Revert "Revert "delete old things!""

gm/rebaseline_server/imagediffdb.py

Index: gm/rebaseline_server/imagediffdb.py
diff --git a/gm/rebaseline_server/imagediffdb.py b/gm/rebaseline_server/imagediffdb.py
deleted file mode 100644
index 0bc75cfca4d9c9dce9a47759dddb8ec99aa6383a..0000000000000000000000000000000000000000
--- a/gm/rebaseline_server/imagediffdb.py
+++ /dev/null
@@ -1,477 +0,0 @@
-#!/usr/bin/python
-
-"""
-Copyright 2013 Google Inc.
-
-Use of this source code is governed by a BSD-style license that can be
-found in the LICENSE file.
-
-Calulate differences between image pairs, and store them in a database.
-"""
-
-# System-level imports
-import contextlib
-import errno
-import json
-import logging
-import os
-import Queue
-import re
-import shutil
-import tempfile
-import threading
-import time
-import urllib
-
-# Must fix up PYTHONPATH before importing from within Skia
-import rs_fixpypath  # pylint: disable=W0611
-
-# Imports from within Skia
-import find_run_binary
-from py.utils import gs_utils
-
-
-SKPDIFF_BINARY = find_run_binary.find_path_to_program('skpdiff')
-
-DEFAULT_IMAGE_SUFFIX = '.png'
-DEFAULT_IMAGES_SUBDIR = 'images'
-# TODO(epoger): Figure out a better default number of threads; for now,
-# using a conservative default value.
-DEFAULT_NUM_WORKER_THREADS = 1
-
-DISALLOWED_FILEPATH_CHAR_REGEX = re.compile('[^\w\-]')
-
-RGBDIFFS_SUBDIR = 'diffs'
-WHITEDIFFS_SUBDIR = 'whitediffs'
-
-# Keys used within DiffRecord dictionary representations.
-# NOTE: Keep these in sync with static/constants.js
-KEY__DIFFERENCES__MAX_DIFF_PER_CHANNEL = 'maxDiffPerChannel'
-KEY__DIFFERENCES__NUM_DIFF_PIXELS = 'numDifferingPixels'
-KEY__DIFFERENCES__PERCENT_DIFF_PIXELS = 'percentDifferingPixels'
-KEY__DIFFERENCES__PERCEPTUAL_DIFF = 'perceptualDifference'
-KEY__DIFFERENCES__DIFF_URL = 'diffUrl'
-KEY__DIFFERENCES__WHITE_DIFF_URL = 'whiteDiffUrl'
-
-# Special values within ImageDiffDB._diff_dict
-_DIFFRECORD_FAILED = 'failed'
-_DIFFRECORD_PENDING = 'pending'
-
-# How often to report tasks_queue size
-QUEUE_LOGGING_GRANULARITY = 1000
-
-# Temporary variable to keep track of how many times we download
-# the same file in multiple threads.
-# TODO(epoger): Delete this, once we see that the number stays close to 0.
-global_file_collisions = 0
-
-
-class DiffRecord(object):
-  """ Record of differences between two images. """
-
-  def __init__(self, gs, storage_root,
-               expected_image_url, expected_image_locator,
-               actual_image_url, actual_image_locator,
-               expected_images_subdir=DEFAULT_IMAGES_SUBDIR,
-               actual_images_subdir=DEFAULT_IMAGES_SUBDIR,
-               image_suffix=DEFAULT_IMAGE_SUFFIX):
-    """Download this pair of images (unless we already have them on local disk),
-    and prepare a DiffRecord for them.
-
-    Args:
-      gs: instance of GSUtils object we can use to download images
-      storage_root: root directory on local disk within which we store all
-          images
-      expected_image_url: file, GS, or HTTP url from which we will download the
-          expected image
-      expected_image_locator: a unique ID string under which we will store the
-          expected image within storage_root (probably including a checksum to
-          guarantee uniqueness)
-      actual_image_url: file, GS, or HTTP url from which we will download the
-          actual image
-      actual_image_locator: a unique ID string under which we will store the
-          actual image within storage_root (probably including a checksum to
-          guarantee uniqueness)
-      expected_images_subdir: the subdirectory expected images are stored in.
