Class Sequel::ThreadedConnectionPool
In: lib/sequel/connection_pool/threaded.rb
Parent: Sequel::ConnectionPool

A connection pool allowing multi-threaded access to a pool of connections.

Methods

disconnect   hold   new   size  

External Aliases

make_new -> default_make_new
  Alias the default make_new method, so subclasses can call it directly.

Attributes

allocated  [R]  A hash with thread keys and connection values for currently allocated connections.
available_connections  [R]  An array of connections that are available for use by the pool.
max_size  [R]  The maximum number of connections this pool will create (per shard/server if sharding).

Public Class methods

The following additional options are respected:

  • :max_connections - The maximum number of connections the connection pool will open (default 4)
  • :pool_sleep_time - The amount of time to sleep before attempting to acquire a connection again (default 0.001)
  • :pool_timeout - The amount of seconds to wait to acquire a connection before raising a PoolTimeoutError (default 5)

[Source]

    # File lib/sequel/connection_pool/threaded.rb, line 21
21:   def initialize(opts = {}, &block)
22:     super
23:     @max_size = Integer(opts[:max_connections] || 4)
24:     raise(Sequel::Error, ':max_connections must be positive') if @max_size < 1
25:     @mutex = Mutex.new  
26:     @available_connections = []
27:     @allocated = {}
28:     @timeout = Integer(opts[:pool_timeout] || 5)
29:     @sleep_time = Float(opts[:pool_sleep_time] || 0.001)
30:   end

Public Instance methods

Removes all connection currently available on all servers, optionally yielding each connection to the given block. This method has the effect of disconnecting from the database, assuming that no connections are currently being used. If connections are being used, they are scheduled to be disconnected as soon as they are returned to the pool.

Once a connection is requested using hold, the connection pool creates new connections to the database.

[Source]

    # File lib/sequel/connection_pool/threaded.rb, line 46
46:   def disconnect(opts={}, &block)
47:     block ||= @disconnection_proc
48:     sync do
49:       @available_connections.each{|conn| block.call(conn)} if block
50:       @available_connections.clear
51:     end
52:   end

Chooses the first available connection to the given server, or if none are available, creates a new connection. Passes the connection to the supplied block:

  pool.hold {|conn| conn.execute('DROP TABLE posts')}

Pool#hold is re-entrant, meaning it can be called recursively in the same thread without blocking.

If no connection is immediately available and the pool is already using the maximum number of connections, Pool#hold will block until a connection is available or the timeout expires. If the timeout expires before a connection can be acquired, a Sequel::PoolTimeout is raised.

[Source]

    # File lib/sequel/connection_pool/threaded.rb, line 68
68:   def hold(server=nil)
69:     t = Thread.current
70:     if conn = owned_connection(t)
71:       return yield(conn)
72:     end
73:     begin
74:       unless conn = acquire(t)
75:         time = Time.now
76:         timeout = time + @timeout
77:         sleep_time = @sleep_time
78:         sleep sleep_time
79:         until conn = acquire(t)
80:           raise(::Sequel::PoolTimeout) if Time.now > timeout
81:           sleep sleep_time
82:         end
83:       end
84:       yield conn
85:     rescue Sequel::DatabaseDisconnectError
86:       @disconnection_proc.call(conn) if @disconnection_proc && conn
87:       @allocated.delete(t)
88:       conn = nil
89:       raise
90:     ensure
91:       sync{release(t)} if conn
92:     end
93:   end

The total number of connections opened for the given server, should be equal to available_connections.length + allocated.length.

[Source]

    # File lib/sequel/connection_pool/threaded.rb, line 34
34:   def size
35:     @allocated.length + @available_connections.length
36:   end

[Validate]