Source/WTF/wtf/cf/RunLoopCF.cpp

/*
 * Copyright (C) 2010-2019 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "config.h"
#include <wtf/RunLoop.h>

#include <wtf/AutodrainedPool.h>
#include <wtf/SchedulePair.h>

namespace WTF {

static RetainPtr<CFRunLoopTimerRef> createTimer(Seconds interval, bool repeat, void(*timerFired)(CFRunLoopTimerRef, void*), void* info)
{
    CFRunLoopTimerContext context = { 0, info, 0, 0, 0 };
    Seconds repeatInterval = repeat ? interval : 0_s;
    return adoptCF(CFRunLoopTimerCreate(kCFAllocatorDefault, CFAbsoluteTimeGetCurrent() + interval.seconds(), repeatInterval.seconds(), 0, 0, timerFired, &context));
}

void RunLoop::performWork(void* context)
{
    AutodrainedPool pool;
    static_cast<RunLoop*>(context)->performWork();
}

RunLoop::RunLoop()
    : m_runLoop(CFRunLoopGetCurrent())
{
    CFRunLoopSourceContext context = { 0, this, 0, 0, 0, 0, 0, 0, 0, performWork };
    lazyInitialize(m_runLoopSource, adoptCF(CFRunLoopSourceCreate(kCFAllocatorDefault, 0, &context)));
    CFRunLoopAddSource(m_runLoop.get(), m_runLoopSource.get(), kCFRunLoopCommonModes);
}

RunLoop::~RunLoop()
{
    CFRunLoopSourceInvalidate(m_runLoopSource.get());
}

void RunLoop::wakeUp()
{
    CFRunLoopSourceSignal(m_runLoopSource.get());
    CFRunLoopWakeUp(m_runLoop.get());
}

RunLoop::CycleResult RunLoop::cycle(RunLoopMode mode)
{
    CFTimeInterval timeInterval = 0.05;
    CFRunLoopRunInMode(mode, timeInterval, true);
    return CycleResult::Continue;
}

void RunLoop::run()
{
    AutodrainedPool pool;
    CFRunLoopRun();
}

void RunLoop::stop()
{
    ASSERT(m_runLoop == CFRunLoopGetCurrent());
    CFRunLoopStop(m_runLoop.get());
}

void RunLoop::dispatch(const SchedulePairHashSet& schedulePairs, Function<void()>&& function)
{
    auto timer = createTimer(0_s, false, [] (CFRunLoopTimerRef timer, void* context) {
        AutodrainedPool pool;

        CFRunLoopTimerInvalidate(timer);

        auto function = adopt(static_cast<Function<void()>::Impl*>(context));
        function();
    }, function.leak());

    for (auto& schedulePair : schedulePairs)
        CFRunLoopAddTimer(protect(schedulePair->runLoop()).get(), timer.get(), protect(schedulePair->mode()).get());
}

// RunLoop::Timer

RunLoop::TimerBase::TimerBase(Ref<RunLoop>&& runLoop, ASCIILiteral description)
    : m_runLoop(WTF::move(runLoop))
    , m_description(description)
{
    m_runLoop->registerTimer(*this);
}

RunLoop::TimerBase::~TimerBase()
{
    stop();
    m_runLoop->unregisterTimer(*this);
}

void RunLoop::TimerBase::start(Seconds interval, bool repeat)
{
    if (m_timer) {
        bool canReschedule = !repeat && !CFRunLoopTimerDoesRepeat(m_timer.get()) && CFRunLoopTimerIsValid(m_timer.get());
        if (canReschedule) {
            CFRunLoopTimerSetNextFireDate(m_timer.get(), CFAbsoluteTimeGetCurrent() + interval.seconds());
            return;
        }

        // Re-arm the timer by invalidating the old CFRunLoopTimer in place. Unlike stop(), this does
        // NOT assert run-loop affinity: start() may legitimately be called from another thread to (re)arm
        // a timer -- e.g. JSRunLoopTimer::Manager arms its per-VM timer from GC and Wasm compiler threads.
        // This does not free the TimerBase, so it cannot cause the cross-thread use-after-free that stop()
        // and the destructor guard against.
        CFRunLoopTimerInvalidate(m_timer.get());
        m_timer = nullptr;
    }

    m_timer = createTimer(interval, repeat, [] (CFRunLoopTimerRef cfTimer, void* context) {
        AutodrainedPool pool;

        auto timer = static_cast<TimerBase*>(context);
        if (!CFRunLoopTimerDoesRepeat(cfTimer))
            CFRunLoopTimerInvalidate(cfTimer);

        timer->fired();
    }, this);

    CFRunLoopAddTimer(m_runLoop->m_runLoop.get(), m_timer.get(), kCFRunLoopCommonModes);
}

void RunLoop::TimerBase::stop()
{
    if (!m_timer)
        return;

    // An active timer must be stopped (and destroyed) on its run loop's thread: the CFRunLoopTimer
    // holds a raw pointer to this TimerBase as its callback context, and CFRunLoopTimerInvalidate()
    // does not synchronize with a callback already dispatching on the run loop's thread, so invalidating
    // from another thread races with the in-flight callback and can leave it reading freed memory.
    // (Starting a timer cross-thread is safe and supported -- that is how dispatch()/dispatchAfter()
    // schedule work onto another run loop.)
    releaseAssertIsCurrent(m_runLoop);
    CFRunLoopTimerInvalidate(m_timer.get());
    m_timer = nullptr;
}

bool RunLoop::TimerBase::isActive() const
{
    return m_timer && CFRunLoopTimerIsValid(m_timer.get());
}

Seconds RunLoop::TimerBase::secondsUntilFire() const
{
    if (isActive())
        return std::max<Seconds>(Seconds { CFRunLoopTimerGetNextFireDate(m_timer.get()) - CFAbsoluteTimeGetCurrent() }, 0_s);
    return 0_s;
}

} // namespace WTF