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 13
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 36
def add(element)
  synchronize do
    @queue.push element
    @cond.signal
  end
end
πŸ”Ž See on GitHub

add_back(element)

Add element to the back of the queue. Never blocks.

πŸ“ Source code 
# File activerecord/lib/active_record/connection_adapters/abstract/connection_pool/queue.rb, line 44
def add_back(element)
  synchronize do
    @queue.unshift 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 21
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 59
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 52
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 29
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 86
def poll(timeout = nil)
  synchronize { internal_poll(timeout) }
end
πŸ”Ž See on GitHub

size()

Number of elements in the queue.

πŸ“ Source code 
# File activerecord/lib/active_record/connection_adapters/abstract/connection_pool/queue.rb, line 66
def size
  synchronize do
    @queue.size
  end
end
πŸ”Ž See on GitHub

Definition files