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improved and now optional Galera cluster health check

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This commit is contained in:
Ralf Becker 2015-07-15 20:47:49 +00:00
parent f0ebb448a2
commit e1ad625fca
1 changed files with 36 additions and 6 deletions
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42
phpgwapi/inc/class.egw_db.inc.php
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@ -170,6 +170,13 @@ class egw_db
*/
static $tablealiases = array();
/**
* Callback to check if selected node is healty / should be used
*
* @var callback throwing egw_exception_db_connection, if connected node should NOT be used
*/
static $health_check;
/**
* db allows sub-queries, true for everything but mysql < 4.1
*
@ -349,13 +356,10 @@ class egw_db
//error_log(__METHOD__."() this->Host(s)=$this->Host, n=$n --> host=$host");
$new_connection = !$this->Link_ID || !$this->Link_ID->IsConnected();
$this->_connect($host);
// check Galera wsrep_local_state for node is not in state Synced, eg. Donor
// check is only done for Type=mysql and will succed if no Galera
if ($new_connection && $this->Type == 'mysql' && strpos($this->Host, ';') !== false &&
($state = $this->query("SHOW STATUS LIKE 'wsrep_local_state'")->fetchColumn(1)) !== false &&
$state != 4) // 4 = Synced
// check if connected node is healty
if ($new_connection && self::$health_check)
{
throw new egw_exception_db_connection('wsrep-local-state='.array2string($state).' != 4');
call_user_func(self::$health_check, $this);
}
//error_log(__METHOD__."() host=$host, new_connection=$new_connection, this->Type=$this->Type, this->Host=$this->Host, wsrep_local_state=".array2string($state));
return $this->Link_ID;
@ -370,6 +374,32 @@ class egw_db
throw $e;
}
/**
* Check if just connected Galera cluster node is healthy / fully operational
*
* A node in state "Donor/Desynced" will block updates at the end of a SST.
* Therefore we try to avoid that node, if we have an alternative.
*
* To enable this check add the following to your header.inc.php:
*
* egw_db::$health_check = array('egw_db', 'galera_cluster_health');
*
* @param egw_db $db already connected egw_db instance to check
* @throws egw_exception_db_connection if node should NOT be used
*/
static function galera_cluster_health(egw_db $db)
{
if (($state = $db->query("SHOW STATUS WHERE Variable_name in ('wsrep_cluster_size','wsrep_local_state','wsrep_local_state_comment')")->GetAssoc()))
{
if ($state['wsrep_local_state_comment'] == 'Synced' ||
// if we have only 2 nodes (2. one starting), we can only use the donor
$state['wsrep_local_state_comment'] == 'Donor/Desynced' &&
$state['wsrep_cluster_size'] == 2) return;
throw new egw_exception_db_connection('Node is NOT Synced! '.array2string($state));
}
}
/**
* Get one of multiple (semicolon-separated) DB-hosts to use
*