citra/src/core/hle/kernel/mutex.cpp

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// Copyright 2014 Citra Emulator Project
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// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.
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#include <map>
#include <vector>
#include <boost/range/algorithm_ext/erase.hpp>
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#include "common/assert.h"
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#include "core/hle/kernel/kernel.h"
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#include "core/hle/kernel/mutex.h"
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#include "core/hle/kernel/thread.h"
namespace Kernel {
/**
* Resumes a thread waiting for the specified mutex
* @param mutex The mutex that some thread is waiting on
*/
static void ResumeWaitingThread(Mutex* mutex) {
// Reset mutex lock thread handle, nothing is waiting
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mutex->lock_count = 0;
mutex->holding_thread = nullptr;
// Find the next waiting thread for the mutex...
auto next_thread = mutex->WakeupNextThread();
if (next_thread != nullptr) {
mutex->Acquire(next_thread);
}
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}
void ReleaseThreadMutexes(Thread* thread) {
for (auto& mtx : thread->held_mutexes) {
ResumeWaitingThread(mtx.get());
}
thread->held_mutexes.clear();
}
Mutex::Mutex() {}
Mutex::~Mutex() {}
SharedPtr<Mutex> Mutex::Create(bool initial_locked, std::string name) {
SharedPtr<Mutex> mutex(new Mutex);
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mutex->lock_count = 0;
mutex->name = std::move(name);
mutex->holding_thread = nullptr;
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// Acquire mutex with current thread if initialized as locked...
if (initial_locked)
mutex->Acquire();
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return mutex;
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}
bool Mutex::ShouldWait() {
auto thread = GetCurrentThread();
bool wait = lock_count > 0 && holding_thread != thread;
// If the holding thread of the mutex is lower priority than this thread, that thread should
// temporarily inherit this thread's priority
if (wait && thread->current_priority < holding_thread->current_priority)
holding_thread->BoostPriority(thread->current_priority);
return wait;
}
void Mutex::Acquire() {
Acquire(GetCurrentThread());
}
void Mutex::Acquire(SharedPtr<Thread> thread) {
ASSERT_MSG(!ShouldWait(), "object unavailable!");
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// Actually "acquire" the mutex only if we don't already have it...
if (lock_count == 0) {
thread->held_mutexes.insert(this);
holding_thread = std::move(thread);
}
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lock_count++;
}
void Mutex::Release() {
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// Only release if the mutex is held...
if (lock_count > 0) {
lock_count--;
// Yield to the next thread only if we've fully released the mutex...
if (lock_count == 0) {
holding_thread->held_mutexes.erase(this);
ResumeWaitingThread(this);
}
}
HLE::Reschedule(__func__);
}
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} // namespace