Do not precache when the cache size is small

components/precache/content/precache_manager_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/content/precache_manager.h"
 
 #include <stddef.h>
 
 #include <map>
 #include <memory>
@@ skipping 10 matching lines @@
 #include "base/run_loop.h"
 #include "base/single_thread_task_runner.h"
 #include "base/test/histogram_tester.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "components/history/core/browser/history_constants.h"
 #include "components/history/core/browser/history_service.h"
 #include "components/history/core/browser/history_types.h"
 #include "components/precache/core/precache_database.h"
 #include "components/precache/core/precache_switches.h"
 #include "components/precache/core/proto/unfinished_work.pb.h"
+#include "components/variations/variations_params_manager.h"
 #include "content/public/browser/browser_thread.h"
+#include "content/public/browser/storage_partition.h"
 #include "content/public/test/test_browser_context.h"
 #include "content/public/test/test_browser_thread_bundle.h"
+#include "net/base/test_completion_callback.h"
+#include "net/disk_cache/simple/simple_backend_impl.h"
 #include "net/http/http_response_headers.h"
 #include "net/http/http_response_info.h"
 #include "net/http/http_status_code.h"
+#include "net/test/gtest_util.h"
 #include "net/url_request/test_url_fetcher_factory.h"
 #include "net/url_request/url_request_status.h"
 #include "net/url_request/url_request_test_util.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "url/gurl.h"
 
 namespace precache {
 
 namespace {
@@ skipping 169 matching lines @@
   base::ScopedTempDir scoped_temp_dir_;
   PrecacheDatabase* precache_database_;
   content::TestBrowserContext browser_context_;
   std::unique_ptr<PrecacheManagerUnderTest> precache_manager_;
   TestURLFetcherCallback url_callback_;
   net::FakeURLFetcherFactory factory_;
   TestPrecacheCompletionCallback precache_callback_;
   testing::NiceMock<MockHistoryService> history_service_;
   base::HistogramTester histograms_;
   net::HttpResponseInfo info_;
+  variations::testing::VariationParamsManager variation_params_;
 };
 
 TEST_F(PrecacheManagerTest, StartAndFinishPrecaching) {
   EXPECT_FALSE(precache_manager_->IsPrecaching());
 
   MockHistoryService::TopHostsCallback top_hosts_callback;
   EXPECT_CALL(history_service_, TopHosts(NumTopHosts(), _))
       .WillOnce(SaveArg<1>(&top_hosts_callback));
 
   factory_.SetFakeResponse(GURL(kConfigURL), "", net::HTTP_OK,
@@ skipping 10 matching lines @@
   base::RunLoop().RunUntilIdle();  // For PrecacheFetcher.
   EXPECT_FALSE(precache_manager_->IsPrecaching());
   EXPECT_TRUE(precache_callback_.was_on_done_called());
 
   std::multiset<GURL> expected_requested_urls;
   expected_requested_urls.insert(GURL(kConfigURL));
   expected_requested_urls.insert(GURL(kGoodManifestURL));
   EXPECT_EQ(expected_requested_urls, url_callback_.requested_urls());
 }
 
