class ActiveRecord::Bogacs::DefaultPool::Queue
@private
Public Class Methods
# File lib/active_record/bogacs/default_pool.rb, line 25 def initialize(lock) @lock = lock @cond = @lock.new_cond @num_waiting = 0 @queue = [] end
Public Instance Methods
Add element
to the queue. Never blocks.
# File lib/active_record/bogacs/default_pool.rb, line 48 def add(element) synchronize do @queue.push element @cond.signal end end
Test if any threads are currently waiting on the queue.
# File lib/active_record/bogacs/default_pool.rb, line 33 def any_waiting? synchronize do @num_waiting > 0 end end
Remove all elements from the queue.
# File lib/active_record/bogacs/default_pool.rb, line 63 def clear synchronize do @queue.clear end end
If element
is in the queue, remove and return it, or nil.
# File lib/active_record/bogacs/default_pool.rb, line 56 def delete(element) synchronize do @queue.delete(element) end end
Returns the number of threads currently waiting on this queue.
# File lib/active_record/bogacs/default_pool.rb, line 41 def num_waiting synchronize do @num_waiting end end
Remove the head of the queue.
If timeout
is not given, remove and return the head the queue if the number of available elements is strictly greater than the number of threads currently waiting (that is, don’t jump ahead in line). Otherwise, return nil.
If timeout
is given, block if it there is no element available, waiting up to timeout
seconds for an element to become available.
@raise [ActiveRecord::ConnectionTimeoutError] if timeout
given and no element becomes available after timeout
seconds
# File lib/active_record/bogacs/default_pool.rb, line 82 def poll(timeout = nil) synchronize { internal_poll(timeout) } end
Private Instance Methods
Test if the queue currently contains any elements.
# File lib/active_record/bogacs/default_pool.rb, line 106 def any? !@queue.empty? end
A thread can remove an element from the queue without waiting if and only if the number of currently available connections is strictly greater than the number of waiting threads.
# File lib/active_record/bogacs/default_pool.rb, line 114 def can_remove_no_wait? @queue.size > @num_waiting end
# File lib/active_record/bogacs/default_pool.rb, line 88 def internal_poll(timeout) conn = no_wait_poll || (timeout && wait_poll(timeout)) # Connections must be leased while holding the main pool mutex. This is # an internal subclass that also +.leases+ returned connections while # still in queue's critical section (queue synchronizes with the same # <tt>@lock</tt> as the main pool) so that a returned connection is already # leased and there is no need to re-enter synchronized block. # # NOTE: avoid the need for ConnectionLeasingQueue, since BiasableQueue is not implemented conn.lease if conn conn end
Remove and return the head the queue if the number of available elements is strictly greater than the number of threads currently waiting. Otherwise, return nil
.
# File lib/active_record/bogacs/default_pool.rb, line 126 def no_wait_poll remove if can_remove_no_wait? end
Removes and returns the head of the queue if possible, or nil
.
# File lib/active_record/bogacs/default_pool.rb, line 119 def remove @queue.pop end
# File lib/active_record/bogacs/default_pool.rb, line 101 def synchronize(&block) @lock.synchronize(&block) end
Waits on the queue up to timeout
seconds, then removes and returns the head of the queue.
# File lib/active_record/bogacs/default_pool.rb, line 132 def wait_poll(timeout) @num_waiting += 1 t0 = Time.now elapsed = 0 while true @cond.wait(timeout - elapsed) return remove if any? elapsed = Time.now - t0 if elapsed >= timeout msg = 'could not obtain a database connection within %0.3f seconds (waited %0.3f seconds)' % [timeout, elapsed] raise ConnectionTimeoutError, msg end end ensure @num_waiting -= 1 end