[android] Push only updated files in PushIfNeeded when few files have changed.

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 4cf070d0711a9626edf1ba6eae35efe0f7bb7e40..cb72fffba55ae46025c824bdd0e060fa52e658ed 100644
--- a/build/android/pylib/android_commands.py
+++ b/build/android/pylib/android_commands.py
@@ -184,14 +184,15 @@ def _GetFilesFromRecursiveLsOutput(path, ls_output, re_file, utc_offset=None):
   return files
 
 
-def _ComputeFileListHash(md5sum_output):
+def _ParseMd5SumOutput(md5sum_output):
   """Returns a list of tuples from the provided md5sum output.
 
   Args:
     md5sum_output: output directly from md5sum binary.
 
   Returns:
-    List of namedtuples (hash, path).
+    List of namedtuples with attributes |hash| and |path|, where |path| is the
+    absolute path to the file with an Md5Sum of |hash|.
   """
   HashAndPath = collections.namedtuple('HashAndPath', ['hash', 'path'])
   split_lines = [line.split('  ') for line in md5sum_output]
@@ -418,7 +419,8 @@ class AndroidCommands(object):
     # Check if package is already installed and up to date.
     if package_name:
       installed_apk_path = self.GetApplicationPath(package_name)
-      if installed_apk_path and self.CheckMd5Sum(apk_path, installed_apk_path):
+      if (installed_apk_path and
+          not self.GetFilesChanged(apk_path, installed_apk_path)):
         logging.info('Skipped install: identical %s APK already installed' %
             package_name)
         return
@@ -738,15 +740,16 @@ class AndroidCommands(object):
     """
     self.RunShellCommand('input keyevent %d' % keycode)
 
-  def CheckMd5Sum(self, local_path, device_path):
-    """Compares the md5sum of a local path against a device path.
+  def _RunMd5Sum(self, host_path, device_path):
+    """Gets the md5sum of a host path and device path.
 
     Args:
-      local_path: Path (file or directory) on the host.
+      host_path: Path (file or directory) on the host.
       device_path: Path on the device.
 
     Returns:
-      True if the md5sums match.
+      A tuple containing lists of the host and device md5sum results as
+      created by _ParseMd5SumOutput().
     """
     if not self._md5sum_build_dir:
       default_build_type = os.environ.get('BUILD_TYPE', 'Debug')
@@ -763,73 +766,112 @@ class AndroidCommands(object):
 
     cmd = (MD5SUM_LD_LIBRARY_PATH + ' ' + self._util_wrapper + ' ' +
            MD5SUM_DEVICE_PATH + ' ' + device_path)
-    device_hash_tuples = _ComputeFileListHash(
+    device_hash_tuples = _ParseMd5SumOutput(
         self.RunShellCommand(cmd, timeout_time=2 * 60))
-    assert os.path.exists(local_path), 'Local path not found %s' % local_path
+    assert os.path.exists(host_path), 'Local path not found %s' % host_path
     md5sum_output = cmd_helper.GetCmdOutput(
-        ['%s/md5sum_bin_host' % self._md5sum_build_dir, local_path])
-    host_hash_tuples = _ComputeFileListHash(md5sum_output.splitlines())
+        ['%s/md5sum_bin_host' % self._md5sum_build_dir, host_path])
+    host_hash_tuples = _ParseMd5SumOutput(md5sum_output.splitlines())
+    return (host_hash_tuples, device_hash_tuples)
+
+  def GetFilesChanged(self, host_path, device_path):
+    """Compares the md5sum of a host path against a device path.
+
+    Note: Ignores extra files on the device.
+
+    Args:
+      host_path: Path (file or directory) on the host.
+      device_path: Path on the device.
+
+    Returns:
+      A list of tuples of the form (host_path, device_path) for files whose
+      md5sums do not match.
+    """
+    host_hash_tuples, device_hash_tuples = self._RunMd5Sum(
+        host_path, device_path)
 
     # Ignore extra files on the device.
     if len(device_hash_tuples) > len(host_hash_tuples):
       host_files = [os.path.relpath(os.path.normpath(p.path),
-                    os.path.normpath(local_path)) for p in host_hash_tuples]
+                    os.path.normpath(host_path)) for p in host_hash_tuples]
 
-      def _host_has(fname):
+      def HostHas(fname):
         return any(path in fname for path in host_files)
 
