Linux/CrOS: Retry connecting to mtpd.

dbus/bus.h

 // 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.
 
 #ifndef DBUS_BUS_H_
 #define DBUS_BUS_H_
 
 #include <dbus/dbus.h>
 
 #include <map>
 #include <set>
 #include <string>
 #include <utility>
+#include <vector>
 
 #include "base/callback.h"
 #include "base/memory/ref_counted.h"
 #include "base/synchronization/waitable_event.h"
 #include "base/threading/platform_thread.h"
 #include "dbus/dbus_export.h"
 #include "dbus/object_path.h"
 
 namespace base {
 class SequencedTaskRunner;
 class SingleThreadTaskRunner;
-class Thread;
 }
 
 namespace tracked_objects {
 class Location;
 }
 
 namespace dbus {
 
 class ExportedObject;
 class ObjectManager;
@@ skipping 520 matching lines @@
   //
   // BLOCKING CALL.
   virtual std::string GetServiceOwnerAndBlock(const std::string& service_name,
                                               GetServiceOwnerOption options);
 
   // A non-blocking version of GetServiceOwnerAndBlock().
   // Must be called in the origin thread.
   virtual void GetServiceOwner(const std::string& service_name,
                                const GetServiceOwnerCallback& callback);
 
+  // Whenever the owner for |service_name| changes, run |callback| with the
+  // name of the new owner.

[satorux1, 2013/06/03 02:26:06]

What's gonna happen if the service name just disappears. In that case will the
callback receive an empty string? Please document.

Please also document that it's OK to add multiple listeners (callbacks) for the
same service name (but duplicate listeners are ignored)

[Lei Zhang, 2013/06/04 00:35:53]

Done.

+  // Must be called in the origin thread.
+  virtual void ListenForServiceOwnerChange(
+      const std::string& service_name,
+      const GetServiceOwnerCallback& callback);
+
+  // Stop listening for |service_name| owner changes for |callback|.
+  // Must be called in the origin thread.
+  virtual void UnlistenForServiceOwnerChange(
+      const std::string& service_name,
+      const GetServiceOwnerCallback& callback);

[satorux1, 2013/06/03 02:26:06]

Could you write unit tests for the new functions? 'dbus' maintains high test
coverage. :)

+
   // Returns true if the bus is connected to D-Bus.
   bool is_connected() { return connection_ != NULL; }
 
  protected:
   // This is protected, so we can define sub classes.
   virtual ~Bus();
 
  private:
   friend class base::RefCountedThreadSafe<Bus>;
 
   // Helper function used for RemoveObjectProxy().
   void RemoveObjectProxyInternal(scoped_refptr<dbus::ObjectProxy> object_proxy,
                                  const base::Closure& callback);
 
   // Helper function used for UnregisterExportedObject().
   void UnregisterExportedObjectInternal(
       scoped_refptr<dbus::ExportedObject> exported_object);
 
   // Helper function used for ShutdownOnDBusThreadAndBlock().
   void ShutdownOnDBusThreadAndBlockInternal();
 
   // Helper function used for RequestOwnership().
   void RequestOwnershipInternal(const std::string& service_name,
                                 OnOwnershipCallback on_ownership_callback);
 
   // Helper function used for GetServiceOwner().
   void GetServiceOwnerInternal(const std::string& service_name,
                                const GetServiceOwnerCallback& callback);
 
+  // Helper function used for ListenForServiceOwnerChange().
+  void ListenForServiceOwnerChangeInternal(
+      const std::string& service_name,
+      const GetServiceOwnerCallback& callback);
+
+  // Helper function used for UnListenForServiceOwnerChange().
+  void UnlistenForServiceOwnerChangeInternal(
+      const std::string& service_name,
+      const GetServiceOwnerCallback& callback);
+
   // Processes the all incoming data to the connection, if any.
   //
   // BLOCKING CALL.
   void ProcessAllIncomingDataIfAny();
 
   // Called when a watch object is added. Used to start monitoring the
   // file descriptor used for D-Bus communication.
   dbus_bool_t OnAddWatch(DBusWatch* raw_watch);
 
