Beside the new order being consistent with the ThreadPool API and making
more sense, this shuffling allows to write the context argument type in
terms of the startFn arguments, reducing the use of anytype (eg. less
explicit casts when using comptime_int parameters, yay).
Sorry for the breakage.
Closes#8082
* move concurrency primitives that always operate on kernel threads to
the std.Thread namespace
* remove std.SpinLock. Nobody should use this in a non-freestanding
environment; the other primitives are always preferable. In
freestanding, it will be necessary to put custom spin logic in there,
so there are no use cases for a std lib version.
* move some std lib files to the top level fields convention
* add std.Thread.spinLoopHint
* add std.Thread.Condition
* add std.Thread.Semaphore
* new implementation of std.Thread.Mutex for Windows and non-pthreads Linux
* add std.Thread.RwLock
Implementations provided by @kprotty
* split std.ResetEvent into:
- ResetEvent - requires init() at runtime and it can fail. Also
requires deinit().
- StaticResetEvent - can be statically initialized and requires no
deinitialization. Initialization cannot fail.
* the POSIX sem_t implementation can in fact fail on initialization
because it is allowed to be implemented as a file descriptor.
* Completely define, clarify, and explain in detail the semantics of
these APIs. Remove the `isSet` function.
* `ResetEvent.timedWait` returns an enum instead of a possible error.
* `ResetEvent.init` takes a pointer to the ResetEvent instead of
returning a copy.
* On Darwin, `ResetEvent` is implemented using Grand Central Dispatch,
which is exposed by libSystem.
stage2 changes:
* ThreadPool: use a single, pre-initialized `ResetEvent` per worker.
* WaitGroup: now requires init() and deinit() and init() can fail.
- Add a `reset` function.
- Compilation initializes one for the work queue in creation and
re-uses it for every update.
- Rename `stop` to `finish`.
- Simplify the implementation based on the usage pattern.
