Introduce functionality for syncing with the media services

* The global synchro semaphore is provided with the purpose of
being used to avoid threads lock up when the media_server is in
an undefined state. There's still room for improvements.
* BMediaRoster::SyncToServices lock up on a semaphore until
the multi_audio correctly connected to the mixer.

headers/os/media/MediaRoster.h

@@ -42,7 +42,11 @@ class BMediaRoster : public BLooper {
 				// same time.
 
 	// Check if the media services are running.
-	static bool					IsRunning();
+	static	bool				IsRunning();
+
+	// This functions blocks until the media services are available,
+	// don't abuse of it.
+	static	status_t			SyncToServices(bigtime_t timeout = -1);
 
 	// Getting common instances of system nodes:
 			status_t			GetVideoInput(media_node* _node);

headers/private/media/ServerInterface.h

@@ -28,6 +28,9 @@ enum {
 	// add_system_beep_event()
 	MEDIA_SERVER_ADD_SYSTEM_BEEP_EVENT,
 
+	// sent by the rescan thread
+	MEDIA_SERVER_RESCAN_COMPLETED,
+
 	// media add-on server
 	MEDIA_ADD_ON_SERVER_PLAY_MEDIA = '_TRU'
 };
@@ -370,6 +373,7 @@ struct server_register_app_request : request_data {
 };
 
 struct server_register_app_reply : reply_data {
+	sem_id					global_synchro;
 };
 
 struct server_unregister_app_request : request_data {

src/kits/media/MediaRoster.cpp

@@ -107,6 +107,7 @@ static bool sServerIsUp = false;
 static List<RosterNotification> sNotificationList;
 static BLocker sInitLocker("BMediaRoster::Roster locker");
 static List<LocalNode> sRegisteredNodes;
+static sem_id sGlobalSynchro = -1;
 
 
 class MediaRosterUndertaker {
@@ -3344,6 +3345,27 @@ BMediaRoster::IsRunning()
 }
 
 
+status_t
+BMediaRoster::SyncToServices(bigtime_t timeout)
+{
+	if (!IsRunning())
+		return B_ERROR;
+
+	TRACE("BMediaRoster::SyncToServer: Syncing to the media server");
+
+	// This sem is valid only when the server started
+	// but it's not ready to supply the services.
+	if (sGlobalSynchro > -1)
+		acquire_sem_etc(sGlobalSynchro, 1, B_RELATIVE_TIMEOUT, timeout);
+
+	// TODO: Ideally this function should take into account
+	// the startup latencies of the system nodes and sleep
+	// for the resulting sum.
+
+	return B_OK;
+}
+
+
 ssize_t
 BMediaRoster::AudioBufferSizeFor(int32 channelCount, uint32 sampleFormat,
 	float frameRate, bus_type busKind)
@@ -3445,7 +3467,9 @@ BMediaRoster::MessageReceived(BMessage* message)
 
 			// Send the notification to our subscribers
 			if (BMediaRoster::IsRunning()) {
+				SyncToServices();
 				sServerIsUp = true;
+				sGlobalSynchro = -1;
 				// Wait for media services to wake up
 				// TODO: This should be solved so that the server
 				// have a way to notify us when the system is really

src/servers/media/AppManager.cpp

@@ -50,11 +50,14 @@ AppManager::AppManager()
 	:
 	BLocker("media app manager")
 {
+	fGlobalSynchro = create_sem(0, "media server global synchro");
 }
 
 
 AppManager::~AppManager()
 {
+	if (fGlobalSynchro != -1)
+		delete_sem(fGlobalSynchro);
 }
 
 
@@ -67,7 +70,8 @@ AppManager::HasTeam(team_id team)
 
 
 status_t
-AppManager::RegisterTeam(team_id team, const BMessenger& messenger)
+AppManager::RegisterTeam(team_id team, const BMessenger& messenger,
+	sem_id* sync)
 {
 	BAutolock lock(this);
 
@@ -84,6 +88,8 @@ AppManager::RegisterTeam(team_id team, const BMessenger& messenger)
 		return B_NO_MEMORY;
 	}
 
+	*sync = fGlobalSynchro;
+
 	return B_OK;
 }
 
@@ -150,6 +156,13 @@ AppManager::Dump()
 }
 
 
+void
+AppManager::UnlockGlobalSynchro()
+{
+	delete_sem(fGlobalSynchro);
+}
+
+
 void
 AppManager::_CleanupTeam(team_id team)
 {

src/servers/media/AppManager.h

@@ -18,7 +18,7 @@ class AppManager : BLocker {
 								~AppManager();
 
 			status_t			RegisterTeam(team_id team,
-									const BMessenger& messenger);
+									const BMessenger& messenger, sem_id* sync);
 			status_t			UnregisterTeam(team_id team);
 			bool				HasTeam(team_id team);
 
@@ -28,13 +28,16 @@ class AppManager : BLocker {
 
 			void				Dump();
 
+			void				UnlockGlobalSynchro();
+
 private:
 			void				_CleanupTeam(team_id team);
 
 private:
 			typedef std::map<team_id, BMessenger> AppMap;
 
 			AppMap				fMap;
+			sem_id				fGlobalSynchro;
 };
 
 

src/servers/media/DefaultManager.cpp

@@ -16,9 +16,11 @@
 #include <TimeSource.h>
 #include <string.h>
 
+#include "debug.h"
 #include "DormantNodeManager.h"
+#include "media_server.h"
 #include "NodeManager.h"
-#include "debug.h"
+
 
 /* no locking used in this file, we assume that the caller (NodeManager) does it.
  */
@@ -411,6 +413,9 @@ DefaultManager::_RescanThread()
 			add_on_server_rescan_finished_notify_command cmd;
 			SendToAddOnServer(ADD_ON_SERVER_RESCAN_FINISHED_NOTIFY, &cmd,
 				sizeof(cmd));
+
+			BMessage msg(MEDIA_SERVER_RESCAN_COMPLETED);
+			be_app->PostMessage(&msg);
 		}
 
 		locker.Lock();

src/servers/media/media_server.cpp

@@ -305,7 +305,7 @@ ServerApp::_HandleMessage(int32 code, const void* data, size_t size)
 			server_register_app_reply reply;
 
 			status_t status = gAppManager->RegisterTeam(request.team,
-				request.messenger);
+				request.messenger, &reply.global_synchro);
 			request.SendReply(status, &reply, sizeof(reply));
 			break;
 		}
@@ -938,6 +938,12 @@ ServerApp::MessageReceived(BMessage* msg)
 			gMediaFilesManager->HandleAddSystemBeepEvent(msg);
 			break;
 
+		case MEDIA_SERVER_RESCAN_COMPLETED:
+		{
+			gAppManager->UnlockGlobalSynchro();
+			break;
+		}
+
 		case B_SOME_APP_QUIT:
 		{
 			BString mimeSig;