   // Called when a watch object is removed.
@@ skipping 13 matching lines @@
   void OnToggleTimeout(DBusTimeout* raw_timeout);
 
   // Called when the dispatch status (i.e. if any incoming data is
   // available) is changed.
   void OnDispatchStatusChanged(DBusConnection* connection,
                                DBusDispatchStatus status);
 
   // Called when the connection is diconnected.
   void OnConnectionDisconnected(DBusConnection* connection);
 
+  // Called when a service owner change occurs.
+  DBusHandlerResult OnServiceOwnerChanged(DBusMessage* message);
+
   // Callback helper functions. Redirects to the corresponding member function.
   static dbus_bool_t OnAddWatchThunk(DBusWatch* raw_watch, void* data);
   static void OnRemoveWatchThunk(DBusWatch* raw_watch, void* data);
   static void OnToggleWatchThunk(DBusWatch* raw_watch, void* data);
   static dbus_bool_t OnAddTimeoutThunk(DBusTimeout* raw_timeout, void* data);
   static void OnRemoveTimeoutThunk(DBusTimeout* raw_timeout, void* data);
   static void OnToggleTimeoutThunk(DBusTimeout* raw_timeout, void* data);
   static void OnDispatchStatusChangedThunk(DBusConnection* connection,
                                            DBusDispatchStatus status,
                                            void* data);
 
-  // Calls OnConnectionDisconnected if the Diconnected signal is received.
+  // Calls OnConnectionDisconnected if the Disconnected signal is received.
   static DBusHandlerResult OnConnectionDisconnectedFilter(
       DBusConnection* connection,
       DBusMessage* message,
       void* user_data);
 
+  // Calls OnServiceOwnerChanged for a NameOwnerChanged signal.
+  static DBusHandlerResult OnServiceOwnerChangedFilter(
+      DBusConnection* connection,
+      DBusMessage* message,
+      void* user_data);
+
   const BusType bus_type_;
   const ConnectionType connection_type_;
   scoped_refptr<base::SequencedTaskRunner> dbus_task_runner_;
   base::WaitableEvent on_shutdown_;
   DBusConnection* connection_;
 
   scoped_refptr<base::SingleThreadTaskRunner> origin_task_runner_;
   base::PlatformThreadId origin_thread_id_;
 
   std::set<std::string> owned_service_names_;
@@ skipping 22 matching lines @@
                    scoped_refptr<dbus::ExportedObject> > ExportedObjectTable;
   ExportedObjectTable exported_object_table_;
 
   // ObjectManagerTable is used to hold the object managers created by the
   // bus object. Key is a concatenated string of service name + object path,
   // like "org.chromium.TestService/org/chromium/TestObject".
   typedef std::map<std::string,
                    scoped_refptr<dbus::ObjectManager> > ObjectManagerTable;
   ObjectManagerTable object_manager_table_;
 
+  // A map of NameOwnerChanged signals to listen for and the callbacks to run
+  // on the origin thread when the owner changes.
+  // Only accessed on the DBus thread.
+  // Key: Service name
+  // Value: Vector of callbacks. Unique and expected to be small. Not using
+  //        std::set here because base::Callbacks don't have a '<' operator.
+  typedef std::map<std::string, std::vector<GetServiceOwnerCallback> >
+      ServiceOwnerChangedListenerMap;
+  ServiceOwnerChangedListenerMap service_owner_changed_listener_map_;
+
   bool async_operations_set_up_;
   bool shutdown_completed_;
 
   // Counters to make sure that OnAddWatch()/OnRemoveWatch() and
   // OnAddTimeout()/OnRemoveTimeou() are balanced.
   int num_pending_watches_;
   int num_pending_timeouts_;
 
   std::string address_;
   base::Closure on_disconnected_closure_;
 
   DISALLOW_COPY_AND_ASSIGN(Bus);
 };
 
 }  // namespace dbus
 
 #endif  // DBUS_BUS_H_