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