-      actual_images_subdir: the subdirectory actual images are stored in.
-      image_suffix: the suffix of images.
-    """
-    expected_image_locator = _sanitize_locator(expected_image_locator)
-    actual_image_locator = _sanitize_locator(actual_image_locator)
-
-    # Download the expected/actual images, if we don't have them already.
-    expected_image_file = os.path.join(
-        storage_root, expected_images_subdir,
-        str(expected_image_locator) + image_suffix)
-    actual_image_file = os.path.join(
-        storage_root, actual_images_subdir,
-        str(actual_image_locator) + image_suffix)
-    for image_file, image_url in [
-        (expected_image_file, expected_image_url),
-        (actual_image_file, actual_image_url)]:
-      if image_file and image_url:
-        try:
-          _download_file(gs, image_file, image_url)
-        except Exception:
-          logging.exception('unable to download image_url %s to file %s' %
-                            (image_url, image_file))
-          raise
-
-    # Return early if we do not need to generate diffs.
-    if (expected_image_url == actual_image_url or
-        not expected_image_url or not actual_image_url):
-      return
-
-    # Get all diff images and values using the skpdiff binary.
-    skpdiff_output_dir = tempfile.mkdtemp()
-    try:
-      skpdiff_summary_file = os.path.join(skpdiff_output_dir,
-                                          'skpdiff-output.json')
-      skpdiff_rgbdiff_dir = os.path.join(storage_root, RGBDIFFS_SUBDIR)
-      skpdiff_whitediff_dir = os.path.join(storage_root, WHITEDIFFS_SUBDIR)
-      _mkdir_unless_exists(skpdiff_rgbdiff_dir)
-      _mkdir_unless_exists(skpdiff_rgbdiff_dir)
-
-      # TODO(epoger): Consider calling skpdiff ONCE for all image pairs,
-      # instead of calling it separately for each image pair.
-      # Pro: we'll incur less overhead from making repeated system calls,
-      # spinning up the skpdiff binary, etc.
-      # Con: we would have to wait until all image pairs were loaded before
-      # generating any of the diffs?
-      # Note(stephana): '--longnames' was added to allow for this 
-      # case (multiple files at once) versus specifying output diffs 
-      # directly.
-      find_run_binary.run_command(
-          [SKPDIFF_BINARY, '-p', expected_image_file, actual_image_file,
-           '--jsonp', 'false',
-           '--longnames', 'true',
-           '--output', skpdiff_summary_file,
-           '--differs', 'perceptual', 'different_pixels',
-           '--rgbDiffDir', skpdiff_rgbdiff_dir,
-           '--whiteDiffDir', skpdiff_whitediff_dir,
-           ])
-
-      # Get information out of the skpdiff_summary_file.
-      with contextlib.closing(open(skpdiff_summary_file)) as fp:
-        data = json.load(fp)
-
-      # For now, we can assume there is only one record in the output summary,
-      # since we passed skpdiff only one pair of images.
-      record = data['records'][0]
-      self._width = record['width']
-      self._height = record['height']
-      self._diffUrl = os.path.split(record['rgbDiffPath'])[1]
-      self._whiteDiffUrl = os.path.split(record['whiteDiffPath'])[1]
-
-      # TODO: make max_diff_per_channel a tuple instead of a list, because the
-      # structure is meaningful (first element is red, second is green, etc.)
