chromium_org/ipc/ipc_sync_channel_unittest.cc

// Copyright (c) 2012 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 "ipc/ipc_sync_channel.h"

#include <string>
#include <vector>

#include "base/basictypes.h"
#include "base/bind.h"
#include "base/logging.h"
#include "base/memory/scoped_ptr.h"
#include "base/message_loop/message_loop.h"
#include "base/process/process_handle.h"
#include "base/run_loop.h"
#include "base/strings/string_util.h"
#include "base/synchronization/waitable_event.h"
#include "base/threading/platform_thread.h"
#include "base/threading/thread.h"
#include "ipc/ipc_listener.h"
#include "ipc/ipc_message.h"
#include "ipc/ipc_sender.h"
#include "ipc/ipc_sync_message_filter.h"
#include "ipc/ipc_sync_message_unittest.h"
#include "testing/gtest/include/gtest/gtest.h"

using base::WaitableEvent;

namespace IPC {
namespace {

// Base class for a "process" with listener and IPC threads.
class Worker : public Listener, public Sender {
 public:
  // Will create a channel without a name.
  Worker(Channel::Mode mode, const std::string& thread_name)
      : done_(new WaitableEvent(false, false)),
        channel_created_(new WaitableEvent(false, false)),
        mode_(mode),
        ipc_thread_((thread_name + "_ipc").c_str()),
        listener_thread_((thread_name + "_listener").c_str()),
        overrided_thread_(NULL),
        shutdown_event_(true, false),
        is_shutdown_(false) {
  }

  // Will create a named channel and use this name for the threads' name.
  Worker(const std::string& channel_name, Channel::Mode mode)
      : done_(new WaitableEvent(false, false)),
        channel_created_(new WaitableEvent(false, false)),
        channel_name_(channel_name),
        mode_(mode),
        ipc_thread_((channel_name + "_ipc").c_str()),
        listener_thread_((channel_name + "_listener").c_str()),
        overrided_thread_(NULL),
        shutdown_event_(true, false),
        is_shutdown_(false) {
  }

  virtual ~Worker() {
    // Shutdown() must be called before destruction.
    CHECK(is_shutdown_);
  }
  void AddRef() { }
  void Release() { }
  virtual bool Send(Message* msg) OVERRIDE { return channel_->Send(msg); }
  void WaitForChannelCreation() { channel_created_->Wait(); }
  void CloseChannel() {
    DCHECK(base::MessageLoop::current() == ListenerThread()->message_loop());
    channel_->Close();
  }
  void Start() {
    StartThread(&listener_thread_, base::MessageLoop::TYPE_DEFAULT);
    ListenerThread()->message_loop()->PostTask(
        FROM_HERE, base::Bind(&Worker::OnStart, this));
  }
  void Shutdown() {
    // The IPC thread needs to outlive SyncChannel. We can't do this in
    // ~Worker(), since that'll reset the vtable pointer (to Worker's), which
    // may result in a race conditions. See http://crbug.com/25841.
    WaitableEvent listener_done(false, false), ipc_done(false, false);
    ListenerThread()->message_loop()->PostTask(
        FROM_HERE, base::Bind(&Worker::OnListenerThreadShutdown1, this,
                              &listener_done, &ipc_done));
    listener_done.Wait();
    ipc_done.Wait();
    ipc_thread_.Stop();
    listener_thread_.Stop();
    is_shutdown_ = true;
  }
  void OverrideThread(base::Thread* overrided_thread) {
    DCHECK(overrided_thread_ == NULL);
    overrided_thread_ = overrided_thread;
  }
  bool SendAnswerToLife(bool pump, bool succeed) {
    int answer = 0;
    SyncMessage* msg = new SyncChannelTestMsg_AnswerToLife(&answer);
    if (pump)
      msg->EnableMessagePumping();
    bool result = Send(msg);
    DCHECK_EQ(result, succeed);
    DCHECK_EQ(answer, (succeed ? 42 : 0));
    return result;
  }
  bool SendDouble(bool pump, bool succeed) {
    int answer = 0;
    SyncMessage* msg = new SyncChannelTestMsg_Double(5, &answer);
    if (pump)
      msg->EnableMessagePumping();
    bool result = Send(msg);
    DCHECK_EQ(result, succeed);
    DCHECK_EQ(answer, (succeed ? 10 : 0));
    return result;
  }
  const std::string& channel_name() { return channel_name_; }
  Channel::Mode mode() { return mode_; }
  WaitableEvent* done_event() { return done_.get(); }
  WaitableEvent* shutdown_event() { return &shutdown_event_; }
  void ResetChannel() { channel_.reset(); }
  // Derived classes need to call this when they've completed their part of
  // the test.
  void Done() { done_->Signal(); }

 protected:
  SyncChannel* channel() { return channel_.get(); }
  // Functions for dervied classes to implement if they wish.
  virtual void Run() { }
  virtual void OnAnswer(int* answer) { NOTREACHED(); }
  virtual void OnAnswerDelay(Message* reply_msg) {
    // The message handler map below can only take one entry for
    // SyncChannelTestMsg_AnswerToLife, so since some classes want
    // the normal version while other want the delayed reply, we
    // call the normal version if the derived class didn't override
    // this function.
    int answer;
    OnAnswer(&answer);
    SyncChannelTestMsg_AnswerToLife::WriteReplyParams(reply_msg, answer);
    Send(reply_msg);
  }
  virtual void OnDouble(int in, int* out) { NOTREACHED(); }
  virtual void OnDoubleDelay(int in, Message* reply_msg) {
    int result;
    OnDouble(in, &result);
    SyncChannelTestMsg_Double::WriteReplyParams(reply_msg, result);
    Send(reply_msg);
  }

  virtual void OnNestedTestMsg(Message* reply_msg) {
    NOTREACHED();
  }

  virtual SyncChannel* CreateChannel() {
    return new SyncChannel(channel_name_,
                           mode_,
                           this,
                           ipc_thread_.message_loop_proxy().get(),
                           true,
                           &shutdown_event_);
  }

  base::Thread* ListenerThread() {
    return overrided_thread_ ? overrided_thread_ : &listener_thread_;
  }

  const base::Thread& ipc_thread() const { return ipc_thread_; }

 private:
  // Called on the listener thread to create the sync channel.
  void OnStart() {
    // Link ipc_thread_, listener_thread_ and channel_ altogether.
    StartThread(&ipc_thread_, base::MessageLoop::TYPE_IO);
    channel_.reset(CreateChannel());
    channel_created_->Signal();
    Run();
  }

  void OnListenerThreadShutdown1(WaitableEvent* listener_event,
                                 WaitableEvent* ipc_event) {
    // SyncChannel needs to be destructed on the thread that it was created on.
    channel_.reset();

    base::RunLoop().RunUntilIdle();

    ipc_thread_.message_loop()->PostTask(
        FROM_HERE, base::Bind(&Worker::OnIPCThreadShutdown, this,
                              listener_event, ipc_event));
  }

  void OnIPCThreadShutdown(WaitableEvent* listener_event,
                           WaitableEvent* ipc_event) {
    base::RunLoop().RunUntilIdle();
    ipc_event->Signal();

    listener_thread_.message_loop()->PostTask(
        FROM_HERE, base::Bind(&Worker::OnListenerThreadShutdown2, this,
                              listener_event));
  }

  void OnListenerThreadShutdown2(WaitableEvent* listener_event) {
    base::RunLoop().RunUntilIdle();
    listener_event->Signal();
  }

