Addition of Read Connection Balancer for Query Routing

modules/include/readconnection.h

@@ -0,0 +1,62 @@
+#ifndef _READCONNECTION_H
+#define _READCONNECTION_H
+/*
+ * This file is distributed as part of the SkySQL Gateway.  It 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,
+ * version 2.
+ *
+ * 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.
+ *
+ * Copyright SkySQL Ab 2013
+ */
+
+/*
+ * The read connection balancing query module heder file
+ *
+ * Revision History
+ *
+ * Date		Who		Description
+ * 14/06/13	Mark Riddoch	Initial implementation
+ *
+ */
+#include <dcb.h>
+
+/*
+ * Internal structure used to define the set of backend servers we are routing
+ * connections to.
+ */
+typedef struct backend {
+	char		*hostname;	/* Server hostname */
+	unsigned short	port;		/* Port on which the server listens */
+	int		count;		/* Number of connections to the server */
+} BACKEND;
+
+/*
+ * The client session structure used within this router.
+ */
+typedef struct client_session {
+	BACKEND		*backend;	/* Backend used by the client session */
+	DCB		*dcb;		/* DCB Connection to the backend */
+	struct client_session
+			*next;
+} CLIENT_SESSION;
+
+/*
+ * The per instance data for the router.
+ */
+typedef struct instance {
+	SERVICE		*service;	/* Pointer to the service using this router */
+	CLIENT_SESSION	*connections;	/* Link list of all the client connections */
+	SPINLOCK	lock;		/* Spinlock for the instance data */
+	BACKEND		**servers;	/* The set of backend servers for this instance */
+	struct instance	*next;
+} INSTANCE;
+#endif