Class: Sequel::ThreadedConnectionPool

Inherits:
ConnectionPool show all
Defined in:
lib/sequel/connection_pool/threaded.rb

Overview

A connection pool allowing multi-threaded access to a pool of connections. This is the default connection pool used by Sequel.

Direct Known Subclasses

ShardedThreadedConnectionPool

Constant Summary

Constants inherited from ConnectionPool

ConnectionPool::CONNECTION_POOL_MAP, ConnectionPool::DEFAULT_SERVER

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods inherited from ConnectionPool

#created_count, #servers

Methods included from ConnectionPool::ClassMethods

#get_pool

Constructor Details

#initialize(opts = {}, &block) ⇒ ThreadedConnectionPool

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)

Raises:



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# File 'lib/sequel/connection_pool/threaded.rb', line 22

def initialize(opts = {}, &block)
  super
  @max_size = Integer(opts[:max_connections] || 4)
  raise(Sequel::Error, ':max_connections must be positive') if @max_size < 1
  @mutex = Mutex.new  
  @available_connections = []
  @allocated = {}
  @timeout = Integer(opts[:pool_timeout] || 5)
  @sleep_time = Float(opts[:pool_sleep_time] || 0.001)
end

Instance Attribute Details

#allocated ⇒ Object (readonly)

A hash with thread keys and connection values for currently allocated connections.



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# File 'lib/sequel/connection_pool/threaded.rb', line 13

def allocated
  @allocated
end

#available_connections ⇒ Object (readonly)

An array of connections that are available for use by the pool.



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# File 'lib/sequel/connection_pool/threaded.rb', line 9

def available_connections
  @available_connections
end

#max_size ⇒ Object (readonly)

The maximum number of connections this pool will create (per shard/server if sharding).



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# File 'lib/sequel/connection_pool/threaded.rb', line 6

def max_size
  @max_size
end

Instance Method Details

#disconnect(opts = {}, &block) ⇒ Object

Removes all connections 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.

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



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# File 'lib/sequel/connection_pool/threaded.rb', line 46

def disconnect(opts={}, &block)
  block ||= @disconnection_proc
  sync do
    @available_connections.each{|conn| block.call(conn)} if block
    @available_connections.clear
  end
end

#hold(server = nil) ⇒ Object

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.



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

def hold(server=nil)
  t = Thread.current
  if conn = owned_connection(t)
    return yield(conn)
  end
  begin
    unless conn = acquire(t)
      time = Time.now
      timeout = time + @timeout
      sleep_time = @sleep_time
      sleep sleep_time
      until conn = acquire(t)
        raise(::Sequel::PoolTimeout) if Time.now > timeout
        sleep sleep_time
      end
    end
    yield conn
  rescue Sequel::DatabaseDisconnectError
    oconn = conn
    conn = nil
    @disconnection_proc.call(oconn) if @disconnection_proc && oconn
    @allocated.delete(t)
    raise
  ensure
    sync{release(t)} if conn
  end
end

#size ⇒ Object

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



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# File 'lib/sequel/connection_pool/threaded.rb', line 35

def size
  @allocated.length + @available_connections.length
end