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// Copyright 2008, Google 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:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * 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.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "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 THE COPYRIGHT
// OWNER 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 "base/watchdog.h"
#include "base/string_util.h"
#include "base/thread.h"
//------------------------------------------------------------------------------
// Public API methods.
// Start thread running in a Disarmed state.
Watchdog::Watchdog(const TimeDelta& duration,
const std::wstring& thread_watched_name,
bool enabled)
: lock_(),
condition_variable_(&lock_),
state_(DISARMED),
duration_(duration),
thread_watched_name_(thread_watched_name),
handle_(NULL),
thread_id_(0) {
if (!enabled)
return; // Don't start thread, or doing anything really.
handle_ = CreateThread(NULL, // security
0, // Default stack size.
Watchdog::ThreadStart,
reinterpret_cast<void*>(this),
CREATE_SUSPENDED,
&thread_id_);
DCHECK(NULL != handle_);
if (NULL == handle_)
return ;
ResumeThread(handle_); // WINAPI call.
}
// Notify watchdog thread, and wait for it to finish up.
Watchdog::~Watchdog() {
if (NULL == handle_)
return;
{
AutoLock lock(lock_);
state_ = SHUTDOWN;
}
condition_variable_.Signal();
DWORD results = WaitForSingleObject(handle_, INFINITE);
DCHECK(WAIT_OBJECT_0 == results);
CloseHandle(handle_);
handle_ = NULL;
}
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() {
if (NULL == handle_)
return;
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.
}
//------------------------------------------------------------------------------
// Internal private methods that the watchdog thread uses.
// static
DWORD __stdcall Watchdog::ThreadStart(void* pThis) {
Watchdog* watchdog = reinterpret_cast<Watchdog*>(pThis);
return watchdog->Run();
}
unsigned Watchdog::Run() {
SetThreadName();
TimeDelta remaining_duration;
while (1) {
AutoLock lock(lock_);
while (DISARMED == state_)
condition_variable_.Wait();
if (SHUTDOWN == state_)
return 0;
DCHECK(ARMED == state_);
remaining_duration = duration_ - (TimeTicks::Now() - start_time_);
if (remaining_duration.InMilliseconds() > 0) {
// Spurios wake? Timer drifts? Go back to sleep for remaining time.
condition_variable_.TimedWait(remaining_duration);
} else {
// 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_ > start_time_) {
// False alarm: we started our clock before the debugger break (last
// alarm time).
start_time_ += last_debugged_alarm_delay_;
if (last_debugged_alarm_time_ > start_time_)
state_ = DISARMED; // Too many alarms must have taken place.
continue;
}
}
state_ = DISARMED; // Only alarm at most once.
TimeTicks last_alarm_time = TimeTicks::Now();
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)) {
// 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::SetThreadName() const {
std::string name = StringPrintf("%s Watchdog",
WideToASCII(thread_watched_name_).c_str());
Thread::SetThreadName(name.c_str(), thread_id_);
DLOG(INFO) << "Watchdog active: " << name;
}
// 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_;
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