  virtual bool OnMessageReceived(const Message& message) OVERRIDE {
    IPC_BEGIN_MESSAGE_MAP(Worker, message)
     IPC_MESSAGE_HANDLER_DELAY_REPLY(SyncChannelTestMsg_Double, OnDoubleDelay)
     IPC_MESSAGE_HANDLER_DELAY_REPLY(SyncChannelTestMsg_AnswerToLife,
                                     OnAnswerDelay)
     IPC_MESSAGE_HANDLER_DELAY_REPLY(SyncChannelNestedTestMsg_String,
                                     OnNestedTestMsg)
    IPC_END_MESSAGE_MAP()
    return true;
  }

  void StartThread(base::Thread* thread, base::MessageLoop::Type type) {
    base::Thread::Options options;
    options.message_loop_type = type;
    thread->StartWithOptions(options);
  }

  scoped_ptr<WaitableEvent> done_;
  scoped_ptr<WaitableEvent> channel_created_;
  std::string channel_name_;
  Channel::Mode mode_;
  scoped_ptr<SyncChannel> channel_;
  base::Thread ipc_thread_;
  base::Thread listener_thread_;
  base::Thread* overrided_thread_;

  base::WaitableEvent shutdown_event_;

  bool is_shutdown_;

  DISALLOW_COPY_AND_ASSIGN(Worker);
};


// Starts the test with the given workers.  This function deletes the workers
// when it's done.
void RunTest(std::vector<Worker*> workers) {
  // First we create the workers that are channel servers, or else the other
  // workers' channel initialization might fail because the pipe isn't created..
  for (size_t i = 0; i < workers.size(); ++i) {
    if (workers[i]->mode() & Channel::MODE_SERVER_FLAG) {
      workers[i]->Start();
      workers[i]->WaitForChannelCreation();
    }
  }

  // now create the clients
  for (size_t i = 0; i < workers.size(); ++i) {
    if (workers[i]->mode() & Channel::MODE_CLIENT_FLAG)
      workers[i]->Start();
  }

  // wait for all the workers to finish
  for (size_t i = 0; i < workers.size(); ++i)
    workers[i]->done_event()->Wait();

  for (size_t i = 0; i < workers.size(); ++i) {
    workers[i]->Shutdown();
    delete workers[i];
  }
}

class IPCSyncChannelTest : public testing::Test {
 private:
  base::MessageLoop message_loop_;
};

//------------------------------------------------------------------------------

class SimpleServer : public Worker {
 public:
  explicit SimpleServer(bool pump_during_send)
      : Worker(Channel::MODE_SERVER, "simpler_server"),
        pump_during_send_(pump_during_send) { }
  virtual void Run() OVERRIDE {
    SendAnswerToLife(pump_during_send_, true);
    Done();
  }

  bool pump_during_send_;
};

class SimpleClient : public Worker {
 public:
  SimpleClient() : Worker(Channel::MODE_CLIENT, "simple_client") { }

  virtual void OnAnswer(int* answer) OVERRIDE {
    *answer = 42;
    Done();
  }
};

void Simple(bool pump_during_send) {
  std::vector<Worker*> workers;
  workers.push_back(new SimpleServer(pump_during_send));
  workers.push_back(new SimpleClient());
  RunTest(workers);
}

// Tests basic synchronous call
TEST_F(IPCSyncChannelTest, Simple) {
  Simple(false);
  Simple(true);
}

//------------------------------------------------------------------------------

// Worker classes which override how the sync channel is created to use the
// two-step initialization (calling the lightweight constructor and then
// ChannelProxy::Init separately) process.
class TwoStepServer : public Worker {
 public:
  explicit TwoStepServer(bool create_pipe_now)
      : Worker(Channel::MODE_SERVER, "simpler_server"),
        create_pipe_now_(create_pipe_now) { }

  virtual void Run() OVERRIDE {
    SendAnswerToLife(false, true);
    Done();
  }

  virtual SyncChannel* CreateChannel() OVERRIDE {
    SyncChannel* channel = new SyncChannel(
        this, ipc_thread().message_loop_proxy().get(), shutdown_event());
    channel->Init(channel_name(), mode(), create_pipe_now_);
    return channel;
  }

  bool create_pipe_now_;
};

class TwoStepClient : public Worker {
 public:
  TwoStepClient(bool create_pipe_now)
      : Worker(Channel::MODE_CLIENT, "simple_client"),
        create_pipe_now_(create_pipe_now) { }

  virtual void OnAnswer(int* answer) OVERRIDE {
    *answer = 42;
    Done();
  }

  virtual SyncChannel* CreateChannel() OVERRIDE {
    SyncChannel* channel = new SyncChannel(
        this, ipc_thread().message_loop_proxy().get(), shutdown_event());
    channel->Init(channel_name(), mode(), create_pipe_now_);
    return channel;
  }

  bool create_pipe_now_;
};

void TwoStep(bool create_server_pipe_now, bool create_client_pipe_now) {
  std::vector<Worker*> workers;
  workers.push_back(new TwoStepServer(create_server_pipe_now));
  workers.push_back(new TwoStepClient(create_client_pipe_now));
  RunTest(workers);
}

// Tests basic two-step initialization, where you call the lightweight
// constructor then Init.
TEST_F(IPCSyncChannelTest, TwoStepInitialization) {
  TwoStep(false, false);
  TwoStep(false, true);
  TwoStep(true, false);
  TwoStep(true, true);
}

//------------------------------------------------------------------------------

class DelayClient : public Worker {
 public:
  DelayClient() : Worker(Channel::MODE_CLIENT, "delay_client") { }

  virtual void OnAnswerDelay(Message* reply_msg) OVERRIDE {
    SyncChannelTestMsg_AnswerToLife::WriteReplyParams(reply_msg, 42);
    Send(reply_msg);
    Done();
  }
};

void DelayReply(bool pump_during_send) {
  std::vector<Worker*> workers;
  workers.push_back(new SimpleServer(pump_during_send));
  workers.push_back(new DelayClient());
  RunTest(workers);
}

// Tests that asynchronous replies work
TEST_F(IPCSyncChannelTest, DelayReply) {
  DelayReply(false);
  DelayReply(true);
}

//------------------------------------------------------------------------------

class NoHangServer : public Worker {
 public:
  NoHangServer(WaitableEvent* got_first_reply, bool pump_during_send)
      : Worker(Channel::MODE_SERVER, "no_hang_server"),
        got_first_reply_(got_first_reply),
        pump_during_send_(pump_during_send) { }
  virtual void Run() OVERRIDE {
    SendAnswerToLife(pump_during_send_, true);
    got_first_reply_->Signal();

    SendAnswerToLife(pump_during_send_, false);
    Done();
  }

  WaitableEvent* got_first_reply_;
  bool pump_during_send_;
};

class NoHangClient : public Worker {
 public:
  explicit NoHangClient(WaitableEvent* got_first_reply)
    : Worker(Channel::MODE_CLIENT, "no_hang_client"),
      got_first_reply_(got_first_reply) { }

  virtual void OnAnswerDelay(Message* reply_msg) OVERRIDE {
    // Use the DELAY_REPLY macro so that we can force the reply to be sent
    // before this function returns (when the channel will be reset).
    SyncChannelTestMsg_AnswerToLife::WriteReplyParams(reply_msg, 42);
    Send(reply_msg);
    got_first_reply_->Wait();
    CloseChannel();
    Done();
  }

  WaitableEvent* got_first_reply_;
};

void NoHang(bool pump_during_send) {
  WaitableEvent got_first_reply(false, false);
  std::vector<Worker*> workers;
  workers.push_back(new NoHangServer(&got_first_reply, pump_during_send));
  workers.push_back(new NoHangClient(&got_first_reply));
  RunTest(workers);
}

