So, while fixing that memory leak, I noticed that in the last 10 days

there have been 260,000 connects (and 260,000 disconnects) to the
mysqld server. 240,000 of them were from the TMCD! I've changed the DB
code to keep the connection to the server open, and let the server
time it out. The client side code library code already deals with a
auto reconnect if the server goes away, so no reason to open/close
this connection for every single DB query. Besides, it might help
reduce the amount of time it takes to answer a single tmcd query, and
that would be a good thing.

tmcd/tmcd.c

@@ -2000,10 +2000,47 @@ doreset(int sock, struct in_addr ipaddr, char *rdata, int tcp)
 /*
  * DB stuff
  */
+static MYSQL	db;
+static int	db_connected;
+static char     db_dbname[DBNAME_SIZE];
+static void	mydb_disconnect();
+
+static int
+mydb_connect()
+{
+	/*
+	 * Each time we talk to the DB, we check to see if the name
+	 * matches the last connection. If so, nothing more needs to
+	 * be done. If we switched DBs (checkdbredirect()), then drop
+	 * the current connection and form a new one.
+	 */
+	if (db_connected) {
+		if (strcmp(db_dbname, dbname) == 0)
+			return 1;
+		mydb_disconnect();
+	}
+	
+	mysql_init(&db);
+	if (mysql_real_connect(&db, 0, 0, 0,
+			       dbname, 0, 0, CLIENT_INTERACTIVE) == 0) {
+		syslog(LOG_ERR, "%s: connect failed: %s",
+			dbname, mysql_error(&db));
+		return 1;
+	}
+	strcpy(db_dbname, dbname);
+	db_connected = 1;
+}
+
+static void
+mydb_disconnect()
+{
+	mysql_close(&db);
+	db_connected = 0;
+}
+
 MYSQL_RES *
 mydb_query(char *query, int ncols, ...)
 {
-	MYSQL		db;
 	MYSQL_RES	*res;
 	char		querybuf[2*MYBUFSIZE];
 	va_list		ap;
@@ -2016,17 +2053,13 @@ mydb_query(char *query, int ncols, ...)
 		return (MYSQL_RES *) 0;
 	}
 
-	mysql_init(&db);
-	if (mysql_real_connect(&db, 0, 0, 0, dbname, 0, 0, 0) == 0) {
-		syslog(LOG_ERR, "%s: connect failed: %s",
-			dbname, mysql_error(&db));
+	if (! mydb_connect())
 		return (MYSQL_RES *) 0;
-	}
 
 	if (mysql_real_query(&db, querybuf, n) != 0) {
 		syslog(LOG_ERR, "%s: query failed: %s",
 			dbname, mysql_error(&db));
-		mysql_close(&db);
+		mydb_disconnect();
 		return (MYSQL_RES *) 0;
 	}
 
@@ -2034,10 +2067,9 @@ mydb_query(char *query, int ncols, ...)
 	if (res == 0) {
 		syslog(LOG_ERR, "%s: store_result failed: %s",
 			dbname, mysql_error(&db));
-		mysql_close(&db);
+		mydb_disconnect();
 		return (MYSQL_RES *) 0;
 	}
-	mysql_close(&db);
 
 	if (ncols && ncols != (int)mysql_num_fields(res)) {
 		syslog(LOG_ERR, "%s: Wrong number of fields returned "
@@ -2052,7 +2084,6 @@ mydb_query(char *query, int ncols, ...)
 int
 mydb_update(char *query, ...)
 {
-	MYSQL		db;
 	char		querybuf[MYBUFSIZE];
 	va_list		ap;
 	int		n;
@@ -2064,20 +2095,15 @@ mydb_update(char *query, ...)
 		return 1;
 	}
 
-	mysql_init(&db);
-	if (mysql_real_connect(&db, 0, 0, 0, dbname, 0, 0, 0) == 0) {
-		syslog(LOG_ERR, "%s: connect failed: %s",
-			dbname, mysql_error(&db));
+	if (! mydb_connect())
 		return 1;
-	}
 
 	if (mysql_real_query(&db, querybuf, n) != 0) {
 		syslog(LOG_ERR, "%s: query failed: %s",
 			dbname, mysql_error(&db));
-		mysql_close(&db);
+		mydb_disconnect();
 		return 1;
 	}
-	mysql_close(&db);
 	return 0;
 }