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

Methods

Class Public methods

new(lock = Monitor.new)

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb, line 86
        def initialize(lock = Monitor.new)
          @lock = lock
          @cond = @lock.new_cond
          @num_waiting = 0
          @queue = []
        end
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Instance Public methods

add(element)

Add element to the queue. Never blocks.

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb, line 109
        def add(element)
          synchronize do
            @queue.push element
            @cond.signal
          end
        end
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any_waiting?()

Test if any threads are currently waiting on the queue.

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb, line 94
        def any_waiting?
          synchronize do
            @num_waiting > 0
          end
        end
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clear()

Remove all elements from the queue.

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb, line 124
        def clear
          synchronize do
            @queue.clear
          end
        end
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delete(element)

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

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb, line 117
        def delete(element)
          synchronize do
            @queue.delete(element)
          end
        end
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num_waiting()

Returns the number of threads currently waiting on this queue.

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb, line 102
        def num_waiting
          synchronize do
            @num_waiting
          end
        end
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poll(timeout = nil)

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 there is no element available, waiting up to timeout seconds for an element to become available.

Raises:

becomes available within timeout seconds,

📝 Source code 
# File activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb, line 144
        def poll(timeout = nil)
          synchronize { internal_poll(timeout) }
        end
🔎 See on GitHub