// Tests that caller doesn't hang if receiver dies
TEST_F(IPCSyncChannelTest, NoHang) {
  NoHang(false);
  NoHang(true);
}

//------------------------------------------------------------------------------

class UnblockServer : public Worker {
 public:
  UnblockServer(bool pump_during_send, bool delete_during_send)
    : Worker(Channel::MODE_SERVER, "unblock_server"),
      pump_during_send_(pump_during_send),
      delete_during_send_(delete_during_send) { }
  virtual void Run() OVERRIDE {
    if (delete_during_send_) {
      // Use custom code since race conditions mean the answer may or may not be
      // available.
      int answer = 0;
      SyncMessage* msg = new SyncChannelTestMsg_AnswerToLife(&answer);
      if (pump_during_send_)
        msg->EnableMessagePumping();
      Send(msg);
    } else {
      SendAnswerToLife(pump_during_send_, true);
    }
    Done();
  }

  virtual void OnDoubleDelay(int in, Message* reply_msg) OVERRIDE {
    SyncChannelTestMsg_Double::WriteReplyParams(reply_msg, in * 2);
    Send(reply_msg);
    if (delete_during_send_)
      ResetChannel();
  }

  bool pump_during_send_;
  bool delete_during_send_;
};

class UnblockClient : public Worker {
 public:
  explicit UnblockClient(bool pump_during_send)
    : Worker(Channel::MODE_CLIENT, "unblock_client"),
      pump_during_send_(pump_during_send) { }

  virtual void OnAnswer(int* answer) OVERRIDE {
    SendDouble(pump_during_send_, true);
    *answer = 42;
    Done();
  }

  bool pump_during_send_;
};

void Unblock(bool server_pump, bool client_pump, bool delete_during_send) {
  std::vector<Worker*> workers;
  workers.push_back(new UnblockServer(server_pump, delete_during_send));
  workers.push_back(new UnblockClient(client_pump));
  RunTest(workers);
}

// Tests that the caller unblocks to answer a sync message from the receiver.
TEST_F(IPCSyncChannelTest, Unblock) {
  Unblock(false, false, false);
  Unblock(false, true, false);
  Unblock(true, false, false);
  Unblock(true, true, false);
}

//------------------------------------------------------------------------------

// Tests that the the SyncChannel object can be deleted during a Send.
TEST_F(IPCSyncChannelTest, ChannelDeleteDuringSend) {
  Unblock(false, false, true);
  Unblock(false, true, true);
  Unblock(true, false, true);
  Unblock(true, true, true);
}

//------------------------------------------------------------------------------

class RecursiveServer : public Worker {
 public:
  RecursiveServer(bool expected_send_result, bool pump_first, bool pump_second)
      : Worker(Channel::MODE_SERVER, "recursive_server"),
        expected_send_result_(expected_send_result),
        pump_first_(pump_first), pump_second_(pump_second) {}
  virtual void Run() OVERRIDE {
    SendDouble(pump_first_, expected_send_result_);
    Done();
  }

  virtual void OnDouble(int in, int* out) OVERRIDE {
    *out = in * 2;
    SendAnswerToLife(pump_second_, expected_send_result_);
  }

  bool expected_send_result_, pump_first_, pump_second_;
};

class RecursiveClient : public Worker {
 public:
  RecursiveClient(bool pump_during_send, bool close_channel)
      : Worker(Channel::MODE_CLIENT, "recursive_client"),
        pump_during_send_(pump_during_send), close_channel_(close_channel) {}

  virtual void OnDoubleDelay(int in, Message* reply_msg) OVERRIDE {
    SendDouble(pump_during_send_, !close_channel_);
    if (close_channel_) {
      delete reply_msg;
    } else {
      SyncChannelTestMsg_Double::WriteReplyParams(reply_msg, in * 2);
      Send(reply_msg);
    }
    Done();
  }

  virtual void OnAnswerDelay(Message* reply_msg) OVERRIDE {
    if (close_channel_) {
      delete reply_msg;
      CloseChannel();
    } else {
      SyncChannelTestMsg_AnswerToLife::WriteReplyParams(reply_msg, 42);
      Send(reply_msg);
    }
  }

  bool pump_during_send_, close_channel_;
};

void Recursive(
    bool server_pump_first, bool server_pump_second, bool client_pump) {
  std::vector<Worker*> workers;
  workers.push_back(
      new RecursiveServer(true, server_pump_first, server_pump_second));
  workers.push_back(new RecursiveClient(client_pump, false));
  RunTest(workers);
}

// Tests a server calling Send while another Send is pending.
TEST_F(IPCSyncChannelTest, Recursive) {
  Recursive(false, false, false);
  Recursive(false, false, true);
  Recursive(false, true, false);
  Recursive(false, true, true);
  Recursive(true, false, false);
  Recursive(true, false, true);
  Recursive(true, true, false);
  Recursive(true, true, true);
}

//------------------------------------------------------------------------------

void RecursiveNoHang(
    bool server_pump_first, bool server_pump_second, bool client_pump) {
  std::vector<Worker*> workers;
  workers.push_back(
      new RecursiveServer(false, server_pump_first, server_pump_second));
  workers.push_back(new RecursiveClient(client_pump, true));
  RunTest(workers);
}

// Tests that if a caller makes a sync call during an existing sync call and
// the receiver dies, neither of the Send() calls hang.
TEST_F(IPCSyncChannelTest, RecursiveNoHang) {
  RecursiveNoHang(false, false, false);
  RecursiveNoHang(false, false, true);
  RecursiveNoHang(false, true, false);
  RecursiveNoHang(false, true, true);
  RecursiveNoHang(true, false, false);
  RecursiveNoHang(true, false, true);
  RecursiveNoHang(true, true, false);
  RecursiveNoHang(true, true, true);
}

//------------------------------------------------------------------------------

class MultipleServer1 : public Worker {
 public:
  explicit MultipleServer1(bool pump_during_send)
    : Worker("test_channel1", Channel::MODE_SERVER),
      pump_during_send_(pump_during_send) { }

  virtual void Run() OVERRIDE {
    SendDouble(pump_during_send_, true);
    Done();
  }

  bool pump_during_send_;
};

class MultipleClient1 : public Worker {
 public:
  MultipleClient1(WaitableEvent* client1_msg_received,
                  WaitableEvent* client1_can_reply) :
      Worker("test_channel1", Channel::MODE_CLIENT),
      client1_msg_received_(client1_msg_received),
      client1_can_reply_(client1_can_reply) { }

  virtual void OnDouble(int in, int* out) OVERRIDE {
    client1_msg_received_->Signal();
    *out = in * 2;
    client1_can_reply_->Wait();
    Done();
  }

 private:
  WaitableEvent *client1_msg_received_, *client1_can_reply_;
};

class MultipleServer2 : public Worker {
 public:
  MultipleServer2() : Worker("test_channel2", Channel::MODE_SERVER) { }

  virtual void OnAnswer(int* result) OVERRIDE {
    *result = 42;
    Done();
  }
};

class MultipleClient2 : public Worker {
 public:
  MultipleClient2(
    WaitableEvent* client1_msg_received, WaitableEvent* client1_can_reply,
    bool pump_during_send)
    : Worker("test_channel2", Channel::MODE_CLIENT),
      client1_msg_received_(client1_msg_received),
      client1_can_reply_(client1_can_reply),
      pump_during_send_(pump_during_send) { }

  virtual void Run() OVERRIDE {
    client1_msg_received_->Wait();
    SendAnswerToLife(pump_during_send_, true);
    client1_can_reply_->Signal();
    Done();
  }

 private:
  WaitableEvent *client1_msg_received_, *client1_can_reply_;
  bool pump_during_send_;
};

void Multiple(bool server_pump, bool client_pump) {
  std::vector<Worker*> workers;

