[android] Add timeout_retry module to pylib/utils/.

build/android/pylib/utils/timeout_retry.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.
+
+"""A utility to run functions with timeouts and retries."""
+
+import functools
+import threading
+
+import reraiser_thread
+import watchdog_timer
+
+
+def Run(func, timeout, retries, args=[], kwargs={}):
+  """Runs the passed function in a separate thread with timeouts and retries.
+
+  Args:
+    func: the function to be wrapped.
+    timeout: the timeout in seconds for each try.
+    retries: the number of retries.
+    args: list of positional args to pass to |func|.
+    kwargs: dictionary of keyword args to pass to |func|.
+
+  Returns:
+    The return value of func(*args, **kwargs).
+  """
+  # The return value uses a list because Python variables are references, not
+  # values. Closures make a copy of the reference, so updating the closure's
+  # reference wouldn't update where the original reference pointed.
+  ret = [None]
+  def RunOnTimeoutThread():
+    ret[0] = func(*args, **kwargs)
+
+  while True:
+    try:
+      name = 'TimeoutThread-for-%s' % threading.current_thread().name
+      thread_group = reraiser_thread.ReraiserThreadGroup(
+          [reraiser_thread.ReraiserThread(RunOnTimeoutThread, name=name)])
+      thread_group.StartAll()
+      thread_group.JoinAll(watchdog_timer.WatchdogTimer(timeout))
+      return ret[0]
+    except:
+      if retries <= 0:
+        raise
+      retries -= 1