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Class: ActiveRecord::ConnectionAdapters::ConnectionPool::Queue

Relationships & Source Files
Extension / Inclusion / Inheritance Descendants
Subclasses:
ActiveRecord::ConnectionAdapters::ConnectionPool::ConnectionLeasingQueue
Inherits: Object
Defined in: activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb

Overview

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

Class Method Summary

Instance Attribute Summary

Instance Method Summary

Constructor Details

.new(lock = Monitor.new) ⇒ Queue

[ GitHub ]

  
# 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

Instance Attribute Details

#any_waiting?Boolean (readonly)

Test if any threads are currently waiting on the queue.

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb', line 94

def any_waiting?
  synchronize do
    @num_waiting > 0
  end
end

Instance Method Details

#add(element)

Add element to the queue. Never blocks.

[ GitHub ]

  
# 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

#clear

Remove all elements from the queue.

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb', line 124

def clear
  synchronize do
    @queue.clear
  end
end

#delete(element)

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

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb', line 117

def delete(element)
  synchronize do
    @queue.delete(element)
  end
end

#num_waiting

Returns the number of threads currently waiting on this queue.

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb', line 102

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 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,

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb', line 144

def poll(timeout = nil)
  synchronize { internal_poll(timeout) }
end