Real world impact script: scalable manual rendering QA

tools/real_world_impact/real_world_impact.py

Index: tools/real_world_impact/real_world_impact.py
diff --git a/tools/real_world_impact/real_world_impact.py b/tools/real_world_impact/real_world_impact.py
new file mode 100755
index 0000000000000000000000000000000000000000..cbfad3bd3b18eff0ed76bef7bcd0d1ff7b333427
--- /dev/null
+++ b/tools/real_world_impact/real_world_impact.py
@@ -0,0 +1,554 @@
+#!/usr/bin/env python
+# Copyright (c) 2014 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.
+
+# Tool for seeing the real world impact of a patch.
+#
+# Layout Tests can tell you whether something has changed, but this can help
+# you determine whether a subtle/controversial change is beneficial or not.
+#
+# It dumps the rendering of a large number of sites, both with and without a
+# patch being evaluated, then sorts them by greatest difference in rendering,
+# such that a human reviewer can quickly review the most impacted sites,
+# rather than having to manually try sites to see if anything changes.
+#
+# In future it might be possible to extend this to other kinds of differences,
+# e.g. page load times.
+
+import argparse
+from argparse import RawTextHelpFormatter
+from contextlib import closing
+import datetime
+import errno
+from distutils.spawn import find_executable
+from operator import itemgetter
+import multiprocessing
+import os
+import re
+from cStringIO import StringIO
+import subprocess
+import sys
+import textwrap
+import time
+from urllib2 import urlopen
+from urlparse import urlparse
+import webbrowser
+from zipfile import ZipFile
+
+from nsfw_urls import nsfw_urls
+
+action = None
+allow_js = False
+additional_content_shell_flags = ""
+chromium_src_root = ""
+chromium_out_dir = ""
+image_diff = ""
+content_shell = ""
+output_dir = ""
+num_sites = 100
+urls = []
+print_lock = multiprocessing.Lock()
+
+
+def MakeDirsIfNotExist(dir):
+  try:
+    os.makedirs(dir)
+  except OSError as e:
+    if e.errno != errno.EEXIST:
+      raise
+
+
+def SetupPathsAndOut():
+  global chromium_src_root, chromium_out_dir, output_dir
+  global image_diff, content_shell
+  chromium_src_root = os.path.abspath(os.path.join(os.path.dirname(__file__),
+                                                   os.pardir,
+                                                   os.pardir))
+  # Find out directory (might be out_linux for users of cr).
+  for out_suffix in ["_linux", ""]:
+    out_dir = os.path.join(chromium_src_root, "out" + out_suffix)
+    if os.path.exists(out_dir):
+      chromium_out_dir = out_dir
+      break
+  if not chromium_out_dir:
+    return False
+
+  this_script_name = "real_world_impact"
+  output_dir = os.path.join(chromium_out_dir,
+                            "Release",
+                            this_script_name)
+  MakeDirsIfNotExist(output_dir)
+
+  image_diff = os.path.join(chromium_out_dir, "Release", "image_diff")
+
+  if sys.platform == 'darwin':
+    content_shell = os.path.join(chromium_out_dir, "Release",
+                    "Content Shell.app/Contents/MacOS/Content Shell")
+  elif sys.platform.startswith('linux'):
+    content_shell = os.path.join(chromium_out_dir, "Release",
+                    "content_shell")
+  elif sys.platform.startswith('win'):
+    content_shell = os.path.join(chromium_out_dir, "Release",
+                    "content_shell.exe")
+  return True
+
+
+def CheckPrerequisites():
+  if not find_executable("wget"):
+    print "wget not found! Install wget and re-run this."
+    return False
+  if not os.path.exists(image_diff):
+    print "image_diff not found (%s)!" % image_diff
+    print "Build the image_diff target and re-run this."
+    return False
+  if not os.path.exists(content_shell):
+    print "Content shell not found (%s)!" % content_shell
+    print "Build Release/content_shell and re-run this."
+    return False
+  return True
+
+
+def PickSampleUrls():
+  global urls
+  data_dir = os.path.join(output_dir, "data")
+  MakeDirsIfNotExist(data_dir)
+
+  # Download Alexa top 1,000,000 sites
+  # TODO(johnme): Should probably update this when it gets too stale...
