thread.cpp

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/*
   Copyright (C) 2003 - 2016 by David White <[email protected]>
   Part of the Battle for Wesnoth Project http://www.wesnoth.org/

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY.

   See the COPYING file for more details.
*/

#include "global.hpp"

#include <vector>

#include "log.hpp"
#include "thread.hpp"

#include <SDL_mutex.h>
#include <SDL_thread.h>
#include <SDL_version.h>

#define ERR_G LOG_STREAM(err, lg::general())

boost::uint32_t threading::thread::get_id() { return SDL_GetThreadID(thread_); }

boost::uint32_t threading::get_current_thread_id() { return SDL_ThreadID(); }

static int run_async_operation(void* data)
{
    threading::async_operation_ptr op(*reinterpret_cast<threading::async_operation_ptr*>(data));
    op->run();

    const threading::lock l(op->get_mutex());
    op->notify_finished(); //in case the operation didn't notify of finishing

    return 0;
}

namespace {

std::vector<SDL_Thread*> detached_threads;

}

namespace threading {

manager::~manager()
{
    for(std::vector<SDL_Thread*>::iterator i = detached_threads.begin(); i != detached_threads.end(); ++i) {
        SDL_WaitThread(*i,nullptr);
    }
}

thread::thread(int (*f)(void*), void* data)
    : thread_(SDL_CreateThread(f, "", data))
{
}

thread::~thread()
{
    join();
}

void thread::join()
{
    if(thread_ != nullptr) {
        SDL_WaitThread(thread_,nullptr);
        thread_ = nullptr;
    }
}

void thread::detach()
{
    detached_threads.push_back(thread_);
    thread_ = nullptr;
}

mutex::mutex() : m_(SDL_CreateMutex())
{}

mutex::~mutex()
{
    SDL_DestroyMutex(m_);
}

lock::lock(mutex& m) : m_(m)
{
    SDL_mutexP(m_.m_);
}

lock::~lock()
{
    SDL_mutexV(m_.m_);
}

condition::condition() : cond_(SDL_CreateCond())
{}

condition::~condition()
{
    SDL_DestroyCond(cond_);
}

bool condition::wait(const mutex& m)
{
    return SDL_CondWait(cond_,m.m_) == 0;
}

condition::WAIT_TIMEOUT_RESULT condition::wait_timeout(const mutex& m, unsigned int timeout)
{
    const int res = SDL_CondWaitTimeout(cond_,m.m_,timeout);
    switch(res) {
        case 0: return WAIT_OK;
        case SDL_MUTEX_TIMEDOUT: return WAIT_TIMED_OUT;
        default:
            ERR_G << "SDL_CondWaitTimeout: " << SDL_GetError() << std::endl;
            return WAIT_ERROR;
    }
}

bool condition::notify_one()
{
    if(SDL_CondSignal(cond_) < 0) {
        ERR_G << "SDL_CondSignal: " << SDL_GetError() << std::endl;
        return false;
    }

    return true;
}

bool condition::notify_all()
{
    if(SDL_CondBroadcast(cond_) < 0) {
        ERR_G << "SDL_CondBroadcast: " << SDL_GetError() << std::endl;
        return false;
    }
    return true;
}

bool async_operation::notify_finished()
{
    finishedVar_ = true;
    return finished_.notify_one();
}
active_operation_list async_operation::active_;

async_operation::RESULT async_operation::execute(async_operation_ptr this_ptr, waiter& wait)
{
    //the thread must be created after the lock, and also destroyed after it.
    //this is because during the thread's execution, we must always hold the mutex
    //unless we are waiting on notification that the thread is finished, or we have
    //already received that notification.
    //
    //we cannot hold the mutex while waiting for the thread to join though, because
    //the thread needs access to the mutex before it terminates
    {
        const lock l(get_mutex());
        active_.push_back(this_ptr);
        thread_.reset(new thread(run_async_operation,&this_ptr));

        bool completed = false;
        while(wait.process() == waiter::WAIT) {
            const condition::WAIT_TIMEOUT_RESULT res = finished_.wait_timeout(get_mutex(),20);
            if(res == condition::WAIT_OK || finishedVar_) {
                completed = true;
                break;
            } else if(res == condition::WAIT_ERROR) {
                break;
            }
        }

        if(!completed) {
            aborted_ = true;
            return ABORTED;
        }
    }

    return COMPLETED;
}


}