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

BUG=318387
TEST=None
NOTRY=True

Review URL: https://codereview.chromium.org/60043003

git-svn-id: http://src.chromium.org/svn/trunk/src/build@235776 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

android/pylib/cmd_helper.py

@@ -4,14 +4,13 @@
 
 """A wrapper for subprocess to make calling shell commands easier."""
 
-import os
 import logging
 import pipes
 import signal
 import subprocess
 import tempfile
 
-import constants
+from utils import timeout_retry
 
 
 def Popen(args, stdout=None, stderr=None, shell=None, cwd=None, env=None):
@@ -73,7 +72,7 @@ def GetCmdStatusAndOutput(args, cwd=None, shell=False):
     shell: Whether to execute args as a shell command.
 
   Returns:
-    The tuple (exit code, output).
+    The 2-tuple (exit code, output).
   """
   if isinstance(args, basestring):
     args_repr = args
@@ -104,3 +103,18 @@ def GetCmdStatusAndOutput(args, cwd=None, shell=False):
     logging.debug('Truncated output:')
   logging.debug(stdout[:4096])
   return (exit_code, stdout)
+
+
+def GetCmdStatusAndOutputWithTimeoutAndRetries(args, timeout, retries):
+  """Executes a subprocess with a timeout and retries.
+
+  Args:
+    args: List of arguments to the program, the program to execute is the first
+      element.
+    timeout: the timeout in seconds.
+    retries: the number of retries.
+
+  Returns:
+    The 2-tuple (exit code, output).
+  """
+  return timeout_retry.Run(GetCmdStatusAndOutput, timeout, retries, [args])

android/pylib/utils/timeout_retry.py

@@ -0,0 +1,45 @@
+# 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

android/pylib/utils/timeout_retry_unittest.py

@@ -0,0 +1,52 @@
+# 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.
+
+"""Unittests for timeout_and_retry.py."""
+
+import unittest
+
+import reraiser_thread
+import timeout_retry
+
+
+class TestException(Exception):
+  pass
+
+
+def _NeverEnding(tries=[0]):
+  tries[0] += 1
+  while True:
+    pass
+
+
+def _CountTries(tries):
+  tries[0] += 1
+  raise TestException
+
+
+class TestRun(unittest.TestCase):
+  """Tests for timeout_retry.Run."""
+
+  def testRun(self):
+    self.assertTrue(timeout_retry.Run(
+        lambda x: x, 30, 3, [True], {}))
+
+  def testTimeout(self):
+    tries = [0]
+    self.assertRaises(reraiser_thread.TimeoutError,
+        timeout_retry.Run, lambda: _NeverEnding(tries), 0, 3)
+    self.assertEqual(tries[0], 4)
+
+  def testRetries(self):
+    tries = [0]
+    self.assertRaises(TestException,
+        timeout_retry.Run, lambda: _CountTries(tries), 30, 3)
+    self.assertEqual(tries[0], 4)
+
+  def testReturnValue(self):
+    self.assertTrue(timeout_retry.Run(lambda: True, 30, 3))
+
+
+if __name__ == '__main__':
+  unittest.main()