instance method
checkout
Ruby on Rails 3.2.22.5
Since v2.2.3Signature
checkout()Check-out a database connection from the pool, indicating that you want to use it. You should call #checkin when you no longer need this.
This is done by either returning an existing connection, or by creating a new connection. If the maximum number of connections for this pool has already been reached, but the pool is empty (i.e. they’re all being used), then this method will wait until a thread has checked in a connection. The wait time is bounded however: if no connection can be checked out within the timeout specified for this pool, then a ConnectionTimeoutError exception will be raised.
Returns: an AbstractAdapter object.
Raises:
-
ConnectionTimeoutError: no connection can be obtained from the pool within the timeout period.
Source
# File activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb, line 238
def checkout
synchronize do
waited_time = 0
loop do
conn = @connections.find { |c| c.lease }
unless conn
if @connections.size < @size
conn = checkout_new_connection
conn.lease
end
end
if conn
checkout_and_verify conn
return conn
end
if waited_time >= @timeout
raise ConnectionTimeoutError, "could not obtain a database connection#{" within #{@timeout} seconds" if @timeout} (waited #{waited_time} seconds). The max pool size is currently #{@size}; consider increasing it."
end
# Sometimes our wait can end because a connection is available,
# but another thread can snatch it up first. If timeout hasn't
# passed but no connection is avail, looks like that happened --
# loop and wait again, for the time remaining on our timeout.
before_wait = Time.now
@queue.wait( [@timeout - waited_time, 0].max )
waited_time += (Time.now - before_wait)
# Will go away in Rails 4, when we don't clean up
# after leaked connections automatically anymore. Right now, clean
# up after we've returned from a 'wait' if it looks like it's
# needed, then loop and try again.
if(active_connections.size >= @connections.size)
clear_stale_cached_connections!
end
end
end
end
Defined in activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb line 238
· View on GitHub
· Improve this page
· Find usages on GitHub