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, the Symbol 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

CONNECTION_POOL_MAP

A map of [single threaded, sharded] values to symbols or ConnectionPool subclasses.

DEFAULT_SERVER

The default server to use

OPTS

Attributes

after_connect[RW]

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.

db[RW]

The Sequel::Database object tied to this connection pool.

Public Class Methods

new(db, opts=OPTS) click to toggle source

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.

: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, line 84
def initialize(db, opts=OPTS)
  @db = db
  @after_connect = opts[:after_connect]
  @error_classes = db.send(:database_error_classes).dup.freeze
end

Public Instance Methods

created_count(*args) click to toggle source

Alias for size, not aliased directly for ease of subclass implementation

# File lib/sequel/connection_pool.rb, line 91
def created_count(*args)
  size(*args)
end
servers() click to toggle source

An array of symbols for all shards/servers, which is a single :default by default.

# File lib/sequel/connection_pool.rb, line 96
def servers
  [DEFAULT_SERVER]
end

Private Instance Methods

disconnect_connection(conn) click to toggle source

Remove the connection from the pool.

# File lib/sequel/connection_pool.rb, line 103
def disconnect_connection(conn)
  db.disconnect_connection(conn)
end
disconnect_error?(exception) click to toggle source

Whether the given exception is a disconnect exception.

# File lib/sequel/connection_pool.rb, line 108
def disconnect_error?(exception)
  exception.is_a?(Sequel::DatabaseDisconnectError) || db.send(:disconnect_error?, exception, OPTS)
end
make_new(server) click to toggle source

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, line 114
def make_new(server)
  begin
    conn = @db.connect(server)
    if ac = @after_connect
      if ac.arity == 2
        ac.call(conn, server)
      else
        ac.call(conn)
      end
    end
  rescue Exception=>exception
    raise Sequel.convert_exception_class(exception, Sequel::DatabaseConnectionError)
  end
  raise(Sequel::DatabaseConnectionError, "Connection parameters not valid") unless conn
  conn
end