Add HostCachePersistenceManager for Cronet

components/cronet/host_cache_persistence_manager_unittest.cc

Index: components/cronet/host_cache_persistence_manager_unittest.cc
diff --git a/components/cronet/host_cache_persistence_manager_unittest.cc b/components/cronet/host_cache_persistence_manager_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..7a8eaae86f93c5018960f29c75d5cce4b421a7be
--- /dev/null
+++ b/components/cronet/host_cache_persistence_manager_unittest.cc
@@ -0,0 +1,182 @@
+// Copyright 2017 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/cronet/host_cache_persistence_manager.h"
+
+#include "base/test/scoped_mock_time_message_loop_task_runner.h"
+#include "base/test/scoped_task_environment.h"
+#include "base/values.h"
+#include "components/prefs/pref_registry_simple.h"
+#include "components/prefs/testing_pref_service.h"
+#include "net/base/net_errors.h"
+#include "net/dns/host_cache.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace cronet {
+
+class HostCachePersistenceManagerTest : public testing::Test {
+ protected:
+  void SetUp() override {
+    cache_ = net::HostCache::CreateDefaultCache();
+    pref_service_ = base::MakeUnique<TestingPrefServiceSimple>();
+    pref_service_->registry()->RegisterListPref(kPrefName);
+  }
+
+  void MakePersistenceManager(base::TimeDelta delay) {
+    persistence_manager_ = base::MakeUnique<HostCachePersistenceManager>(
+        cache_.get(), pref_service_.get(), kPrefName, delay);
+  }
+
+  // Sets an entry in the HostCache in order to trigger a pref write. The
+  // caller is responsible for making sure this is a change that will trigger
+  // a write, and the HostCache's interaction with its PersistenceDelegate is
+  // assumed to work (it's tested in net/dns/host_cache_unittest.cc).
+  void WriteToCache(const std::string& host) {
+    net::HostCache::Key key(host, net::ADDRESS_FAMILY_UNSPECIFIED, 0);
+    net::HostCache::Entry entry(net::OK, net::AddressList());
+    cache_->Set(key, entry, base::TimeTicks::Now(),
+                base::TimeDelta::FromSeconds(1));
+  }
+
+  // Reads the current value of the pref from the TestingPrefServiceSimple
+  // and deserializes it into a temporary new HostCache. Only checks the size,
+  // not the full contents, since the tests in this file are only intended
+  // to test that writes happen when they're supposed to, not serialization
+  // correctness.
+  void CheckPref(uint size) {
+    const base::Value* value = pref_service_->GetUserPref(kPrefName);
+    base::ListValue list;
+    if (value)
+      list = base::ListValue(value->GetList());
+    net::HostCache temp_cache(10);
+    temp_cache.RestoreFromListValue(list);
+    ASSERT_EQ(size, temp_cache.size());
+  }
+
+  // Generates a temporary HostCache with a few entries and uses it to
+  // initialize the value in prefs.
+  void InitializePref() {
+    net::HostCache temp_cache(10);
+
+    net::HostCache::Key key1("1", net::ADDRESS_FAMILY_UNSPECIFIED, 0);
+    net::HostCache::Key key2("2", net::ADDRESS_FAMILY_UNSPECIFIED, 0);
+    net::HostCache::Key key3("3", net::ADDRESS_FAMILY_UNSPECIFIED, 0);
+    net::HostCache::Entry entry(net::OK, net::AddressList());
+
+    temp_cache.Set(key1, entry, base::TimeTicks::Now(),
+                   base::TimeDelta::FromSeconds(1));
+    temp_cache.Set(key2, entry, base::TimeTicks::Now(),
+                   base::TimeDelta::FromSeconds(1));
+    temp_cache.Set(key3, entry, base::TimeTicks::Now(),
+                   base::TimeDelta::FromSeconds(1));
+
+    base::ListValue value;
+    temp_cache.GetAsListValue(&value, false);
+    pref_service_->Set(kPrefName, value);
+  }
+
+  static const char kPrefName[];
+
+  base::test::ScopedTaskEnvironment scoped_task_environment_;
+  base::ScopedMockTimeMessageLoopTaskRunner task_runner_;
+
+  // The HostCache and PrefService have to outlive the
+  // HostCachePersistenceManager.
