mirror of
https://codeberg.org/ziglang/zig.git
synced 2025-12-06 13:54:21 +00:00
39 lines
1.1 KiB
Zig
39 lines
1.1 KiB
Zig
// 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 Semaphore = @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();
|
|
}
|