+  csv_path = os.path.join(data_dir, "top-1m.csv")
+  if not os.path.exists(csv_path):
+    print "Downloading list of top 1,000,000 sites from Alexa..."
+    csv_url = "http://s3.amazonaws.com/alexa-static/top-1m.csv.zip"
+    with closing(urlopen(csv_url)) as stream:
+      ZipFile(StringIO(stream.read())).extract("top-1m.csv", data_dir)
+
+  bad_urls_path = os.path.join(data_dir, "bad_urls.txt")
+  if os.path.exists(bad_urls_path):
+    with open(bad_urls_path) as f:
+      bad_urls = set(f.read().splitlines())
+  else:
+    bad_urls = set()
+
+  # See if we've already selected a sample of size num_sites (this way, if you
+  # call this script with arguments "before N" then "after N", where N is the
+  # same number, we'll use the same sample, as expected!).
+  urls_path = os.path.join(data_dir, "%06d_urls.txt" % num_sites)
+  if not os.path.exists(urls_path):
+    if action == 'compare':
+      print ("Error: you must run 'before %d' and 'after %d' before "
+             "running 'compare %d'") % (num_sites, num_sites, num_sites)
+      return False
+    print "Picking %d sample urls..." % num_sites
+
+    # TODO(johnme): For now this just gets the top num_sites entries. In future
+    # this should pick a weighted random sample. For example, it could fit a
+    # power-law distribution, which is a good model of website popularity
+    # (http://www.useit.com/alertbox/9704b.html).
+    urls = []
+    remaining_num_sites = num_sites
+    with open(csv_path) as f:
+      for entry in f:
+        if remaining_num_sites <= 0:
+          break
+        remaining_num_sites -= 1
+        hostname = entry.strip().split(',')[1]
+        if not '/' in hostname:  # Skip Alexa 1,000,000 entries that have paths.
+          url = "http://%s/" % hostname
+          if not url in bad_urls:
+            urls.append(url)
+    # Don't write these to disk yet; we'll do that in SaveWorkingUrls below
+    # once we have tried to download them and seen which ones fail.
+  else:
+    with open(urls_path) as f:
+      urls = [u for u in f.read().splitlines() if not u in bad_urls]
+  return True
+
+
+def SaveWorkingUrls():
+  # TODO(johnme): Update the list if a url that used to work goes offline.
+  urls_path = os.path.join(output_dir, "data", "%06d_urls.txt" % num_sites)
+  if not os.path.exists(urls_path):
+    with open(urls_path, 'w') as f:
+      f.writelines(u + '\n' for u in urls)
+
+
+def PrintElapsedTime(elapsed, detail=""):
+  elapsed = round(elapsed * 10) / 10.0
+  m = elapsed / 60
+  s = elapsed % 60
+  print "Took %dm%.1fs" % (m, s), detail
+
+
+def DownloadStaticCopyTask(url):
+  url_parts = urlparse(url)
+  host_dir = os.path.join(output_dir, "data", url_parts.hostname)
+  # Use wget for now, as does a reasonable job of spidering page dependencies
+  # (e.g. CSS, JS, images).
