php - MySQL with ND connection failover with PhalconPHP/PDO -

in this part of mysql-nd manual described how implement recommended way of failing on when loosing connection slave mysql server.

i'am willing implement in phalconphp. have couple of important projects using phalcon , mysql-nd, important me in right place.

trying find documentation, can't find example start with. trying find eventmanager approach, looking phalcon documentation here , here can't find way transparently.

most attractive way use event manager capture error event , query same again if connection error.

1 update

after reading phalcon sources found, there may no way run same query second time in standard way - mean here via kind of pdo parameter or using phalcons' eventmanager attached db service. 1 possible attempt found run query after db:afterconnection event, not solution.

2 update

db:afterconnection hardly reachable, instead possible gather during db:beforequery. problem is, pdo run phalcon pdo::attr_errmode => pdo::errmode_exception, when connection slave dies can't reach db:afterconnection event. possible obtain pdo instance during db:beforequery , change attribute via eventmanager, gives nothing, because if able send same query second time, can't find way return in proper place (cannot override query result during db:afterquery) because obtained statement not part of event send, , eventmanager result not being used @ all:

    if typeof statement == "object" {         if typeof eventsmanager == "object" {             eventsmanager->fire("db:afterquery", this, bindparams);         }         return new resultpdo(this, statement, sqlstatement, bindparams, bindtypes);     } 

for seems fixed configuration:

{     "db-cluster": {         "master": {             "master": {                 "host": "master.local",                 "port": 3306             }         },         "slave": {             "slave-1": {                 "host": "slave-1.local",                 "port": 3306             },             "slave-2": {                 "host": "slave-2.local",                 "port": 3306             },             "slave-3": {                 "host": "slave-3.local",                 "port": 3306             }         },         "filters": {             "roundrobin": []         },         "failover": {             "strategy": "loop_before_master",             "remember_failed": true,             "max_retries": 1         },         "server_charset": "utf8"     } } 

if server unreachable fallbacks other, problem was trying connect unreachable server @ least 3 seconds. walkaround be:

$eventsmanager = new eventsmanager(); $connection->seteventsmanager($eventsmanager);  $eventsmanager->attach('db:beforequery', function($event, $connection) {      // fix: if slave not respond, without goes on 3 seconds before trying next 1     !defined('dst') && define('dst', ini_get('default_socket_timeout'));     ini_set("default_socket_timeout", 1);  });  $eventsmanager->attach('db:afterquery', function($event, $connection) {     ini_set('default_socket_timeout', defined('dst') ? dst : 60); }); 

even if works (when slave unreachable hangs on @ 1 second - , still lot of time), still not allow me put hands on connection php source write recommended solution.

update

it possible override executeprepared method phalcon\db\adapter\pdo class via extending phalcon\db\adapter\pdo\mysql class:

namespace application;  use \pdoexception;  class mysql extends \phalcon\db\adapter\pdo\mysql {      public function executeprepared(statement, placeholders, datatypes) {          try {             !defined('dst') && define('dst', ini_set('default_socket_timeout', 1));             $stmt = parent::executeprepared(statement, placeholders, datatypes);             ini_set('default_socket_timeout', dst ?: 60);             return $stmt;         } catch(pdoexception $e) {              if(/* logic find [2002, 2003, 2005] sql errors */) {                 return $this->executeprepared(statement, placeholders, datatypes);             }              throw $e;         }     } } 

and build db service it.