+TEST_F(PrecacheManagerTest, StartPrecachingWithGoodSizedCache) {
+  variation_params_.SetVariationParams(kPrecacheFieldTrialName,
+                                       {{kMinCacheSizeParam, "1"}});
+
+  // Let's store something in the cache so we pass the min_cache_size threshold.
+  disk_cache::Backend* cache_backend;
+  {
+    // Get the CacheBackend.
+    net::TestCompletionCallback cb;
+    net::HttpCache* cache =
+        content::BrowserContext::GetDefaultStoragePartition(&browser_context_)
+            ->GetURLRequestContext()
+            ->GetURLRequestContext()
+            ->http_transaction_factory()
+            ->GetCache();
+    CHECK_NE(nullptr, cache);
+    int rv = cache->GetBackend(&cache_backend, cb.callback());
+    CHECK_EQ(net::OK, cb.GetResult(rv));
+    CHECK_NE(nullptr, cache_backend);
+    CHECK_EQ(cache_backend, cache->GetCurrentBackend());
+  }
+  disk_cache::Entry* entry = nullptr;
+  {
+    // Create a cache Entry.
+    net::TestCompletionCallback cb;
+    int rv = cache_backend->CreateEntry("key", &entry, cb.callback());
+    CHECK_EQ(net::OK, cb.GetResult(rv));
+    CHECK_NE(nullptr, entry);
+  }
+  {
+    // Store some data in the cache Entry.
+    const std::string data(1, 'a');
+    scoped_refptr<net::StringIOBuffer> buffer(new net::StringIOBuffer(data));
+    net::TestCompletionCallback cb;
+    int rv = entry->WriteData(0, 0, buffer.get(), buffer->size(), cb.callback(),
+                              false);
+    entry->Close();
+    CHECK_EQ(buffer->size(), cb.GetResult(rv));
+  }
+  {
+    // Make sure everything went according to plan.
+    net::TestCompletionCallback cb;
+    int rv = cache_backend->CalculateSizeOfAllEntries(cb.callback());
+    CHECK_LE(1, cb.GetResult(rv));
+  }
+  EXPECT_FALSE(precache_manager_->IsPrecaching());
+
+  precache_manager_->StartPrecaching(precache_callback_.GetCallback());
+  base::RunLoop().RunUntilIdle();
+
+  EXPECT_TRUE(precache_manager_->IsPrecaching());
+  // Now it should be waiting for the top hosts.
+}
+
+TEST_F(PrecacheManagerTest, StartPrecachingStopsOnSmallCaches) {
+  // We don't have any entry in the cache, so the reported cache_size = 0 and
+  // thus it will fall below the threshold of 1.
+  variation_params_.SetVariationParams(kPrecacheFieldTrialName,
+                                       {{kMinCacheSizeParam, "1"}});
+  EXPECT_FALSE(precache_manager_->IsPrecaching());
+
+  precache_manager_->StartPrecaching(precache_callback_.GetCallback());
+  base::RunLoop().RunUntilIdle();
+
+  EXPECT_FALSE(precache_manager_->IsPrecaching());
+  EXPECT_TRUE(precache_callback_.was_on_done_called());
+  EXPECT_TRUE(url_callback_.requested_urls().empty());
+}
+
 TEST_F(PrecacheManagerTest, StartAndFinishPrecachingWithUnfinishedHosts) {
   std::unique_ptr<PrecacheUnfinishedWork> unfinished_work(
       new PrecacheUnfinishedWork());
   unfinished_work->add_top_host()->set_hostname("evil-manifest.com");
   unfinished_work->set_start_time(base::Time::Now().ToInternalValue());
   precache_database_->SaveUnfinishedWork(std::move(unfinished_work));
 
   EXPECT_FALSE(precache_manager_->IsPrecaching());
 
   factory_.SetFakeResponse(GURL(kConfigURL), "", net::HTTP_OK,
@@ skipping 82 matching lines @@
   good_manifest.add_resource()->set_url("http://good-resource.com");
 
   EXPECT_CALL(history_service_, TopHosts(NumTopHosts(), _))
       .WillOnce(ReturnHosts(
           history::TopHostsList(1, std::make_pair("starting-url.com", 1))));
 
   precache_manager_->StartPrecaching(precache_callback_.GetCallback());
 
   EXPECT_TRUE(precache_manager_->IsPrecaching());
   // Run a task to get unfinished work, and to get hosts.
-  for (int i = 0; i < 2; ++i) {
+  // We need to call run_loop.Run as many times as needed to go through the
+  // chain of callbacks :-(.
+  for (int i = 0; i < 4; ++i) {
     base::RunLoop run_loop;
     base::ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE,
                                                   run_loop.QuitClosure());
     run_loop.Run();
   }
   // base::RunLoop().RunUntilIdle();
   precache_manager_->CancelPrecaching();
   EXPECT_FALSE(precache_manager_->IsPrecaching());
 
   base::RunLoop().RunUntilIdle();  // For PrecacheFetcher.
@@ skipping 42 matching lines @@
   EXPECT_TRUE(precache_manager_->IsPrecaching());
   RecordStatsForPrecacheFetch(GURL("http://url.com"), std::string(),
                               base::TimeDelta(), base::Time(), info_, 1000);
   base::RunLoop().RunUntilIdle();
   precache_manager_->CancelPrecaching();
 