+  success = True
+  try:
+    subprocess.check_call(["wget",
+                           "--execute", "robots=off",
+                           ("--user-agent=Mozilla/5.0 (Macintosh; Intel Mac OS "
+                            "X 10_8_5) AppleWebKit/537.36 (KHTML, like Gecko) C"
+                            "hrome/32.0.1700.14 Safari/537.36"),
+                           "--page-requisites",
+                           "--span-hosts",
+                           "--adjust-extension",
+                           "--convert-links",
+                           "--directory-prefix=" + host_dir,
+                           "--force-directories",
+                           "--default-page=index.html",
+                           "--no-check-certificate",
+                           "--timeout=5", # 5s timeout
+                           "--tries=2",
+                           "--quiet",
+                           url])
+  except KeyboardInterrupt:
+    success = False
+  except subprocess.CalledProcessError:
+    # Ignoring these for now, as some sites have issues with their subresources
+    # yet still produce a renderable index.html
+    pass #success = False
+  if success:
+    download_path = os.path.join(host_dir, url_parts.hostname, "index.html")
+    if not os.path.exists(download_path):
+      success = False
+    else:
+      with print_lock:
+        print "Downloaded:", url
+  if not success:
+    with print_lock:
+      print "Failed to download:", url
+    return False
+  return True
+
+
+def DownloadStaticCopies():
+  global urls
+  new_urls = []
+  for url in urls:
+    url_parts = urlparse(url)
+    host_dir = os.path.join(output_dir, "data", url_parts.hostname)
+    download_path = os.path.join(host_dir, url_parts.hostname, "index.html")
+    if not os.path.exists(download_path):
+      new_urls.append(url)
+
+  if new_urls:
+    print "Downloading static copies of %d sites..." % len(new_urls)
+    start_time = time.time()
+
+    results = multiprocessing.Pool(20).map(DownloadStaticCopyTask, new_urls)
+    failed_urls = [new_urls[i] for i,ret in enumerate(results) if not ret]
+    if failed_urls:
+      bad_urls_path = os.path.join(output_dir, "data", "bad_urls.txt")
+      with open(bad_urls_path, 'a') as f:
+        f.writelines(u + '\n' for u in failed_urls)
+      failed_urls_set = set(failed_urls)
+      urls = [u for u in urls if u not in failed_urls_set]
+
+    PrintElapsedTime(time.time() - start_time)
+
+  SaveWorkingUrls()
+
+
+def RunDrtTask(url):
+  url_parts = urlparse(url)
+  host_dir = os.path.join(output_dir, "data", url_parts.hostname)
+  html_path = os.path.join(host_dir, url_parts.hostname, "index.html")
+
+  if not allow_js:
+    nojs_path = os.path.join(host_dir, url_parts.hostname, "index-nojs.html")
+    if not os.path.exists(nojs_path):
+      with open(html_path) as f:
+        html = f.read()
+      if not html:
+        return False
+      # These aren't intended to be XSS safe :)
+      block_tags = (r'<\s*(script|object|video|audio|iframe|frameset|frame)'
+                    r'\b.*?<\s*\/\s*\1\s*>')
+      block_attrs = r'\s(onload|onerror)\s*=\s*(\'[^\']*\'|"[^"]*|\S*)'
+      html = re.sub(block_tags, '', html, flags=re.I|re.S)
+      html = re.sub(block_attrs, '', html, flags=re.I)
+      with open(nojs_path, 'w') as f:
+        f.write(html)
+    html_path = nojs_path
+
+  start_time = time.time()
+
+  with open(os.devnull, "w") as fnull:
+    p = subprocess.Popen([content_shell,
+                          "--dump-render-tree",
+                          additional_content_shell_flags,
+                          # The single quote is not a typo, it's a separator!
+                          html_path + "'--pixel-test"
+                         ],
+                         shell=False,
+                         stdout=subprocess.PIPE,
+                         stderr=fnull)
+  result = p.stdout.read()
+  PNG_START = b"\x89\x50\x4E\x47\x0D\x0A\x1A\x0A"
+  PNG_END = b"\x49\x45\x4E\x44\xAE\x42\x60\x82"
+  try:
+    start = result.index(PNG_START)
+    end = result.rindex(PNG_END) + 8
+  except ValueError:
+    return False
+
+  png_path = os.path.join(output_dir, action, url_parts.hostname + ".png")
+  MakeDirsIfNotExist(os.path.dirname(png_path))
+  with open(png_path, 'wb') as f:
+    f.write(result[start:end])
+  elapsed_time = (time.time() - start_time, url)
+  return elapsed_time
+
+
+def RunDrt():
+  print "Taking screenshots of %d pages..." % len(urls)
+  start_time = time.time()
+
+  results = multiprocessing.Pool().map(RunDrtTask, urls, 1)
+
+  max_time, url = max(t for t in results if t)
+  elapsed_detail = "(slowest: %.2fs on %s)" % (max_time, url)
+  PrintElapsedTime(time.time() - start_time, elapsed_detail)
+
+
+def CompareResultsTask(url):
+  url_parts = urlparse(url)
+  before_path = os.path.join(output_dir, "before", url_parts.hostname + ".png")
+  after_path = os.path.join(output_dir, "after", url_parts.hostname + ".png")
+  diff_path = os.path.join(output_dir, "diff", url_parts.hostname + ".png")
+  MakeDirsIfNotExist(os.path.join(output_dir, "diff"))
+
+  # TODO(johnme): Don't hardcode "real_world_impact".