+  std::unique_ptr<net::HostCache> cache_;
+  std::unique_ptr<TestingPrefServiceSimple> pref_service_;
+  std::unique_ptr<HostCachePersistenceManager> persistence_manager_;
+};
+
+const char HostCachePersistenceManagerTest::kPrefName[] = "net.test";
+
+// Make a single change to the HostCache and make sure that it's written
+// when the timer expires. Then repeat.
+TEST_F(HostCachePersistenceManagerTest, SeparateWrites) {
+  MakePersistenceManager(base::TimeDelta::FromSeconds(60));
+
+  WriteToCache("1");
+  task_runner_->FastForwardBy(base::TimeDelta::FromSeconds(59));
+  CheckPref(0);
+  task_runner_->FastForwardBy(base::TimeDelta::FromSeconds(1));
+  CheckPref(1);
+
+  WriteToCache("2");
+  task_runner_->FastForwardBy(base::TimeDelta::FromSeconds(59));
+  CheckPref(1);
+  task_runner_->FastForwardBy(base::TimeDelta::FromSeconds(1));
+  CheckPref(2);
+}
+
+// Write to the HostCache multiple times and make sure that all changes
+// are written to prefs at the appropriate times.
+TEST_F(HostCachePersistenceManagerTest, MultipleWrites) {
+  MakePersistenceManager(base::TimeDelta::FromSeconds(300));
+
+  WriteToCache("1");
+  WriteToCache("2");
+  task_runner_->FastForwardBy(base::TimeDelta::FromSeconds(299));
+  CheckPref(0);
+  task_runner_->FastForwardBy(base::TimeDelta::FromSeconds(1));
+  CheckPref(2);
+
+  WriteToCache("3");
+  WriteToCache("4");
+  task_runner_->FastForwardBy(base::TimeDelta::FromSeconds(299));
+  CheckPref(2);
+  task_runner_->FastForwardBy(base::TimeDelta::FromSeconds(1));
+  CheckPref(4);
+}
+
+// Make changes to the HostCache at different times and ensure that the writes
+// to prefs are batched as expected.
+TEST_F(HostCachePersistenceManagerTest, BatchedWrites) {
+  MakePersistenceManager(base::TimeDelta::FromMilliseconds(100));
+
+  WriteToCache("1");
+  task_runner_->FastForwardBy(base::TimeDelta::FromMilliseconds(30));
+  WriteToCache("2");
+  task_runner_->FastForwardBy(base::TimeDelta::FromMilliseconds(30));
+  WriteToCache("3");
+  CheckPref(0);
+  task_runner_->FastForwardBy(base::TimeDelta::FromMilliseconds(40));
+  CheckPref(3);
+
+  // Add a delay in between batches.
+  task_runner_->FastForwardBy(base::TimeDelta::FromMilliseconds(50));
+
+  WriteToCache("4");
+  task_runner_->FastForwardBy(base::TimeDelta::FromMilliseconds(30));
+  WriteToCache("5");
+  task_runner_->FastForwardBy(base::TimeDelta::FromMilliseconds(30));
+  WriteToCache("6");
+  CheckPref(3);
+  task_runner_->FastForwardBy(base::TimeDelta::FromMilliseconds(40));
+  CheckPref(6);
+}
+
+// Set the pref before the HostCachePersistenceManager is created, and make
+// sure it gets picked up by the HostCache.
+TEST_F(HostCachePersistenceManagerTest, InitAfterPrefs) {
+  CheckPref(0);
+  InitializePref();
+  CheckPref(3);
+
+  MakePersistenceManager(base::TimeDelta::FromSeconds(1));
+  task_runner_->RunUntilIdle();
+  ASSERT_EQ(3u, cache_->size());
+}
+
+// Set the pref after the HostCachePersistenceManager is created, and make
+// sure it gets picked up by the HostCache.
+TEST_F(HostCachePersistenceManagerTest, InitBeforePrefs) {
+  MakePersistenceManager(base::TimeDelta::FromSeconds(1));
+  ASSERT_EQ(0u, cache_->size());
+
+  CheckPref(0);
+  InitializePref();
+  CheckPref(3);
+  ASSERT_EQ(3u, cache_->size());
+}
+
+}  // namespace cronet