-      # See http://stackoverflow.com/a/626871
-      self._max_diff_per_channel = [
-          record['maxRedDiff'], record['maxGreenDiff'], record['maxBlueDiff']]
-      per_differ_stats = record['diffs']
-      for stats in per_differ_stats:
-        differ_name = stats['differName']
-        if differ_name == 'different_pixels':
-          self._num_pixels_differing = stats['pointsOfInterest']
-        elif differ_name == 'perceptual':
-          perceptual_similarity = stats['result']
-
-      # skpdiff returns the perceptual similarity; convert it to get the
-      # perceptual difference percentage.
-      # skpdiff outputs -1 if the images are different sizes. Treat any
-      # output that does not lie in [0, 1] as having 0% perceptual
-      # similarity.
-      if not 0 <= perceptual_similarity <= 1:
-        perceptual_similarity = 0
-      self._perceptual_difference = 100 - (perceptual_similarity * 100)
-    finally:
-      shutil.rmtree(skpdiff_output_dir)
-
-  # TODO(epoger): Use properties instead of getters throughout.
-  # See http://stackoverflow.com/a/6618176
-  def get_num_pixels_differing(self):
-    """Returns the absolute number of pixels that differ."""
-    return self._num_pixels_differing
-
-  def get_percent_pixels_differing(self):
-    """Returns the percentage of pixels that differ, as a float between
-    0 and 100 (inclusive)."""
-    return ((float(self._num_pixels_differing) * 100) /
-            (self._width * self._height))
-
-  def get_perceptual_difference(self):
-    """Returns the perceptual difference percentage."""
-    return self._perceptual_difference
-
-  def get_max_diff_per_channel(self):
-    """Returns the maximum difference between the expected and actual images
-    for each R/G/B channel, as a list."""
-    return self._max_diff_per_channel
-
-  def as_dict(self):
-    """Returns a dictionary representation of this DiffRecord, as needed when
-    constructing the JSON representation."""
-    return {
-        KEY__DIFFERENCES__NUM_DIFF_PIXELS: self._num_pixels_differing,
-        KEY__DIFFERENCES__PERCENT_DIFF_PIXELS:
-            self.get_percent_pixels_differing(),
-        KEY__DIFFERENCES__MAX_DIFF_PER_CHANNEL: self._max_diff_per_channel,
-        KEY__DIFFERENCES__PERCEPTUAL_DIFF: self._perceptual_difference,
-        KEY__DIFFERENCES__DIFF_URL: self._diffUrl,
-        KEY__DIFFERENCES__WHITE_DIFF_URL: self._whiteDiffUrl, 
-    }
-
-
-
-class ImageDiffDB(object):
-  """ Calculates differences between image pairs, maintaining a database of
-  them for download."""
-
-  def __init__(self, storage_root, gs=None,
-               num_worker_threads=DEFAULT_NUM_WORKER_THREADS):
-    """
-    Args:
-      storage_root: string; root path within the DB will store all of its stuff
-      gs: instance of GSUtils object we can use to download images
-      num_worker_threads: how many threads that download images and
-          generate diffs simultaneously
-    """
-    self._storage_root = storage_root
-    self._gs = gs
-
-    # Mechanism for reporting queue size periodically.
-    self._last_queue_size_reported = None
-    self._queue_size_report_lock = threading.RLock()
-
-    # Dictionary of DiffRecords, keyed by (expected_image_locator,
-    # actual_image_locator) tuples.
-    # Values can also be _DIFFRECORD_PENDING, _DIFFRECORD_FAILED.
-    #
-    # Any thread that modifies _diff_dict must first acquire
-    # _diff_dict_writelock!
-    #
-    # TODO(epoger): Disk is limitless, but RAM is not... so, we should probably
-    # remove items from self._diff_dict if they haven't been accessed for a
-    # long time.  We can always regenerate them by diffing the images we
-    # previously downloaded to local disk.
-    # I guess we should figure out how expensive it is to download vs diff the
-    # image pairs... if diffing them is expensive too, we can write these
-    # _diff_dict objects out to disk if there's too many to hold in RAM.
-    # Or we could use virtual memory to handle that automatically.
