Class: NIO::Selector

Inherits:
Object
  • Object
show all
Defined in:
lib/nio/selector.rb,
ext/nio4r/selector.c

Overview

Selectors monitor IO objects for events of interest

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Object

Methods



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# File 'lib/nio/selector.rb', line 5

def initialize
  @selectables = {}
  @lock = Mutex.new

  # Other threads can wake up a selector
  @wakeup, @waker = IO.pipe
  @closed = false
end

Instance Method Details

#close ⇒ Object

Close this selector and free its resources



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# File 'lib/nio/selector.rb', line 110

def close
  @lock.synchronize do
    return if @closed

    @wakeup.close rescue nil
    @waker.close rescue nil
    @closed = true
  end
end

#closed? ⇒ Boolean

Is this selector closed?

Returns:

  • (Boolean) 


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# File 'lib/nio/selector.rb', line 121

def closed?; @closed end

#deregister(io) ⇒ Object

Deregister the given IO object from the selector



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# File 'lib/nio/selector.rb', line 33

def deregister(io)
  @lock.synchronize do
    monitor = @selectables.delete io
    monitor.close(false) if monitor and not monitor.closed?
    monitor
  end
end

#empty? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'ext/nio4r/selector.c', line 31

def empty?
  @selectables.empty?
end

#register(io, interest) ⇒ Object

Register interest in an IO object with the selector for the given types of events. Valid event types for interest are:

  • :r - is the IO readable?

  • :w - is the IO writeable?

  • :rw - is the IO either readable or writeable?



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# File 'lib/nio/selector.rb', line 19

def register(io, interest)
  @lock.synchronize do
    if monitor = @selectables[io]
      raise ArgumentError, "this IO is already registered with the selector as #{monitor.interests.inspect}"
    end

    monitor = Monitor.new(io, interest, self)
    @selectables[io] = monitor

    monitor
  end
end

#registered?(io) ⇒ Boolean

Is the given IO object registered with the selector?

Returns:

  • (Boolean) 


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# File 'lib/nio/selector.rb', line 42

def registered?(io)
  @lock.synchronize { @selectables.has_key? io }
end

#select(timeout = nil) ⇒ Object

Select which monitors are ready



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# File 'lib/nio/selector.rb', line 47

def select(timeout = nil)
  @lock.synchronize do
    readers, writers = [@wakeup], []

    @selectables.each do |io, monitor|
      readers << io if monitor.interests == :r || monitor.interests == :rw
      writers << io if monitor.interests == :w || monitor.interests == :rw
      monitor.readiness = nil
    end

    ready_readers, ready_writers = Kernel.select readers, writers, [], timeout
    return unless ready_readers # timeout or wakeup
    
    selected_monitors = Set.new

    ready_readers.each do |io|
      if io == @wakeup
        # Clear all wakeup signals we've received by reading them
        # Wakeups should have level triggered behavior
        @wakeup.read(@wakeup.stat.size)
        return
      else
        monitor = @selectables[io]
        monitor.readiness = :r
        selected_monitors << monitor
      end
    end
    
    ready_writers.each do |io|
      monitor = @selectables[io]
      monitor.readiness = case monitor.readiness
      when :r
        :rw
      else
        :w
      end
      selected_monitors << monitor
    end
    
    if block_given?
      selected_monitors.each do |m|
        yield m
      end
      selected_monitors.size
    else
      selected_monitors
    end
  end
end

#wakeup ⇒ Object

Wake up a thread that’s in the middle of selecting on this selector, if any such thread exists.

Invoking this method more than once between two successive select calls has the same effect as invoking it just once. In other words, it provides level-triggered behavior.



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# File 'lib/nio/selector.rb', line 103

def wakeup
  # Send the selector a signal in the form of writing data to a pipe
  @waker.write "\0"
  nil
end