  // A shared worker thread so that server1 and server2 run on one thread.
  base::Thread worker_thread("Multiple");
  ASSERT_TRUE(worker_thread.Start());

  // Server1 sends a sync msg to client1, which blocks the reply until
  // server2 (which runs on the same worker thread as server1) responds
  // to a sync msg from client2.
  WaitableEvent client1_msg_received(false, false);
  WaitableEvent client1_can_reply(false, false);

  Worker* worker;

  worker = new MultipleServer2();
  worker->OverrideThread(&worker_thread);
  workers.push_back(worker);

  worker = new MultipleClient2(
      &client1_msg_received, &client1_can_reply, client_pump);
  workers.push_back(worker);

  worker = new MultipleServer1(server_pump);
  worker->OverrideThread(&worker_thread);
  workers.push_back(worker);

  worker = new MultipleClient1(
      &client1_msg_received, &client1_can_reply);
  workers.push_back(worker);

  RunTest(workers);
}

// Tests that multiple SyncObjects on the same listener thread can unblock each
// other.
TEST_F(IPCSyncChannelTest, Multiple) {
  Multiple(false, false);
  Multiple(false, true);
  Multiple(true, false);
  Multiple(true, true);
}

//------------------------------------------------------------------------------

// This class provides server side functionality to test the case where
// multiple sync channels are in use on the same thread on the client and
// nested calls are issued.
class QueuedReplyServer : public Worker {
 public:
  QueuedReplyServer(base::Thread* listener_thread,
                    const std::string& channel_name,
                    const std::string& reply_text)
      : Worker(channel_name, Channel::MODE_SERVER),
        reply_text_(reply_text) {
    Worker::OverrideThread(listener_thread);
  }

  virtual void OnNestedTestMsg(Message* reply_msg) OVERRIDE {
    VLOG(1) << __FUNCTION__ << " Sending reply: " << reply_text_;
    SyncChannelNestedTestMsg_String::WriteReplyParams(reply_msg, reply_text_);
    Send(reply_msg);
    Done();
  }

 private:
  std::string reply_text_;
};

// The QueuedReplyClient class provides functionality to test the case where
// multiple sync channels are in use on the same thread and they make nested
// sync calls, i.e. while the first channel waits for a response it makes a
// sync call on another channel.
// The callstack should unwind correctly, i.e. the outermost call should
// complete first, and so on.
class QueuedReplyClient : public Worker {
 public:
  QueuedReplyClient(base::Thread* listener_thread,
                    const std::string& channel_name,
                    const std::string& expected_text,
                    bool pump_during_send)
      : Worker(channel_name, Channel::MODE_CLIENT),
        pump_during_send_(pump_during_send),
        expected_text_(expected_text) {
    Worker::OverrideThread(listener_thread);
  }

  virtual void Run() OVERRIDE {
    std::string response;
    SyncMessage* msg = new SyncChannelNestedTestMsg_String(&response);
    if (pump_during_send_)
      msg->EnableMessagePumping();
    bool result = Send(msg);
    DCHECK(result);
    DCHECK_EQ(response, expected_text_);

    VLOG(1) << __FUNCTION__ << " Received reply: " << response;
    Done();
  }

 private:
  bool pump_during_send_;
  std::string expected_text_;
};

void QueuedReply(bool client_pump) {
  std::vector<Worker*> workers;

  // A shared worker thread for servers
  base::Thread server_worker_thread("QueuedReply_ServerListener");
  ASSERT_TRUE(server_worker_thread.Start());

  base::Thread client_worker_thread("QueuedReply_ClientListener");
  ASSERT_TRUE(client_worker_thread.Start());

  Worker* worker;

  worker = new QueuedReplyServer(&server_worker_thread,
                                 "QueuedReply_Server1",
                                 "Got first message");
  workers.push_back(worker);

  worker = new QueuedReplyServer(&server_worker_thread,
                                 "QueuedReply_Server2",
                                 "Got second message");
  workers.push_back(worker);

  worker = new QueuedReplyClient(&client_worker_thread,
                                 "QueuedReply_Server1",
                                 "Got first message",
                                 client_pump);
  workers.push_back(worker);

  worker = new QueuedReplyClient(&client_worker_thread,
                                 "QueuedReply_Server2",
                                 "Got second message",
                                 client_pump);
  workers.push_back(worker);

  RunTest(workers);
}

// While a blocking send is in progress, the listener thread might answer other
// synchronous messages.  This tests that if during the response to another
// message the reply to the original messages comes, it is queued up correctly
// and the original Send is unblocked later.
// We also test that the send call stacks unwind correctly when the channel
// pumps messages while waiting for a response.
TEST_F(IPCSyncChannelTest, QueuedReply) {
  QueuedReply(false);
  QueuedReply(true);
}

//------------------------------------------------------------------------------

class ChattyClient : public Worker {
 public:
  ChattyClient() :
      Worker(Channel::MODE_CLIENT, "chatty_client") { }

  virtual void OnAnswer(int* answer) OVERRIDE {
    // The PostMessage limit is 10k.  Send 20% more than that.
    const int kMessageLimit = 10000;
    const int kMessagesToSend = kMessageLimit * 120 / 100;
    for (int i = 0; i < kMessagesToSend; ++i) {
      if (!SendDouble(false, true))
        break;
    }
    *answer = 42;
    Done();
  }
};

void ChattyServer(bool pump_during_send) {
  std::vector<Worker*> workers;
  workers.push_back(new UnblockServer(pump_during_send, false));
  workers.push_back(new ChattyClient());
  RunTest(workers);
}

// Tests http://b/1093251 - that sending lots of sync messages while
// the receiver is waiting for a sync reply does not overflow the PostMessage
// queue.
TEST_F(IPCSyncChannelTest, ChattyServer) {
  ChattyServer(false);
  ChattyServer(true);
}

//------------------------------------------------------------------------------

void NestedCallback(Worker* server) {
  // Sleep a bit so that we wake up after the reply has been received.
  base::PlatformThread::Sleep(base::TimeDelta::FromMilliseconds(250));
  server->SendAnswerToLife(true, true);
}

bool timeout_occurred = false;

void TimeoutCallback() {
  timeout_occurred = true;
}

class DoneEventRaceServer : public Worker {
 public:
  DoneEventRaceServer()
      : Worker(Channel::MODE_SERVER, "done_event_race_server") { }

  virtual void Run() OVERRIDE {
    base::MessageLoop::current()->PostTask(FROM_HERE,
                                           base::Bind(&NestedCallback, this));
    base::MessageLoop::current()->PostDelayedTask(
        FROM_HERE,
        base::Bind(&TimeoutCallback),
        base::TimeDelta::FromSeconds(9));
    // Even though we have a timeout on the Send, it will succeed since for this
    // bug, the reply message comes back and is deserialized, however the done
    // event wasn't set.  So we indirectly use the timeout task to notice if a
    // timeout occurred.
    SendAnswerToLife(true, true);
    DCHECK(!timeout_occurred);
    Done();
  }
};

// Tests http://b/1474092 - that if after the done_event is set but before
// OnObjectSignaled is called another message is sent out, then after its
// reply comes back OnObjectSignaled will be called for the first message.
TEST_F(IPCSyncChannelTest, DoneEventRace) {
  std::vector<Worker*> workers;
  workers.push_back(new DoneEventRaceServer());
  workers.push_back(new SimpleClient());
  RunTest(workers);
}

