Add base to the repository.

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@8 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 111 insertions, 0 deletions

diff --git a/base/watchdog.h b/base/watchdog.h
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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.
+
+// The Watchdog class creates a second thread that can Alarm if a specific
+// duration of time passes without proper attention.  The duration of time is
+// specified at construction time.  The Watchdog may be used many times by
+// simply calling Arm() (to start timing) and Disarm() (to reset the timer).
+// The Watchdog is typically used under a debugger, where the stack traces on
+// other threads can be examined if/when the Watchdog alarms.
+
+// Some watchdogs will be enabled or disabled via command line switches. To
+// facilitate such code, an "enabled" argument for the constuctor can be used
+// to permanently disable the watchdog.  Disabled watchdogs don't even spawn
+// a second thread, and their methods call (Arm() and Disarm()) return very
+// quickly.
+
+#ifndef BASE_WATCHDOG_H__
+#define BASE_WATCHDOG_H__
+
+#include <string>
+
+#include "base/condition_variable.h"
+#include "base/lock.h"
+#include "base/time.h"
+
+class Watchdog {
+ public:
+  // TODO(JAR)change default arg to required arg after all users have migrated.
+  // Constructor specifies how long the Watchdog will wait before alarming.
+  Watchdog(const TimeDelta& duration,
+           const std::wstring& thread_watched_name,
+           bool enabled = true);
+  virtual ~Watchdog();
+
+  // Start timing, and alarm when time expires (unless we're disarm()ed.)
+  void Arm();  // Arm  starting now.
+  void ArmSomeTimeDeltaAgo(const TimeDelta& time_delta);
+  void ArmAtStartTime(const TimeTicks start_time);
+
+  // Reset time, and do not set off the alarm.
+  void Disarm();
+
+  // Alarm is called if the time expires after an Arm() without someone calling
+  // Disarm().  This method can be overridden to create testable classes.
+  virtual void Alarm() {
+    DLOG(INFO) << "Watchdog alarmed for " << thread_watched_name_;
+  }
+
+ private:
+  enum State {ARMED, DISARMED, SHUTDOWN };
+
+  // Windows thread start callback
+  static DWORD WINAPI ThreadStart(void* pThis);
+
+  // Loop and test function for our watchdog thread.
+  unsigned Run();
+  void Watchdog::SetThreadName() const;
+
+  Lock lock_;  // Mutex for state_.
+  ConditionVariable condition_variable_;
+  State state_;
+  const TimeDelta duration_;  // How long after start_time_ do we alarm?
+  const std::wstring thread_watched_name_;
+  HANDLE handle_;  // Handle for watchdog thread.
+  DWORD thread_id_;  // Also for watchdog thread.
+
+  TimeTicks start_time_;  // Start of epoch, and alarm after duration_.
+
+  // When the debugger breaks (when we alarm), all the other alarms that are
+  // armed will expire (also alarm).  To diminish this effect, we track any
+  // delay due to debugger breaks, and we *try* to adjust the effective start
+  // time of other alarms to step past the debugging break.
+  // Without this safety net, any alarm will typically trigger a host of follow
+  // on alarms from callers that specify old times.
+  static Lock static_lock_;  // Lock for access of static data...
+  // When did we last alarm and get stuck (for a while) in a debugger?
+  static TimeTicks last_debugged_alarm_time_;
+  // How long did we sit on a break in the debugger?
+  static TimeDelta last_debugged_alarm_delay_;
+
+
+  DISALLOW_EVIL_CONSTRUCTORS(Watchdog);
+};
+
+#endif  // BASE_WATCHDOG_H__