citra/src/common/thread.h

// 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

// Don't include common.h here as it will break LogManager
#include "common/common_types.h"
#include <cstdio>
#include <cstring>
#include <thread>
#include <condition_variable>
#include <mutex>

// This may not be defined outside _WIN32
#ifndef _WIN32
#ifndef INFINITE
#define INFINITE 0xffffffff
#endif

//for gettimeofday and struct time(spec|val)
#include <time.h>
#include <sys/time.h>
#include <unistd.h>
#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(m_mutex);
        if (!is_set)
        {
            is_set = true;
            m_condvar.notify_one();
        }
    }

    void Wait()
    {
        std::unique_lock<std::mutex> lk(m_mutex);
        m_condvar.wait(lk, IsSet(this));
        is_set = false;
    }

    void Reset()
    {
        std::unique_lock<std::mutex> lk(m_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:
    class IsSet
    {
    public:
        IsSet(const Event* ev)
            : m_event(ev)
        {}

        bool operator()()
        {
            return m_event->is_set;
        }

    private:
        const Event* const m_event;
    };

    volatile bool is_set;
    std::condition_variable m_condvar;
    std::mutex m_mutex;
};

// TODO: doesn't work on windows with (count > 2)
class Barrier
{
public:
    Barrier(size_t count)
        : m_count(count), m_waiting(0)
    {}

    // block until "count" threads call Sync()
    bool Sync()
    {
        std::unique_lock<std::mutex> lk(m_mutex);

        // TODO: broken when next round of Sync()s
        // is entered before all waiting threads return from the notify_all

        if (m_count == ++m_waiting)
        {
            m_waiting = 0;
            m_condvar.notify_all();
            return true;
        }
        else
        {
            m_condvar.wait(lk, IsDoneWating(this));
            return false;
        }
    }

private:
    class IsDoneWating
    {
    public:
        IsDoneWating(const Barrier* bar)
            : m_bar(bar)
        {}

        bool operator()()
        {
            return (0 == m_bar->m_waiting);
        }

    private:
        const Barrier* const m_bar;
    };

    std::condition_variable m_condvar;
    std::mutex m_mutex;
    const size_t m_count;
    volatile size_t m_waiting;
};

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