//------------------------------------------------------------------------------

class TestSyncMessageFilter : public SyncMessageFilter {
 public:
  TestSyncMessageFilter(base::WaitableEvent* shutdown_event,
                        Worker* worker,
                        scoped_refptr<base::MessageLoopProxy> message_loop)
      : SyncMessageFilter(shutdown_event),
        worker_(worker),
        message_loop_(message_loop) {
  }

  virtual void OnFilterAdded(Channel* channel) OVERRIDE {
    SyncMessageFilter::OnFilterAdded(channel);
    message_loop_->PostTask(
        FROM_HERE,
        base::Bind(&TestSyncMessageFilter::SendMessageOnHelperThread, this));
  }

  void SendMessageOnHelperThread() {
    int answer = 0;
    bool result = Send(new SyncChannelTestMsg_AnswerToLife(&answer));
    DCHECK(result);
    DCHECK_EQ(answer, 42);

    worker_->Done();
  }

 private:
  virtual ~TestSyncMessageFilter() {}

  Worker* worker_;
  scoped_refptr<base::MessageLoopProxy> message_loop_;
};

class SyncMessageFilterServer : public Worker {
 public:
  SyncMessageFilterServer()
      : Worker(Channel::MODE_SERVER, "sync_message_filter_server"),
        thread_("helper_thread") {
    base::Thread::Options options;
    options.message_loop_type = base::MessageLoop::TYPE_DEFAULT;
    thread_.StartWithOptions(options);
    filter_ = new TestSyncMessageFilter(shutdown_event(), this,
                                        thread_.message_loop_proxy());
  }

  virtual void Run() OVERRIDE {
    channel()->AddFilter(filter_.get());
  }

  base::Thread thread_;
  scoped_refptr<TestSyncMessageFilter> filter_;
};

// This class provides functionality to test the case that a Send on the sync
// channel does not crash after the channel has been closed.
class ServerSendAfterClose : public Worker {
 public:
  ServerSendAfterClose()
     : Worker(Channel::MODE_SERVER, "simpler_server"),
       send_result_(true) {
  }

  bool SendDummy() {
    ListenerThread()->message_loop()->PostTask(
        FROM_HERE, base::Bind(base::IgnoreResult(&ServerSendAfterClose::Send),
                              this, new SyncChannelTestMsg_NoArgs));
    return true;
  }

  bool send_result() const {
    return send_result_;
  }

 private:
  virtual void Run() OVERRIDE {
    CloseChannel();
    Done();
  }

  virtual bool Send(Message* msg) OVERRIDE {
    send_result_ = Worker::Send(msg);
    Done();
    return send_result_;
  }

  bool send_result_;
};

// Tests basic synchronous call
TEST_F(IPCSyncChannelTest, SyncMessageFilter) {
  std::vector<Worker*> workers;
  workers.push_back(new SyncMessageFilterServer());
  workers.push_back(new SimpleClient());
  RunTest(workers);
}

// Test the case when the channel is closed and a Send is attempted after that.
TEST_F(IPCSyncChannelTest, SendAfterClose) {
  ServerSendAfterClose server;
  server.Start();

  server.done_event()->Wait();
  server.done_event()->Reset();

  server.SendDummy();
  server.done_event()->Wait();

  EXPECT_FALSE(server.send_result());

  server.Shutdown();
}

//------------------------------------------------------------------------------

class RestrictedDispatchServer : public Worker {
 public:
  RestrictedDispatchServer(WaitableEvent* sent_ping_event,
                           WaitableEvent* wait_event)
      : Worker("restricted_channel", Channel::MODE_SERVER),
        sent_ping_event_(sent_ping_event),
        wait_event_(wait_event) { }

  void OnDoPing(int ping) {
    // Send an asynchronous message that unblocks the caller.
    Message* msg = new SyncChannelTestMsg_Ping(ping);
    msg->set_unblock(true);
    Send(msg);
    // Signal the event after the message has been sent on the channel, on the
    // IPC thread.
    ipc_thread().message_loop()->PostTask(
        FROM_HERE, base::Bind(&RestrictedDispatchServer::OnPingSent, this));
  }

  void OnPingTTL(int ping, int* out) {
    *out = ping;
    wait_event_->Wait();
  }

  base::Thread* ListenerThread() { return Worker::ListenerThread(); }

 private:
  virtual bool OnMessageReceived(const Message& message) OVERRIDE {
    IPC_BEGIN_MESSAGE_MAP(RestrictedDispatchServer, message)
     IPC_MESSAGE_HANDLER(SyncChannelTestMsg_NoArgs, OnNoArgs)
     IPC_MESSAGE_HANDLER(SyncChannelTestMsg_PingTTL, OnPingTTL)
     IPC_MESSAGE_HANDLER(SyncChannelTestMsg_Done, Done)
    IPC_END_MESSAGE_MAP()
    return true;
  }

  void OnPingSent() {
    sent_ping_event_->Signal();
  }

  void OnNoArgs() { }
  WaitableEvent* sent_ping_event_;
  WaitableEvent* wait_event_;
};

class NonRestrictedDispatchServer : public Worker {
 public:
  NonRestrictedDispatchServer(WaitableEvent* signal_event)
      : Worker("non_restricted_channel", Channel::MODE_SERVER),
        signal_event_(signal_event) {}

  base::Thread* ListenerThread() { return Worker::ListenerThread(); }

  void OnDoPingTTL(int ping) {
    int value = 0;
    Send(new SyncChannelTestMsg_PingTTL(ping, &value));
    signal_event_->Signal();
  }

 private:
  virtual bool OnMessageReceived(const Message& message) OVERRIDE {
    IPC_BEGIN_MESSAGE_MAP(NonRestrictedDispatchServer, message)
     IPC_MESSAGE_HANDLER(SyncChannelTestMsg_NoArgs, OnNoArgs)
     IPC_MESSAGE_HANDLER(SyncChannelTestMsg_Done, Done)
    IPC_END_MESSAGE_MAP()
    return true;
  }

  void OnNoArgs() { }
  WaitableEvent* signal_event_;
};

class RestrictedDispatchClient : public Worker {
 public:
  RestrictedDispatchClient(WaitableEvent* sent_ping_event,
                           RestrictedDispatchServer* server,
                           NonRestrictedDispatchServer* server2,
                           int* success)
      : Worker("restricted_channel", Channel::MODE_CLIENT),
        ping_(0),
        server_(server),
        server2_(server2),
        success_(success),
        sent_ping_event_(sent_ping_event) {}

  virtual void Run() OVERRIDE {
    // Incoming messages from our channel should only be dispatched when we
    // send a message on that same channel.
    channel()->SetRestrictDispatchChannelGroup(1);

    server_->ListenerThread()->message_loop()->PostTask(
        FROM_HERE, base::Bind(&RestrictedDispatchServer::OnDoPing, server_, 1));
    sent_ping_event_->Wait();
    Send(new SyncChannelTestMsg_NoArgs);
    if (ping_ == 1)
      ++*success_;
    else
      LOG(ERROR) << "Send failed to dispatch incoming message on same channel";

    non_restricted_channel_.reset(
        new SyncChannel("non_restricted_channel",
                        Channel::MODE_CLIENT,
                        this,
                        ipc_thread().message_loop_proxy().get(),
                        true,
                        shutdown_event()));

    server_->ListenerThread()->message_loop()->PostTask(
        FROM_HERE, base::Bind(&RestrictedDispatchServer::OnDoPing, server_, 2));
    sent_ping_event_->Wait();
    // Check that the incoming message is *not* dispatched when sending on the
    // non restricted channel.
    // TODO(piman): there is a possibility of a false positive race condition
    // here, if the message that was posted on the server-side end of the pipe
    // is not visible yet on the client side, but I don't know how to solve this
    // without hooking into the internals of SyncChannel. I haven't seen it in
    // practice (i.e. not setting SetRestrictDispatchToSameChannel does cause
    // the following to fail).
    non_restricted_channel_->Send(new SyncChannelTestMsg_NoArgs);
    if (ping_ == 1)
      ++*success_;
    else
      LOG(ERROR) << "Send dispatched message from restricted channel";

