threads module prototype

[stepancheg]

• threads.core -- basic threads implementation
• threads.future -- C++11-like future utility

[stepancheg]

@jckarter you are right, thanks for pointing it out. Fixed with another hack of shared pointers.

Function cannot be stored in Thread object, because in certain situations thread needs to be detached. We cannot implement thread detach if thread contains a reference to currently executed code. Thread procedure must be responsible for destroying of Function object (however, more generic code still can be moved from platform module to core module, and platform module should work only with code pointers).

I think lib-clay needs something like lambda.Function that can be parameterized by smart pointer type. So uniquepointers should be used instead of sharedpointers.

[jckarter]

It's probably sufficient to have a UniqueFunction counterpart to Function. That would definitely make this easier to reason about—sole ownership of the Function should be moved to the thread procedure once it's started.

[stepancheg]

@jckarter uploaded a better and simpler version with FunctionBody made public. UniqueFunction (as well as parameterized Function) seems to be overcomplication for this task.

[jckarter]

That looks much better indeed. Making the memory management explicit in this case is easier to follow than the implicit memory management of the smarter types.

[jckarter]

This looks good now, aside from the lack of synchronization in join you noted in a comment, though having multiple threads trying to join the same thread in a program sounds like a problematic design anyway.

[ghost]

Linux test failures:

[lib-clay/threads/future]
Failure: compiler error
Error:

 /tmp/clayobj-69edae33.obj:/home/jeremy/dev/clay/clay/test/lib-clay/threads/future/test.clay:function threads.core.platform.startThreadImpl_28_Pointer_5B_FunctionBody_5B__5B__5D__2C__20__5B__5D__5D__5D__29__20_UInt64_20_clay: error: undefined reference to 'pthread_create'
 /tmp/clayobj-69edae33.obj:/home/jeremy/dev/clay/clay/test/lib-clay/threads/future/test.clay:function threads.core.joinThread_28_Thread_29__20_clay: error: undefined reference to 'pthread_join'
 clang: error: linker command failed with exit code 1 (use -v to see invocation)

[lib-clay/threads/core/simple]
Failure: compiler error
Error:

 /tmp/clayobj-d8890559.obj:/home/jeremy/dev/clay/clay/test/lib-clay/threads/core/simple/main.clay:function main: error: undefined reference to 'pthread_create'
 /tmp/clayobj-d8890559.obj:/home/jeremy/dev/clay/clay/test/lib-clay/threads/core/simple/main.clay:function main: error: undefined reference to 'pthread_join'
 clang: error: linker command failed with exit code 1 (use -v to see invocation)

[lib-clay/threads/core/unhandledexception]
Failure: compiler error
Error:

 /tmp/clayobj-ca95d797.obj:/home/jeremy/dev/clay/clay/test/lib-clay/threads/core/unhandledexception/main.clay:function main: error: undefined reference to 'pthread_create'
 /tmp/clayobj-ca95d797.obj:/home/jeremy/dev/clay/clay/test/lib-clay/threads/core/unhandledexception/main.clay:function main: error: undefined reference to 'pthread_join'
 clang: error: linker command failed with exit code 1 (use -v to see invocation)

[stepancheg]

In Linux we need to link with -lpthread. How to fix it properly?

[jckarter]

You could add a buildflags.linux.txt to the tests containing -lpthread.