// Copyright 2014 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "components/timers/alarm_timer_chromeos.h"
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#include <stdint.h>
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#include <sys/timerfd.h>
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#include <algorithm>
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#include <memory>
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#include <utility>
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#include "base/bind.h"
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#include "base/debug/task_annotator.h"
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#include "base/files/file_util.h"
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#include "base/logging.h"
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#include "base/pending_task.h"
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#include "base/trace_event/trace_event.h"
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namespace timers {
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SimpleAlarmTimer::SimpleAlarmTimer()
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: alarm_fd_(timerfd_create(CLOCK_REALTIME_ALARM, 0)), weak_factory_(this) {}
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SimpleAlarmTimer::~SimpleAlarmTimer() {
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DCHECK(origin_task_runner_->RunsTasksInCurrentSequence());
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Stop();
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}
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void SimpleAlarmTimer::Stop() {
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DCHECK(origin_task_runner_->RunsTasksInCurrentSequence());
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if (!IsRunning())
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return;
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if (!CanWakeFromSuspend()) {
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base::RetainingOneShotTimer::Stop();
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return;
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}
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// Cancel any previous callbacks.
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weak_factory_.InvalidateWeakPtrs();
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base::RetainingOneShotTimer::set_is_running(false);
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alarm_fd_watcher_.reset();
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pending_task_.reset();
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}
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void SimpleAlarmTimer::Reset() {
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DCHECK(origin_task_runner_->RunsTasksInCurrentSequence());
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DCHECK(!base::RetainingOneShotTimer::user_task().is_null());
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if (!CanWakeFromSuspend()) {
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base::RetainingOneShotTimer::Reset();
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return;
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}
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// Cancel any previous callbacks and stop watching |alarm_fd_|.
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weak_factory_.InvalidateWeakPtrs();
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alarm_fd_watcher_.reset();
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// Ensure that the delay is not negative.
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const base::TimeDelta delay = std::max(
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base::TimeDelta(), base::RetainingOneShotTimer::GetCurrentDelay());
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// Set up the pending task.
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base::RetainingOneShotTimer::set_desired_run_time(
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delay.is_zero() ? base::TimeTicks() : base::TimeTicks::Now() + delay);
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pending_task_ = std::make_unique<base::PendingTask>(
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base::RetainingOneShotTimer::posted_from(),
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base::RetainingOneShotTimer::user_task(),
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base::RetainingOneShotTimer::desired_run_time());
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// Set |alarm_fd_| to be signaled when the delay expires. If the delay is
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// zero, |alarm_fd_| will never be signaled. This overrides the previous
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// delay, if any.
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itimerspec alarm_time = {};
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alarm_time.it_value.tv_sec = delay.InSeconds();
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alarm_time.it_value.tv_nsec =
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(delay.InMicroseconds() % base::Time::kMicrosecondsPerSecond) *
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base::Time::kNanosecondsPerMicrosecond;
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if (timerfd_settime(alarm_fd_, 0, &alarm_time, NULL) < 0)
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PLOG(ERROR) << "Error while setting alarm time. Timer will not fire";
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// The timer is running.
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base::RetainingOneShotTimer::set_is_running(true);
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// If the delay is zero, post the task now.
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if (delay.is_zero()) {
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origin_task_runner_->PostTask(
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FROM_HERE, base::BindOnce(&SimpleAlarmTimer::OnTimerFired,
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weak_factory_.GetWeakPtr()));
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} else {
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// Otherwise, if the delay is not zero, generate a tracing event to indicate
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// that the task was posted and watch |alarm_fd_|.
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base::debug::TaskAnnotator().WillQueueTask("SimpleAlarmTimer::Reset",
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pending_task_.get());
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alarm_fd_watcher_ = base::FileDescriptorWatcher::WatchReadable(
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alarm_fd_,
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base::BindRepeating(&SimpleAlarmTimer::OnAlarmFdReadableWithoutBlocking,
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weak_factory_.GetWeakPtr()));
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}
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}
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void SimpleAlarmTimer::OnAlarmFdReadableWithoutBlocking() {
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DCHECK(origin_task_runner_->RunsTasksInCurrentSequence());
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DCHECK(base::RetainingOneShotTimer::IsRunning());
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// Read from |alarm_fd_| to ack the event.
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char val[sizeof(uint64_t)];
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if (!base::ReadFromFD(alarm_fd_, val, sizeof(uint64_t)))
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PLOG(DFATAL) << "Unable to read from timer file descriptor.";
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OnTimerFired();
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}
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void SimpleAlarmTimer::OnTimerFired() {
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DCHECK(origin_task_runner_->RunsTasksInCurrentSequence());
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DCHECK(base::RetainingOneShotTimer::IsRunning());
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DCHECK(pending_task_.get());
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// Take ownership of the PendingTask to prevent it from being deleted if the
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// SimpleAlarmTimer is deleted.
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const auto pending_user_task = std::move(pending_task_);
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base::WeakPtr<SimpleAlarmTimer> weak_ptr = weak_factory_.GetWeakPtr();
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// Run the task.
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TRACE_TASK_EXECUTION("SimpleAlarmTimer::OnTimerFired", *pending_user_task);
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base::debug::TaskAnnotator().RunTask("SimpleAlarmTimer::Reset",
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pending_user_task.get());
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// If the timer wasn't deleted, stopped or reset by the callback, stop it.
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if (weak_ptr)
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Stop();
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}
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bool SimpleAlarmTimer::CanWakeFromSuspend() const {
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return alarm_fd_ != -1;
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}
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} // namespace timers
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