Class: ActiveRecord::ConnectionAdapters::ConnectionPool::Queue
Relationships & Source Files | |
Extension / Inclusion / Inheritance Descendants | |
Subclasses:
ActiveRecord::ConnectionAdapters::ConnectionPool::ConnectionLeasingQueue
|
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Inherits: | Object |
Defined in: | activerecord/lib/active_record/connection_adapters/abstract/connection_pool/queue.rb |
Overview
Active Record Connection Pool Queue
Threadsafe, fair, LIFO queue. Meant to be used by ::ActiveRecord::ConnectionAdapters::ConnectionPool
with which it shares a Monitor.
Class Method Summary
- .new(lock = Monitor.new) ⇒ Queue constructor
Instance Attribute Summary
-
#any_waiting? ⇒ Boolean
readonly
Test if any threads are currently waiting on the queue.
Instance Method Summary
-
#add(element)
Add
element
to the queue. -
#clear
Remove all elements from the queue.
-
#delete(element)
If
element
is in the queue, remove and return it, ornil
. -
#num_waiting
Returns the number of threads currently waiting on this queue.
-
#poll(timeout = nil)
Remove the head of the queue.
Constructor Details
.new(lock = Monitor.new) ⇒ Queue
# 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 Attribute Details
#any_waiting? ⇒ Boolean
(readonly)
Test if any threads are currently waiting on the queue.
# File 'activerecord/lib/active_record/connection_adapters/abstract/connection_pool/queue.rb', line 22
def any_waiting? synchronize do @num_waiting > 0 end end
Instance Method Details
#add(element)
Add element
to the queue. Never blocks.
# 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
#clear
Remove all elements from the queue.
# 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
.
# 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.
# 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:
-
::ActiveRecord::ConnectionTimeoutError
iftimeout
is given and no element
becomes available within timeout
seconds,
# File 'activerecord/lib/active_record/connection_adapters/abstract/connection_pool/queue.rb', line 72
def poll(timeout = nil) synchronize { internal_poll(timeout) } end