› Async › Source › Async › WorkerPool › Promise

class Promise

Execute the given work in a background thread.

Definitions

def initialize(work)

Create a new promise.

Signature
parameter　work　Proc

The work to be done.

Implementation

 
def initialize(work)
	@work = work
	@state = :pending
	@value = nil
	@guard = ::Mutex.new
	@condition = ::ConditionVariable.new
	@thread = nil
end

def call

Execute the work and resolve the promise.

Implementation

 
def call
	work = nil
	
	@guard.synchronize do
		@thread = ::Thread.current
		
		return unless work = @work
	end
	
	resolve(work.call)
rescue Exception => error
	reject(error)
end

def cancel

Cancel the work and raise an exception in the background thread.

Implementation

 
def cancel
	return unless @work
	
	@guard.synchronize do
		@work = nil
		@state = :cancelled
		@thread&.raise(Interrupt)
	end
end

def wait

Wait for the work to be done.

Signature
returns　Object

The result of the work.

Implementation

 
def wait
	@guard.synchronize do
		while @state == :pending
			@condition.wait(@guard)
		end
		
		if @state == :failed
			raise @value
		else
			return @value
		end
	end
end

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