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. This is the default connection pool used by Sequel.

Methods

all_connections   disconnect   hold   new   pool_type   size  

Constants

USE_WAITER = true

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_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 25
25:   def initialize(db, opts = OPTS)
26:     super
27:     @max_size = Integer(opts[:max_connections] || 4)
28:     raise(Sequel::Error, ':max_connections must be positive') if @max_size < 1
29:     @mutex = Mutex.new  
30:     @connection_handling = opts[:connection_handling]
31:     @available_connections = []
32:     @allocated = {}
33:     @timeout = Float(opts[:pool_timeout] || 5)
34:     @waiter = ConditionVariable.new
35:   end

Public Instance methods

Yield all of the available connections, and the one currently allocated to this thread. This will not yield connections currently allocated to other threads, as it is not safe to operate on them. This holds the mutex while it is yielding all of the available connections, which means that until the method‘s block returns, the pool is locked.

[Source]

    # File lib/sequel/connection_pool/threaded.rb, line 42
42:   def all_connections
43:     hold do |c|
44:       sync do
45:         yield c
46:         @available_connections.each{|conn| yield conn}
47:       end
48:     end
49:   end

Removes all connections currently available, 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 you want to be able to disconnect connections that are currently in use, use the ShardedThreadedConnectionPool, which can do that. This connection pool does not, for performance reasons. To use the sharded pool, pass the servers: {} option when connecting to the database.

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 61
61:   def disconnect(opts=OPTS)
62:     conns = nil
63:     sync do
64:       conns = @available_connections.dup
65:       @available_connections.clear
66:       @waiter.signal
67:     end
68:     conns.each{|conn| disconnect_connection(conn)}
69:   end

Chooses the first available connection, 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 84
 84:   def hold(server=nil)
 85:     t = Thread.current
 86:     if conn = owned_connection(t)
 87:       return yield(conn)
 88:     end
 89:     begin
 90:       conn = acquire(t)
 91:       yield conn
 92:     rescue Sequel::DatabaseDisconnectError, *@error_classes => e
 93:       if disconnect_error?(e)
 94:         oconn = conn
 95:         conn = nil
 96:         disconnect_connection(oconn) if oconn
 97:         sync do 
 98:           @allocated.delete(t)
 99:           @waiter.signal
100:         end
101:       end
102:       raise
103:     ensure
104:       if conn
105:         sync{release(t)}
106:         if @connection_handling == :disconnect
107:           disconnect_connection(conn)
108:         end
109:       end
110:     end
111:   end

[Source]

     # File lib/sequel/connection_pool/threaded.rb, line 113
113:   def pool_type
114:     :threaded
115:   end

The total number of connections opened, either available or allocated. The calling code should not have the mutex before calling this.

[Source]

     # File lib/sequel/connection_pool/threaded.rb, line 119
119:   def size
120:     @mutex.synchronize{_size}
121:   end

[Validate]