Class: Async::Reactor

Inherits:
Object
  • Object
show all
Extended by:
Forwardable
Defined in:
lib/async/reactor.rb

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(wrappers: IO) ⇒ Reactor

Returns a new instance of Reactor.



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# File 'lib/async/reactor.rb', line 42

def initialize(wrappers: IO)
  @wrappers = wrappers
  
  @selector = NIO::Selector.new
  @timers = Timers::Group.new
  
  @fibers = []
  
  @stopped = true
end

Instance Attribute Details

#stopped ⇒ Object (readonly)

Returns the value of attribute stopped.



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# File 'lib/async/reactor.rb', line 54

def stopped
  @stopped
end

#wrappers ⇒ Object (readonly)

Returns the value of attribute wrappers.



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# File 'lib/async/reactor.rb', line 53

def wrappers
  @wrappers
end

Class Method Details

.run(*args, &block) ⇒ Object 



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# File 'lib/async/reactor.rb', line 36

def self.run(*args, &block)
  reactor = self.new
  
  reactor.async(*args, &block)
end

Instance Method Details

#async(*ios, &block) ⇒ Object 



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# File 'lib/async/reactor.rb', line 68

def async(*ios, &block)
  task = Task.new(ios, self, &block)
  
  # I want to take a moment to explain the logic of this.
  # When calling an async block, we deterministically execute it until the
  # first blocking operation. We don't *have* to do this - we could schedule
  # it for later execution, but it's useful to:
  # - Fail at the point of call where possible.
  # - Execute determinstically where possible.
  # - Avoid overhead if no blocking operation is performed.
  fiber = task.run
  
  # We only start tracking this if the fiber is still alive:
  @fibers << fiber if fiber.alive?
  
  # Async.logger.debug "Initial execution of task #{fiber} complete (#{result} -> #{fiber.alive?})..."
  return task
end

#register(*args) ⇒ Object 



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# File 'lib/async/reactor.rb', line 87

def register(*args)
  @selector.register(*args)
end

#run(*args, &block) ⇒ Object 



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# File 'lib/async/reactor.rb', line 95

def run(*args, &block)
  @stopped = false
  
  # Allow the user to kick of the initial async tasks.
  async(*args, &block) if block_given?
  
  @timers.wait do |interval|
    # - nil: no timers
    # - -ve: timers expired already
    # -   0: timers ready to fire
    # - +ve: timers waiting to fire
    interval = 0 if interval && interval < 0
    
    # Async.logger.debug "[#{self} Pre] Updating #{@fibers.count} fibers..."
    # Async.logger.debug @fibers.collect{|fiber| [fiber, fiber.alive?]}.inspect
    # As timeouts may have been updated, and caused fibers to complete, we should check this.
    @fibers.delete_if{|fiber| !fiber.alive?}
    
    # If there is nothing to do, then finish:
    # Async.logger.debug "[#{self}] @fibers.empty? = #{@fibers.empty?} && interval #{interval.inspect}"
    return if @fibers.empty? && interval.nil?
    
    # Async.logger.debug "Selecting with #{@fibers.count} fibers interval = #{interval}..."
    if monitors = @selector.select(interval)
      monitors.each do |monitor|
        if task = monitor.value
          # Async.logger.debug "Resuming task #{task} due to IO..."
          task.resume
        end
      end
    end
  end until @stopped
ensure
  # Async.logger.debug "[#{self} Ensure] Exiting run-loop (stopped: #{@stopped} exception: #{$!})..."
  # Async.logger.debug @fibers.collect{|fiber| [fiber, fiber.alive?]}.inspect
  @stopped = true
end

#sleep(duration) ⇒ Object 



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# File 'lib/async/reactor.rb', line 133

def sleep(duration)
  task = Fiber.current
  
  timer = self.after(duration) do
    if task.alive?
      task.resume
    end
  end
  
  result = Fiber.yield
  
  raise result if result.is_a? Exception
ensure
  timer.cancel if timer
end

#stop ⇒ Object 



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

def stop
  @stopped = true
end

#timeout(duration) ⇒ Object 



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# File 'lib/async/reactor.rb', line 149

def timeout(duration)
  backtrace = caller
  task = Fiber.current
  
  timer = self.after(duration) do
    if task.alive?
      error = TimeoutError.new("execution expired")
      error.set_backtrace backtrace
      task.resume error
    end
  end
  
  yield
ensure
  timer.cancel if timer
end

#with(io, &block) ⇒ Object 



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# File 'lib/async/reactor.rb', line 62

def with(io, &block)
  async do |task|
    task.with(io, &block)
  end
end

#wrap(io, task) ⇒ Object 



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

def wrap(io, task)
  @wrappers[io].new(io, task)
end