Fix thread usage in chromoting host

remoting/host/chromoting_host.h

 // Copyright (c) 2010 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.
 
 #ifndef REMOTING_CHROMOTING_HOST_H_
 #define REMOTING_CHROMOTING_HOST_H_
 
 #include <string>
 
 #include "base/thread.h"
 #include "remoting/host/capturer.h"
 #include "remoting/host/client_connection.h"
 #include "remoting/host/encoder.h"
 #include "remoting/host/event_executor.h"
 #include "remoting/host/heartbeat_sender.h"
 #include "remoting/host/session_manager.h"
 #include "remoting/jingle_glue/jingle_client.h"
 #include "remoting/jingle_glue/jingle_thread.h"
 
-namespace base {
-class WaitableEvent;
-}  // namespace base
+class Task;
 
 namespace remoting {
 
+class ChromotingHostContext;
 class MutableHostConfig;
 
 // A class to implement the functionality of a host process.
 //
 // Here's the work flow of this class:
 // 1. We should load the saved GAIA ID token or if this is the first
 //    time the host process runs we should prompt user for the
 //    credential. We will use this token or credentials to authenicate
 //    and register the host.
 //
 // 2. We listen for incoming connection using libjingle. We will create
 //    a ClientConnection object that wraps around linjingle for transport. Also
 //    create a SessionManager with appropriate Encoder and Capturer and
 //    add the ClientConnection to this SessionManager for transporting the
 //    screen captures. A EventExecutor is created and registered with the
 //    ClientConnection to receive mouse / keyboard events from the remote
 //    client.
 //    This is also the right time to create multiple threads to host
 //    the above objects. After we have done all the initialization
 //    we'll start the SessionManager. We'll then enter the running state
 //    of the host process.
 //
 // 3. When the user is disconencted, we will pause the SessionManager
 //    and try to terminate the threads we have created. This will allow
 //    all pending tasks to complete. After all of that completed we
 //    return to the idle state. We then go to step (2) if there a new
 //    incoming connection.
 class ChromotingHost : public base::RefCountedThreadSafe<ChromotingHost>,
-                   public ClientConnection::EventHandler,
-                   public JingleClient::Callback {
+                       public ClientConnection::EventHandler,
+                       public JingleClient::Callback {
  public:
-  ChromotingHost(MutableHostConfig* config, Capturer* capturer,
-                 Encoder* encoder, EventExecutor* executor,
-                 base::WaitableEvent* host_done);
+  ChromotingHost(ChromotingHostContext* context, MutableHostConfig* config,
+                 Capturer* capturer, Encoder* encoder, EventExecutor* executor);
   virtual ~ChromotingHost();
 
-  // Run the host porcess. This method returns only after the message loop
-  // of the host process exits.
-  void Run();
+  // Start the host porcess. This methods starts the chromoting host
+  // asynchronously.
+  //
+  // |shutdown_task| is called if Start() has failed ot Shutdown() is called
+  // and all related operations are completed.
+  //
+  // This method can only be called once during the lifetime of this object.
+  void Start(Task* shutdown_task);
 
   // This method is called when we need to the host process.
-  void DestroySession();
-
-  // This method talks to the cloud to register the host process. If
-  // successful we will start listening to network requests.
-  void RegisterHost();
+  void Shutdown();
 
   // This method is called if a client is connected to this object.
   void OnClientConnected(ClientConnection* client);
 
   // This method is called if a client is disconnected from the host.
   void OnClientDisconnected(ClientConnection* client);
 
   ////////////////////////////////////////////////////////////////////////////
   // ClientConnection::EventHandler implementations
   virtual void HandleMessages(ClientConnection* client,
                               ClientMessageList* messages);
   virtual void OnConnectionOpened(ClientConnection* client);
   virtual void OnConnectionClosed(ClientConnection* client);
   virtual void OnConnectionFailed(ClientConnection* client);
 
   ////////////////////////////////////////////////////////////////////////////
   // JingleClient::Callback implementations
   virtual void OnStateChange(JingleClient* client, JingleClient::State state);
   virtual bool OnAcceptConnection(
       JingleClient* jingle, const std::string& jid,
       JingleChannel::Callback** channel_callback);
   virtual void OnNewConnection(
       JingleClient* jingle,
       scoped_refptr<JingleChannel> channel);
 
  private:
-  // The message loop that this class runs on.
-  MessageLoop* message_loop();
+  enum State {
+    kInitial,
+    kStarted,
+    kStopped,
+  };
 
-  // The main thread that this object runs on.
-  base::Thread main_thread_;
+  // This method connects to the talk network and start listening for incoming
+  // connections.
+  void DoStart(Task* shutdown_task);
 
-  // Used to handle the Jingle connection.
-  JingleThread network_thread_;
+  // This method shuts down the host process.
+  void DoShutdown();
 
-  // A thread that hosts capture operations.
-  base::Thread capture_thread_;
-
-  // A thread that hosts encode operations.
-  base::Thread encode_thread_;
+  // The context that the chromoting host runs on.
+  ChromotingHostContext* context_;
 
   scoped_refptr<MutableHostConfig> config_;
 
   // Capturer to be used by SessionManager. Once the SessionManager is
   // constructed this is set to NULL.
   scoped_ptr<Capturer> capturer_;
 
   // Encoder to be used by the SessionManager. Once the SessionManager is
   // constructed this is set to NULL.
   scoped_ptr<Encoder> encoder_;
 
   // EventExecutor executes input events received from the client.
   scoped_ptr<EventExecutor> executor_;
 
   // The libjingle client. This is used to connect to the talk network to
   // receive connection requests from chromoting client.
   scoped_refptr<JingleClient> jingle_client_;
 
   // Objects that takes care of sending heartbeats to the chromoting bot.
   scoped_refptr<HeartbeatSender> heartbeat_sender_;
 
   // A ClientConnection manages the connectino to a remote client.
   // TODO(hclam): Expand this to a list of clients.
   scoped_refptr<ClientConnection> client_;
 
   // Session manager for the host process.
   scoped_refptr<SessionManager> session_;
 
-  // Signals the host is ready to be destroyed.
-  base::WaitableEvent* host_done_;
+  // This task gets executed when this object fails to connect to the
+  // talk network or Shutdown() is called.
+  scoped_ptr<Task> shutdown_task_;
+
+  // Tracks the internal state of the host.
+  // This variable is written on the main thread of ChromotingHostContext
+  // and read by jingle thread.
+  State state_;
+
+  // Lock is to lock the access to |state_|.
+  Lock lock_;
 
   DISALLOW_COPY_AND_ASSIGN(ChromotingHost);
 };
 
 }  // namespace remoting
 
 #endif  // REMOTING_HOST_CHROMOTING_HOST_H_