Class: Celluloid::Future

Inherits:
Object
  • Object
show all
Defined in:
lib/celluloid/future.rb

Overview

Celluloid::Future objects allow methods and blocks to run in the background, their values requested later

Defined Under Namespace

Classes: Result

Instance Method Summary collapse

Constructor Details

#initialize(*args, &block) ⇒ Future

Create a future bound to a given receiver, or with a block to compute



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# File 'lib/celluloid/future.rb', line 8

def initialize(*args, &block)
  @mutex = Mutex.new
  @ready = false
  @result = nil
  @forwards = nil

  if block
    @call = SyncCall.new(self, :call, args)
    InternalPool.get do
      begin
        @call.dispatch(block)
      rescue
        # Exceptions in blocks will get raised when the value is retrieved
      end
    end
  else
    @call = nil
  end
end

Instance Method Details

#execute(receiver, method, args, block) ⇒ Object

Execute the given method in future context



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# File 'lib/celluloid/future.rb', line 29

def execute(receiver, method, args, block)
  @mutex.synchronize do
    raise "already calling" if @call
    @call = SyncCall.new(self, method, args, block)
  end

  receiver << @call
end

#signal(value) ⇒ Object Also known as: <<

Signal this future with the given result value



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# File 'lib/celluloid/future.rb', line 78

def signal(value)
  result = Result.new(value, self)

  @mutex.synchronize do
    raise "the future has already happened!" if @ready

    if @forwards
      @forwards.is_a?(Array) ? @forwards.each { |f| f << result } : @forwards << result
    end

    @result = result
    @ready = true
  end
end

#value(timeout = nil) ⇒ Object Also known as: call

Obtain the value for this Future



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# File 'lib/celluloid/future.rb', line 39

def value(timeout = nil)
  ready = result = nil

  begin
    @mutex.lock
    raise "no call requested" unless @call

    if @ready
      ready = true
      result = @result
    else
      case @forwards
      when Array
        @forwards << Thread.mailbox
      when NilClass
        @forwards = Thread.mailbox
      else
        @forwards = [@forwards, Thread.mailbox]
      end
    end
  ensure
    @mutex.unlock
  end

  unless ready
    result = Thread.receive(timeout) do |msg|
      msg.is_a?(Future::Result) && msg.future == self
    end
  end

  if result
    result.value
  else
    raise "Timed out"
  end
end