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Serenity Operating System
1/*
2 * Copyright (c) 2021, kleines Filmröllchen <filmroellchen@serenityos.org>.
3 *
4 * SPDX-License-Identifier: BSD-2-Clause
5 */
6
7#pragma once
8
9#include <AK/Function.h>
10#include <LibThreading/Mutex.h>
11#include <pthread.h>
12#include <sys/types.h>
13
14namespace Threading {
15
16// A signaling condition variable that wraps over the pthread_cond_* APIs.
17class ConditionVariable {
18 friend class Mutex;
19
20public:
21 ConditionVariable(Mutex& to_wait_on)
22 : m_to_wait_on(to_wait_on)
23 {
24 auto result = pthread_cond_init(&m_condition, nullptr);
25 VERIFY(result == 0);
26 }
27
28 ALWAYS_INLINE ~ConditionVariable()
29 {
30 auto result = pthread_cond_destroy(&m_condition);
31 VERIFY(result == 0);
32 }
33
34 // As with pthread APIs, the mutex must be locked or undefined behavior ensues.
35 ALWAYS_INLINE void wait()
36 {
37 auto result = pthread_cond_wait(&m_condition, &m_to_wait_on.m_mutex);
38 VERIFY(result == 0);
39 }
40 ALWAYS_INLINE void wait_while(Function<bool()> condition)
41 {
42 while (condition())
43 wait();
44 }
45 // Release at least one of the threads waiting on this variable.
46 ALWAYS_INLINE void signal()
47 {
48 auto result = pthread_cond_signal(&m_condition);
49 VERIFY(result == 0);
50 }
51 // Release all of the threads waiting on this variable.
52 ALWAYS_INLINE void broadcast()
53 {
54 auto result = pthread_cond_broadcast(&m_condition);
55 VERIFY(result == 0);
56 }
57
58private:
59 pthread_cond_t m_condition;
60 Mutex& m_to_wait_on;
61};
62
63}