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a9667b5a85
* 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
40 lines
1.1 KiB
Zig
40 lines
1.1 KiB
Zig
// SPDX-License-Identifier: MIT
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// Copyright (c) 2015-2021 Zig Contributors
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// This file is part of [zig](https://ziglang.org/), which is MIT licensed.
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// The MIT license requires this copyright notice to be included in all copies
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// and substantial portions of the software.
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//! A semaphore is an unsigned integer that blocks the kernel thread if
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//! the number would become negative.
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//! This API supports static initialization and does not require deinitialization.
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mutex: Mutex = .{},
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cond: Condition = .{},
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//! It is OK to initialize this field to any value.
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permits: usize = 0,
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const RwLock = @This();
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const std = @import("../std.zig");
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const Mutex = std.Thread.Mutex;
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const Condition = std.Thread.Condition;
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pub fn wait(sem: *Semaphore) void {
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const held = sem.mutex.acquire();
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defer held.release();
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while (sem.permits == 0)
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sem.cond.wait(&sem.mutex);
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sem.permits -= 1;
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if (sem.permits > 0)
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sem.cond.signal();
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}
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pub fn post(sem: *Semaphore) void {
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const held = sem.mutex.acquire();
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defer held.release();
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sem.permits += 1;
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sem.cond.signal();
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}
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