    Send(new SyncChannelTestMsg_NoArgs);
    if (ping_ == 2)
      ++*success_;
    else
      LOG(ERROR) << "Send failed to dispatch incoming message on same channel";

    // Check that the incoming message on the non-restricted channel is
    // dispatched when sending on the restricted channel.
    server2_->ListenerThread()->message_loop()->PostTask(
        FROM_HERE,
        base::Bind(&NonRestrictedDispatchServer::OnDoPingTTL, server2_, 3));
    int value = 0;
    Send(new SyncChannelTestMsg_PingTTL(4, &value));
    if (ping_ == 3 && value == 4)
      ++*success_;
    else
      LOG(ERROR) << "Send failed to dispatch message from unrestricted channel";

    non_restricted_channel_->Send(new SyncChannelTestMsg_Done);
    non_restricted_channel_.reset();
    Send(new SyncChannelTestMsg_Done);
    Done();
  }

 private:
  virtual bool OnMessageReceived(const Message& message) OVERRIDE {
    IPC_BEGIN_MESSAGE_MAP(RestrictedDispatchClient, message)
     IPC_MESSAGE_HANDLER(SyncChannelTestMsg_Ping, OnPing)
     IPC_MESSAGE_HANDLER_DELAY_REPLY(SyncChannelTestMsg_PingTTL, OnPingTTL)
    IPC_END_MESSAGE_MAP()
    return true;
  }

  void OnPing(int ping) {
    ping_ = ping;
  }

  void OnPingTTL(int ping, IPC::Message* reply) {
    ping_ = ping;
    // This message comes from the NonRestrictedDispatchServer, we have to send
    // the reply back manually.
    SyncChannelTestMsg_PingTTL::WriteReplyParams(reply, ping);
    non_restricted_channel_->Send(reply);
  }

  int ping_;
  RestrictedDispatchServer* server_;
  NonRestrictedDispatchServer* server2_;
  int* success_;
  WaitableEvent* sent_ping_event_;
  scoped_ptr<SyncChannel> non_restricted_channel_;
};

TEST_F(IPCSyncChannelTest, RestrictedDispatch) {
  WaitableEvent sent_ping_event(false, false);
  WaitableEvent wait_event(false, false);
  RestrictedDispatchServer* server =
      new RestrictedDispatchServer(&sent_ping_event, &wait_event);
  NonRestrictedDispatchServer* server2 =
      new NonRestrictedDispatchServer(&wait_event);

  int success = 0;
  std::vector<Worker*> workers;
  workers.push_back(server);
  workers.push_back(server2);
  workers.push_back(new RestrictedDispatchClient(
      &sent_ping_event, server, server2, &success));
  RunTest(workers);
  EXPECT_EQ(4, success);
}

//------------------------------------------------------------------------------

// This test case inspired by crbug.com/108491
// We create two servers that use the same ListenerThread but have
// SetRestrictDispatchToSameChannel set to true.
// We create clients, then use some specific WaitableEvent wait/signalling to
// ensure that messages get dispatched in a way that causes a deadlock due to
// a nested dispatch and an eligible message in a higher-level dispatch's
// delayed_queue. Specifically, we start with client1 about so send an
// unblocking message to server1, while the shared listener thread for the
// servers server1 and server2 is about to send a non-unblocking message to
// client1. At the same time, client2 will be about to send an unblocking
// message to server2. Server1 will handle the client1->server1 message by
// telling server2 to send a non-unblocking message to client2.
// What should happen is that the send to server2 should find the pending,
// same-context client2->server2 message to dispatch, causing client2 to
// unblock then handle the server2->client2 message, so that the shared
// servers' listener thread can then respond to the client1->server1 message.
// Then client1 can handle the non-unblocking server1->client1 message.
// The old code would end up in a state where the server2->client2 message is
// sent, but the client2->server2 message (which is eligible for dispatch, and
// which is what client2 is waiting for) is stashed in a local delayed_queue
// that has server1's channel context, causing a deadlock.
// WaitableEvents in the events array are used to:
//   event 0: indicate to client1 that server listener is in OnDoServerTask
//   event 1: indicate to client1 that client2 listener is in OnDoClient2Task
//   event 2: indicate to server1 that client2 listener is in OnDoClient2Task
//   event 3: indicate to client2 that server listener is in OnDoServerTask

class RestrictedDispatchDeadlockServer : public Worker {
 public:
  RestrictedDispatchDeadlockServer(int server_num,
                                   WaitableEvent* server_ready_event,
                                   WaitableEvent** events,
                                   RestrictedDispatchDeadlockServer* peer)
      : Worker(server_num == 1 ? "channel1" : "channel2", Channel::MODE_SERVER),
        server_num_(server_num),
        server_ready_event_(server_ready_event),
        events_(events),
        peer_(peer) { }

  void OnDoServerTask() {
    events_[3]->Signal();
    events_[2]->Wait();
    events_[0]->Signal();
    SendMessageToClient();
  }

  virtual void Run() OVERRIDE {
    channel()->SetRestrictDispatchChannelGroup(1);
    server_ready_event_->Signal();
  }

  base::Thread* ListenerThread() { return Worker::ListenerThread(); }

 private:
  virtual bool OnMessageReceived(const Message& message) OVERRIDE {
    IPC_BEGIN_MESSAGE_MAP(RestrictedDispatchDeadlockServer, message)
     IPC_MESSAGE_HANDLER(SyncChannelTestMsg_NoArgs, OnNoArgs)
     IPC_MESSAGE_HANDLER(SyncChannelTestMsg_Done, Done)
    IPC_END_MESSAGE_MAP()
    return true;
  }

  void OnNoArgs() {
    if (server_num_ == 1) {
      DCHECK(peer_ != NULL);
      peer_->SendMessageToClient();
    }
  }

  void SendMessageToClient() {
    Message* msg = new SyncChannelTestMsg_NoArgs;
    msg->set_unblock(false);
    DCHECK(!msg->should_unblock());
    Send(msg);
  }

  int server_num_;
  WaitableEvent* server_ready_event_;
  WaitableEvent** events_;
  RestrictedDispatchDeadlockServer* peer_;
};

class RestrictedDispatchDeadlockClient2 : public Worker {
 public:
  RestrictedDispatchDeadlockClient2(RestrictedDispatchDeadlockServer* server,
                                    WaitableEvent* server_ready_event,
                                    WaitableEvent** events)
      : Worker("channel2", Channel::MODE_CLIENT),
        server_ready_event_(server_ready_event),
        events_(events),
        received_msg_(false),
        received_noarg_reply_(false),
        done_issued_(false) {}

  virtual void Run() OVERRIDE {
    server_ready_event_->Wait();
  }

  void OnDoClient2Task() {
    events_[3]->Wait();
    events_[1]->Signal();
    events_[2]->Signal();
    DCHECK(received_msg_ == false);

