Introduce new PyAuto test to measure EPT, TTP metrics.

chrome/test/functional/media/media_cn_perf.py

+#!/usr/bin/env python

[Ami GONE FROM CHROMIUM, 2011/12/07 01:33:08]

Ditto filename comment

[DaleCurtis, 2011/12/07 22:57:32]

Done.

+# Copyright (c) 2011 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.
+
+"""Records metrics on playing media under constrained network conditions.
+
+Spins up a Constrained Network Server (CNS) and runs through a test matrix of
+bandwidth, latency, and packet loss settings.  Each run records a
+time-to-playback (TTP) and extra-play-time (EPT) metric in a format consumable
+by the Chromium perf bots.
+
+See design document "Testing Video Performance Over Constrained Networks" for
+more information -- http://goo.gl/EdAWU

[Ami GONE FROM CHROMIUM, 2011/12/07 01:33:08]

Move this to a public doc, or remove pointer from here?

[DaleCurtis, 2011/12/07 22:57:32]

Removed it, relevant information is already included in this file.

+
+Since even a small number of different settings yields a large test matrix, the
+design is threaded... however PyAuto is not, so a global lock is used when calls
+into PyAuto are necessary.  The number of threads can be set by _TEST_THREADS.
+
+The CNS code is located under: <root>/src/media/tools/constrained_network_server
+"""
+
+import itertools
+import os
+import Queue
+import subprocess
+import sys
+import threading
+
+import pyauto_media
+import pyauto
+import pyauto_paths
+import pyauto_utils
+
+
+# Settings for each network constraint.
+_BANDWIDTH_SETTINGS_KBPS = {'None': 0, 'Low': 256, 'Medium': 2000, 'High': 5000}
+_LATENCY_SETTINGS_MS = {'None': 0, 'Low': 43, 'Medium': 105, 'High': 180}
+_PACKET_LOSS_SETTINGS_PERCENT = {'None': 0, 'Medium': 2, 'High': 5}
+
+# Test constraints are all possible combination of the above settings.  Each
+# tuple must be of the form (Bandwidth, Latency, Packet Loss).
+_TEST_CONSTRAINTS = itertools.product(
+    _BANDWIDTH_SETTINGS_KBPS.values(),
+    _LATENCY_SETTINGS_MS.values(),
+    _PACKET_LOSS_SETTINGS_PERCENT.values())
+
+_TEST_CONSTRAINT_NAMES = itertools.product(
+    _BANDWIDTH_SETTINGS_KBPS.keys(),
+    _LATENCY_SETTINGS_MS.keys(),
+    _PACKET_LOSS_SETTINGS_PERCENT.keys())
+
+# HTML test path; relative to src/chrome/test/data.  Loads a test video and
+# records metrics in JavaScript.
+_TEST_HTML_PATH = os.path.join('media', 'html', 'media_cn.html')
+
+# Number of threads to use during testing.
+# TODO(dalecurtis): Should be set on the command line.

[Ami GONE FROM CHROMIUM, 2011/12/07 01:33:08]

Why?

[DaleCurtis, 2011/12/07 22:57:32]

Good point. I was looking at this as more of a utility than a test. Removed.

+_TEST_THREADS = 3
+
+# File name of video to collect metrics for.
+# TODO(dalecurtis): Should be set on the command line.
+_TEST_VIDEO = 'roller.webm'
+
+# Path to CNS executable relative to source root.
+_CNS_PATH = os.path.join(
+    'media', 'tools', 'constrained_network_server', 'cns.py')
+
+# Port to start the CNS on.
+_CNS_PORT = 9000

[Ami GONE FROM CHROMIUM, 2011/12/07 01:33:08]

Is there a way to get a known-unused port on the bot slaves?

[DaleCurtis, 2011/12/07 22:57:32]

Short of trying to open a socket on each port and iterating, probably not. I'll
see what I can find out.

+
+# Base CNS URL, only requires & separated parameter names appended.
+_CNS_BASE_URL = 'http://127.0.0.1:%d/ServeConstrained?' % _CNS_PORT
+
+
+class TestWorker(threading.Thread):
+  """Worker thread.  For each queue entry: opens tab, runs test, closes tab."""
+
+  # Atomic, monotonically increasing task identifier.  Used to ID tabs.
+  _task_id = itertools.count()
+
+  def __init__(self, pyauto_test, tasks, automation_lock, url):
+    """Sets up TestWorker class variables.
+
+    Args:
+      pyauto_test: Reference to a pyauto.PyUITest instance.
+      tasks: Queue containing (settings, name) tuples.
+      automation_lock: Global automation lock for pyauto calls.
+      url: File URL to HTML/JavaScript test code.
+    """
+    threading.Thread.__init__(self)
+    self._tasks = tasks
+    self._automation_lock = automation_lock
+    self._pyauto = pyauto_test
+    self._url = url
+    self.start()
+
+  def _FindTab(self, url):
+    """Returns the tab index for the tab belonging to this url."""
+    for tab in self._pyauto.GetBrowserInfo()['windows'][0]['tabs']:

[Ami GONE FROM CHROMIUM, 2011/12/07 01:33:08]

No lock?

[DaleCurtis, 2011/12/07 22:57:32]

Already locked in _HaveMetrics() I'll add a comment.

+      if tab['url'] == url:
+        return tab['index']
+
+  def _HaveMetrics(self, unique_url):
+    """Returns true if metrics are ready.  Set self.{_ept,_ttp} < 0 pre-run."""

[Ami GONE FROM CHROMIUM, 2011/12/07 01:33:08]

Why not set to -1 in the ctor instead of "pre-run"?

