( got == 2p ) {
+                                while( this.ptr != 1p ) Pause();
+                                got = 1p;
+                        }
+
+                        // The future is completed delete it now
+                        /* paranoid */ verify( this.ptr != 1p );
+                        free( &this );
+                        return true;
+                }
+
+                // from the server side, mark the future as fulfilled
+                // delete it if needed
+                bool fulfil( future_t & this ) {
+                        for() {
+                                struct oneshot * expected = this.ptr;
+                                // was this abandoned?
+                                #if defined(__GNUC__) && __GNUC__ >= 7
+                                        #pragma GCC diagnostic push
+                                        #pragma GCC diagnostic ignored "-Wfree-nonheap-object"
+                                #endif
+                                        if( expected == 3p ) { free( &this ); return false; }
+                                #if defined(__GNUC__) && __GNUC__ >= 7
+                                        #pragma GCC diagnostic pop
+                                #endif
+
+                                /* paranoid */ verify( expected != 1p ); // Future is already fulfilled, should not happen
+                                /* paranoid */ verify( expected != 2p ); // Future is bein fulfilled by someone else, this is even less supported then the previous case.
+
+                                // If there is a wait context, we need to consume it and mark it as consumed after
+                                // If there is no context then we can skip the in progress phase
+                                struct oneshot * want = expected == 0p ? 1p : 2p;
+                                if(__atomic_compare_exchange_n(&this.ptr, &expected, want, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST)) {
+                                        if( expected == 0p ) { /* paranoid */ verify( this.ptr == 1p); return false; }
+                                        bool ret = post( *expected );
+                                        __atomic_store_n( &this.ptr, 1p, __ATOMIC_SEQ_CST);
+                                        return ret;
+                                }
+                        }
+
+                }
+
+                // Wait for the future to be fulfilled
+                bool wait( future_t & this ) {
+                        oneshot temp;
+                        if( !setup(this, temp) ) return false;
+
+                        // Wait context is setup, just wait on it
+                        bool ret = wait( temp );
+
+                        // Wait for the future to tru
+                        while( this.ptr == 2p ) Pause();
+                        // Make sure the state makes sense
+                        // Should be fulfilled, could be in progress but it's out of date if so
+                        // since if that is the case, the oneshot was fulfilled (unparking this thread)
+                        // and the oneshot should not be needed any more
+                        __attribute__((unused)) struct oneshot * was = this.ptr;
+                        /* paranoid */ verifyf( was == 1p, "Expected this.ptr to be 1p, was %p\n", was );
+
+                        // Mark the future as fulfilled, to be consistent
+                        // with potential calls to avail
+                        // this.ptr = 1p;
+                        return ret;
+                }
         }
 #endif