Add Precache.Fetch.MinWeight UMA.

components/precache/core/precache_fetcher_unittest.cc

 // 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.
 
 #include "components/precache/core/precache_fetcher.h"
 
 #include <stdint.h>
 
 #include <cstring>
 #include <memory>
@@ skipping 1073 matching lines @@
 // PrecacheFetcher::Fetcher constructor.
 //
 // TODO(twifkak): Port these tests from FakeURLFetcherFactory to
 // MockURLFetcherFactory or EmbeddedTestServer, and add a test that fetches are
 // cancelled midstream.
 
 TEST_F(PrecacheFetcherTest, MaxBytesTotal) {
   SetDefaultFlags();
   std::unique_ptr<PrecacheUnfinishedWork> unfinished_work(
       new PrecacheUnfinishedWork());
-  unfinished_work->add_top_host()->set_hostname("good-manifest.com");
+  auto* top_host = unfinished_work->add_top_host();
+  top_host->set_hostname("good-manifest.com");
+  top_host->set_visits(1);
   unfinished_work->set_start_time(base::Time::UnixEpoch().ToInternalValue());
 
   // Should be greater than kMaxParallelFetches, so that we can observe
   // PrecacheFetcher not fetching the remaining resources after max bytes is
   // exceeded.
   const size_t kNumResources = kMaxParallelFetches + 5;
   // Should be smaller than kNumResources - kMaxParallelFetches, such that the
   // max bytes is guaranteed to be exceeded before all fetches have been
   // requested. In this case, after 3 fetches have been completed, 3 more are
   // added to the fetcher pool, but 2 out of 5 still remain.
   const size_t kResourcesWithinMax = 3;
   // Should be big enough that the size of the config, manifest, and HTTP
   // headers are negligible for max bytes computation.
   const size_t kBytesPerResource = 500;
   const size_t kMaxBytesTotal = kResourcesWithinMax * kBytesPerResource;
 
   PrecacheConfigurationSettings config;
   config.set_max_bytes_total(kMaxBytesTotal);
+  config.set_global_ranking(true);
 
   factory_.SetFakeResponse(GURL(kConfigURL), config.SerializeAsString(),
                            net::HTTP_OK, net::URLRequestStatus::SUCCESS);
 
   PrecacheManifest good_manifest;
   for (size_t i = 0; i < kNumResources; ++i) {
     const std::string url = "http://good-manifest.com/" + std::to_string(i);
-    good_manifest.add_resource()->set_url(url);
+    auto* resource = good_manifest.add_resource();
+    resource->set_url(url);
+    resource->set_weight_ratio(static_cast<double>(i) / kNumResources);
     factory_.SetFakeResponse(GURL(url), std::string(kBytesPerResource, '.'),
                              net::HTTP_OK, net::URLRequestStatus::SUCCESS);
   }
 
   factory_.SetFakeResponse(GURL(kGoodManifestURL),
                            good_manifest.SerializeAsString(), net::HTTP_OK,
                            net::URLRequestStatus::SUCCESS);
 
   base::HistogramTester histogram;
 
   {
     PrecacheFetcher precache_fetcher(
         request_context_.get(), GURL(), std::string(),
         std::move(unfinished_work), kExperimentID,
         precache_database_.GetWeakPtr(), task_runner(), &precache_delegate_);
     precache_fetcher.Start();
 
     base::RunLoop().RunUntilIdle();
   }
 
   // Fetcher should request config, manifest, and all but 3 resources.
-  // TODO(twifkak): I expected all but 2 resources; this result is surprising.
-  // Figure it out and explain it here.
-  EXPECT_EQ(kNumResources - 1, url_callback_.requested_urls().size());
+  EXPECT_EQ(kNumResources - 2, url_callback_.requested_urls().size());

[jamartin, 2017/02/24 21:23:29]

If it is config (1), manifest (1) and all but 3 resources (kNumResources - 3),
shouldn't you EXPECT_EQ(kNumResources - 3 + 1 + 1, ...?

[twifkak, 2017/02/25 01:13:39]

Good point. Added a comment, and clarified the math.

 
   EXPECT_TRUE(precache_delegate_.was_on_done_called());
 
   histogram.ExpectTotalCount("Precache.Fetch.PercentCompleted", 1);
   histogram.ExpectTotalCount("Precache.Fetch.TimeToComplete", 1);
+
+  const double expected_min_weight =
+      good_manifest.resource(kNumResources - 3).weight_ratio();

[jamartin, 2017/02/24 21:23:29]

good_manifest.resource.weight_ratio is the weight ratio as served from the
backend. I thought you wanted to report weight_ratio * <either the
visit-frequency of the top-host or the probability of visiting the top-host>.

