Class: Sequel::ConnectionPool

Inherits:
Object
  • Object
show all
Extended by:
ClassMethods
Defined in:
lib/sequel/connection_pool.rb

Overview

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.

Defined Under Namespace

Modules: ClassMethods

Constant Summary collapse

OPTS = 
Sequel::OPTS
DEFAULT_SERVER =

The default server to use

:default
CONNECTION_POOL_MAP =

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

{[true, false] => :single, 
[true, true] => :sharded_single,
[false, false] => :threaded,
[false, true] => :sharded_threaded}

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from ClassMethods

get_pool

Constructor Details

#initialize(db, opts = OPTS) ⇒ ConnectionPool

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.



84
85
86
87
88
 
# 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

Instance Attribute Details

#after_connect ⇒ Object

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.



67
68
69
 
# File 'lib/sequel/connection_pool.rb', line 67

def after_connect
  @after_connect
end

#db ⇒ Object

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



70
71
72
 
# File 'lib/sequel/connection_pool.rb', line 70

def db
  @db
end

Instance Method Details

#created_count(*args) ⇒ Object

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



91
92
93
 
# File 'lib/sequel/connection_pool.rb', line 91

def created_count(*args)
  size(*args)
end

#servers ⇒ Object

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



96
97
98
 
# File 'lib/sequel/connection_pool.rb', line 96

def servers
  [DEFAULT_SERVER]
end