rippled/modules/beast_core/threads/beast_TimeSliceThread.cpp

//------------------------------------------------------------------------------
/*
    This file is part of Beast: https://github.com/vinniefalco/Beast
    Copyright 2013, Vinnie Falco <vinnie.falco@gmail.com>

    Portions of this file are from JUCE.
    Copyright (c) 2013 - Raw Material Software Ltd.
    Please visit http://www.juce.com

    Permission to use, copy, modify, and/or distribute this software for any
    purpose  with  or without fee is hereby granted, provided that the above
    copyright notice and this permission notice appear in all copies.

    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
//==============================================================================

TimeSliceThread::TimeSliceThread (const String& name)
    : Thread (name),
      clientBeingCalled (nullptr)
{
}

TimeSliceThread::~TimeSliceThread()
{
    stopThread (2000);
}

//==============================================================================
void TimeSliceThread::addTimeSliceClient (TimeSliceClient* const client, int millisecondsBeforeStarting)
{
    if (client != nullptr)
    {
        const ScopedLock sl (listLock);
        client->nextCallTime = Time::getCurrentTime() + RelativeTime::milliseconds (millisecondsBeforeStarting);
        clients.addIfNotAlreadyThere (client);
        notify();
    }
}

void TimeSliceThread::removeTimeSliceClient (TimeSliceClient* const client)
{
    const ScopedLock sl1 (listLock);

    // if there's a chance we're in the middle of calling this client, we need to
    // also lock the outer lock..
    if (clientBeingCalled == client)
    {
        const ScopedUnlock ul (listLock); // unlock first to get the order right..

        const ScopedLock sl2 (callbackLock);
        const ScopedLock sl3 (listLock);

        clients.removeFirstMatchingValue (client);
    }
    else
    {
        clients.removeFirstMatchingValue (client);
    }
}

void TimeSliceThread::moveToFrontOfQueue (TimeSliceClient* client)
{
    const ScopedLock sl (listLock);

    if (clients.contains (client))
    {
        client->nextCallTime = Time::getCurrentTime();
        notify();
    }
}

int TimeSliceThread::getNumClients() const
{
    return clients.size();
}

TimeSliceClient* TimeSliceThread::getClient (const int i) const
{
    const ScopedLock sl (listLock);
    return clients [i];
}

//==============================================================================
TimeSliceClient* TimeSliceThread::getNextClient (int index) const
{
    Time soonest;
    TimeSliceClient* client = nullptr;

    for (int i = clients.size(); --i >= 0;)
    {
        TimeSliceClient* const c = clients.getUnchecked ((i + index) % clients.size());

        if (client == nullptr || c->nextCallTime < soonest)
        {
            client = c;
            soonest = c->nextCallTime;
        }
    }

    return client;
}

void TimeSliceThread::run()
{
    int index = 0;

    while (! threadShouldExit())
    {
        int timeToWait = 500;

        {
            Time nextClientTime;

            {
                const ScopedLock sl2 (listLock);

                index = clients.size() > 0 ? ((index + 1) % clients.size()) : 0;

                if (TimeSliceClient* const firstClient = getNextClient (index))
                    nextClientTime = firstClient->nextCallTime;
            }

            const Time now (Time::getCurrentTime());

            if (nextClientTime > now)
            {
                timeToWait = (int) bmin ((int64) 500, (nextClientTime - now).inMilliseconds());
            }
            else
            {
                timeToWait = index == 0 ? 1 : 0;

                const ScopedLock sl (callbackLock);

                {
                    const ScopedLock sl2 (listLock);
                    clientBeingCalled = getNextClient (index);
                }

                if (clientBeingCalled != nullptr)
                {
                    const int msUntilNextCall = clientBeingCalled->useTimeSlice();

                    const ScopedLock sl2 (listLock);

                    if (msUntilNextCall >= 0)
                        clientBeingCalled->nextCallTime = now + RelativeTime::milliseconds (msUntilNextCall);
                    else
                        clients.removeFirstMatchingValue (clientBeingCalled);

                    clientBeingCalled = nullptr;
                }
            }
        }

        if (timeToWait > 0)
            wait (timeToWait);
    }
}