[android] Switch test scripts to use last modified time instead of md5sum when checking dependencie…

build/android/pylib/android_commands.py

Index: build/android/pylib/android_commands.py
diff --git a/build/android/pylib/android_commands.py b/build/android/pylib/android_commands.py
index 48116b88ffd8e7e7a889ea679ff99e55569e702c..6b97ec270f326d434d38a5fa43434d485cc3746d 100644
--- a/build/android/pylib/android_commands.py
+++ b/build/android/pylib/android_commands.py
@@ -61,10 +61,6 @@ KEYCODE_DPAD_RIGHT = 22
 KEYCODE_ENTER = 66
 KEYCODE_MENU = 82
 
-MD5SUM_DEVICE_FOLDER = constants.TEST_EXECUTABLE_DIR + '/md5sum/'
-MD5SUM_DEVICE_PATH = MD5SUM_DEVICE_FOLDER + 'md5sum_bin'
-MD5SUM_LD_LIBRARY_PATH = 'LD_LIBRARY_PATH=%s' % MD5SUM_DEVICE_FOLDER
-
 def GetEmulators():
   """Returns a list of emulators.  Does not filter by status (e.g. offline).
 
@@ -176,6 +172,21 @@ def _ComputeFileListHash(md5sum_output):
   return [line.split('  ')[0] for line in md5sum_output]
 
 
+def _ComputeFileListTimesModified(timemodified_output):
+  """Returns a list of tuples from the provided timemodified output.
+
+  Args:
+    timemodified_output: output directly from timemodified binary.
+
+  Returns:
+    List of namedtuples (time, path).
+  """
+  TimeAndPath = collections.namedtuple('TimeAndPath', ['time', 'path'])
+  split_lines = [line.split('  ') for line in timemodified_output]
+  assert all(len(s) == 2 for s in split_lines), 'Invalid timemodified output'
+  return [TimeAndPath._make(s) for s in split_lines]
+
+
 def _HasAdbPushSucceeded(command_output):
   """Returns whether adb push has succeeded from the provided output."""
   # TODO(frankf): We should look at the return code instead of the command
@@ -225,6 +236,7 @@ class AndroidCommands(object):
     self._potential_push_size = 0
     self._actual_push_size = 0
     self._md5sum_build_dir = ''
+    self._timemodified_build_dir = ''
     self._external_storage = ''
     self._util_wrapper = ''
 
@@ -712,6 +724,9 @@ class AndroidCommands(object):
     Returns:
       True if the md5sums match.
     """
+    MD5SUM_DEVICE_FOLDER = constants.TEST_EXECUTABLE_DIR + '/md5sum/'
+    MD5SUM_DEVICE_PATH = MD5SUM_DEVICE_FOLDER + 'md5sum_bin'
+    MD5SUM_LD_LIBRARY_PATH = 'LD_LIBRARY_PATH=%s' % MD5SUM_DEVICE_FOLDER
     if not self._md5sum_build_dir:
       default_build_type = os.environ.get('BUILD_TYPE', 'Debug')
       build_dir = '%s/%s/' % (
@@ -740,11 +755,81 @@ class AndroidCommands(object):
 
     return hashes_on_device == hashes_on_host
 
+  def _AreFilesUnsynchronized(self, local_path, device_path):
+    """Compares the time modified of a local path against a device path.
+
+    NOTE: Files transferred via "adb push" keep the host's modified time.
+
+    Args:
+      local_path: Path (file or directory) on the host.
+      device_path: Path (file or directory) on the device.
+
+    Returns:
+      True if the time the files were modified match.
+    """
+    TIMEMODIFIED_DEVICE_DIRECTORY = (constants.TEST_EXECUTABLE_DIR +
+                                     '/timemodified/')
+    TIMEMODIFIED_DEVICE_PATH = (TIMEMODIFIED_DEVICE_DIRECTORY +
+                                'timemodified_bin')
+    TIMEMODIFIED_LD_LIBRARY_PATH = ('LD_LIBRARY_PATH=%s' %
+                                    TIMEMODIFIED_DEVICE_DIRECTORY)
+    assert os.path.exists(local_path), 'Local path not found %s' % local_path
+
+    if not self._timemodified_build_dir:
+      default_build_type = os.environ.get('BUILD_TYPE', 'Debug')
+      build_dir = '%s/%s/' % (
+          cmd_helper.OutDirectory().get(), default_build_type)
+      host_timemodified_dist_path = '%s/timemodified_dist' % build_dir
+      if not os.path.exists(host_timemodified_dist_path):
+        build_dir = '%s/Release/' % cmd_helper.OutDirectory().get()
+        host_timemodified_dist_path = '%s/timemodified_dist' % build_dir
+        assert os.path.exists(host_timemodified_dist_path), 'Build timemodified'
+      command = 'push %s %s' % (host_timemodified_dist_path,
+                                TIMEMODIFIED_DEVICE_DIRECTORY)
+      assert _HasAdbPushSucceeded(self._adb.SendCommand(command))
+      self._timemodified_build_dir = build_dir
+
+    self._pushed_files.append(device_path)
+    device_timemodified_output = self.RunShellCommand(
+        TIMEMODIFIED_LD_LIBRARY_PATH + ' ' + self._util_wrapper + ' ' +
+        TIMEMODIFIED_DEVICE_PATH + ' ' + device_path)
+    device_time_tuples = _ComputeFileListTimesModified(
+        device_timemodified_output)
+    assert os.path.exists(local_path), 'Local path not found %s' % local_path
+    host_timemodified_output = cmd_helper.GetCmdOutput(
+        ['%s/timemodified_bin_host' % self._timemodified_build_dir, local_path])
+    host_time_tuples = _ComputeFileListTimesModified(
+        host_timemodified_output.splitlines())
+
+    if len(device_time_tuples) < len(host_time_tuples):
+      return True
+
+    # Ignore extra files on the device.
+    if len(device_time_tuples) > len(host_time_tuples):
+      host_files = [os.path.relpath(os.path.normpath(p.path),
+                    os.path.normpath(local_path)) for p in host_time_tuples]
+
+      def _host_has(fname):
+        return any(path in fname for path in host_files)
+
+      times_on_device = [t.time for t in device_time_tuples if
+                         _host_has(t.path)]
+    else:
+      times_on_device = [t.time for t in device_time_tuples]
+
+    # Compare timestamps between host and device files.
+    times_on_host = [t.time for t in host_time_tuples]
+    times_on_device.sort()
+    times_on_host.sort()
+    return any(int(dtime) != int(htime) for dtime, htime in
+        zip(times_on_device, times_on_host))
+
   def PushIfNeeded(self, local_path, device_path):
     """Pushes |local_path| to |device_path|.
 
     Works for files and directories. This method skips copying any paths in
-    |test_data_paths| that already exist on the device with the same hash.
+    |test_data_paths| that already exist on the device with the same modified
+    time.
 
     All pushed files can be removed by calling RemovePushedFiles().
     """
@@ -753,7 +838,7 @@ class AndroidCommands(object):
     self._pushed_files.append(device_path)
     self._potential_push_size += size
 
-    if self.CheckMd5Sum(local_path, device_path):
+    if not self._AreFilesUnsynchronized(local_path, device_path):
       return
 
     self._actual_push_size += size
@@ -1305,7 +1390,7 @@ class AndroidCommands(object):
 
   def SetUtilWrapper(self, util_wrapper):
     """Sets a wrapper prefix to be used when running a locally-built
-    binary on the device (ex.: md5sum_bin).
+    binary on the device (ex.: timemodified_bin).
     """
     self._util_wrapper = util_wrapper