-      hashes_on_device = [h.hash for h in device_hash_tuples if
-                         _host_has(h.path)]
-    else:
-      hashes_on_device = [h.hash for h in device_hash_tuples]
+      device_hash_tuples = [h for h in device_hash_tuples if HostHas(h.path)]
+
+    # Constructs the target device path from a given host path. Don't use when
+    # only a single file is given as the base name given in device_path may
+    # differ from that in host_path.
+    def HostToDevicePath(host_file_path):
+      return os.path.join(os.path.dirname(device_path), os.path.relpath(
+          host_file_path, os.path.dirname(os.path.normpath(host_path))))
 
-    # Compare md5sums between host and device files.
-    hashes_on_host = [h.hash for h in host_hash_tuples]
-    hashes_on_device.sort()
-    hashes_on_host.sort()
-    return hashes_on_device == hashes_on_host
+    device_hashes = [h.hash for h in device_hash_tuples]
+    return [(t.path, HostToDevicePath(t.path) if os.path.isdir(host_path) else
+             device_path)
+            for t in host_hash_tuples if t.hash not in device_hashes]
 
-  def PushIfNeeded(self, local_path, device_path):
-    """Pushes |local_path| to |device_path|.
+  def PushIfNeeded(self, host_path, device_path):
+    """Pushes |host_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.
 
     All pushed files can be removed by calling RemovePushedFiles().
     """
-    assert os.path.exists(local_path), 'Local path not found %s' % local_path
-    size = int(cmd_helper.GetCmdOutput(['du', '-sb', local_path]).split()[0])
+    MAX_INDIVIDUAL_PUSHES = 50
+    assert os.path.exists(host_path), 'Local path not found %s' % host_path
+
+    def GetHostSize(path):
+      return int(cmd_helper.GetCmdOutput(['du', '-sb', path]).split()[0])
+
+    size = GetHostSize(host_path)
     self._pushed_files.append(device_path)
     self._potential_push_size += size
 
-    if self.CheckMd5Sum(local_path, device_path):
+    changed_files = self.GetFilesChanged(host_path, device_path)
+    if not changed_files:
       return
 
-    self._actual_push_size += size
-    # They don't match, so remove everything first and then create it.
-    if os.path.isdir(local_path):
-      self.RunShellCommand('rm -r %s' % device_path, timeout_time=2 * 60)
-      self.RunShellCommand('mkdir -p %s' % device_path)
-
-    # NOTE: We can't use adb_interface.Push() because it hardcodes a timeout of
-    # 60 seconds which isn't sufficient for a lot of users of this method.
-    push_command = 'push %s %s' % (local_path, device_path)
-    self._LogShell(push_command)
-
-    # Retry push with increasing backoff if the device is busy.
-    retry = 0
-    while True:
-      output = self._adb.SendCommand(push_command, timeout_time=30 * 60)
-      if _HasAdbPushSucceeded(output):
-        return
-      if 'resource busy' in output and retry < 3:
-        retry += 1
-        wait_time = 5 * retry
-        logging.error('Push failed, retrying in %d seconds: %s' %
-                      (wait_time, output))
-        time.sleep(wait_time)
-      else:
-        raise Exception('Push failed: %s' % output)
+    def Push(host, device):
+      # NOTE: We can't use adb_interface.Push() because it hardcodes a timeout
+      # of 60 seconds which isn't sufficient for a lot of users of this method.
+      push_command = 'push %s %s' % (host, device)
+      self._LogShell(push_command)
+
+      # Retry push with increasing backoff if the device is busy.
+      retry = 0
+      while True:
+        output = self._adb.SendCommand(push_command, timeout_time=30 * 60)
+        if _HasAdbPushSucceeded(output):
+          return
+        if retry < 3:
+          retry += 1
+          wait_time = 5 * retry
+          logging.error('Push failed, retrying in %d seconds: %s' %
+                        (wait_time, output))
+          time.sleep(wait_time)
+        else:
+          raise Exception('Push failed: %s' % output)
+
+    diff_size = 0
+    if len(changed_files) <= MAX_INDIVIDUAL_PUSHES:
+      diff_size = sum(GetHostSize(f[0]) for f in changed_files)
+
+    # TODO(craigdh): Replace this educated guess with a heuristic that
+    # approximates the push time for each method.
+    if len(changed_files) > MAX_INDIVIDUAL_PUSHES or diff_size > 0.5 * size:
+      # We're pushing everything, remove everything first and then create it.
+      self._actual_push_size += size
+      if os.path.isdir(host_path):
+        self.RunShellCommand('rm -r %s' % device_path, timeout_time=2 * 60)
+        self.RunShellCommand('mkdir -p %s' % device_path)
+      Push(host_path, device_path)
+    else:
+      for f in changed_files:
+        Push(f[0], f[1])
+      self._actual_push_size += diff_size
 
   def GetPushSizeInfo(self):
     """Get total size of pushes to the device done via PushIfNeeded()