sandwich: Use cachetool's batch mode to speed-up cache processing.

tools/android/loading/sandwich_swr.py

 # Copyright 2016 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 csv
 import logging
 import os
 import shutil
 
 import chrome_cache
 import common_util
 import loading_trace
 import request_track
 import sandwich_metrics
 import sandwich_runner
 import task_manager
 
 
 def _BuildPatchedCache(original_cache_run_path, original_cache_archive_path,
       cache_archive_dest_path):
   CACHE_CONTROL_VALUE = 'max-age=0,stale-while-revalidate=315360000'
   trace_path = os.path.join(
       original_cache_run_path, '0', sandwich_runner.TRACE_FILENAME)
   trace = loading_trace.LoadingTrace.FromJsonFile(trace_path)
   patch_count = 0
   with common_util.TemporaryDirectory(prefix='sandwich_tmp') as tmp_path:
     cache_path = os.path.join(tmp_path, 'cache')
     chrome_cache.UnzipDirectoryContent(original_cache_archive_path, cache_path)
-    cache_backend = chrome_cache.CacheBackend(cache_path, 'simple')
-    cache_keys = set(cache_backend.ListKeys())
-    for request in trace.request_track.GetEvents():
-      if request.url not in cache_keys:
-        continue
-      caching_policy = request_track.CachingPolicy(request)
-      assert caching_policy.IsCacheable()
-      freshness = caching_policy.GetFreshnessLifetimes()
-      if freshness[0] == 0:
-        continue
-      request.SetHTTPResponseHeader('cache-control', CACHE_CONTROL_VALUE)
-      raw_headers = request.GetRawResponseHeaders()
-      cache_backend.UpdateRawResponseHeaders(request.url, raw_headers)
-      patch_count += 1
+    with chrome_cache.OnlineCacheBackend(
+        cache_path, chrome_cache.CacheBackendType.SIMPLE) as cache_backend:
+      cache_keys = set(cache_backend.ListKeys())
+      for request in trace.request_track.GetEvents():
+        if request.url not in cache_keys:
+          continue
+        caching_policy = request_track.CachingPolicy(request)
+        assert caching_policy.IsCacheable()
+        freshness = caching_policy.GetFreshnessLifetimes()
+        if freshness[0] == 0:
+          continue
+        request.SetHTTPResponseHeader('cache-control', CACHE_CONTROL_VALUE)
+        raw_headers = request.GetRawResponseHeaders()
+        cache_backend.UpdateRawResponseHeaders(request.url, raw_headers)
+        patch_count += 1
     chrome_cache.ZipDirectoryContent(cache_path, cache_archive_dest_path)
   logging.info('Patched %d cached resources out of %d' % (
       patch_count, len(cache_keys)))
 
 
 class StaleWhileRevalidateBenchmarkBuilder(task_manager.Builder):
   """A builder for a graph of tasks for Stale-While-Revalidate study benchmarks.
   """
 
   def __init__(self, common_builder):
@@ skipping 90 matching lines @@
 
       run_metrics_list.sort(key=lambda e: e['repeat_id'])
       with open(ExtractMetrics.path, 'w') as csv_file:
         writer = csv.DictWriter(csv_file, fieldnames=(additional_column_names +
                                     sandwich_metrics.COMMON_CSV_COLUMN_NAMES))
         writer.writeheader()
         for trace_metrics in run_metrics_list:
           writer.writerow(trace_metrics)
 
     self._common_builder.default_final_tasks.append(ExtractMetrics)