    Message* message = new SyncChannelTestMsg_NoArgs;
    message->set_unblock(true);
    Send(message);
    received_noarg_reply_ = true;
  }

  base::Thread* ListenerThread() { return Worker::ListenerThread(); }
 private:
  virtual bool OnMessageReceived(const Message& message) OVERRIDE {
    IPC_BEGIN_MESSAGE_MAP(RestrictedDispatchDeadlockClient2, message)
     IPC_MESSAGE_HANDLER(SyncChannelTestMsg_NoArgs, OnNoArgs)
    IPC_END_MESSAGE_MAP()
    return true;
  }

  void OnNoArgs() {
    received_msg_ = true;
    PossiblyDone();
  }

  void PossiblyDone() {
    if (received_noarg_reply_ && received_msg_) {
      DCHECK(done_issued_ == false);
      done_issued_ = true;
      Send(new SyncChannelTestMsg_Done);
      Done();
    }
  }

  WaitableEvent* server_ready_event_;
  WaitableEvent** events_;
  bool received_msg_;
  bool received_noarg_reply_;
  bool done_issued_;
};

class RestrictedDispatchDeadlockClient1 : public Worker {
 public:
  RestrictedDispatchDeadlockClient1(RestrictedDispatchDeadlockServer* server,
                                    RestrictedDispatchDeadlockClient2* peer,
                                    WaitableEvent* server_ready_event,
                                    WaitableEvent** events)
      : Worker("channel1", Channel::MODE_CLIENT),
        server_(server),
        peer_(peer),
        server_ready_event_(server_ready_event),
        events_(events),
        received_msg_(false),
        received_noarg_reply_(false),
        done_issued_(false) {}

  virtual void Run() OVERRIDE {
    server_ready_event_->Wait();
    server_->ListenerThread()->message_loop()->PostTask(
        FROM_HERE,
        base::Bind(&RestrictedDispatchDeadlockServer::OnDoServerTask, server_));
    peer_->ListenerThread()->message_loop()->PostTask(
        FROM_HERE,
        base::Bind(&RestrictedDispatchDeadlockClient2::OnDoClient2Task, peer_));
    events_[0]->Wait();
    events_[1]->Wait();
    DCHECK(received_msg_ == false);

    Message* message = new SyncChannelTestMsg_NoArgs;
    message->set_unblock(true);
    Send(message);
    received_noarg_reply_ = true;
    PossiblyDone();
  }

 private:
  virtual bool OnMessageReceived(const Message& message) OVERRIDE {
    IPC_BEGIN_MESSAGE_MAP(RestrictedDispatchDeadlockClient1, message)
     IPC_MESSAGE_HANDLER(SyncChannelTestMsg_NoArgs, OnNoArgs)
    IPC_END_MESSAGE_MAP()
    return true;
  }

  void OnNoArgs() {
    received_msg_ = true;
    PossiblyDone();
  }

  void PossiblyDone() {
    if (received_noarg_reply_ && received_msg_) {
      DCHECK(done_issued_ == false);
      done_issued_ = true;
      Send(new SyncChannelTestMsg_Done);
      Done();
    }
  }

  RestrictedDispatchDeadlockServer* server_;
  RestrictedDispatchDeadlockClient2* peer_;
  WaitableEvent* server_ready_event_;
  WaitableEvent** events_;
  bool received_msg_;
  bool received_noarg_reply_;
  bool done_issued_;
};

TEST_F(IPCSyncChannelTest, RestrictedDispatchDeadlock) {
  std::vector<Worker*> workers;

  // A shared worker thread so that server1 and server2 run on one thread.
  base::Thread worker_thread("RestrictedDispatchDeadlock");
  ASSERT_TRUE(worker_thread.Start());

  WaitableEvent server1_ready(false, false);
  WaitableEvent server2_ready(false, false);

  WaitableEvent event0(false, false);
  WaitableEvent event1(false, false);
  WaitableEvent event2(false, false);
  WaitableEvent event3(false, false);
  WaitableEvent* events[4] = {&event0, &event1, &event2, &event3};

  RestrictedDispatchDeadlockServer* server1;
  RestrictedDispatchDeadlockServer* server2;
  RestrictedDispatchDeadlockClient1* client1;
  RestrictedDispatchDeadlockClient2* client2;

  server2 = new RestrictedDispatchDeadlockServer(2, &server2_ready, events,
                                                 NULL);
  server2->OverrideThread(&worker_thread);
  workers.push_back(server2);

  client2 = new RestrictedDispatchDeadlockClient2(server2, &server2_ready,
                                                  events);
  workers.push_back(client2);

  server1 = new RestrictedDispatchDeadlockServer(1, &server1_ready, events,
                                                 server2);
  server1->OverrideThread(&worker_thread);
  workers.push_back(server1);

  client1 = new RestrictedDispatchDeadlockClient1(server1, client2,
                                                  &server1_ready, events);
  workers.push_back(client1);

  RunTest(workers);
}

//------------------------------------------------------------------------------

// This test case inspired by crbug.com/120530
// We create 4 workers that pipe to each other W1->W2->W3->W4->W1 then we send a
// message that recurses through 3, 4 or 5 steps to make sure, say, W1 can
// re-enter when called from W4 while it's sending a message to W2.
// The first worker drives the whole test so it must be treated specially.

class RestrictedDispatchPipeWorker : public Worker {
 public:
  RestrictedDispatchPipeWorker(
      const std::string &channel1,
      WaitableEvent* event1,
      const std::string &channel2,
      WaitableEvent* event2,
      int group,
      int* success)
      : Worker(channel1, Channel::MODE_SERVER),
        event1_(event1),
        event2_(event2),
        other_channel_name_(channel2),
        group_(group),
        success_(success) {
  }

  void OnPingTTL(int ping, int* ret) {
    *ret = 0;
    if (!ping)
      return;
    other_channel_->Send(new SyncChannelTestMsg_PingTTL(ping - 1, ret));
    ++*ret;
  }

  void OnDone() {
    if (is_first())
      return;
    other_channel_->Send(new SyncChannelTestMsg_Done);
    other_channel_.reset();
    Done();
  }

  virtual void Run() OVERRIDE {
    channel()->SetRestrictDispatchChannelGroup(group_);
    if (is_first())
      event1_->Signal();
    event2_->Wait();
    other_channel_.reset(
        new SyncChannel(other_channel_name_,
                        Channel::MODE_CLIENT,
                        this,
                        ipc_thread().message_loop_proxy().get(),
                        true,
                        shutdown_event()));
    other_channel_->SetRestrictDispatchChannelGroup(group_);
    if (!is_first()) {
      event1_->Signal();
      return;
    }
    *success_ = 0;
    int value = 0;
    OnPingTTL(3, &value);
    *success_ += (value == 3);
    OnPingTTL(4, &value);
    *success_ += (value == 4);
    OnPingTTL(5, &value);
    *success_ += (value == 5);
    other_channel_->Send(new SyncChannelTestMsg_Done);
    other_channel_.reset();
    Done();
  }

  bool is_first() { return !!success_; }

 private:
  virtual bool OnMessageReceived(const Message& message) OVERRIDE {
    IPC_BEGIN_MESSAGE_MAP(RestrictedDispatchPipeWorker, message)
     IPC_MESSAGE_HANDLER(SyncChannelTestMsg_PingTTL, OnPingTTL)
     IPC_MESSAGE_HANDLER(SyncChannelTestMsg_Done, OnDone)
    IPC_END_MESSAGE_MAP()
    return true;
  }

  scoped_ptr<SyncChannel> other_channel_;
  WaitableEvent* event1_;
  WaitableEvent* event2_;
  std::string other_channel_name_;
  int group_;
  int* success_;
};

