Lime3DS/src/common/thread.h
2016-04-14 13:59:58 +01:00

109 lines
3.0 KiB
C++

// Copyright 2013 Dolphin Emulator Project / 2014 Citra Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.
#pragma once
#include <cstddef>
#include <thread>
#include <condition_variable>
#include <mutex>
#include "common/common_types.h"
// Support for C++11's thread_local keyword was surprisingly spotty in compilers until very
// recently. Fortunately, thread local variables have been well supported for compilers for a while,
// but with semantics supporting only POD types, so we can use a few defines to get some amount of
// backwards compat support.
// WARNING: This only works correctly with POD types.
#if defined(__clang__)
# if !__has_feature(cxx_thread_local)
# define thread_local __thread
# endif
#elif defined(__GNUC__)
# if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 8)
# define thread_local __thread
# endif
#elif defined(_MSC_VER)
# if _MSC_VER < 1900
# define thread_local __declspec(thread)
# endif
#endif
namespace Common {
int CurrentThreadId();
void SetThreadAffinity(std::thread::native_handle_type thread, u32 mask);
void SetCurrentThreadAffinity(u32 mask);
class Event {
public:
Event() : is_set(false) {}
void Set() {
std::lock_guard<std::mutex> lk(mutex);
if (!is_set) {
is_set = true;
condvar.notify_one();
}
}
void Wait() {
std::unique_lock<std::mutex> lk(mutex);
condvar.wait(lk, [&]{ return is_set; });
is_set = false;
}
void Reset() {
std::unique_lock<std::mutex> lk(mutex);
// no other action required, since wait loops on the predicate and any lingering signal will get cleared on the first iteration
is_set = false;
}
private:
bool is_set;
std::condition_variable condvar;
std::mutex mutex;
};
class Barrier {
public:
explicit Barrier(size_t count_) : count(count_), waiting(0), generation(0) {}
/// Blocks until all "count" threads have called Sync()
void Sync() {
std::unique_lock<std::mutex> lk(mutex);
const size_t current_generation = generation;
if (++waiting == count) {
generation++;
waiting = 0;
condvar.notify_all();
} else {
condvar.wait(lk, [this, current_generation]{ return current_generation != generation; });
}
}
private:
std::condition_variable condvar;
std::mutex mutex;
const size_t count;
size_t waiting;
size_t generation; // Incremented once each time the barrier is used
};
void SleepCurrentThread(int ms);
void SwitchCurrentThread(); // On Linux, this is equal to sleep 1ms
// Use this function during a spin-wait to make the current thread
// relax while another thread is working. This may be more efficient
// than using events because event functions use kernel calls.
inline void YieldCPU() {
std::this_thread::yield();
}
void SetCurrentThreadName(const char *name);
} // namespace Common