[twifkak, 2017/02/25 01:13:39]

Per line 1096, top_host->visits() == 1, up until line 1139, when the std::move()
invalidates top_host. I added a `* 1` for you.

+  histogram.ExpectBucketCount("Precache.Fetch.MinWeight",
+                              1000.0 * expected_min_weight, 1);
 }
 
 // Tests the parallel fetch behaviour when more precache resource and manifest
 // requests are available than the maximum capacity of fetcher pool.
 TEST_F(PrecacheFetcherTest, FetcherPoolMaxLimitReached) {
   SetDefaultFlags();
 
   const size_t kNumTopHosts = 5;
   const size_t kNumResources = kMaxParallelFetches + 5;
 
@@ skipping 451 matching lines @@
   EXPECT_TRUE(cancelled_work->top_host().empty());
   EXPECT_EQ(kNumTopHosts * kNumResources,
             static_cast<size_t>(cancelled_work->resource().size()));
   EXPECT_FALSE(precache_delegate_.was_on_done_called());
 
   url_callback_.clear_requested_urls();
 
   // Continuing with the precache should fetch all resources, as the previous
   // run was cancelled before any finished. They should be fetched in global
   // ranking order.
+
+  base::HistogramTester histogram;
+
   {
     PrecacheFetcher precache_fetcher(
         request_context_.get(), GURL(), std::string(),
         std::move(cancelled_work), kExperimentID,
         precache_database_.GetWeakPtr(), task_runner(), &precache_delegate_);
     LOG(INFO) << "Resuming prefetch.";
     precache_fetcher.Start();
     base::RunLoop().RunUntilIdle();
   }
   EXPECT_EQ(expected_requested_urls, url_callback_.requested_urls());
   EXPECT_TRUE(precache_delegate_.was_on_done_called());
+
+  histogram.ExpectBucketCount("Precache.Fetch.MinWeight",
+                              1000.0 * resources.back().second, 1);
 }
 
 TEST_F(PrecacheFetcherTest, MaxTotalResources) {
   SetDefaultFlags();
 
   const size_t kNumResources = 5;
 
   std::vector<GURL> expected_requested_urls;
 
   PrecacheConfigurationSettings config;
@@ skipping 25 matching lines @@
     resource->set_weight_ratio(weight);
     factory_.SetFakeResponse(GURL(resource_url), "good", net::HTTP_OK,
                              net::URLRequestStatus::SUCCESS);
     if (i < config.total_resources_count())
       expected_requested_urls.emplace_back(resource_url);
   }
   factory_.SetFakeResponse(GURL(kManifestURLPrefix + top_host->hostname()),
                            manifest.SerializeAsString(), net::HTTP_OK,
                            net::URLRequestStatus::SUCCESS);
 
+  base::HistogramTester histogram;
+
   {
     PrecacheFetcher precache_fetcher(
         request_context_.get(), GURL(), std::string(),
         std::move(unfinished_work), kExperimentID,
         precache_database_.GetWeakPtr(), task_runner(), &precache_delegate_);
     precache_fetcher.Start();
     base::RunLoop().RunUntilIdle();
   }
 
   EXPECT_EQ(expected_requested_urls, url_callback_.requested_urls());
   EXPECT_TRUE(precache_delegate_.was_on_done_called());
+
+  const float expected_min_weight =
+      manifest.resource(config.total_resources_count() - 1).weight_ratio();
+  histogram.ExpectUniqueSample("Precache.Fetch.MinWeight",
+                               1000.0 * expected_min_weight, 1);
 }
 
 TEST_F(PrecacheFetcherTest, MinWeight) {
   SetDefaultFlags();
 
   const size_t kNumResources = 5;
 
   std::vector<GURL> expected_requested_urls;
 
   PrecacheConfigurationSettings config;
@@ skipping 239 matching lines @@
   EXPECT_EQ(expected_requested_urls, url_callback_.requested_urls());
 
   EXPECT_TRUE(precache_delegate_.was_on_done_called());
 
   histogram.ExpectTotalCount("Precache.Fetch.PercentCompleted", 2);
   histogram.ExpectTotalCount("Precache.Fetch.ResponseBytes.Total", 2);
   histogram.ExpectTotalCount("Precache.Fetch.TimeToComplete", 2);
 }
 
 }  // namespace precache