Implement compression on backend (#363)

For compatibility reason, compression flag on mysql_servers table is not changed:
values greater than 1 are accepted, but handled as 1

Closes #363

lib/MySQL_HostGroups_Manager.cpp

@@ -660,11 +660,12 @@ MySQL_Connection * MySrvConnList::get_random_MyConn() {
 		conn = new MySQL_Connection();
 		conn->parent=mysrvc;
 		//conn->options.charset=mysrvc->charset;
-		conn->options.server_capabilities=0;
+		// deprecating this . #363
-		if (mysql_thread___have_compress==true && mysrvc->compression) {
+		//conn->options.server_capabilities=0;
-			conn->options.server_capabilities|=CLIENT_COMPRESS;
+		//if (mysql_thread___have_compress==true && mysrvc->compression) {
-			conn->options.compression_min_length=mysrvc->compression;
+		//	conn->options.server_capabilities|=CLIENT_COMPRESS;
-		}
+		//	conn->options.compression_min_length=mysrvc->compression;
+		//}
 		__sync_fetch_and_add(&MyHGM->status.server_connections_created, 1);
 		proxy_debug(PROXY_DEBUG_MYSQL_CONNPOOL, 7, "Returning MySQL Connection %p, server %s:%d\n", conn, conn->parent->address, conn->parent->port);
 		return  conn;

lib/mysql_connection.cpp

@@ -305,6 +305,8 @@ void MySQL_Connection::connect_start() {
 	unsigned long client_flags = 0;
 	if (mysql_thread___client_found_rows)
 		client_flags += CLIENT_FOUND_ROWS;
+	if (parent->compression)
+		client_flags += CLIENT_COMPRESS;
 	if (parent->port) {
 		async_exit_status=mysql_real_connect_start(&ret_mysql, mysql, parent->address, userinfo->username, userinfo->password, userinfo->schemaname, parent->port, NULL, client_flags);
 	} else {