[Android] Switch to new interfaces of GetAVDs and RestartAdbServer.

build/android/pylib/device/device_utils.py

 # Copyright 2014 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.
 
 """
 Provides a variety of device interactions based on adb.
 
 Eventually, this will be based on adb_wrapper.
 """
+# pylint: disable=W0613
 
 import pylib.android_commands
 from pylib.device import adb_wrapper
+from pylib.utils import reraiser_thread
+from pylib.utils import timeout_retry
 
 
-def GetAVDs():
+_DEFAULT_TIMEOUT = 30
+_DEFAULT_RETRIES = 3
+
+
+def WithTimeoutAndRetries(default_timeout, default_retries):
+  """ An annotation that handles timeouts and retries using the provided
+      default timeout and retry values if they aren't specified as a kwarg.
+  """
+  def ResultingAnnotation(f):
+    def wrapper(*args, **kwargs):
+      if 'timeout' in kwargs:
+        timeout = kwargs['timeout']
+      else:
+        timeout = default_timeout
+        kwargs['timeout'] = timeout
+      if 'retries' in kwargs:
+        retries = kwargs['retries']
+      else:
+        retries = default_retries
+        kwargs['retries'] = retries

[bulach, 2014/05/01 11:18:57]

nit: how about:
timeout = kwargs['timeout'] = kwargs.get('timeout', default_timeout)

+      def _impl():
+        return f(*args, **kwargs)
+      try:
+        return timeout_retry.Run(_impl, timeout, retries)
+      except reraiser_thread.TimeoutError as e:
+        raise adb_wrapper.CommandTimeoutError(str(e))
+    return wrapper
+  return ResultingAnnotation
+
+
+def WithTimeoutAndRetriesFromInstance(f):
+  """ An annotation that handles timeouts and retries using default timeout
+      and retry values from the object if they aren't specified as a kwarg.
+  """
+  def wrapper(device, *args, **kwargs):
+    timeout = device._default_timeout # pylint: disable=W0212
+    retries = device._default_retries # pylint: disable=W0212
+    return WithTimeoutAndRetries(timeout, retries)(f)(device, *args, **kwargs)
+  return wrapper
+
+
+@WithTimeoutAndRetries(_DEFAULT_TIMEOUT, _DEFAULT_RETRIES)

[bulach, 2014/05/01 11:18:57]

to be very honest... :)

this is neat, but I think it just adds extra indirections.. I'd rather have
slightly more code, but more explicit everywhere (remember, this will be running
in the bots, so the more explicit, the simpler it'll be the debug the eventual
error messages, etc...).

as such, I'd suggest having a straightforward helper:

def RunWithTimeoutAndRetries(callable, timeout, retries):
  while ...
    callable() ...

then:
def GetAVDs(timeout=_DEFAULT_TIMEOUT, retries=_DEFAULT_RETRIES):
  return RunWithTimeoutAndRetries(pylib.android_commands.GetAVDs, timeout,
retries)

this would be more straightforward, and I bet error messages would be less
convoluted. also, the RunWithTimeoutAndRetries takes a callable, so it can be
just as easily tested.

wdyt?

of course, I may be missing the advantages of using out-of-band annotations, so
please let me know! :)

+def GetAVDs(timeout=None, retries=None):
+  """ Returns a list of Android Virtual Devices.
+
+  Args:
+    timeout: The length of time to wait before giving up on either killing or
+             restarting the server.
+    retries: The number of times to retry either killing or restarting the
+             server.
+  Returns:
+    A list containing the configured AVDs.
+  """
   return pylib.android_commands.GetAVDs()
 
 
+@WithTimeoutAndRetries(_DEFAULT_TIMEOUT, _DEFAULT_RETRIES)
+def RestartServer(timeout=None, retries=None):
+  """ Restarts the adb server.
+
+  Args:
+    timeout: The length of time to wait before giving up on either killing or
+             restarting the server.
+    retries: The number of times to retry either killing or restarting the
+             server.
+  Raises:
+    CommandFailedError if we fail to kill or restart the server.
+  """
+  pylib.android_commands.AndroidCommands().RestartAdbServer()
+
+
 class DeviceUtils(object):
 
   def __init__(self, device):
     self.old_interface = None
     if isinstance(device, basestring):
       self.old_interface = pylib.android_commands.AndroidCommands(device)
     elif isinstance(device, adb_wrapper.AdbWrapper):
       self.old_interface = pylib.android_commands.AndroidCommands(str(device))
     elif isinstance(device, pylib.android_commands.AndroidCommands):
       self.old_interface = device
     elif not device:
       self.old_interface = pylib.android_commands.AndroidCommands()