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

server up or down automatically.

modules/monitor/mysql_mon.c

@@ -0,0 +1,223 @@
+/*
+ * 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 <stdio.h>
+#include <stdlib.h>
+#include <monitor.h>
+#include <mysqlmon.h>
+#include <thread.h>
+
+static	void	monitorMain(void *);
+
+static char *version_str = "V1.0.0";
+
+static	void 	*startMonitor();
+static	void	stopMonitor(void *);
+static	void	registerServer(void *, SERVER *);
+static	void	unregisterServer(void *, SERVER *);
+
+static MONITOR_OBJECT MyObject = { startMonitor, stopMonitor, registerServer, unregisterServer };
+
+/**
+ * Implementation of the mandatory version entry point
+ *
+ * @return version string of the module
+ */
+char *
+version()
+{
+	return version_str;
+}
+
+/**
+ * The module initialisation routine, called when the module
+ * is first loaded.
+ */
+void
+ModuleInit()
+{
+	fprintf(stderr, "Initialise the MySQL Monitor module.\n");
+}
+
+/**
+ * The module entry point routine. It is this routine that
+ * must populate the structure that is referred to as the
+ * "module object", this is a structure with the set of
+ * external entry points for this module.
+ *
+ * @return The module object
+ */
+MONITOR_OBJECT *
+GetModuleObject()
+{
+	return &MyObject;
+}
+
+/**
+ * Start the instance of the monitor, returning a handle on the monitor.
+ *
+ * This function creates a thread to execute the actual monitoring.
+ *
+ * @return A handle to use when interacting with the monitor
+ */
+static	void 	*
+startMonitor()
+{
+MYSQL_MONITOR *handle;
+
+	if ((handle = (MYSQL_MONITOR *)malloc(sizeof(MYSQL_MONITOR))) == NULL)
+		return NULL;
+	handle->databases = NULL;
+	handle->shutdown = 0;
+	spinlock_init(&handle->lock);
+	thread_start(monitorMain, handle);
+	return handle;
+}
+
+/**
+ * Stop a running monitor
+ *
+ * @param handle	Handle on thr running monior
+ */
+static	void	
+stopMonitor(void *arg)
+{
+MYSQL_MONITOR	*handle = (MYSQL_MONITOR *)arg;
+
+	handle->shutdown = 1;
+}
+
+/**
+ * Register a server that must be added to the monitored servers for
+ * a monitoring module.
+ *
+ * @param handle	A handle on the running monitor module
+ * @param server	The server to add
+ */
+static	void	
+registerServer(void *arg, SERVER *server)
+{
+MYSQL_MONITOR	*handle = (MYSQL_MONITOR *)arg;
+MONITOR_SERVERS	*ptr, *db;
+
+	if ((db = (MONITOR_SERVERS *)malloc(sizeof(MONITOR_SERVERS))) == NULL)
+		return;
+	db->server = server;
+	db->con = NULL;
+	db->next = NULL;
+	spinlock_acquire(&handle->lock);
+	if (handle->databases == NULL)
+		handle->databases = db;
+	else
+	{
+		ptr = handle->databases;
+		while (ptr->next != NULL)
+			ptr = ptr->next;
+		ptr->next = db;
+	}
+	spinlock_release(&handle->lock);
+}
+
+/**
+ * Remove a server from those being monitored by a monitoring module
+ *
+ * @param handle	A handle on the running monitor module
+ * @param server	The server to remove
+ */
+static	void	
+unregisterServer(void *arg, SERVER *server)
+{
+MYSQL_MONITOR	*handle = (MYSQL_MONITOR *)arg;
+MONITOR_SERVERS	*ptr, *lptr;
+
+	spinlock_acquire(&handle->lock);
+	if (handle->databases == NULL)
+	{
+		spinlock_release(&handle->lock);
+		return;
+	}
+	if (handle->databases->server == server)
+	{
+		ptr = handle->databases;
+		handle->databases = handle->databases->next;
+		free(ptr);
+	}
+	else
+	{
+		ptr = handle->databases;
+		while (ptr->next != NULL && ptr->next->server != server)
+			ptr = ptr->next;
+		if (ptr->next)
+		{
+			lptr = ptr->next;
+			ptr->next = ptr->next->next;
+			free(lptr);
+		}
+	}
+	spinlock_release(&handle->lock);
+}
+
+/**
+ * Monitor an individual server
+ *
+ * @param database	The database to probe
+ */
+static void
+monitorDatabase(MONITOR_SERVERS	*database)
+{
+	if (database->con == NULL || mysql_ping(database->con) != 0)
+	{
+		database->con = mysql_init(NULL);
+		if (mysql_real_connect(database->con, database->server->name,
+			database->server->monuser, database->server->monpw,
+				NULL, database->server->port, NULL, 0) == NULL)
+		{
+			server_clear_status(database->server, SERVER_RUNNING);
+			return;
+		}
+	}
+
+	// If we get this far then we have a workign connection
+	server_set_status(database->server, SERVER_RUNNING);
+	
+}
+
+/**
+ * The entry point for the monitoring module thread
+ *
+ * @param arg	The handle of the monitor
+ */
+static void
+monitorMain(void *arg)
+{
+MYSQL_MONITOR	*handle = (MYSQL_MONITOR *)arg;
+MONITOR_SERVERS	*ptr;
+
+	while (1)
+	{
+		thread_millisleep(1000);
+
+		if (handle->shutdown)
+			return;
+		ptr = handle->databases;
+		while (ptr)
+		{
+			monitorDatabase(ptr);
+			ptr = ptr->next;
+		}
+	}
+}