Quelle TimeoutExecutor.cpp Sprache: C

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "TimeoutExecutor.h"

#include "mozilla/EventQueue.h"
#include "mozilla/Logging.h"
#include "mozilla/dom/TimeoutManager.h"
#include "nsComponentManagerUtils.h"
#include "nsIEventTarget.h"
#include "nsString.h"
#include "nsThreadUtils.h"

extern mozilla::LazyLogModule gTimeoutLog;

namespace mozilla::dom {

NS_IMPL_ISUPPORTS(TimeoutExecutor, nsIRunnable, nsITimerCallback, nsINamed)

TimeoutExecutor::~TimeoutExecutor() {
  // The TimeoutManager should keep the Executor alive until its destroyed,
  // and then call Shutdown() explicitly.
  MOZ_DIAGNOSTIC_ASSERT(mMode == Mode::Shutdown);
  MOZ_DIAGNOSTIC_ASSERT(!mOwner);
  MOZ_DIAGNOSTIC_ASSERT(!mTimer);
}

nsresult TimeoutExecutor::ScheduleImmediate(const TimeStamp& aDeadline,
                                            const TimeStamp& aNow) {
  MOZ_DIAGNOSTIC_ASSERT(mDeadline.IsNull());
  MOZ_DIAGNOSTIC_ASSERT(mMode == Mode::None);
  MOZ_DIAGNOSTIC_ASSERT(aDeadline <= (aNow + mAllowedEarlyFiringTime));

  nsresult rv;
  if (mIsIdleQueue) {
    RefPtr<TimeoutExecutor> runnable(this);
    MOZ_LOG(gTimeoutLog, LogLevel::Debug, ("Starting IdleDispatch runnable"));
    rv = NS_DispatchToCurrentThreadQueue(runnable.forget(), mMaxIdleDeferMS,
                                         EventQueuePriority::DeferredTimers);
  } else {
    rv = mOwner->EventTarget()->Dispatch(this, nsIEventTarget::DISPATCH_NORMAL);
  }
  NS_ENSURE_SUCCESS(rv, rv);

  mMode = Mode::Immediate;
  mDeadline = aDeadline;

  return NS_OK;
}

nsresult TimeoutExecutor::ScheduleDelayed(const TimeStamp& aDeadline,
                                          const TimeStamp& aNow,
                                          const TimeDuration& aMinDelay) {
  MOZ_DIAGNOSTIC_ASSERT(mDeadline.IsNull());
  MOZ_DIAGNOSTIC_ASSERT(mMode == Mode::None);
  MOZ_DIAGNOSTIC_ASSERT(!aMinDelay.IsZero() ||
                        aDeadline > (aNow + mAllowedEarlyFiringTime));

  nsresult rv = NS_OK;

  if (mIsIdleQueue) {
    // Nothing goes into the idletimeouts list if it wasn't going to
    // fire at that time, so we can always schedule idle-execution of
    // these immediately
    return ScheduleImmediate(aNow, aNow);
  }

  if (!mTimer) {
    mTimer = NS_NewTimer(mOwner->EventTarget());
    NS_ENSURE_TRUE(mTimer, NS_ERROR_OUT_OF_MEMORY);

    uint32_t earlyMicros = 0;
    MOZ_ALWAYS_SUCCEEDS(
        mTimer->GetAllowedEarlyFiringMicroseconds(&earlyMicros));
    mAllowedEarlyFiringTime = TimeDuration::FromMicroseconds(earlyMicros);
    // Re-evaluate if we should have scheduled this immediately
    if (aDeadline <= (aNow + mAllowedEarlyFiringTime)) {
      return ScheduleImmediate(aDeadline, aNow);
    }
  } else {
    // Always call Cancel() in case we are re-using a timer.
    rv = mTimer->Cancel();
    NS_ENSURE_SUCCESS(rv, rv);
  }

  // Calculate the delay based on the deadline and current time.  If we have
  // a minimum delay set then clamp to that value.
  //
  // Note, we don't actually adjust our mDeadline for the minimum delay, just
  // the nsITimer value.  This is necessary to avoid lots of needless
  // rescheduling if more deadlines come in between now and the minimum delay
  // firing time.
  TimeDuration delay = TimeDuration::Max(aMinDelay, aDeadline - aNow);

  // Note, we cannot use the normal nsITimer init methods that take
  // integer milliseconds.  We need higher precision.  Consider this
  // situation:
  //
  // 1. setTimeout(f, 1);
  // 2. do some work for 500us
  // 3. setTimeout(g, 1);
  //
  // This should fire f() and g() 500us apart.
  //
  // In the past worked because each setTimeout() got its own nsITimer.  The 1ms
  // was preserved and passed through to nsITimer which converted it to a
  // TimeStamp, etc.
  //
  // Now, however, there is only one nsITimer.  We fire f() and then try to
  // schedule a new nsITimer for g().  Its only 500us in the future, though.  We
  // must be able to pass this fractional value to nsITimer in order to get an
  // accurate wakeup time.
  rv = mTimer->InitHighResolutionWithCallback(this, delay,
                                              nsITimer::TYPE_ONE_SHOT);
  NS_ENSURE_SUCCESS(rv, rv);

  mMode = Mode::Delayed;
  mDeadline = aDeadline;

  return NS_OK;
}

nsresult TimeoutExecutor::Schedule(const TimeStamp& aDeadline,
                                   const TimeDuration& aMinDelay) {
  TimeStamp now(TimeStamp::Now());

