Initial implementation of the monitor modules and a simple mysql monitor to set

server up or down automatically.

include/modules.h

@@ -29,6 +29,7 @@
  *
  * Date		Who		Description
  * 13/06/13	Mark Riddoch	Initial implementation
+ * 08/07/13	Mark Riddoch	Addition of monitor modules
  * @endverbatim
  */
 
@@ -47,6 +48,7 @@ typedef struct modules {
  */
 #define	MODULE_PROTOCOL	"Protocol"	/**< A protocol module type */
 #define	MODULE_ROUTER	"Router"	/**< A router module type */
+#define	MODULE_MONITOR	"Monitor"	/**< A database monitor module type */
 
 
 extern	void 	*load_module(const char *module, const char *type);

include/monitor.h

@@ -0,0 +1,79 @@
+#ifndef _MONITOR_H
+#define _MONITOR_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
+ */
+#include <server.h>
+
+/**
+ * @file monitor.h	The interface to the monitor module
+ *
+ * @verbatim
+ * Revision History
+ *
+ * Date		Who		Description
+ * 07/07/13	Mark Riddoch	Initial implementation
+ *
+ * @endverbatim
+ */
+
+/**
+ * The "Module Object" for a monitor module.
+ *
+ * The monitor modules are designed to monitor the backend databases that the gateway 
+ * connects to and provide information regarding the status of the databases that
+ * is used in the routing decisions.
+ *
+ * startMonitor is called to start the monitoring process, it is called on the main
+ * thread of the gateway and is responsible for creating a thread for the monitor
+ * itself to run on. This should use the entry points defined in the thread.h 
+ * header file rather than make direct calls to the operating system thrading libraries.
+ * The return from startMonitor is a void * handle that will be passed to all other monitor
+ * API calls.
+ *
+ * stopMonitor is responsible for shuting down and destroying a monitor, it is called 
+ * with the void * handle that was returned by startMonitor.
+ *
+ * registerServer is called to register a server that must be monitored with a running
+ * monitor. this will be called with the handle returned from the startMonitor call and
+ * the SERVER structure that the monitor must update and monitor. The SERVER structure
+ * contains the information required to connect to the monitored server.
+ *
+ * unregisterServer is called to remove a server from the set of servers that need to be
+ * monitored.
+ */
+typedef struct {
+	void 	*(*startMonitor)();
+	void	(*stopMonitor)(void *);
+	void	(*registerServer)(void *, SERVER *);
+	void	(*unregisterServer)(void *, SERVER *);
+} MONITOR_OBJECT;
+
+/**
+ * Representation of the running monitor.
+ */
+typedef struct monitor {
+	char		*name;		/**< The name of the monitor module */
+	MONITOR_OBJECT	*module;	/**< The "monitor object" */
+	void		*handle;	/**< Handle returned from startMonitor */
+	struct monitor	*next;		/**< Next monitor in the linked list */
+} MONITOR;
+
+extern MONITOR	*monitor_alloc(char *, char *);
+extern void	monitor_free(MONITOR *);
+extern void	monitorAddServer(MONITOR *, SERVER *);
+#endif

include/server.h

@@ -54,6 +54,8 @@ typedef struct server {
 	unsigned short	port;		/**< Port to listen on */
 	char		*protocol;	/**< Protocol module to use */
 	unsigned int	status;		/**< Status flag bitmap for the server */
+	char		*monuser;	/**< User name to use to monitor the db */
+	char		*monpw;		/**< Password to use to monitor the db */
 	SERVER_STATS	stats;		/**< The server statistics */
 	struct	server	*next;		/**< Next server */
 	struct	server	*nextdb;	/**< Next server in list attached to a service */
@@ -100,4 +102,5 @@ extern void	dprintServer(DCB *, SERVER *);
 extern char	*server_status(SERVER *);
 extern void	server_set_status(SERVER *, int);
 extern void	server_clear_status(SERVER *, int);
+extern void	serverAddMonUser(SERVER *, char *, char *);
 #endif

include/thread.h

@@ -33,5 +33,6 @@
 
 extern void 	*thread_start(void (*entry)(void *), void *arg);
 extern void	thread_wait(void *thd);
+extern void	thread_millisleep(int ms);
 
 #endif