+  red_path = ("data:image/gif;base64,R0lGODlhAQABAPAAAP8AAP///yH5BAAAAAAALAAAAA"
+              "ABAAEAAAICRAEAOw==")
+
+  before_exists = os.path.exists(before_path)
+  after_exists = os.path.exists(after_path)
+  if not before_exists and not after_exists:
+    # TODO(johnme): Make this more informative.
+    return (-100, url, red_path)
+  if before_exists != after_exists:
+    # TODO(johnme): Make this more informative.
+    return (200, url, red_path)
+
+  # Get percentage difference.
+  p = subprocess.Popen([image_diff, "--histogram",
+                        before_path, after_path],
+                        shell=False,
+                        stdout=subprocess.PIPE)
+  output,_ = p.communicate()
+  if p.returncode == 0:
+    return (0, url, before_path)
+  diff_match = re.match(r'histogram diff: (\d+\.\d{2})% (?:passed|failed)\n'
+                         'exact diff: (\d+\.\d{2})% (?:passed|failed)', output)
+  if not diff_match:
+    raise Exception("image_diff output format changed")
+  histogram_diff = float(diff_match.group(1))
+  exact_diff = float(diff_match.group(2))
+  combined_diff = max(histogram_diff + exact_diff / 8, 0.001)
+
+  # Produce diff PNG.
+  subprocess.call([image_diff, "--diff", before_path, after_path, diff_path])
+  return (combined_diff, url, diff_path)
+
+
+def CompareResults():
+  print "Running image_diff on %d pages..." % len(urls)
+  start_time = time.time()
+
+  results = multiprocessing.Pool().map(CompareResultsTask, urls)
+  results.sort(key=itemgetter(0), reverse=True)
+
+  PrintElapsedTime(time.time() - start_time)
+
+  now = datetime.datetime.today().strftime("%a %Y-%m-%d %H:%M")
+  html_start = textwrap.dedent("""\
+  <!DOCTYPE html>
+  <html>
+  <head>
+  <title>Real World Impact report %s</title>
+  <script>
+    var togglingImg = null;
+    var toggleTimer = null;
+
+    var before = true;
+    function toggle() {
+      var newFolder = before ? "before" : "after";
+      togglingImg.src = togglingImg.src.replace(/before|after|diff/, newFolder);
+      before = !before;
+      toggleTimer = setTimeout(toggle, 300);
+    }
+
+    function startToggle(img) {
+      before = true;
+      togglingImg = img;
+      if (!img.origSrc)
+        img.origSrc = img.src;
+      toggle();
+    }
+    function stopToggle(img) {
+      clearTimeout(toggleTimer);
+      img.src = img.origSrc;
+    }
+
+    document.onkeydown = function(e) {
+      e = e || window.event;
+      var keyCode = e.keyCode || e.which;
+      var newFolder;
+      switch (keyCode) {
+        case 49: //'1'
+          newFolder = "before"; break;
+        case 50: //'2'
+          newFolder = "after"; break;
+        case 51: //'3'
+          newFolder = "diff"; break;
+        default:
+          return;
+      }
+      var imgs = document.getElementsByTagName("img");
+      for (var i = 0; i < imgs.length; i++) {
+        imgs[i].src = imgs[i].src.replace(/before|after|diff/, newFolder);
+      }
+    };
+  </script>
+  <style>
+    h1 {
+      font-family: sans;
+    }
+    h2 {
+      font-family: monospace;
+      white-space: pre;
+    }
+    .nsfw-spacer {
+      height: 50vh;
+    }
+    .nsfw-warning {
+      background: yellow;
+      border: 10px solid red;
+    }
+    .info {
+      font-size: 1.2em;
+      font-style: italic;
+    }
+    body:not(.details-supported) details {
+      display: none;
+    }
+  </style>
+  </head>
+  <body>
+    <script>
+    if ('open' in document.createElement('details'))
+      document.body.className = "details-supported";
+    </script>
+    <!--<div class="nsfw-spacer"></div>-->
+    <p class="nsfw-warning">Warning: sites below are taken from the Alexa top %d
+    and may be NSFW.</p>
+    <!--<div class="nsfw-spacer"></div>-->
+    <h1>Real World Impact report %s</h1>
