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 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

new(opts = {}, &block)

The following additional options are respected:

- :connection_handling - Set how to handle available connections. By default, uses a a stack for performance. Can be set to :queue to use a queue, which reduces the chances of connections becoming stale.
- :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 25
    25:   def initialize(opts = {}, &block)
    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:     @queue = opts[:connection_handling] == :queue
    31:     @available_connections = []
    32:     @allocated = {}
    33:     @timeout = Integer(opts[:pool_timeout] || 5)
    34:     @sleep_time = Float(opts[:pool_sleep_time] || 0.001)
    35:   end

### Public Instance methods

all_connections() {|c| ...}

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 48
    48:   def all_connections
    49:     hold do |c|
    50:       sync do
    51:         yield c
    52:         @available_connections.each{|c| yield c}
    53:       end
    54:     end
    55:   end

disconnect(opts={}, &block)

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 67
    67:   def disconnect(opts={}, &block)
    68:     block ||= @disconnection_proc
    69:     sync do
    70:       @available_connections.each{|conn| block.call(conn)} if block
    71:       @available_connections.clear
    72:     end
    73:   end

hold(server=nil) {|conn| ...}

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 89
     89:   def hold(server=nil)
     90:     t = Thread.current
     91:     if conn = owned_connection(t)
     92:       return yield(conn)
     93:     end
     94:     begin
     95:       unless conn = acquire(t)
     96:         time = Time.now
     97:         timeout = time + @timeout
     98:         sleep_time = @sleep_time
     99:         sleep sleep_time
    100:         until conn = acquire(t)
    101:           raise(::Sequel::PoolTimeout) if Time.now > timeout
    102:           sleep sleep_time
    103:         end
    104:       end
    105:       yield conn
    106:     rescue Sequel::DatabaseDisconnectError
    107:       oconn = conn
    108:       conn = nil
    109:       @disconnection_proc.call(oconn) if @disconnection_proc && oconn
    110:       @allocated.delete(t)
    111:       raise
    112:     ensure
    113:       sync{release(t)} if conn
    114:     end
    115:   end

size()

The total number of connections opened, either available or allocated. This may not be completely accurate as it isn‘t protected by the mutex.

[Source]

        # File lib/sequel/connection_pool/threaded.rb, line 39
    39:   def size
    40:     @allocated.length + @available_connections.length
    41:   end

[Validate]