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Active Record Connection Pool Queue

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

Methods
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C
D
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P

Class Public methods

new(lock = Monitor.new)

Source: show 

# 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

Instance Public methods

add(element)

Add element to the queue. Never blocks.

Source: show 

# 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

any_waiting?()

Test if any threads are currently waiting on the queue.

Source: show 

# File activerecord/lib/active_record/connection_adapters/abstract/connection_pool/queue.rb, line 22
def any_waiting?
  synchronize do
    @num_waiting > 0
  end
end

clear()

Remove all elements from the queue.

Source: show 

# File activerecord/lib/active_record/connection_adapters/abstract/connection_pool/queue.rb, line 52
def clear
  synchronize do
    @queue.clear
  end
end

delete(element)

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

Source: show 

# File activerecord/lib/active_record/connection_adapters/abstract/connection_pool/queue.rb, line 45
def delete(element)
  synchronize do
    @queue.delete(element)
  end
end

num_waiting()

Returns the number of threads currently waiting on this queue.

Source: show 

# File activerecord/lib/active_record/connection_adapters/abstract/connection_pool/queue.rb, line 30
def num_waiting
  synchronize do
    @num_waiting
  end
end

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,

Source: show 

# File activerecord/lib/active_record/connection_adapters/abstract/connection_pool/queue.rb, line 72
def poll(timeout = nil)
  synchronize { internal_poll(timeout) }
end