+    <p class="info">Press 1, 2 and 3 to switch between before, after and diff
+    screenshots respectively; or hover over the images to rapidly alternate
+    between before and after.</p>
+  """ % (now, num_sites, now))
+
+  html_same_row = """\
+  <h2>No difference on <a href="%s">%s</a>.</h2>
+  """
+
+  html_diff_row = """\
+  <h2>%7.3f%% difference on <a href="%s">%s</a>:</h2>
+  <img src="%s" width="800" height="600"
+       onmouseover="startToggle(this)" onmouseout="stopToggle(this)">
+  """
+
+  html_nsfw_diff_row = """\
+  <h2>%7.3f%% difference on <a href="%s">%s</a>:</h2>
+  <details>
+    <summary>This site may be NSFW. Click to expand/collapse.</summary>
+    <img src="%s" width="800" height="600"
+         onmouseover="startToggle(this)" onmouseout="stopToggle(this)">
+  </details>
+  """
+
+  html_end = textwrap.dedent("""\
+  </body>
+  </html>""")
+
+  html_path = os.path.join(output_dir, "diff.html")
+  with open(html_path, 'w') as f:
+    f.write(html_start)
+    for (diff_float, url, diff_path) in results:
+      diff_path = os.path.relpath(diff_path, output_dir)
+      if diff_float == 0:
+        f.write(html_same_row % (url, url))
+      elif url in nsfw_urls:
+        f.write(html_nsfw_diff_row % (diff_float, url, url, diff_path))
+      else:
+        f.write(html_diff_row % (diff_float, url, url, diff_path))
+    f.write(html_end)
+
+  webbrowser.open_new_tab("file://" + html_path)
+
+
+def main(argv):
+  global num_sites, action, allow_js, additional_content_shell_flags
+
+  parser = argparse.ArgumentParser(
+      formatter_class=RawTextHelpFormatter,
+      description="Compare the real world impact of a content shell change.",
+      epilog=textwrap.dedent("""\
+          Example usage:
+            1. Build content_shell in out/Release without any changes.
+            2. Run: %s before [num sites to test (default %d)].
+            3. Either:
+                 a. Apply your controversial patch and rebuild content_shell.
+                 b. Pass --additional_flags="--enable_your_flag" in step 4.
+            4. Run: %s after [num sites to test (default %d)].
+            5. Run: %s compare [num sites to test (default %d)].
+               This will open the results in your web browser.
+          """ % (argv[0], num_sites, argv[0], num_sites, argv[0], num_sites)))
+  parser.add_argument("--allow_js", help="Don't disable Javascript",
+                      action="store_true")
+  parser.add_argument("--additional_flags",
+                      help="Additional flags to pass to content shell")
+  parser.add_argument("action",
+                      help=textwrap.dedent("""\
+                        Action to perform.
+                          download - Just download the sites.
+                          before - Run content shell and record 'before' result.
+                          after - Run content shell and record 'after' result.
+                          compare - Compare before and after results.
+                      """),
+                      choices=["download", "before", "after", "compare"])
+  parser.add_argument("num_sites",
+                      help="Number of sites (default %s)" % num_sites,
+                      type=int, default=num_sites, nargs='?')
+  args = parser.parse_args()
+
+  action = args.action
+
+  if (args.num_sites):
+    num_sites = args.num_sites
+
+  if (args.allow_js):
+    allow_js = args.allow_js
+
+  if (args.additional_flags):
+    additional_content_shell_flags = args.additional_flags
+
+  if not SetupPathsAndOut() or not CheckPrerequisites() or not PickSampleUrls():
+    return 1
+
+  if action == 'compare':
+    CompareResults()
+  else:
+    DownloadStaticCopies()
+    if action != 'download':
+      RunDrt()
+  return 0
+
+
+if __name__ == '__main__':
+  sys.exit(main(sys.argv))