Add a snapshot of flutter/engine/src/build to our sdk

build/android/pylib/perf/surface_stats_collector.py

Index: build/android/pylib/perf/surface_stats_collector.py
diff --git a/build/android/pylib/perf/surface_stats_collector.py b/build/android/pylib/perf/surface_stats_collector.py
new file mode 100644
index 0000000000000000000000000000000000000000..c7e7527a1e25c2ef663f5f80c09f6f80696bbba7
--- /dev/null
+++ b/build/android/pylib/perf/surface_stats_collector.py
@@ -0,0 +1,191 @@
+# 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.
+
+import Queue
+import datetime
+import logging
+import re
+import threading
+from pylib import android_commands
+from pylib.device import device_utils
+
+
+# Log marker containing SurfaceTexture timestamps.
+_SURFACE_TEXTURE_TIMESTAMPS_MESSAGE = 'SurfaceTexture update timestamps'
+_SURFACE_TEXTURE_TIMESTAMP_RE = r'\d+'
+
+
+class SurfaceStatsCollector(object):
+  """Collects surface stats for a SurfaceView from the output of SurfaceFlinger.
+
+  Args:
+    device: A DeviceUtils instance.
+  """
+
+  def __init__(self, device):
+    # TODO(jbudorick) Remove once telemetry gets switched over.
+    if isinstance(device, android_commands.AndroidCommands):
+      device = device_utils.DeviceUtils(device)
+    self._device = device
+    self._collector_thread = None
+    self._surface_before = None
+    self._get_data_event = None
+    self._data_queue = None
+    self._stop_event = None
+    self._warn_about_empty_data = True
+
+  def DisableWarningAboutEmptyData(self):
+    self._warn_about_empty_data = False
+
+  def Start(self):
+    assert not self._collector_thread
+
+    if self._ClearSurfaceFlingerLatencyData():
+      self._get_data_event = threading.Event()
+      self._stop_event = threading.Event()
+      self._data_queue = Queue.Queue()
+      self._collector_thread = threading.Thread(target=self._CollectorThread)
+      self._collector_thread.start()
+    else:
+      raise Exception('SurfaceFlinger not supported on this device.')
+
+  def Stop(self):
+    assert self._collector_thread
+    (refresh_period, timestamps) = self._GetDataFromThread()
+    if self._collector_thread:
+      self._stop_event.set()
+      self._collector_thread.join()
+      self._collector_thread = None
+    return (refresh_period, timestamps)
+
+  def _CollectorThread(self):
+    last_timestamp = 0
+    timestamps = []
+    retries = 0
+
+    while not self._stop_event.is_set():
+      self._get_data_event.wait(1)
+      try:
+        refresh_period, new_timestamps = self._GetSurfaceFlingerFrameData()
+        if refresh_period is None or timestamps is None:
+          retries += 1
+          if retries < 3:
+            continue
+          if last_timestamp:
+            # Some data has already been collected, but either the app
+            # was closed or there's no new data. Signal the main thread and
+            # wait.
+            self._data_queue.put((None, None))
+            self._stop_event.wait()
+            break
+          raise Exception('Unable to get surface flinger latency data')
+
+        timestamps += [timestamp for timestamp in new_timestamps
+                       if timestamp > last_timestamp]
+        if len(timestamps):
+          last_timestamp = timestamps[-1]
+
+        if self._get_data_event.is_set():
+          self._get_data_event.clear()
+          self._data_queue.put((refresh_period, timestamps))
+          timestamps = []
+      except Exception as e:
+        # On any error, before aborting, put the exception into _data_queue to
+        # prevent the main thread from waiting at _data_queue.get() infinitely.
+        self._data_queue.put(e)
+        raise
+
+  def _GetDataFromThread(self):
+    self._get_data_event.set()
+    ret = self._data_queue.get()
+    if isinstance(ret, Exception):
+      raise ret
+    return ret
+
+  def _ClearSurfaceFlingerLatencyData(self):
+    """Clears the SurfaceFlinger latency data.
+
+    Returns:
+      True if SurfaceFlinger latency is supported by the device, otherwise
+      False.
+    """
+    # The command returns nothing if it is supported, otherwise returns many
+    # lines of result just like 'dumpsys SurfaceFlinger'.
+    results = self._device.RunShellCommand(
+        'dumpsys SurfaceFlinger --latency-clear SurfaceView')
+    return not len(results)
+
+  def GetSurfaceFlingerPid(self):
+    results = self._device.RunShellCommand('ps | grep surfaceflinger')
+    if not results:
+      raise Exception('Unable to get surface flinger process id')
+    pid = results[0].split()[1]
+    return pid
+
+  def _GetSurfaceFlingerFrameData(self):
+    """Returns collected SurfaceFlinger frame timing data.
+
+    Returns:
+      A tuple containing:
+      - The display's nominal refresh period in milliseconds.
+      - A list of timestamps signifying frame presentation times in
+        milliseconds.
+      The return value may be (None, None) if there was no data collected (for
+      example, if the app was closed before the collector thread has finished).
+    """
+    # adb shell dumpsys SurfaceFlinger --latency <window name>
+    # prints some information about the last 128 frames displayed in
+    # that window.
+    # The data returned looks like this:
+    # 16954612
+    # 7657467895508   7657482691352   7657493499756
+    # 7657484466553   7657499645964   7657511077881
+    # 7657500793457   7657516600576   7657527404785
+    # (...)
+    #
+    # The first line is the refresh period (here 16.95 ms), it is followed
+    # by 128 lines w/ 3 timestamps in nanosecond each:
+    # A) when the app started to draw
+    # B) the vsync immediately preceding SF submitting the frame to the h/w
+    # C) timestamp immediately after SF submitted that frame to the h/w
+    #
+    # The difference between the 1st and 3rd timestamp is the frame-latency.
+    # An interesting data is when the frame latency crosses a refresh period
+    # boundary, this can be calculated this way:
+    #
+    # ceil((C - A) / refresh-period)
+    #
+    # (each time the number above changes, we have a "jank").
+    # If this happens a lot during an animation, the animation appears
+    # janky, even if it runs at 60 fps in average.
+    #
+    # We use the special "SurfaceView" window name because the statistics for
+    # the activity's main window are not updated when the main web content is
+    # composited into a SurfaceView.
+    results = self._device.RunShellCommand(
+        'dumpsys SurfaceFlinger --latency SurfaceView')
+    if not len(results):
+      return (None, None)
+
+    timestamps = []
+    nanoseconds_per_millisecond = 1e6
+    refresh_period = long(results[0]) / nanoseconds_per_millisecond
+
+    # If a fence associated with a frame is still pending when we query the
+    # latency data, SurfaceFlinger gives the frame a timestamp of INT64_MAX.
+    # Since we only care about completed frames, we will ignore any timestamps
+    # with this value.
+    pending_fence_timestamp = (1 << 63) - 1
+
+    for line in results[1:]:
+      fields = line.split()
+      if len(fields) != 3:
+        continue
+      timestamp = long(fields[1])
+      if timestamp == pending_fence_timestamp:
+        continue
+      timestamp /= nanoseconds_per_millisecond
+      timestamps.append(timestamp)
+
+    return (refresh_period, timestamps)