-    self._diff_dict = {}
-    self._diff_dict_writelock = threading.RLock()
-
-    # Set up the queue for asynchronously loading DiffRecords, and start the
-    # worker threads reading from it.
-    # The queue maxsize must be 0 (infinite size queue), so that asynchronous
-    # calls can return as soon as possible.
-    self._tasks_queue = Queue.Queue(maxsize=0)
-    self._workers = []
-    for i in range(num_worker_threads):
-      worker = threading.Thread(target=self.worker, args=(i,))
-      worker.daemon = True
-      worker.start()
-      self._workers.append(worker)
-
-  def log_queue_size_if_changed(self, limit_verbosity=True):
-    """Log the size of self._tasks_queue, if it has changed since the last call.
-
-    Reports the current queue size, using log.info(), unless the queue is the
-    same size as the last time we reported it.
-
-    Args:
-      limit_verbosity: if True, only log if the queue size is a multiple of
-          QUEUE_LOGGING_GRANULARITY
-    """
-    # Acquire the lock, to synchronize access to self._last_queue_size_reported
-    self._queue_size_report_lock.acquire()
-    try:
-      size = self._tasks_queue.qsize()
-      if size == self._last_queue_size_reported:
-        return
-      if limit_verbosity and (size % QUEUE_LOGGING_GRANULARITY != 0):
-        return
-      logging.info('tasks_queue size is %d' % size)
-      self._last_queue_size_reported = size
-    finally:
-      self._queue_size_report_lock.release()
-
-  def worker(self, worker_num):
-    """Launch a worker thread that pulls tasks off self._tasks_queue.
-
-    Args:
-      worker_num: (integer) which worker this is
-    """
-    while True:
-      self.log_queue_size_if_changed()
-      params = self._tasks_queue.get()
-      key, expected_image_url, actual_image_url = params
-      try:
-        diff_record = DiffRecord(
-            self._gs, self._storage_root,
-            expected_image_url=expected_image_url,
-            expected_image_locator=key[0],
-            actual_image_url=actual_image_url,
-            actual_image_locator=key[1])
-      except Exception:
-        logging.exception(
-            'exception while creating DiffRecord for key %s' % str(key))
-        diff_record = _DIFFRECORD_FAILED
-      self._diff_dict_writelock.acquire()
-      try:
-        self._diff_dict[key] = diff_record
-      finally:
-        self._diff_dict_writelock.release()
-
-  @property
-  def storage_root(self):
-    return self._storage_root
-
-  def add_image_pair(self,
-                     expected_image_url, expected_image_locator,
-                     actual_image_url, actual_image_locator):
-    """Asynchronously prepare a DiffRecord for a pair of images.
-
-    This method will return quickly; calls to get_diff_record() will block
-    until the DiffRecord is available (or we have given up on creating it).
-
-    If we already have a DiffRecord for this particular image pair, no work
-    will be done.
-
-    If expected_image_url (or its locator) is None, just download actual_image.
-    If actual_image_url (or its locator) is None, just download expected_image.
-
-    Args:
-      expected_image_url: file, GS, or HTTP url from which we will download the
-          expected image
-      expected_image_locator: a unique ID string under which we will store the
-          expected image within storage_root (probably including a checksum to
-          guarantee uniqueness)
-      actual_image_url: file, GS, or HTTP url from which we will download the
-          actual image
-      actual_image_locator: a unique ID string under which we will store the
-          actual image within storage_root (probably including a checksum to
-          guarantee uniqueness)
-    """
-    expected_image_locator = _sanitize_locator(expected_image_locator)
-    actual_image_locator = _sanitize_locator(actual_image_locator)
-    key = (expected_image_locator, actual_image_locator)
-    must_add_to_queue = False
-
-    self._diff_dict_writelock.acquire()
-    try:
-      if not key in self._diff_dict:
-        # If we have already requested a diff between these two images,
-        # we don't need to request it again.