   // For PrecacheFetcher and RecordURLPrecached.
   base::RunLoop().RunUntilIdle();
   EXPECT_THAT(
       histograms_.GetTotalCountsForPrefix("Precache."),
-      UnorderedElementsAre(Pair("Precache.DownloadedPrecacheMotivated", 1),
+      UnorderedElementsAre(Pair("Precache.CacheSize.AllEntries", 1),
+                           Pair("Precache.DownloadedPrecacheMotivated", 1),
                            Pair("Precache.Fetch.PercentCompleted", 1),
                            Pair("Precache.Fetch.ResponseBytes.Network", 1),
                            Pair("Precache.Fetch.ResponseBytes.Total", 1),
                            Pair("Precache.Fetch.TimeToComplete", 1),
                            Pair("Precache.Latency.Prefetch", 1),
                            Pair("Precache.Freshness.Prefetch", 1)));
 }
 
 TEST_F(PrecacheManagerTest, RecordStatsForFetchHTTP) {
   precache_manager_->RecordStatsForFetch(GURL("http://http-url.com"), GURL(),
@@ skipping 59 matching lines @@
   // Precache a bunch of URLs, with different fetch times.
   RecordStatsForPrecacheFetch(
       GURL("http://old-fetch.com"), std::string(), base::TimeDelta(),
       kCurrentTime - base::TimeDelta::FromDays(61), info_, 1000);
   RecordStatsForPrecacheFetch(
       GURL("http://recent-fetch.com"), std::string(), base::TimeDelta(),
       kCurrentTime - base::TimeDelta::FromDays(59), info_, 1000);
   RecordStatsForPrecacheFetch(
       GURL("http://yesterday-fetch.com"), std::string(), base::TimeDelta(),
       kCurrentTime - base::TimeDelta::FromDays(1), info_, 1000);
+  expected_histogram_count_map["Precache.CacheSize.AllEntries"]++;
   expected_histogram_count_map["Precache.DownloadedPrecacheMotivated"] += 3;
   expected_histogram_count_map["Precache.Fetch.PercentCompleted"]++;
   expected_histogram_count_map["Precache.Fetch.ResponseBytes.Network"]++;
   expected_histogram_count_map["Precache.Fetch.ResponseBytes.Total"]++;
   expected_histogram_count_map["Precache.Fetch.TimeToComplete"]++;
   expected_histogram_count_map["Precache.Latency.Prefetch"] += 3;
   expected_histogram_count_map["Precache.Freshness.Prefetch"] += 3;
   base::RunLoop().RunUntilIdle();
 
   precache_manager_->CancelPrecaching();
   base::RunLoop().RunUntilIdle();
 
   // Disable pause-resume.
   precache_database_->DeleteUnfinishedWork();
   base::RunLoop().RunUntilIdle();
 
   // For PrecacheFetcher and RecordURLPrecached.
   base::RunLoop().RunUntilIdle();
   EXPECT_THAT(histograms_.GetTotalCountsForPrefix("Precache."),
               ContainerEq(expected_histogram_count_map));
 
   // The expired precache will be deleted during precaching this time.
   precache_manager_->StartPrecaching(precache_callback_.GetCallback());
   EXPECT_TRUE(precache_manager_->IsPrecaching());
   base::RunLoop().RunUntilIdle();
 
   // The precache fetcher runs until done, which records these histograms,
   // and then cancels precaching, which records these histograms again.
   // In practice
+  expected_histogram_count_map["Precache.CacheSize.AllEntries"]++;
   expected_histogram_count_map["Precache.Fetch.PercentCompleted"]++;
   expected_histogram_count_map["Precache.Fetch.ResponseBytes.Network"]++;
   expected_histogram_count_map["Precache.Fetch.ResponseBytes.Total"]++;
   // For PrecacheFetcher and RecordURLPrecached.
   base::RunLoop().RunUntilIdle();
   EXPECT_FALSE(precache_manager_->IsPrecaching());
 
   // A fetch for the same URL as the expired precache was served from the cache,
   // but it isn't reported as saved bytes because it had expired in the precache
   // history.
@@ skipping 27 matching lines @@
   expected_histogram_count_map["Precache.Saved"] += 2;
   expected_histogram_count_map["Precache.TimeSinceLastPrecache"] += 2;
   expected_histogram_count_map["Precache.Saved.Freshness"] = 2;
 
   base::RunLoop().RunUntilIdle();
   EXPECT_THAT(histograms_.GetTotalCountsForPrefix("Precache."),
               ContainerEq(expected_histogram_count_map));
 }
 
 }  // namespace precache