Class: Async::Task

Inherits:
Node
  • Object
show all
Defined in:
lib/async/task.rb

Overview

Encapsulates the state of a running task and it’s result.

Instance Attribute Summary collapse

Attributes inherited from Node

#annotation, #children, #head, #parent, #tail

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Node

#The parent node.=, #annotate, #children?, #consume, #description, #print_hierarchy, #root, #terminate, #transient?, #traverse

Constructor Details

#initialize(parent = Task.current?, finished: nil, **options, &block) ⇒ Task

Create a new task.



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# File 'lib/async/task.rb', line 65

def initialize(parent = Task.current?, finished: nil, **options, &block)
	super(parent, **options)
	
	@status = :initialized
	@result = nil
	@finished = finished
	
	@block = block
	@fiber = nil
end

Instance Attribute Details

#fiber ⇒ Object (readonly) 



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# File 'lib/async/task.rb', line 106

def fiber
  @fiber
end

#result ⇒ Object (readonly)

Access the result of the task without waiting. May be nil if the task is not completed.



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# File 'lib/async/task.rb', line 154

def result
  @result
end

#status ⇒ Object (readonly) 



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# File 'lib/async/task.rb', line 113

def status
  @status
end

Class Method Details

.current ⇒ Object

Lookup the Async::Task for the current fiber. Raise ‘RuntimeError` if none is available. @raises If task was not #set! for the current fiber.



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# File 'lib/async/task.rb', line 186

def self.current
	Thread.current[:async_task] or raise RuntimeError, "No async task available!"
end

.current? ⇒ Boolean

Check if there is a task defined for the current fiber.

Returns:

  • (Boolean) 


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# File 'lib/async/task.rb', line 192

def self.current?
	Thread.current[:async_task]
end

.yield ⇒ Object

Deprecated.

With no replacement.



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# File 'lib/async/task.rb', line 58

def self.yield
	Fiber.scheduler.transfer
end

Instance Method Details

#alive? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/async/task.rb', line 108

def alive?
	@fiber&.alive?
end

#async(*arguments, **options, &block) ⇒ Object 



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# File 'lib/async/task.rb', line 126

def async(*arguments, **options, &block)
	task = Task.new(self, **options, &block)
	
	task.run(*arguments)
	
	return task
end

#backtrace(*arguments) ⇒ Object 



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# File 'lib/async/task.rb', line 81

def backtrace(*arguments)
	@fiber&.backtrace(*arguments)
end

#complete? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/async/task.rb', line 224

def complete?
	@status == :complete
end

#current? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/async/task.rb', line 196

def current?
	self.equal?(Thread.current[:async_task])
end

#failed? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/async/task.rb', line 212

def failed?
	@status == :failed
end

#finished? ⇒ Boolean

Whether we can remove this node from the reactor graph.

Returns:

  • (Boolean) 


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# File 'lib/async/task.rb', line 208

def finished?
	super && @status != :running
end

#reactor ⇒ Object 



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# File 'lib/async/task.rb', line 76

def reactor
	self.root
end

#run(*arguments) ⇒ Object

Begin the execution of the task.



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# File 'lib/async/task.rb', line 116

def run(*arguments)
	if @status == :initialized
		@status = :running
		
		schedule(arguments)
	else
		raise RuntimeError, "Task already running!"
	end
end

#running? ⇒ Boolean

Check if the task is running.

Returns:

  • (Boolean) 


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# File 'lib/async/task.rb', line 202

def running?
	@status == :running
end

#sleep(duration = nil) ⇒ Object

Deprecated.

Prefer Kernel#sleep except when compatibility with ‘stable-v1` is required.



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# File 'lib/async/task.rb', line 91

def sleep(duration = nil)
	super
end

#stop(later = false) ⇒ Object

Stop the task and all of its children.



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# File 'lib/async/task.rb', line 157

def stop(later = false)
	if self.stopped?
		# If we already stopped this task... don't try to stop it again:
		return
	end
	
	if self.running?
		if self.current?
			if later
				Fiber.scheduler.push Stop::Later.new(self)
			else
				raise Stop, "Stopping current task!"
			end
		elsif @fiber&.alive?
			begin
				Fiber.scheduler.raise(@fiber, Stop)
			rescue FiberError
				Fiber.scheduler.push Stop::Later.new(self)
			end
		end
	else
		# We are not running, but children might be, so transition directly into stopped state:
		stop!
	end
end

#stopped? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/async/task.rb', line 220

def stopped?
	@status == :stopped
end

#stopping? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/async/task.rb', line 216

def stopping?
	@status == :stopping
end

#to_s ⇒ Object 



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# File 'lib/async/task.rb', line 86

def to_s
	"\#<#{self.description} (#{@status})>"
end

#wait ⇒ Object

Retrieve the current result of the task. Will cause the caller to wait until result is available. @raises If the task’s fiber is the current fiber.



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# File 'lib/async/task.rb', line 137

def wait
	raise "Cannot wait on own fiber" if Fiber.current.equal?(@fiber)
	
	if running?
		@finished ||= Condition.new
		@finished.wait
	end
	
	case @result
	when Exception
		raise @result
	else
		return @result
	end
end

#with_timeout(timeout, exception = TimeoutError, message = "execution expired", &block) ⇒ Object

Deprecated.

Replaced by Scheduler#timeout_after.



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# File 'lib/async/task.rb', line 96

def with_timeout(timeout, exception = TimeoutError, message = "execution expired", &block)
	Fiber.scheduler.timeout_after(timeout, exception, message, &block)
end

#yield ⇒ Object

Yield back to the reactor and allow other fibers to execute.



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# File 'lib/async/task.rb', line 101

def yield
	Fiber.scheduler.yield
end