class ActiveRecord::ConnectionAdapters::ConnectionPool::Queue

Active Record Connection Pool Queue¶ ↑

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

Public Class Methods

Source

# File 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

Public Instance Methods

add (element)

Source

# File lib/active_record/connection_adapters/abstract/connection_pool/queue.rb, line 36
def add(element)
  synchronize do
    @queue.push element
    @cond.signal
  end
end

Add element to the queue. Never blocks.

add_back (element)

Source

# File 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

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

any_waiting? ()

Source

# File lib/active_record/connection_adapters/abstract/connection_pool/queue.rb, line 21
def any_waiting?
  synchronize do
    @num_waiting > 0
  end
end

Test if any threads are currently waiting on the queue.

clear ()

Source

# File lib/active_record/connection_adapters/abstract/connection_pool/queue.rb, line 59
def clear
  synchronize do
    @queue.clear
  end
end

Remove all elements from the queue.

delete (element)

Source

# File lib/active_record/connection_adapters/abstract/connection_pool/queue.rb, line 52
def delete(element)
  synchronize do
    @queue.delete(element)
  end
end

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

num_waiting ()

Source

# File lib/active_record/connection_adapters/abstract/connection_pool/queue.rb, line 29
def num_waiting
  synchronize do
    @num_waiting
  end
end

Returns the number of threads currently waiting on this queue.

poll (timeout = nil)

Source

# File lib/active_record/connection_adapters/abstract/connection_pool/queue.rb, line 86
def poll(timeout = nil)
  synchronize { internal_poll(timeout) }
end

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:

ActiveRecord::ConnectionTimeoutError if timeout is given and no element

becomes available within timeout seconds,

size ()

Source

# File lib/active_record/connection_adapters/abstract/connection_pool/queue.rb, line 66
def size
  synchronize do
    @queue.size
  end
end

Number of elements in the queue.