[DaleCurtis, 2011/12/07 22:57:32]

It needs to be set for each call. I suspect there might be a better pattern to
use here, but couldn't think of one.

+    with self._automation_lock:
+      tab = self._FindTab(unique_url)
+
+      if self._ept < 0:
+        self._ept = self._pyauto.GetDOMValue('extra_play_time', tab_index=tab)
+      if self._ttp < 0:
+        self._ttp = self._pyauto.GetDOMValue('time_to_playback', tab_index=tab)
+    return self._ept >= 0 and self._ttp >= 0
+
+  def run(self):
+    """Opens tab, starts HTML test, and records metrics for each queue entry.
+
+    No exception handling is done to make sure the main thread exits properly
+    during Chrome crashes or other failures.  Doing otherwise has the potential
+    to leave the CNS server running in the background.
+
+    For a clean shutdown, put the magic exit value (None, None) in the queue.
+    """
+    while True:
+      settings, name = self._tasks.get()
+
+      # Check for magic exit values.
+      if (settings, name) == (None, None):

[Ami GONE FROM CHROMIUM, 2011/12/07 01:33:08]

So one worker thread gets the magic and exits, but what about the other two?  I
don't understand how your test ever exits (I expect thread.join() at l.220 to
wait forever, as the .get() call above waits for the queue to get another task
appended to it)

[DaleCurtis, 2011/12/07 22:57:32]

A magic exit pair is added to the Queue for each thread. Since each thread only
gets one value before exiting, it's guaranteed that all threads will receive the
magic exit.

Again, I suspect there might be a better pattern here, but after implementing
Python thread pools at least half a dozen times, this is the best evolution I've
come up with.

+        break
+
+      # Build video source URL.  Values <= 0 mean the setting is disabled.
+      video_url = [_CNS_BASE_URL, 'f=' + _TEST_VIDEO]
+      if settings[0] > 0:
+        video_url.append('bandwidth=%d' % settings[0])
+      if settings[1] > 0:
+        video_url.append('latency=%d' % settings[1])
+      if settings[2] > 0:
+        video_url.append('loss=%d' % settings[2])
+      video_url = '&'.join(video_url)
+
+      # Make the test URL unique so we can figure out our tab index later.
+      unique_url = '%s?%d' % (self._url, TestWorker._task_id.next())
+
+      # Start the test!
+      with self._automation_lock:
+        self._pyauto.AppendTab(pyauto.GURL(unique_url))
+        self._pyauto.CallJavascriptFunc(
+            'startTest', [video_url], tab_index=self._FindTab(unique_url))
+
+      # Wait until the necessary metrics have been collected.  Okay to not lock
+      # here since pyauto.WaitUntil doesn't call into Chrome.
+      self._ept = self._ttp = -1
+      self._pyauto.WaitUntil(
+          self._HaveMetrics, args=[unique_url], retry_sleep=2)
+
+      # Record results.
+      # TODO(dalecurtis): Support reference builds.
+      series_name = ''.join(name)
+      pyauto_utils.PrintPerfResult('ept', series_name, self._ept, '%')
+      pyauto_utils.PrintPerfResult('ttp', series_name, self._ttp, 'ms')
+
+      # Close the tab.
+      with self._automation_lock:
+        self._pyauto.GetBrowserWindow(0).GetTab(
+            self._FindTab(unique_url)).Close(True)
+
+      # TODO(dalecurtis): Check results for regressions.
+      self._tasks.task_done()
+
+
+class MediaConstrainedNetworkPerfTest(pyauto.PyUITest):
+  """PyAuto test container.  See file doc string for more information."""
+
+  def setUp(self):
+    """Starts the Constrained Network Server (CNS)."""
+    cmd = [sys.executable, os.path.join(pyauto_paths.GetSourceDir(), _CNS_PATH),
+           '--port', str(_CNS_PORT),
+           '--interface', 'lo',
+           '--www-root', os.path.join(self.DataDir(), 'media')]
+    process = subprocess.Popen(cmd, stderr=subprocess.PIPE)
+
+    # Wait for server to start up.
+    line = True
+    while line:
+      line = process.stderr.readline()
+      if 'STARTED' in line:
+        self._server_pid = process.pid
+        pyauto.PyUITest.setUp(self)
+        return
+    self.fail('Failed to start CNS.')
+
+  def tearDown(self):
+    """Stops the Constrained Network Server (CNS)."""
+    pyauto.PyUITest.tearDown(self)
+    self.Kill(self._server_pid)
+
+  def testConstrainedNetworkPerf(self):
+    """Starts CNS, spins up worker threads to run through _TEST_CONSTRAINTS."""
+    # Convert relative test path into an absolute path.
+    test_url = self.GetFileURLForDataPath(_TEST_HTML_PATH)
+
+    # PyAuto doesn't support threads, so we synchronize all automation calls.
+    automation_lock = threading.Lock()
+
+    # Spin up worker threads.
+    tasks = Queue.Queue()
+    threads = []
+    for _ in xrange(_TEST_THREADS):
+      threads.append(TestWorker(self, tasks, automation_lock, test_url))
+
+    for settings, name in zip(_TEST_CONSTRAINTS, _TEST_CONSTRAINT_NAMES):
+      tasks.put((settings, name))
+
+    # Add shutdown magic to end of queue.
+    for thread in threads:
+      tasks.put((None, None))
+
+    # Wait for threads to exit, gracefully or otherwise.
+    for thread in threads:
+      thread.join()
+
+
+if __name__ == '__main__':
+  # TODO(dalecurtis): Process command line parameters here.
+  pyauto_media.Main()