Class: NIO::Selector

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

Overview

Selectors monitor IO objects for events of interest

Class Method Summary collapse

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

Class Method Details

.iops2sym(interest_ops) ⇒ Object

Convert Java NIO interest ops to the corresponding Ruby symbols



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# File 'lib/nio/jruby/selector.rb', line 29

def self.iops2sym(interest_ops)
  case interest_ops
  when SelectionKey::OP_READ, SelectionKey::OP_ACCEPT
    :r
  when SelectionKey::OP_WRITE, SelectionKey::OP_CONNECT
    :w
  when SelectionKey::OP_READ | SelectionKey::OP_WRITE
    :rw
  when 0 then nil
  else raise ArgumentError, "unknown interest op combination: 0x#{interest_ops.to_s(16)}"
  end
end

.sym2iops(interest, channel) ⇒ Object

Convert nio4r interest symbols to Java NIO interest ops



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# File 'lib/nio/jruby/selector.rb', line 8

def self.sym2iops(interest, channel)
  case interest
  when :r
    if channel.validOps & SelectionKey::OP_ACCEPT != 0
      SelectionKey::OP_ACCEPT
    else
      SelectionKey::OP_READ
    end
  when :w
    if channel.respond_to? :connected? and not channel.connected?
      SelectionKey::OP_CONNECT
    else
      SelectionKey::OP_WRITE
    end
  when :rw
    super(:r, channel) | super(:w, channel)
  else raise ArgumentError, "invalid interest type: #{interest}"
  end
end

Instance Method Details

#close ⇒ Object

Close this selector



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# File 'lib/nio/selector.rb', line 109

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 120

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 31

def deregister(io)
  @lock.synchronize do
    monitor = @selectables.delete io
    monitor.close if monitor
    monitor
  end
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
    raise ArgumentError, "this IO is already registered with the selector" if @selectables[io]

    monitor = Monitor.new(io, interest)
    @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 40

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 45

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
    end

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

    results = []
    ready_readers.each do |io|
      if io == @wakeup
        # Clear all wakeup signals we've received by reading them
        # Wakeups should have level triggered behavior
        begin
          @wakeup.read_nonblock(1024)

          # Loop until we've drained all incoming events
          redo
        rescue Errno::EWOULDBLOCK
        end

        return
      else
        monitor = @selectables[io]
        monitor.readiness = :r
        results << monitor
      end
    end

    ready_readwriters = ready_readers & ready_writers
    ready_writers = ready_writers - ready_readwriters

    [[ready_writers, :w], [ready_readwriters, :rw]].each do |ios, readiness|
      ios.each do |io|
        monitor = @selectables[io]
        monitor.readiness = readiness
        results << monitor
      end
    end

    results
  end
end

#select_each(timeout = nil) ⇒ Object

Iterate across all selectable monitors



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# File 'lib/nio/selector.rb', line 94

def select_each(timeout = nil, &block)
  selected = select(timeout)
  return unless selected
  selected.each(&block)
  selected.size
end

#wakeup ⇒ Object

Wake up the other thread that’s currently blocking on this selector



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# File 'lib/nio/selector.rb', line 102

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