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Developer Documentation
- Bug fixes for general core bugs in 4.3.x will end 7 October 2024 (12 months).
- Bug fixes for security issues in 4.3.x will end 21 April 2025 (18 months).
- PHP version: minimum PHP 8.0.0 Note: minimum PHP version has increased since Moodle 4.1. PHP 8.2.x is supported too.
/lib/adodb/ -> adodb-loadbalancer.inc.php (source)
Differences Between: [Versions 311 and 403] [Versions 400 and 403]
ADOdb Load Balancer ADOdbLoadBalancer is a class that allows the user to do read/write splitting and load balancing across multiple servers. It can handle and load balance any number of write capable (AKA: master) or readonly (AKA: slave) connections, including dealing with connection failures and retrying queries on a different connection instead.
| Copyright: | 2016 Mike Benoit and the ADOdb community |
| License: | BSD-3-Clause |
| License: | LGPL-2.1-or-later |
| File Size: | 813 lines (27 kb) |
| Included or required: | 0 times |
| Referenced: | 0 times |
| Includes or requires: | 0 files |
Defines 2 classes
ADOdbLoadBalancer:: (17 methods):
setSessionInitSQL()
addConnection()
removeConnection()
getConnectionByWeight()
getLoadBalancedConnection()
getConnectionById()
getConnection()
makeValuesReferenced()
setSessionVariable()
executeSessionVariables()
clusterExecute()
isReadOnlyQuery()
execute()
__call()
__get()
__set()
__clone()
ADOdbLoadBalancerConnection:: (4 methods):
__construct()
setConnectionTestCallback()
getConnectionTestCallback()
getADOdbObject()
Class: ADOdbLoadBalancer - X-Ref
Class ADOdbLoadBalancer| setSessionInitSQL($sql) X-Ref |
| Defines SQL queries that are executed each time a new database connection is established. param: $sql return: bool |
| addConnection($obj) X-Ref |
| Adds a new database connection to the pool, but no actual connection is made until its needed. param: $obj return: bool |
| removeConnection($i) X-Ref |
| Removes a database connection from the pool. param: $i return: bool |
| getConnectionByWeight($type) X-Ref |
| Returns a database connection of the specified type. Takes into account the connection weight for load balancing. param: string $type Type of database connection, either: 'write' capable or 'readonly' return: bool|int|string |
| getLoadBalancedConnection($type) X-Ref |
| Returns the proper database connection when taking into account sticky sessions and load balancing. param: $type return: bool|int|mixed|string |
| getConnectionById($connection_id) X-Ref |
| Returns the ADODB connection object by connection_id. Ensures that it's connected and the session variables are executed. param: $connection_id return: bool|ADOConnection |
| getConnection($type = 'write', $pin_connection = null) X-Ref |
| Returns the ADODB connection object by database type. Ensures that it's connected and the session variables are executed. param: string $type param: null $pin_connection return: ADOConnection|bool |
| makeValuesReferenced($arr) X-Ref |
| This is a hack to work around pass by reference error. Parameter 1 to ADOConnection::GetInsertSQL() expected to be a reference, value given in adodb-loadbalancer.inc.php on line 83 param: $arr return: array |
| setSessionVariable($name, $value, $execute_immediately = true) X-Ref |
| Allow setting session variables that are maintained across connections. Its important that these are set using name/value, so it can determine if the same variable is set multiple times causing bloat/clutter when new connections are established. For example if the time_zone is set to many different ones through the course of a single connection, a new connection should only set it to the most recent value. param: $name param: $value param: bool $execute_immediately return: array|bool|mixed |
| executeSessionVariables($adodb_obj = false) X-Ref |
| Executes the session variables on a given ADODB object. param: ADOConnection|bool $adodb_obj return: array|bool|mixed |
| clusterExecute($sql,$inputarr = false,$return_all_results = false,$existing_connections_only = true) X-Ref |
| Executes the same SQL QUERY on the entire cluster of connections. Would be used for things like SET SESSION TIME ZONE calls and such. param: $sql param: bool $inputarr param: bool $return_all_results param: bool $existing_connections_only return: array|bool|mixed |
| isReadOnlyQuery($sql) X-Ref |
| Determines if a SQL query is read-only or not. param: string $sql SQL Query to test. return: bool |
| execute($sql, $inputarr = false) X-Ref |
| Use this instead of __call() as it significantly reduces the overhead of call_user_func_array(). param: $sql param: bool $inputarr return: array|bool|mixed |
| __call($method, $args) X-Ref |
| Magic method to intercept method and callback to the proper ADODB object for write/readonly connections. param: string $method ADODB method to call. param: array $args Arguments to the ADODB method. return: bool|mixed |
| __get($property) X-Ref |
| Magic method to proxy property getter calls back to the proper ADODB object currently in use. param: $property return: mixed |
| __set($property, $value) X-Ref |
| Magic method to proxy property setter calls back to the proper ADODB object currently in use. param: $property param: $value return: mixed |
| __clone() X-Ref |
| Override the __clone() magic method. |
Class: ADOdbLoadBalancerConnection - X-Ref
Class ADOdbLoadBalancerConnection| __construct($driver,$type = 'write',$weight = 1,$persistent_connection = false,$argHostname = '',$argUsername = '',$argPassword = '',$argDatabaseName = '') X-Ref |
| ADOdbLoadBalancerConnection constructor to setup the ADODB object. param: $driver param: string $type param: int $weight param: bool $persistent_connection param: string $argHostname param: string $argUsername param: string $argPassword param: string $argDatabaseName |
| setConnectionTestCallback($callback) X-Ref |
| Anonymous function that is called and must return TRUE for the connection to be usable.* The first argument is the type of connection to test. Useful to check things like replication lag. param: callable $callback return: void |
| getConnectionTestCallback() X-Ref |
return: callable|null |
| getADOdbObject() X-Ref |
| Returns the ADODB object for this connection. return: bool |
