| // Copyright (c) 2010 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #include "base/watchdog.h" |
| |
| #include "base/compiler_specific.h" |
| #include "base/logging.h" |
| #include "base/platform_thread.h" |
| |
| using base::TimeDelta; |
| using base::TimeTicks; |
| |
| //------------------------------------------------------------------------------ |
| // Public API methods. |
| |
| // Start thread running in a Disarmed state. |
| Watchdog::Watchdog(const TimeDelta& duration, |
| const std::string& thread_watched_name, |
| bool enabled) |
| : init_successful_(false), |
| lock_(), |
| condition_variable_(&lock_), |
| state_(DISARMED), |
| duration_(duration), |
| thread_watched_name_(thread_watched_name), |
| ALLOW_THIS_IN_INITIALIZER_LIST(delegate_(this)) { |
| if (!enabled) |
| return; // Don't start thread, or doing anything really. |
| init_successful_ = PlatformThread::Create(0, // Default stack size. |
| &delegate_, |
| &handle_); |
| DCHECK(init_successful_); |
| } |
| |
| // Notify watchdog thread, and wait for it to finish up. |
| Watchdog::~Watchdog() { |
| if (!init_successful_) |
| return; |
| { |
| AutoLock lock(lock_); |
| state_ = SHUTDOWN; |
| } |
| condition_variable_.Signal(); |
| PlatformThread::Join(handle_); |
| } |
| |
| void Watchdog::Arm() { |
| ArmAtStartTime(TimeTicks::Now()); |
| } |
| |
| void Watchdog::ArmSomeTimeDeltaAgo(const TimeDelta& time_delta) { |
| ArmAtStartTime(TimeTicks::Now() - time_delta); |
| } |
| |
| // Start clock for watchdog. |
| void Watchdog::ArmAtStartTime(const TimeTicks start_time) { |
| { |
| AutoLock lock(lock_); |
| start_time_ = start_time; |
| state_ = ARMED; |
| } |
| // Force watchdog to wake up, and go to sleep with the timer ticking with the |
| // proper duration. |
| condition_variable_.Signal(); |
| } |
| |
| // Disable watchdog so that it won't do anything when time expires. |
| void Watchdog::Disarm() { |
| AutoLock lock(lock_); |
| state_ = DISARMED; |
| // We don't need to signal, as the watchdog will eventually wake up, and it |
| // will check its state and time, and act accordingly. |
| } |
| |
| void Watchdog::Alarm() { |
| DVLOG(1) << "Watchdog alarmed for " << thread_watched_name_; |
| } |
| |
| //------------------------------------------------------------------------------ |
| // Internal private methods that the watchdog thread uses. |
| |
| void Watchdog::ThreadDelegate::ThreadMain() { |
| SetThreadName(); |
| TimeDelta remaining_duration; |
| while (1) { |
| AutoLock lock(watchdog_->lock_); |
| while (DISARMED == watchdog_->state_) |
| watchdog_->condition_variable_.Wait(); |
| if (SHUTDOWN == watchdog_->state_) |
| return; |
| DCHECK(ARMED == watchdog_->state_); |
| remaining_duration = watchdog_->duration_ - |
| (TimeTicks::Now() - watchdog_->start_time_); |
| if (remaining_duration.InMilliseconds() > 0) { |
| // Spurios wake? Timer drifts? Go back to sleep for remaining time. |
| watchdog_->condition_variable_.TimedWait(remaining_duration); |
| continue; |
| } |
| // We overslept, so this seems like a real alarm. |
| // Watch out for a user that stopped the debugger on a different alarm! |
| { |
| AutoLock static_lock(static_lock_); |
| if (last_debugged_alarm_time_ > watchdog_->start_time_) { |
| // False alarm: we started our clock before the debugger break (last |
| // alarm time). |
| watchdog_->start_time_ += last_debugged_alarm_delay_; |
| if (last_debugged_alarm_time_ > watchdog_->start_time_) |
| // Too many alarms must have taken place. |
| watchdog_->state_ = DISARMED; |
| continue; |
| } |
| } |
| watchdog_->state_ = DISARMED; // Only alarm at most once. |
| TimeTicks last_alarm_time = TimeTicks::Now(); |
| watchdog_->Alarm(); // Set a break point here to debug on alarms. |
| TimeDelta last_alarm_delay = TimeTicks::Now() - last_alarm_time; |
| if (last_alarm_delay <= TimeDelta::FromMilliseconds(2)) |
| continue; |
| // Ignore race of two alarms/breaks going off at roughly the same time. |
| AutoLock static_lock(static_lock_); |
| // This was a real debugger break. |
| last_debugged_alarm_time_ = last_alarm_time; |
| last_debugged_alarm_delay_ = last_alarm_delay; |
| } |
| } |
| |
| void Watchdog::ThreadDelegate::SetThreadName() const { |
| std::string name = watchdog_->thread_watched_name_ + " Watchdog"; |
| PlatformThread::SetName(name.c_str()); |
| DVLOG(1) << "Watchdog active: " << name; |
| } |
| |
| // static |
| void Watchdog::ResetStaticData() { |
| AutoLock lock(static_lock_); |
| last_debugged_alarm_time_ = TimeTicks(); |
| last_debugged_alarm_delay_ = TimeDelta(); |
| } |
| |
| // static |
| Lock Watchdog::static_lock_; // Lock for access of static data... |
| // static |
| TimeTicks Watchdog::last_debugged_alarm_time_ = TimeTicks(); |
| // static |
| TimeDelta Watchdog::last_debugged_alarm_delay_; |