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/*
* Copyright (C) 2013, 2015 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. ``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
* 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 "Watchdog.h"
#include "CallFrame.h"
#include <wtf/CurrentTime.h>
#include <wtf/MathExtras.h>
namespace JSC {
const std::chrono::microseconds Watchdog::noTimeLimit = std::chrono::microseconds::max();
static std::chrono::microseconds currentWallClockTime()
{
auto steadyTimeSinceEpoch = std::chrono::steady_clock::now().time_since_epoch();
return std::chrono::duration_cast<std::chrono::microseconds>(steadyTimeSinceEpoch);
}
Watchdog::Watchdog()
: m_timerDidFire(false)
, m_timeLimit(noTimeLimit)
, m_cpuDeadline(noTimeLimit)
, m_wallClockDeadline(noTimeLimit)
, m_callback(0)
, m_callbackData1(0)
, m_callbackData2(0)
, m_timerQueue(WorkQueue::create("jsc.watchdog.queue", WorkQueue::Type::Serial, WorkQueue::QOS::Utility))
{
m_timerHandler = [this] {
{
LockHolder locker(m_lock);
this->m_timerDidFire = true;
}
this->deref();
};
}
void Watchdog::setTimeLimit(std::chrono::microseconds limit,
ShouldTerminateCallback callback, void* data1, void* data2)
{
LockHolder locker(m_lock);
m_timeLimit = limit;
m_callback = callback;
m_callbackData1 = data1;
m_callbackData2 = data2;
if (m_hasEnteredVM && hasTimeLimit())
startTimer(locker, m_timeLimit);
}
JS_EXPORT_PRIVATE void Watchdog::terminateSoon()
{
LockHolder locker(m_lock);
m_timeLimit = std::chrono::microseconds(0);
m_cpuDeadline = std::chrono::microseconds(0);
m_wallClockDeadline = std::chrono::microseconds(0);
m_timerDidFire = true;
}
bool Watchdog::shouldTerminateSlow(ExecState* exec)
{
{
LockHolder locker(m_lock);
ASSERT(m_timerDidFire);
m_timerDidFire = false;
if (currentWallClockTime() < m_wallClockDeadline)
return false; // Just a stale timer firing. Nothing to do.
// Set m_wallClockDeadline to noTimeLimit here so that we can reject all future
// spurious wakes.
m_wallClockDeadline = noTimeLimit;
auto cpuTime = currentCPUTime();
if (cpuTime < m_cpuDeadline) {
auto remainingCPUTime = m_cpuDeadline - cpuTime;
startTimer(locker, remainingCPUTime);
return false;
}
}
// Note: we should not be holding the lock while calling the callbacks. The callbacks may
// call setTimeLimit() which will try to lock as well.
// If m_callback is not set, then we terminate by default.
// Else, we let m_callback decide if we should terminate or not.
bool needsTermination = !m_callback
|| m_callback(exec, m_callbackData1, m_callbackData2);
if (needsTermination)
return true;
{
LockHolder locker(m_lock);
// If we get here, then the callback above did not want to terminate execution. As a
// result, the callback may have done one of the following:
// 1. cleared the time limit (i.e. watchdog is disabled),
// 2. set a new time limit via Watchdog::setTimeLimit(), or
// 3. did nothing (i.e. allow another cycle of the current time limit).
//
// In the case of 1, we don't have to do anything.
// In the case of 2, Watchdog::setTimeLimit() would already have started the timer.
// In the case of 3, we need to re-start the timer here.
ASSERT(m_hasEnteredVM);
bool callbackAlreadyStartedTimer = (m_cpuDeadline != noTimeLimit);
if (hasTimeLimit() && !callbackAlreadyStartedTimer)
startTimer(locker, m_timeLimit);
}
return false;
}
bool Watchdog::hasTimeLimit()
{
return (m_timeLimit != noTimeLimit);
}
void Watchdog::enteredVM()
{
m_hasEnteredVM = true;
if (hasTimeLimit()) {
LockHolder locker(m_lock);
startTimer(locker, m_timeLimit);
}
}
void Watchdog::exitedVM()
{
ASSERT(m_hasEnteredVM);
LockHolder locker(m_lock);
stopTimer(locker);
m_hasEnteredVM = false;
}
void Watchdog::startTimer(LockHolder&, std::chrono::microseconds timeLimit)
{
ASSERT(m_hasEnteredVM);
ASSERT(hasTimeLimit());
ASSERT(timeLimit <= m_timeLimit);
m_cpuDeadline = currentCPUTime() + timeLimit;
auto wallClockTime = currentWallClockTime();
auto wallClockDeadline = wallClockTime + timeLimit;
if ((wallClockTime < m_wallClockDeadline)
&& (m_wallClockDeadline <= wallClockDeadline))
return; // Wait for the current active timer to expire before starting a new one.
// Else, the current active timer won't fire soon enough. So, start a new timer.
this->ref(); // m_timerHandler will deref to match later.
m_wallClockDeadline = wallClockDeadline;
m_timerQueue->dispatchAfter(std::chrono::nanoseconds(timeLimit), m_timerHandler);
}
void Watchdog::stopTimer(LockHolder&)
{
m_cpuDeadline = noTimeLimit;
}
} // namespace JSC
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