ladybird/Userland/Libraries/LibThreading/Mutex.h

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/*
* Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2021, kleines Filmröllchen <malu.bertsch@gmail.com>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/Assertions.h>
#include <AK/Noncopyable.h>
#include <AK/Types.h>
#include <pthread.h>
namespace Threading {
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class Mutex {
AK_MAKE_NONCOPYABLE(Mutex);
AK_MAKE_NONMOVABLE(Mutex);
friend class ConditionVariable;
public:
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Mutex()
: m_lock_count(0)
{
pthread_mutexattr_t attr;
pthread_mutexattr_init(&attr);
pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
pthread_mutex_init(&m_mutex, &attr);
}
~Mutex()
{
VERIFY(m_lock_count == 0);
// FIXME: pthread_mutex_destroy() is not implemented.
}
void lock();
void unlock();
private:
pthread_mutex_t m_mutex;
unsigned m_lock_count { 0 };
};
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class MutexLocker {
AK_MAKE_NONCOPYABLE(MutexLocker);
AK_MAKE_NONMOVABLE(MutexLocker);
public:
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ALWAYS_INLINE explicit MutexLocker(Mutex& mutex)
: m_mutex(mutex)
{
lock();
}
ALWAYS_INLINE ~MutexLocker()
{
unlock();
}
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ALWAYS_INLINE void unlock() { m_mutex.unlock(); }
ALWAYS_INLINE void lock() { m_mutex.lock(); }
private:
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Mutex& m_mutex;
};
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ALWAYS_INLINE void Mutex::lock()
{
pthread_mutex_lock(&m_mutex);
m_lock_count++;
}
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ALWAYS_INLINE void Mutex::unlock()
{
VERIFY(m_lock_count > 0);
// FIXME: We need to protect the lock count with the mutex itself.
// This may be bad because we're not *technically* unlocked yet,
// but we're not handling any errors from pthread_mutex_unlock anyways.
m_lock_count--;
pthread_mutex_unlock(&m_mutex);
}
}