DatabasePlugin: add interface DatabaseListener

Allow database plugins to announce that they have been modified.

src/DatabaseGlue.cxx

@@ -37,7 +37,8 @@ static bool db_is_open;
 static bool is_simple;
 
 bool
-DatabaseGlobalInit(const config_param &param, Error &error)
+DatabaseGlobalInit(EventLoop &loop, DatabaseListener &listener,
+		   const config_param &param, Error &error)
 {
 	assert(db == nullptr);
 	assert(!db_is_open);
@@ -53,7 +54,7 @@ DatabaseGlobalInit(const config_param &param, Error &error)
 		return false;
 	}
 
-	db = plugin->create(param, error);
+	db = plugin->create(loop, listener, param, error);
 	return db != nullptr;
 }
 

src/DatabaseGlue.hxx

@@ -23,6 +23,8 @@
 #include "Compiler.h"
 
 struct config_param;
+class EventLoop;
+class DatabaseListener;
 class Database;
 class Error;
 
@@ -32,7 +34,8 @@ class Error;
  * @param param the database configuration block
  */
 bool
-DatabaseGlobalInit(const config_param &param, Error &error);
+DatabaseGlobalInit(EventLoop &loop, DatabaseListener &listener,
+		   const config_param &param, Error &error);
 
 void
 DatabaseGlobalDeinit(void);

src/DatabaseListener.hxx

@@ -0,0 +1,38 @@
+/*
+ * Copyright (C) 2003-2014 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MPD_DATABASE_CLIENT_HXX
+#define MPD_DATABASE_CLIENT_HXX
+
+/**
+ * An object that listens to events from the #Database.
+ *
+ * @see #Instance
+ */
+class DatabaseListener {
+public:
+	/**
+	 * The database has been modified.  This must be called in the
+	 * thread that has created the #Database instance and that
+	 * runs the #EventLoop.
+	 */
+	virtual void OnDatabaseModified() = 0;
+};
+
+#endif

src/DatabasePlugin.hxx

@@ -37,6 +37,8 @@ struct DatabaseSelection;
 struct db_visitor;
 struct Song;
 class Error;
+class EventLoop;
+class DatabaseListener;
 
 struct DatabaseStats {
 	/**
@@ -149,7 +151,8 @@ struct DatabasePlugin {
 	/**
 	 * Allocates and configures a database.
 	 */
-	Database *(*create)(const config_param &param,
+	Database *(*create)(EventLoop &loop, DatabaseListener &listener,
+			    const config_param &param,
 			    Error &error);
 };
 

src/Instance.cxx

@@ -48,3 +48,9 @@ Instance::SyncWithPlayer()
 {
 	partition->SyncWithPlayer();
 }
+
+void
+Instance::OnDatabaseModified()
+{
+	DatabaseModified();
+}

src/Instance.hxx

@@ -21,11 +21,13 @@
 #define MPD_INSTANCE_HXX
 
 #include "check.h"
+#include "DatabaseListener.hxx"
+#include "Compiler.h"
 
 class ClientList;
 struct Partition;
 
-struct Instance {
+struct Instance final : public DatabaseListener {
 	ClientList *client_list;
 
 	Partition *partition;
@@ -48,6 +50,9 @@ struct Instance {
 	 * Synchronize the player with the play queue.
 	 */
 	void SyncWithPlayer();
+
+private:
+	virtual void OnDatabaseModified();
 };
 
 #endif

src/Main.cxx

@@ -186,7 +186,7 @@ glue_db_init_and_load(void)
 		return true;
 
 	Error error;
-	if (!DatabaseGlobalInit(*param, error))
+	if (!DatabaseGlobalInit(*main_loop, *instance, *param, error))
 		FatalError(error);
 
 	delete allocated;

src/db/ProxyDatabasePlugin.cxx

@@ -49,7 +49,8 @@ class ProxyDatabase : public Database {
 	mutable time_t update_stamp;
 
 public:
-	static Database *Create(const config_param &param,
+	static Database *Create(EventLoop &loop, DatabaseListener &listener,
+				const config_param &param,
 				Error &error);
 
 	virtual bool Open(Error &error) override;
@@ -218,7 +219,9 @@ SendConstraints(mpd_connection *connection, const DatabaseSelection &selection)
 }
 
 Database *
-ProxyDatabase::Create(const config_param &param, Error &error)
+ProxyDatabase::Create(gcc_unused EventLoop &loop,
+		      gcc_unused DatabaseListener &listener,
+		      const config_param &param, Error &error)
 {
 	ProxyDatabase *db = new ProxyDatabase();
 	if (!db->Configure(param, error)) {

src/db/SimpleDatabasePlugin.cxx

@@ -38,7 +38,9 @@
 static constexpr Domain simple_db_domain("simple_db");
 
 Database *
-SimpleDatabase::Create(const config_param &param, Error &error)
+SimpleDatabase::Create(gcc_unused EventLoop &loop,
+		       gcc_unused DatabaseListener &listener,
+		       const config_param &param, Error &error)
 {
 	SimpleDatabase *db = new SimpleDatabase();
 	if (!db->Configure(param, error)) {

src/db/SimpleDatabasePlugin.hxx

@@ -53,7 +53,8 @@ public:
 
 	bool Save(Error &error);
 
-	static Database *Create(const config_param &param,
+	static Database *Create(EventLoop &loop, DatabaseListener &listener,
+				const config_param &param,
 				Error &error);
 
 	virtual bool Open(Error &error) override;

src/db/UpnpDatabasePlugin.cxx

@@ -69,7 +69,8 @@ public:
 		: m_lib(0), m_superdir(0), m_root(0)
 	{}
 
-	static Database *Create(const config_param &param,
+	static Database *Create(EventLoop &loop, DatabaseListener &listener,
+				const config_param &param,
 				Error &error);
 
 	virtual bool Open(Error &error) override;
@@ -182,7 +183,9 @@ stringToTokens(const std::string &str,
 }
 
 Database *
-UpnpDatabase::Create(const config_param &param, Error &error)
+UpnpDatabase::Create(gcc_unused EventLoop &loop,
+		     gcc_unused DatabaseListener &listener,
+		     const config_param &param, Error &error)
 {
 	UpnpDatabase *db = new UpnpDatabase();
 	if (db && !db->Configure(param, error)) {