Android: adds instrumentation test runners.

build/android/pylib/sharded_tests_queue.py

Index: build/android/pylib/sharded_tests_queue.py
diff --git a/build/android/pylib/sharded_tests_queue.py b/build/android/pylib/sharded_tests_queue.py
new file mode 100644
index 0000000000000000000000000000000000000000..d2b3779695d294c8a25b9ccddd73c6c010f97dad
--- /dev/null
+++ b/build/android/pylib/sharded_tests_queue.py
@@ -0,0 +1,36 @@
+# Copyright (c) 2012 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 module that contains a queue for running sharded tests."""
+
+import multiprocessing
+
+
+class ShardedTestsQueue(object):
+  """A queue for managing pending tests across different runners.
+
+  This class should only be used when sharding.
+
+  Attributes:
+    num_devices: an integer; the number of attached Android devices.
+    tests: a list of tests to be run.
+    tests_queue: if sharding, a JoinableQueue object that holds tests from
+        |tests|. Otherwise, a list holding tests.
+    results_queue: a Queue object to hold TestResults objects.
+  """
+  _STOP_SENTINEL = 'STOP'  # sentinel value for iter()
+
+  def __init__(self, num_devices, tests):
+    assert num_devices > 1, 'At least two devices must be attached.'
+    self.num_devices = num_devices
+    self.tests_queue = multiprocessing.Queue()
+    for test in tests:
+      self.tests_queue.put(test)
+    for _ in xrange(self.num_devices):
+      self.tests_queue.put(ShardedTestsQueue._STOP_SENTINEL)
+
+  def __iter__(self):
+    """Returns an iterator with the test cases."""
+    return iter(self.tests_queue.get, ShardedTestsQueue._STOP_SENTINEL)