Move some misc thread-related stuff from base to base/thread and into the bas...

base/threading/watchdog.cc

+// 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/threading/watchdog.h"
+
+#include "base/compiler_specific.h"
+#include "base/logging.h"
+#include "base/platform_thread.h"
+
+namespace base {
+
+// 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_;
+
+}  // namespace base