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c7104e7512
ConditionVariable is a thin wrapper over the pthread_cond_* APIs, just as Mutex is a wrapper over pthread_mutex. Because ConditionVariable might want to wait on a high-level Mutex, it needs to be friends with it.
65 lines
1.5 KiB
C++
65 lines
1.5 KiB
C++
/*
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* Copyright (c) 2021, kleines Filmröllchen <malu.bertsch@gmail.com>.
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <AK/Function.h>
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#include <LibThreading/Mutex.h>
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#include <pthread.h>
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#include <sys/cdefs.h>
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#include <sys/types.h>
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namespace Threading {
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// A signaling condition variable that wraps over the pthread_cond_* APIs.
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class ConditionVariable {
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friend class Mutex;
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public:
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ConditionVariable(Mutex& to_wait_on)
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: m_to_wait_on(to_wait_on)
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{
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auto result = pthread_cond_init(&m_condition, nullptr);
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VERIFY(result == 0);
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}
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ALWAYS_INLINE ~ConditionVariable()
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{
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auto result = pthread_cond_destroy(&m_condition);
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VERIFY(result == 0);
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}
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// As with pthread APIs, the mutex must be locked or undefined behavior ensues.
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ALWAYS_INLINE void wait()
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{
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auto result = pthread_cond_wait(&m_condition, &m_to_wait_on.m_mutex);
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VERIFY(result == 0);
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}
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ALWAYS_INLINE void wait_while(Function<bool()> condition)
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{
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while (condition())
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wait();
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}
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// Release at least one of the threads waiting on this variable.
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ALWAYS_INLINE void signal()
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{
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auto result = pthread_cond_signal(&m_condition);
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VERIFY(result == 0);
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}
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// Release all of the threads waiting on this variable.
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ALWAYS_INLINE void broadcast()
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{
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auto result = pthread_cond_broadcast(&m_condition);
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VERIFY(result == 0);
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}
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private:
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pthread_cond_t m_condition;
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Mutex& m_to_wait_on;
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};
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}
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