[GCM] Add connection factory for creating MCS connections

google_apis/gcm/engine/connection_factory_impl_unittest.cc

+// Copyright (c) 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 "google_apis/gcm/engine/connection_factory_impl.h"
+
+#include "base/message_loop/message_loop.h"
+#include "base/run_loop.h"
+#include "base/time/time.h"
+#include "net/base/backoff_entry.h"
+#include "net/http/http_network_session.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+class Policy;
+
+namespace gcm {
+namespace {
+
+const char kMCSEndpoint[] = "http://my.server";
+
+const int kBackoffDelayMs = 1;
+const int kBackoffMultiplier = 2;
+
+// A backoff policy with small enough delays that tests aren't burdened.
+const net::BackoffEntry::Policy kTestBackoffPolicy = {
+  // Number of initial errors (in sequence) to ignore before applying
+  // exponential back-off rules.
+  0,
+
+  // Initial delay for exponential back-off in ms.
+  kBackoffDelayMs,
+
+  // Factor by which the waiting time will be multiplied.
+  kBackoffMultiplier,
+
+  // Fuzzing percentage. ex: 10% will spread requests randomly
+  // between 90%-100% of the calculated time.
+  0,
+
+  // Maximum amount of time we are willing to delay our request in ms.
+  10,
+
+  // Time to keep an entry from being discarded even when it
+  // has no significant state, -1 to never discard.
+  -1,
+
+  // Don't use initial delay unless the last request was an error.
+  false,
+};
+
+// Helper for calculating total expected exponential backoff delay given an
+// arbitrary number of failed attempts. See BackoffEntry::CalculateReleaseTime.
+int CalculateBackoff(int num_attempts) {
+  int delay = kBackoffDelayMs;
+  for (int i = 1; i < num_attempts; ++i) {
+    delay += kBackoffDelayMs*pow(kBackoffMultiplier, i - 1);
+  }
+  DVLOG(1) << "Expected backoff " << delay << " milliseconds.";
+  return delay;
+}
+
+// Helper methods that are never actually called due to real connections being
+// stubbed out.
+void ReadContinuation(
+    scoped_ptr<google::protobuf::MessageLite> message) {
+  // Do nothing.

[akalin, 2013/11/21 04:13:09]

if they aren't called, perhaps ADD_FAILURE() to assert that?

[Nicolas Zea, 2013/11/22 05:39:18]

Done.

+}
+void WriteContinuation() {

[akalin, 2013/11/21 04:13:09]

newline before

[Nicolas Zea, 2013/11/22 05:39:18]

Done.