TEST_F(IPCSyncChannelTest, RestrictedDispatch4WayDeadlock) {
  int success = 0;
  std::vector<Worker*> workers;
  WaitableEvent event0(true, false);
  WaitableEvent event1(true, false);
  WaitableEvent event2(true, false);
  WaitableEvent event3(true, false);
  workers.push_back(new RestrictedDispatchPipeWorker(
        "channel0", &event0, "channel1", &event1, 1, &success));
  workers.push_back(new RestrictedDispatchPipeWorker(
        "channel1", &event1, "channel2", &event2, 2, NULL));
  workers.push_back(new RestrictedDispatchPipeWorker(
        "channel2", &event2, "channel3", &event3, 3, NULL));
  workers.push_back(new RestrictedDispatchPipeWorker(
        "channel3", &event3, "channel0", &event0, 4, NULL));
  RunTest(workers);
  EXPECT_EQ(3, success);
}

//------------------------------------------------------------------------------

// This test case inspired by crbug.com/122443
// We want to make sure a reply message with the unblock flag set correctly
// behaves as a reply, not a regular message.
// We have 3 workers. Server1 will send a message to Server2 (which will block),
// during which it will dispatch a message comming from Client, at which point
// it will send another message to Server2. While sending that second message it
// will receive a reply from Server1 with the unblock flag.

class ReentrantReplyServer1 : public Worker {
 public:
  ReentrantReplyServer1(WaitableEvent* server_ready)
      : Worker("reentrant_reply1", Channel::MODE_SERVER),
        server_ready_(server_ready) { }

  virtual void Run() OVERRIDE {
    server2_channel_.reset(
        new SyncChannel("reentrant_reply2",
                        Channel::MODE_CLIENT,
                        this,
                        ipc_thread().message_loop_proxy().get(),
                        true,
                        shutdown_event()));
    server_ready_->Signal();
    Message* msg = new SyncChannelTestMsg_Reentrant1();
    server2_channel_->Send(msg);
    server2_channel_.reset();
    Done();
  }

 private:
  virtual bool OnMessageReceived(const Message& message) OVERRIDE {
    IPC_BEGIN_MESSAGE_MAP(ReentrantReplyServer1, message)
     IPC_MESSAGE_HANDLER(SyncChannelTestMsg_Reentrant2, OnReentrant2)
     IPC_REPLY_HANDLER(OnReply)
    IPC_END_MESSAGE_MAP()
    return true;
  }

  void OnReentrant2() {
    Message* msg = new SyncChannelTestMsg_Reentrant3();
    server2_channel_->Send(msg);
  }

  void OnReply(const Message& message) {
    // If we get here, the Send() will never receive the reply (thus would
    // hang), so abort instead.
    LOG(FATAL) << "Reply message was dispatched";
  }

  WaitableEvent* server_ready_;
  scoped_ptr<SyncChannel> server2_channel_;
};

class ReentrantReplyServer2 : public Worker {
 public:
  ReentrantReplyServer2()
      : Worker("reentrant_reply2", Channel::MODE_SERVER),
        reply_(NULL) { }

 private:
  virtual bool OnMessageReceived(const Message& message) OVERRIDE {
    IPC_BEGIN_MESSAGE_MAP(ReentrantReplyServer2, message)
     IPC_MESSAGE_HANDLER_DELAY_REPLY(
         SyncChannelTestMsg_Reentrant1, OnReentrant1)
     IPC_MESSAGE_HANDLER(SyncChannelTestMsg_Reentrant3, OnReentrant3)
    IPC_END_MESSAGE_MAP()
    return true;
  }

  void OnReentrant1(Message* reply) {
    DCHECK(!reply_);
    reply_ = reply;
  }

  void OnReentrant3() {
    DCHECK(reply_);
    Message* reply = reply_;
    reply_ = NULL;
    reply->set_unblock(true);
    Send(reply);
    Done();
  }

  Message* reply_;
};

class ReentrantReplyClient : public Worker {
 public:
  ReentrantReplyClient(WaitableEvent* server_ready)
      : Worker("reentrant_reply1", Channel::MODE_CLIENT),
        server_ready_(server_ready) { }

  virtual void Run() OVERRIDE {
    server_ready_->Wait();
    Send(new SyncChannelTestMsg_Reentrant2());
    Done();
  }

 private:
  WaitableEvent* server_ready_;
};

TEST_F(IPCSyncChannelTest, ReentrantReply) {
  std::vector<Worker*> workers;
  WaitableEvent server_ready(false, false);
  workers.push_back(new ReentrantReplyServer2());
  workers.push_back(new ReentrantReplyServer1(&server_ready));
  workers.push_back(new ReentrantReplyClient(&server_ready));
  RunTest(workers);
}

//------------------------------------------------------------------------------

// Generate a validated channel ID using Channel::GenerateVerifiedChannelID().

class VerifiedServer : public Worker {
 public:
  VerifiedServer(base::Thread* listener_thread,
                 const std::string& channel_name,
                 const std::string& reply_text)
      : Worker(channel_name, Channel::MODE_SERVER),
        reply_text_(reply_text) {
    Worker::OverrideThread(listener_thread);
  }

  virtual void OnNestedTestMsg(Message* reply_msg) OVERRIDE {
    VLOG(1) << __FUNCTION__ << " Sending reply: " << reply_text_;
    SyncChannelNestedTestMsg_String::WriteReplyParams(reply_msg, reply_text_);
    Send(reply_msg);
    ASSERT_EQ(channel()->peer_pid(), base::GetCurrentProcId());
    Done();
  }

 private:
  std::string reply_text_;
};

class VerifiedClient : public Worker {
 public:
  VerifiedClient(base::Thread* listener_thread,
                 const std::string& channel_name,
                 const std::string& expected_text)
      : Worker(channel_name, Channel::MODE_CLIENT),
        expected_text_(expected_text) {
    Worker::OverrideThread(listener_thread);
  }

  virtual void Run() OVERRIDE {
    std::string response;
    SyncMessage* msg = new SyncChannelNestedTestMsg_String(&response);
    bool result = Send(msg);
    DCHECK(result);
    DCHECK_EQ(response, expected_text_);
    // expected_text_ is only used in the above DCHECK. This line suppresses the
    // "unused private field" warning in release builds.
    (void)expected_text_;

    VLOG(1) << __FUNCTION__ << " Received reply: " << response;
    ASSERT_EQ(channel()->peer_pid(), base::GetCurrentProcId());
    Done();
  }

 private:
  std::string expected_text_;
};

void Verified() {
  std::vector<Worker*> workers;

  // A shared worker thread for servers
  base::Thread server_worker_thread("Verified_ServerListener");
  ASSERT_TRUE(server_worker_thread.Start());

  base::Thread client_worker_thread("Verified_ClientListener");
  ASSERT_TRUE(client_worker_thread.Start());

  std::string channel_id = Channel::GenerateVerifiedChannelID("Verified");
  Worker* worker;

  worker = new VerifiedServer(&server_worker_thread,
                              channel_id,
                              "Got first message");
  workers.push_back(worker);

  worker = new VerifiedClient(&client_worker_thread,
                              channel_id,
                              "Got first message");
  workers.push_back(worker);

  RunTest(workers);
}

// Windows needs to send an out-of-band secret to verify the client end of the
// channel. Test that we still connect correctly in that case.
TEST_F(IPCSyncChannelTest, Verified) {
  Verified();
}

}  // namespace
}  // namespace IPC