Refactor ChildProcess and related classes to create a framework outside of br...

base/mp/mp_child_process_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 BASE_MP_CHILD_PROCESS_HOST_H_
+#define BASE_MP_CHILD_PROCESS_HOST_H_
+
+#include <list>
+#include <string>
+
+// Must be included early (e.g. before chrome/common/plugin_messages.h)
+#include "ipc/ipc_logging.h"
+
+#include "base/basictypes.h"
+#include "base/scoped_ptr.h"
+#include "base/mp/mp_child_process_context.h"
+#include "base/mp/mp_child_process_launcher.h"
+#include "ipc/ipc_channel.h"
+
+class CommandLine;
+
+namespace base {
+
+// Plugins/workers and other child processes that live on the IO thread should
+// derive from this class.
+//
+// [Browser]RenderProcessHost is the main exception that doesn't derive from
+// this class. That project lives on the UI thread.
+class MpChildProcessHost : public IPC::Channel::Listener,
+                           public MpChildProcessLauncher::Client {
+ public:
+  // Notifications that should be forwarded to the UI thread.
+  enum MpNotificationType {
+    CHILD_INSTANCE_CREATED,
+    CHILD_PROCESS_CRASHED,
+    CHILD_PROCESS_HOST_CONNECTED,
+    CHILD_PROCESS_HOST_DISCONNECTED,
+  };
+
+  virtual ~MpChildProcessHost();
+
+  virtual bool Send(IPC::Message* msg);
+
+ protected:
+  MpChildProcessHost(MpChildProcessContext* context);
+
+  // Launches the child process asynchronously.
+  void Launch(
+#if defined(OS_WIN)
+      const FilePath& exposed_dir,
+#elif defined(OS_POSIX)
+      bool use_zygote,
+      const base::environment_vector& environ,
+#endif
+      CommandLine* cmd_line);
+
+  // Derived classes should send the given notification to the notification
+  // service on the UI thread.
+  virtual void Notify(MpNotificationType type) = 0;
+
+  // Derived classes override this method to handle messages.
+  virtual bool OnDispatchMessageReceived(const IPC::Message& msg,
+                                         bool *msg_is_ok) = 0;
+
+  // Derived classes return the application-specific child process type.
+  virtual int GetType() = 0;
+
+  // Derived classes return true if it's ok to shut down the child process.
+  virtual bool CanShutdown() = 0;
+
+  // Send the shutdown message to the child process, and remove this host from
+  // the host list. Does not check if CanShutdown is true.
+  void ForceShutdown();
+
+  // Creates the IPC channel.  Returns true iff it succeeded.
+  bool CreateChannel();
+
+  // Notifies us that an instance has been created on this child process.
+  void InstanceCreated();
+
+  // IPC::Channel::Listener implementation:
+  virtual void OnMessageReceived(const IPC::Message& msg) { }
+  virtual void OnChannelConnected(int32 peer_pid) { }
+  virtual void OnChannelError() { }
+
+  // MpChildProcessLauncher::Client implementation.
+  virtual void OnProcessLaunched() {}
+
+  // Derived classes can override this to know if the process crashed.
+  virtual void OnProcessCrashed() {}
+
+  bool opening_channel() { return opening_channel_; }
+  const std::string& channel_id() { return channel_id_; }
+
+  virtual bool DidChildCrash();
+
+  // Called when the child process goes away.
+  virtual void OnChildDied();
+
+  // Getter to the process handle.
+  base::ProcessHandle GetHandle() const { return child_process_->GetHandle(); }
+
+ private:
+  // By using an internal class as the IPC::Channel::Listener, we can intercept
+  // OnMessageReceived/OnChannelConnected and do our own processing before
+  // calling the subclass' implementation.
+  class ListenerHook : public IPC::Channel::Listener,
+                       public MpChildProcessLauncher::Client {
+   public:
+    explicit ListenerHook(MpChildProcessHost* host);
+    virtual void OnMessageReceived(const IPC::Message& msg);
+    virtual void OnChannelConnected(int32 peer_pid);
+    virtual void OnChannelError();
+    virtual void OnProcessLaunched();
+   private:
+    MpChildProcessHost* host_;
+  };
+
+  ListenerHook listener_;
+
+  bool opening_channel_;  // True while we're waiting the channel to be opened.
+  scoped_ptr<IPC::Channel> channel_;
+  std::string channel_id_;
+  scoped_ptr<MpChildProcessLauncher> child_process_;
+  MpChildProcessContext* context_;
+};
+
+}  // namespace base
+
+#endif  // BASE_MP_CHILD_PROCESS_HOST_H_