Linux/CrOS: Retry connecting to mtpd.

dbus/bus.h

Index: dbus/bus.h
===================================================================
--- dbus/bus.h	(revision 203218)
+++ dbus/bus.h	(working copy)
@@ -11,6 +11,7 @@
 #include <set>
 #include <string>
 #include <utility>
+#include <vector>
 
 #include "base/callback.h"
 #include "base/memory/ref_counted.h"
@@ -22,7 +23,6 @@
 namespace base {
 class SequencedTaskRunner;
 class SingleThreadTaskRunner;
-class Thread;
 }
 
 namespace tracked_objects {
@@ -563,6 +563,19 @@
   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; }
 
@@ -592,6 +605,16 @@
   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.
@@ -625,6 +648,9 @@
   // 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);
@@ -636,12 +662,18 @@
                                            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_;
@@ -684,6 +716,16 @@
                    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_;