Class: Build::Graph::Task

Inherits:
Object
  • Object
show all
Defined in:
lib/build/graph/task.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(walker, node) ⇒ Task

Returns a new instance of Task.



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# File 'lib/build/graph/task.rb', line 39

def initialize(walker, node)
	@walker = walker
	
	@walker.tasks[node] = self
	
	@node = node
	@fiber = nil
	
	@error = nil
	
	# Tasks that must be complete before finishing this task.
	@children = []
	
	@state = nil
	
	@inputs_failed = false
end

Instance Attribute Details

#children ⇒ Object (readonly)

Returns the value of attribute children.



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# File 'lib/build/graph/task.rb', line 60

def children
  @children
end

#error ⇒ Object (readonly)

The error, if the execution of the node fails.



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# File 'lib/build/graph/task.rb', line 66

def error
  @error
end

#inputs ⇒ Object (readonly)

Returns the value of attribute inputs.



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# File 'lib/build/graph/task.rb', line 57

def inputs
  @inputs
end

#inputs_failed ⇒ Object (readonly)

A list of any inputs whose relevant tasks failed:



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# File 'lib/build/graph/task.rb', line 73

def inputs_failed
  @inputs_failed
end

#node ⇒ Object (readonly)

Returns the value of attribute node.



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# File 'lib/build/graph/task.rb', line 70

def node
  @node
end

#outputs ⇒ Object (readonly)

Returns the value of attribute outputs.



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# File 'lib/build/graph/task.rb', line 58

def outputs
  @outputs
end

#state ⇒ Object (readonly)

The state of the task, one of nil, :complete or :failed.



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# File 'lib/build/graph/task.rb', line 63

def state
  @state
end

#walker ⇒ Object (readonly)

Returns the value of attribute walker.



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# File 'lib/build/graph/task.rb', line 68

def walker
  @walker
end

Instance Method Details

#changed! ⇒ Object 



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# File 'lib/build/graph/task.rb', line 147

def changed!
	@walker.delete(@node) if (@inputs.update! or @outputs.update!)
end

#complete? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/build/graph/task.rb', line 133

def complete?
	@state == :complete
end

#directories ⇒ Object 



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# File 'lib/build/graph/task.rb', line 151

def directories
	(@inputs.roots + @outputs.roots).collect{|path| path.to_s}
end

#dirty? ⇒ Boolean

Returns true if the outputs of the task are out of date w.r.t. the inputs. Currently, does not take into account if the input is a glob and files have been added.

Returns:

  • (Boolean) 


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# File 'lib/build/graph/task.rb', line 139

def dirty?
	if @outputs
		@outputs.dirty?(@inputs)
	else
		true
	end
end

#failed? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/build/graph/task.rb', line 129

def failed?
	@state == :failed
end

#invoke(node) ⇒ Task

Returns the child task that was created to update the node.

Returns:

  • (Task) —

    the child task that was created to update the node.

Raises:

  • (ArgumentError) 


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# File 'lib/build/graph/task.rb', line 119

def invoke(node)
	child_task = @walker.call(node, self)
	
	raise ArgumentError.new("Invalid child task") unless child_task
	
	@children << child_task
	
	return child_task
end

#to_s ⇒ Object 



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# File 'lib/build/graph/task.rb', line 155

def to_s
	"#<#{self.class} #{node_string} #{state_string}>"
end

#visit ⇒ Object

Derived task can override this function to provide appropriate behaviour.



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# File 'lib/build/graph/task.rb', line 76

def visit
	update_inputs_and_outputs
	
	# Inforn the walker a new task is being generated for this node:
	@walker.enter(self)
	
	if @fiber
		raise RuntimeError, "Task is already running!"
	end
	
	@fiber = Fiber.new do
		# If all inputs were good, we can update the node.
		if wait_for_inputs?
			begin
				yield
			rescue TransientError => error
				fail!(error)
			end
		else
			fail!(InputsFailed)
		end
		
		if wait_for_children?
			update_outputs
		else
			fail!(ChildrenFailed)
		end
		
		@state ||= :complete
		
		@walker.exit(self)
		
		@fiber = nil
	end
	
	# Schedule the work, hopefully synchronously:
	@fiber.resume
	
	# This allows the child task to be passed back to the parent when it is first invoked.
	return self
end