  // Schedule an immediate runnable if the desired deadline has passed
  // or is slightly in the future.  This is similar to how nsITimer will
  // fire timers early based on the interval resolution.
  if (aMinDelay.IsZero() && aDeadline <= (now + mAllowedEarlyFiringTime)) {
    return ScheduleImmediate(aDeadline, now);
  }

  return ScheduleDelayed(aDeadline, now, aMinDelay);
}

nsresult TimeoutExecutor::MaybeReschedule(const TimeStamp& aDeadline,
                                          const TimeDuration& aMinDelay) {
  MOZ_DIAGNOSTIC_ASSERT(!mDeadline.IsNull());
  MOZ_DIAGNOSTIC_ASSERT(mMode == Mode::Immediate || mMode == Mode::Delayed);

  if (aDeadline >= mDeadline) {
    return NS_OK;
  }

  if (mMode == Mode::Immediate) {
    // Don't reduce the deadline here as we want to execute the
    // timer we originally scheduled even if its a few microseconds
    // in the future.
    return NS_OK;
  }

  Cancel();
  return Schedule(aDeadline, aMinDelay);
}

void TimeoutExecutor::MaybeExecute() {
  MOZ_DIAGNOSTIC_ASSERT(mMode != Mode::Shutdown && mMode != Mode::None);
  MOZ_DIAGNOSTIC_ASSERT(mOwner);
  MOZ_DIAGNOSTIC_ASSERT(!mDeadline.IsNull());

  TimeStamp deadline(mDeadline);

  // Sometimes nsITimer or canceled timers will fire too early.  If this
  // happens then just cap our deadline to our maximum time in the future
  // and proceed.  If there are no timers ready we will get rescheduled
  // by TimeoutManager.
  TimeStamp now(TimeStamp::Now());
  TimeStamp limit = now + mAllowedEarlyFiringTime;
  if (deadline > limit) {
    deadline = limit;
  }

  Cancel();

  mOwner->RunTimeout(now, deadline, mIsIdleQueue);
}

TimeoutExecutor::TimeoutExecutor(TimeoutManager* aOwner, bool aIsIdleQueue,
                                 uint32_t aMaxIdleDeferMS)
    : mOwner(aOwner),
      mIsIdleQueue(aIsIdleQueue),
      mMaxIdleDeferMS(aMaxIdleDeferMS),
      mMode(Mode::None) {
  MOZ_DIAGNOSTIC_ASSERT(mOwner);
}

void TimeoutExecutor::Shutdown() {
  mOwner = nullptr;

  if (mTimer) {
    mTimer->Cancel();
    mTimer = nullptr;
  }

  mMode = Mode::Shutdown;
  mDeadline = TimeStamp();
}

nsresult TimeoutExecutor::MaybeSchedule(const TimeStamp& aDeadline,
                                        const TimeDuration& aMinDelay) {
  MOZ_DIAGNOSTIC_ASSERT(!aDeadline.IsNull());

  if (mMode == Mode::Shutdown) {
    return NS_OK;
  }

  if (mMode == Mode::Immediate || mMode == Mode::Delayed) {
    return MaybeReschedule(aDeadline, aMinDelay);
  }

  return Schedule(aDeadline, aMinDelay);
}

void TimeoutExecutor::Cancel() {
  if (mTimer) {
    mTimer->Cancel();
  }
  mMode = Mode::None;
  mDeadline = TimeStamp();
}

// MOZ_CAN_RUN_SCRIPT_BOUNDARY until Runnable::Run is MOZ_CAN_RUN_SCRIPT.  See
// bug 1535398.
MOZ_CAN_RUN_SCRIPT_BOUNDARY NS_IMETHODIMP TimeoutExecutor::Run() {
  // If the executor is canceled and then rescheduled its possible to get
  // spurious executions here.  Ignore these unless our current mode matches.
  MOZ_LOG(gTimeoutLog, LogLevel::Debug,
          ("Running Immediate %stimers", mIsIdleQueue ? "Idle" : ""));
  if (mMode == Mode::Immediate) {
    MaybeExecute();
  }
  return NS_OK;
}

// MOZ_CAN_RUN_SCRIPT_BOUNDARY until nsITimerCallback::Notify is
// MOZ_CAN_RUN_SCRIPT.
MOZ_CAN_RUN_SCRIPT_BOUNDARY NS_IMETHODIMP
TimeoutExecutor::Notify(nsITimer* aTimer) {
  // If the executor is canceled and then rescheduled its possible to get
  // spurious executions here.  Ignore these unless our current mode matches.
  if (mMode == Mode::Delayed) {
    MaybeExecute();
  }
  return NS_OK;
}

NS_IMETHODIMP
TimeoutExecutor::GetName(nsACString& aNameOut) {
  aNameOut.AssignLiteral("TimeoutExecutor Runnable");
  return NS_OK;
}

}  // namespace mozilla::dom

quality100%

¤ Dauer der Verarbeitung: 0.16 Sekunden (vorverarbeitet) ¤

Wurzel

Suchen

Beweissystem der NASA

Beweissystem Isabelle

NIST Cobol Testsuite

Cephes Mathematical Library

Wiener Entwicklungsmethode

Haftungshinweis

Die Informationen auf dieser Webseite wurden nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit, noch Qualität der bereit gestellten Informationen zugesichert.

Bemerkung:

Die farbliche Syntaxdarstellung ist noch experimentell.