-        must_add_to_queue = True
-        self._diff_dict[key] = _DIFFRECORD_PENDING
-    finally:
-      self._diff_dict_writelock.release()
-
-    if must_add_to_queue:
-      self._tasks_queue.put((key, expected_image_url, actual_image_url))
-      self.log_queue_size_if_changed()
-
-  def get_diff_record(self, expected_image_locator, actual_image_locator):
-    """Returns the DiffRecord for this image pair.
-
-    This call will block until the diff record is available, or we were unable
-    to generate it.
-
-    Args:
-      expected_image_locator: a unique ID string under which we will store the
-          expected image within storage_root (probably including a checksum to
-          guarantee uniqueness)
-      actual_image_locator: a unique ID string under which we will store the
-          actual image within storage_root (probably including a checksum to
-          guarantee uniqueness)
-
-    Returns the DiffRecord for this image pair, or None if we were unable to
-    generate one.
-    """
-    key = (_sanitize_locator(expected_image_locator),
-           _sanitize_locator(actual_image_locator))
-    diff_record = self._diff_dict[key]
-
-    # If we have no results yet, block until we do.
-    while diff_record == _DIFFRECORD_PENDING:
-      time.sleep(1)
-      diff_record = self._diff_dict[key]
-
-    # Once we have the result...
-    if diff_record == _DIFFRECORD_FAILED:
-      logging.error(
-          'failed to create a DiffRecord for expected_image_locator=%s , '
-          'actual_image_locator=%s' % (
-              expected_image_locator, actual_image_locator))
-      return None
-    else:
-      return diff_record
-
-
-# Utility functions
-
-def _download_file(gs, local_filepath, url):
-  """Download a file from url to local_filepath, unless it is already there.
-
-  Args:
-    gs: instance of GSUtils object, in case the url points at Google Storage
-    local_filepath: path on local disk where the image should be stored
-    url: HTTP or GS URL from which we can download the image if we don't have
-        it yet
-  """
-  global global_file_collisions
-  if not os.path.exists(local_filepath):
-    _mkdir_unless_exists(os.path.dirname(local_filepath))
-
-    # First download the file contents into a unique filename, and
-    # then rename that file.  That way, if multiple threads are downloading
-    # the same filename at the same time, they won't interfere with each
-    # other (they will both download the file, and one will "win" in the end)
-    temp_filename = '%s-%d' % (local_filepath,
-                               threading.current_thread().ident)
-    if gs_utils.GSUtils.is_gs_url(url):
-      (bucket, path) = gs_utils.GSUtils.split_gs_url(url)
-      gs.download_file(source_bucket=bucket, source_path=path,
-                       dest_path=temp_filename)
-    else:
-      with contextlib.closing(urllib.urlopen(url)) as url_handle:
-        with open(temp_filename, 'wb') as file_handle:
-          shutil.copyfileobj(fsrc=url_handle, fdst=file_handle)
-
-    # Rename the file to its real filename.
-    # Keep count of how many colliding downloads we encounter;
-    # if it's a large number, we may want to change our download strategy
-    # to minimize repeated downloads.
-    if os.path.exists(local_filepath):
-      global_file_collisions += 1
-    else:
-      os.rename(temp_filename, local_filepath)
-
-
-def _mkdir_unless_exists(path):
-  """Unless path refers to an already-existing directory, create it.
-
-  Args:
-    path: path on local disk
-  """
-  try:
-    os.makedirs(path)
-  except OSError as e:
-    if e.errno == errno.EEXIST:
-      pass
-
-
-def _sanitize_locator(locator):
-  """Returns a sanitized version of a locator (one in which we know none of the
-  characters will have special meaning in filenames).
-
-  Args:
-    locator: string, or something that can be represented as a string.
-        If None or '', it is returned without modification, because empty
-        locators have a particular meaning ("there is no image for this")
-  """
-  if locator:
-    return DISALLOWED_FILEPATH_CHAR_REGEX.sub('_', str(locator))
-  else:
-    return locator