+  // Do nothing.
+}
+
+// A connection factory that stubs out network requests and overrides the
+// backoff policy.
+class TestConnectionFactoryImpl : public ConnectionFactoryImpl {
+ public:
+  TestConnectionFactoryImpl(const base::Closure& finished_callback);
+  virtual ~TestConnectionFactoryImpl();
+
+  // Overridden stubs.
+  virtual void ConnectImpl() OVERRIDE;
+  virtual void InitHandler() OVERRIDE;
+  virtual scoped_ptr<net::BackoffEntry> CreateBackoffEntry(
+      const net::BackoffEntry::Policy* const policy) OVERRIDE;
+
+  // Helpers for verifying connection attempts are made. Connection results
+  // must be consumed.
+  void SetConnectResult(int connect_result);
+  void SetMultipleConnectResults(int connect_result, int num_expected_attempts);
+
+ private:
+  // The result to return on the next connect attempt.
+  int connect_result_;
+  // The number of expected connection attempts;
+  int num_expected_attempts_;
+  // Whether all expected connection attempts have been fulfilled since an
+  // expectation was last set.
+  bool connections_fulfilled_;
+  // Callback to invoke when all connection attempts have been made.
+  base::Closure finished_callback_;
+};
+
+TestConnectionFactoryImpl::TestConnectionFactoryImpl(
+    const base::Closure& finished_callback)
+  : ConnectionFactoryImpl(GURL(kMCSEndpoint), NULL, NULL),
+    connect_result_(net::ERR_UNEXPECTED),
+    num_expected_attempts_(0),
+    connections_fulfilled_(true),
+    finished_callback_(finished_callback) {
+}
+
+TestConnectionFactoryImpl::~TestConnectionFactoryImpl() {
+  EXPECT_EQ(0, num_expected_attempts_);
+}
+
+void TestConnectionFactoryImpl::ConnectImpl() {
+  ASSERT_GT(num_expected_attempts_, 0);
+
+  OnConnectDone(connect_result_);
+  --num_expected_attempts_;
+  if (num_expected_attempts_ == 0) {
+    connect_result_ = net::ERR_UNEXPECTED;
+    connections_fulfilled_ = true;
+    finished_callback_.Run();
+  }
+}
+
+void TestConnectionFactoryImpl::InitHandler() {
+  EXPECT_NE(connect_result_, net::ERR_UNEXPECTED);
+}
+
+scoped_ptr<net::BackoffEntry> TestConnectionFactoryImpl::CreateBackoffEntry(
+    const net::BackoffEntry::Policy* const policy) {
+  return scoped_ptr<net::BackoffEntry>(
+      new net::BackoffEntry(&kTestBackoffPolicy));
+}
+
+void TestConnectionFactoryImpl::SetConnectResult(int connect_result) {
+  DCHECK_NE(connect_result, net::ERR_UNEXPECTED);
+  ASSERT_EQ(0, num_expected_attempts_);
+  connections_fulfilled_ = false;
+  connect_result_ = connect_result;
+  num_expected_attempts_ = 1;
+}
+
+void TestConnectionFactoryImpl::SetMultipleConnectResults(
+    int connect_result,
+    int num_expected_attempts) {
+  DCHECK_NE(connect_result, net::ERR_UNEXPECTED);
+  DCHECK_GT(num_expected_attempts, 0);
+  ASSERT_EQ(0, num_expected_attempts_);
+  connections_fulfilled_ = false;
+  connect_result_ = connect_result;
+  num_expected_attempts_ = num_expected_attempts;
+}
+
+class ConnectionFactoryImplTest : public testing::Test {
+ public:
+  ConnectionFactoryImplTest();
+  virtual ~ConnectionFactoryImplTest();
+
+  TestConnectionFactoryImpl* factory() { return &factory_; }
+
+  void WaitForConnections();
+
+ private:
+  void ConnectionsComplete();
+
+  TestConnectionFactoryImpl factory_;
+  base::MessageLoop message_loop_;
+  scoped_ptr<base::RunLoop> run_loop_;
+};
+
+ConnectionFactoryImplTest::ConnectionFactoryImplTest()
+   : factory_(base::Bind(&ConnectionFactoryImplTest::ConnectionsComplete,
+                         base::Unretained(this))),
+     run_loop_(new base::RunLoop()) {}
+ConnectionFactoryImplTest::~ConnectionFactoryImplTest() {}
+
+void ConnectionFactoryImplTest::WaitForConnections() {
+  run_loop_->Run();
+  run_loop_.reset(new base::RunLoop());
+}
+
+void ConnectionFactoryImplTest::ConnectionsComplete() {
+  if (!run_loop_)
+    return;
+  run_loop_->Quit();
+}
+
+// Verify building a connection handler works.
+TEST_F(ConnectionFactoryImplTest, BuildConnectionHandler) {
