module BubbleWrap::Reactor::Deferrable
Provides a mixin for deferrable jobs.
Public Instance Methods
Specify a block to be executed if and when the Deferrable
object receives a status of :succeeded. See set_deferred_status
for more information. Calling this method on a Deferrable
object whose status is not yet known will cause the callback block to be stored on an internal list. If you call this method on a Deferrable
whose status is :succeeded, the block will be executed immediately, receiving the parameters given to the prior set_deferred_status
call.
# File motion/reactor/deferrable.rb, line 18 def callback(&blk) return unless blk @deferred_status ||= :unknown if @deferred_status == :succeeded execute_block(&blk) elsif @deferred_status != :failed @callbacks ||= [] @callbacks.unshift blk end end
# File motion/reactor/deferrable.rb, line 71 def callback_delegate(delegate) callback do |*args| delegate.succeed *args end self end
Cancels an outstanding timeout if any. Undoes the action of timeout.
# File motion/reactor/deferrable.rb, line 30 def cancel_timeout @deferred_timeout ||= nil if @deferred_timeout @deferred_timeout.cancel @deferred_timeout = nil end end
# File motion/reactor/deferrable.rb, line 154 def deferred_args @deferred_args end
# File motion/reactor/deferrable.rb, line 150 def deferred_status @deferred_status ||= :unknown end
# File motion/reactor/deferrable.rb, line 58 def delegate(delegate) callback_delegate(delegate) errback_delegate(delegate) self end
Specify a block to be executed if and when the Deferrable
object receives a status of :failed. See set_deferred_status
for more information.
# File motion/reactor/deferrable.rb, line 41 def errback(&blk) return unless blk @deferred_status ||= :unknown if @deferred_status == :failed execute_block(&blk) blk.call(*@deferred_args) elsif @deferred_status != :succeeded @errbacks ||= [] @errbacks.unshift blk end end
# File motion/reactor/deferrable.rb, line 64 def errback_delegate(delegate) errback do |*args| delegate.fail *args end self end
# File motion/reactor/deferrable.rb, line 53 def execute_block(&blk) return unless blk blk.call(*@deferred_args) end
Sugar for set_deferred_status
(:failed, …)
# File motion/reactor/deferrable.rb, line 79 def fail(*args) set_deferred_status :failed, *args end
Sets the “disposition” (status) of the Deferrable
object. See also the large set of sugarings for this method. Note that if you call this method without arguments, no arguments will be passed to the callback/errback. If the user has coded these with arguments, then the user code will throw an argument exception. Implementors of deferrable classes must document the arguments they will supply to user callbacks. OBSERVE SOMETHING VERY SPECIAL here: you may call this method even on the INSIDE of a callback. This is very useful when a previously-registered callback wants to change the parameters that will be passed to subsequently-registered ones. You may give either :succeeded or :failed as the status argument. If you pass :succeeded, then all of the blocks passed to the object using the callback method (if any) will be executed BEFORE the set_deferred_status
method returns. All of the blocks passed to the object using errback will be discarded. If you pass :failed, then all of the blocks passed to the object using the errback method (if any) will be executed BEFORE the set_deferred_status
method returns. All of the blocks passed to the object using # callback will be discarded. If you pass any arguments to set_deferred_status
in addition to the status argument, they will be passed as arguments to any callbacks or errbacks that are executed. It’s your responsibility to ensure that the argument lists specified in your callbacks and errbacks match the arguments given in calls to set_deferred_status
, otherwise Ruby will raise an ArgumentError.
# File motion/reactor/deferrable.rb, line 110 def set_deferred_status(status, *args) cancel_timeout @errbacks ||= nil @callbacks ||= nil @deferred_status = status @deferred_args = args case @deferred_status when :succeeded if @callbacks while cb = @callbacks.pop execute_block(&cb) end end @errbacks.clear if @errbacks when :failed if @errbacks while eb = @errbacks.pop execute_block(&eb) end end @callbacks.clear if @callbacks end end
Sugar for set_deferred_status
(:succeeded, …)
# File motion/reactor/deferrable.rb, line 135 def succeed(*args) set_deferred_status :succeeded, *args end
Setting a timeout on a Deferrable
causes it to go into the failed state after the Timeout expires (passing no arguments to the object’s errbacks). Setting the status at any time prior to a call to the expiration of the timeout will cause the timer to be cancelled.
# File motion/reactor/deferrable.rb, line 144 def timeout(seconds) cancel_timeout me = self @deferred_timeout = Timer.new(seconds) {me.fail} end