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-rw-r--r--dom/base/TimeoutExecutor.cpp257
1 files changed, 257 insertions, 0 deletions
diff --git a/dom/base/TimeoutExecutor.cpp b/dom/base/TimeoutExecutor.cpp
new file mode 100644
index 0000000000..466071bf0a
--- /dev/null
+++ b/dom/base/TimeoutExecutor.cpp
@@ -0,0 +1,257 @@
+/* -*- 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