| 1 | % ======================================================================
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| 2 | % ======================================================================
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| 3 | \chapter{Conclusion}\label{s:conclusion}
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| 4 | % ======================================================================
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| 5 | % ======================================================================
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| 6 | This thesis presented a suite of safe and efficient concurrency tools that provide users with the means to write scalable programs in \CFA through many avenues.
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| 7 | If users prefer the message passing paradigm of concurrency, \CFA now provides tools in the form of a performant actor system and channels.
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| 8 | For shared memory concurrency the mutex statement provides a safe and easy-to-use interface for mutual exclusion.
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| 9 | The waituntil statement provided by this works aids in writing concurrent programs in both the message passing and shared memory worlds of concurrency.
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| 10 | Furthermore no other language provides a synchronous multiplexing tool polymorphic over resources like \CFA's waituntil.
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| 11 | From the novel copy queue data structure in the actor system, to the plethora of user-supporting safety features, all these utilities build upon existing tools with value added.
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| 12 |
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| 13 | \section{Future Work}
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| 14 | \subsection{Further Implicit Concurrency}
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| 15 | This thesis scratches the surface of implicit concurrency by providing an actor system.
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| 16 | There is room for more implicit concurrency tools in \CFA.
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| 17 | User-defined implicit concurrency in the form of annotated loops or recursive functions exists in many other languages~\cite{} and could be implemented and expanded on in \CFA.
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| 18 | Additionally, the problem of automatic parallelism of sequential programs via the compiler is an interesting research space that other languages have approached~\cite{} that could also be explored in \CFA.
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| 19 |
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| 20 |
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| 21 | \subsection{Synchronously Multiplexing System Calls}
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| 22 | There are many tools that try to sychronize on or asynchronously check I/O, since improvements in this area pay dividends in many areas of computer science~\cite{}. %cite all the poll/iouring utilities
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| 23 | Research on improving user-space tools to synchronize over I/O and other system calls is an interesting area to explore in the world of concurrent tooling.
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| 24 |
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| 25 | \subsection{Better Atomics}
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| 26 | When writing low level concurrent programs, expecially lock/wait-free programs, low level atomic instructions need to be used.
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| 27 | In C, the gcc-builtin atomics~\cite{} are commonly used, but leave much to be desired.
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| 28 | Some of the problems include the following.
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| 29 | Archaic and opaque macros often have to be used to ensure that atomic assembly is generated instead of locks.
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| 30 | The builtins are polymorphic, but not type safe since they use void pointers.
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| 31 | The semantics and safety of these builtins require careful navigation since they require the user to have a nuanced understanding of concurrent memory ordering models to pass via flags.
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| 32 | Furthermore, these atomics also often require a user to understand how to fence appropriately to ensure correctness.
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| 33 | All these problems and more could benefit from language support, and adding said language support in \CFA could constitute a great research contribution, and allow for easier writing of low-level safe concurrent code.
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