[Android] Print the stack of deadlocked threads when sharding.

build/android/pylib/utils/watchdog.py

+# Copyright 2013 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.
+
+"""Watchdog timeout objects."""
+
+import time
+
+
+class Watchdog(object):
+  """A resetable timeout-based watchdog.
+
+  This object is threadsafe.
+  """
+
+  def __init__(self, timeout):
+    """Initializes the watchdog.
+
+    Args:
+      timeout: The timeout in seconds.
+    """
+    self._start_time = time.time()
+    self._timeout = timeout
+
+  def Reset(self):
+    """Resets the timeout countdown."""
+    self._start_time = time.time()
+
+  def IsTimedOut(self):
+    """Whether the watchdog has timed out.
+
+    Returns:
+      True if the watchdog has timed out, False otherwise.
+    """
+    return time.time() - self._start_time > self._timeout
+
+
+class MockWatchdog(Watchdog):
+  """A watchdog which never times out."""
+
+  #override
+  def __init__(self, timeout=0):
+    super(MockWatchdog, self).__init__(timeout)
+
+  #override
+  def IsTimedOut(self):
+    return False