class Sequel::ConnectionPool
The base connection pool class, which all other connection pools are based on. This class is not instantiated directly, but subclasses should at the very least implement the following API:
- initialize(Database,
Hash
) -
Initialize using the passed
Sequel::Database
object and options hash. - hold(Symbol, &block)
-
Yield a connection object (obtained from calling the block passed to
initialize
) to the current block. For sharded connection pools, theSymbol
passed is the shard/server to use. - disconnect(Symbol)
-
Disconnect the connection object. For sharded connection pools, the
Symbol
passed is the shard/server to use. - servers
-
An array of shard/server symbols for all shards/servers that this connection pool recognizes.
- size
-
an integer representing the total number of connections in the pool, or for the given shard/server if sharding is supported.
- max_size
-
an integer representing the maximum size of the connection pool, or the maximum size per shard/server if sharding is supported.
For sharded connection pools, the sharded API adds the following methods:
- add_servers(Array of Symbols)
-
start recognizing all shards/servers specified by the array of symbols.
- remove_servers(Array of Symbols)
-
no longer recognize all shards/servers specified by the array of symbols.
Constants
- OPTS
- POOL_CLASS_MAP
Attributes
The after_connect
proc used for this pool. This is called with each new connection made, and is usually used to set custom per-connection settings.
An array of sql strings to execute on each new connection.
The Sequel::Database
object tied to this connection pool.
Public Class Methods
Instantiates a connection pool with the given options. The block is called with a single symbol (specifying the server/shard to use) every time a new connection is needed. The following options are respected for all connection pools:
- :after_connect
-
A callable object called after each new connection is made, with the connection object (and server argument if the callable accepts 2 arguments), useful for customizations that you want to apply to all connections.
- :connect_sqls
-
An array of sql strings to execute on each new connection, after :after_connect runs.
- :preconnect
-
Automatically create the maximum number of connections, so that they don't need to be created as needed. This is useful when connecting takes a long time and you want to avoid possible latency during runtime. Set to :concurrently to create the connections in separate threads. Otherwise they'll be created sequentially.
# File lib/sequel/connection_pool.rb 98 def initialize(db, opts=OPTS) 99 @db = db 100 @after_connect = opts[:after_connect] 101 @connect_sqls = opts[:connect_sqls] 102 @error_classes = db.send(:database_error_classes).dup.freeze 103 end
Public Instance Methods
An array of symbols for all shards/servers, which is a single :default
by default.
# File lib/sequel/connection_pool.rb 106 def servers 107 [:default] 108 end
Private Instance Methods
Remove the connection from the pool. For threaded connections, this should be called without the mutex, because the disconnection may block.
# File lib/sequel/connection_pool.rb 114 def disconnect_connection(conn) 115 db.disconnect_connection(conn) 116 end
Whether the given exception is a disconnect exception.
# File lib/sequel/connection_pool.rb 119 def disconnect_error?(exception) 120 exception.is_a?(Sequel::DatabaseDisconnectError) || db.send(:disconnect_error?, exception, OPTS) 121 end
Return a new connection by calling the connection proc with the given server name, and checking for connection errors.
# File lib/sequel/connection_pool.rb 125 def make_new(server) 126 begin 127 conn = @db.connect(server) 128 129 if ac = @after_connect 130 if ac.arity == 2 131 ac.call(conn, server) 132 else 133 ac.call(conn) 134 end 135 end 136 137 if cs = @connect_sqls 138 cs.each do |sql| 139 db.send(:log_connection_execute, conn, sql) 140 end 141 end 142 rescue Exception=>exception 143 raise Sequel.convert_exception_class(exception, Sequel::DatabaseConnectionError) 144 end 145 raise(Sequel::DatabaseConnectionError, "Connection parameters not valid") unless conn 146 conn 147 end