+  EXPECT_FALSE(factory()->IsEndpointReachable());
+  ConnectionHandler* handler = factory()->BuildConnectionHandler(
+      base::Bind(&ReadContinuation),
+      base::Bind(&WriteContinuation));
+  ASSERT_TRUE(handler);
+  EXPECT_FALSE(factory()->IsEndpointReachable());
+}
+
+// An initial successful connection should not result in backoff.
+TEST_F(ConnectionFactoryImplTest, ConnectSuccess) {
+  factory()->BuildConnectionHandler(
+      ConnectionHandler::ProtoReceivedCallback(),
+      ConnectionHandler::ProtoSentCallback());
+  factory()->SetConnectResult(net::OK);
+  factory()->Connect(mcs_proto::LoginRequest());
+  EXPECT_TRUE(factory()->NextRetryAttempt().is_null());
+}
+
+// A connection failure should result in backoff.
+TEST_F(ConnectionFactoryImplTest, ConnectFail) {
+  factory()->BuildConnectionHandler(
+      ConnectionHandler::ProtoReceivedCallback(),
+      ConnectionHandler::ProtoSentCallback());
+  factory()->SetConnectResult(net::ERR_CONNECTION_FAILED);
+  factory()->Connect(mcs_proto::LoginRequest());
+  EXPECT_FALSE(factory()->NextRetryAttempt().is_null());
+}
+
+// A connection success after a failure should reset backoff.
+TEST_F(ConnectionFactoryImplTest, FailThenSucceed) {
+  factory()->BuildConnectionHandler(
+      ConnectionHandler::ProtoReceivedCallback(),
+      ConnectionHandler::ProtoSentCallback());
+  factory()->SetConnectResult(net::ERR_CONNECTION_FAILED);
+  base::TimeTicks connect_time = base::TimeTicks::Now();
+  factory()->Connect(mcs_proto::LoginRequest());
+  WaitForConnections();
+  base::TimeTicks retry_time = factory()->NextRetryAttempt();
+  EXPECT_FALSE(retry_time.is_null());
+  EXPECT_GE((retry_time - connect_time).InMilliseconds(), CalculateBackoff(1));
+  factory()->SetConnectResult(net::OK);
+  WaitForConnections();
+  EXPECT_TRUE(factory()->NextRetryAttempt().is_null());
+}
+
+// Multiple connection failures should retry with an exponentially increasing
+// backoff, then reset on success.
+TEST_F(ConnectionFactoryImplTest, MultipleFailuresThenSucceed) {
+  factory()->BuildConnectionHandler(
+      ConnectionHandler::ProtoReceivedCallback(),
+      ConnectionHandler::ProtoSentCallback());
+
+  const int kNumAttempts = 5;
+  factory()->SetMultipleConnectResults(net::ERR_CONNECTION_FAILED,
+                                       kNumAttempts);
+
+  base::TimeTicks connect_time = base::TimeTicks::Now();
+  factory()->Connect(mcs_proto::LoginRequest());
+  WaitForConnections();
+  base::TimeTicks retry_time = factory()->NextRetryAttempt();
+  EXPECT_FALSE(retry_time.is_null());
+  EXPECT_GE((retry_time - connect_time).InMilliseconds(),
+            CalculateBackoff(kNumAttempts));
+
+  factory()->SetConnectResult(net::OK);
+  WaitForConnections();
+  EXPECT_TRUE(factory()->NextRetryAttempt().is_null());
+}
+
+// IP events should reset backoff.
+TEST_F(ConnectionFactoryImplTest, FailThenIPEvent) {
+  factory()->BuildConnectionHandler(
+      ConnectionHandler::ProtoReceivedCallback(),
+      ConnectionHandler::ProtoSentCallback());
+  factory()->SetConnectResult(net::ERR_CONNECTION_FAILED);
+  factory()->Connect(mcs_proto::LoginRequest());
+  WaitForConnections();
+  EXPECT_FALSE(factory()->NextRetryAttempt().is_null());
+
+  factory()->OnIPAddressChanged();
+  EXPECT_TRUE(factory()->NextRetryAttempt().is_null());
+}
+
+// Connection type events should reset backoff.
+TEST_F(ConnectionFactoryImplTest, FailThenConnectionTypeEvent) {
+  factory()->BuildConnectionHandler(
+      ConnectionHandler::ProtoReceivedCallback(),
+      ConnectionHandler::ProtoSentCallback());
+  factory()->SetConnectResult(net::ERR_CONNECTION_FAILED);
+  factory()->Connect(mcs_proto::LoginRequest());
+  WaitForConnections();
+  EXPECT_FALSE(factory()->NextRetryAttempt().is_null());
+
+  factory()->OnConnectionTypeChanged(
+      net::NetworkChangeNotifier::CONNECTION_WIFI);
+  EXPECT_TRUE(factory()->NextRetryAttempt().is_null());
+}
+
+}  // namespace
+}  // namespace gcm