class ActiveRecord::Bogacs::DefaultPool::Queue

@private

Public Class Methods

new(lock) click to toggle source
# 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) click to toggle source

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
any_waiting?() click to toggle source

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
clear() click to toggle source

Remove all elements from the queue.

# File lib/active_record/bogacs/default_pool.rb, line 63
def clear
  synchronize do
    @queue.clear
  end
end
delete(element) click to toggle source

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
num_waiting() click to toggle source

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
poll(timeout = nil) click to toggle source

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

any?() click to toggle source

Test if the queue currently contains any elements.

# File lib/active_record/bogacs/default_pool.rb, line 106
def any?
  !@queue.empty?
end
can_remove_no_wait?() click to toggle source

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
internal_poll(timeout) click to toggle source
# 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
no_wait_poll() click to toggle source

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
remove() click to toggle source

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
synchronize(&block) click to toggle source
# File lib/active_record/bogacs/default_pool.rb, line 101
def synchronize(&block)
  @lock.synchronize(&block)
end
wait_poll(timeout) click to toggle source

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