Active Record Connection Pool Queue

Threadsafe, fair, LIFO queue. Meant to be used by ConnectionPool with which it shares a Monitor.

Methods

Class Public methods

new(lock = Monitor.new)

πŸ“ Source code 
# File activerecord/lib/active_record/connection_adapters/abstract/connection_pool/queue.rb, line 14
        def initialize(lock = Monitor.new)
          @lock = lock
          @cond = @lock.new_cond
          @num_waiting = 0
          @queue = []
        end
πŸ”Ž See on GitHub

Instance Public methods

add(element)

Add element to the queue. Never blocks.

πŸ“ Source code 
# File activerecord/lib/active_record/connection_adapters/abstract/connection_pool/queue.rb, line 37
        def add(element)
          synchronize do
            @queue.push element
            @cond.signal
          end
        end
πŸ”Ž See on GitHub

any_waiting?()

Test if any threads are currently waiting on the queue.

πŸ“ Source code 
# File activerecord/lib/active_record/connection_adapters/abstract/connection_pool/queue.rb, line 22
        def any_waiting?
          synchronize do
            @num_waiting > 0
          end
        end
πŸ”Ž See on GitHub

clear()

Remove all elements from the queue.

πŸ“ Source code 
# File activerecord/lib/active_record/connection_adapters/abstract/connection_pool/queue.rb, line 52
        def clear
          synchronize do
            @queue.clear
          end
        end
πŸ”Ž See on GitHub

delete(element)

If element is in the queue, remove and return it, or nil.

πŸ“ Source code 
# File activerecord/lib/active_record/connection_adapters/abstract/connection_pool/queue.rb, line 45
        def delete(element)
          synchronize do
            @queue.delete(element)
          end
        end
πŸ”Ž See on GitHub

num_waiting()

Returns the number of threads currently waiting on this queue.

πŸ“ Source code 
# File activerecord/lib/active_record/connection_adapters/abstract/connection_pool/queue.rb, line 30
        def num_waiting
          synchronize do
            @num_waiting
          end
        end
πŸ”Ž See on GitHub

poll(timeout = nil)

Remove the head of the queue.

If timeout is not given, remove and return the head of 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 there is no element available, waiting up to timeout seconds for an element to become available.

Raises:

becomes available within timeout seconds,

πŸ“ Source code 
# File activerecord/lib/active_record/connection_adapters/abstract/connection_pool/queue.rb, line 72
        def poll(timeout = nil)
          synchronize { internal_poll(timeout) }
        end
πŸ”Ž See on GitHub