Class: Spork::Forker

Inherits:
Object
  • Object
show all
Defined in:
lib/spork/forker.rb

Overview

A helper class that allows you to run a block inside of a fork, and then get the result from that block.

Example:

forker = Spork::Forker.new do
  sleep 3
  "success"
end

forker.result # => "success"

Defined Under Namespace

Classes: ForkDiedException

Instance Method Summary collapse

Constructor Details

#initialize(&block) ⇒ Forker

Returns a new instance of Forker


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# File 'lib/spork/forker.rb', line 15

def initialize(&block)
  return unless block_given?
  @child_io, @server_io = UNIXSocket.socketpair
  @child_pid = Kernel.fork do
    begin
      @server_io.close
      Marshal.dump(yield, @child_io)
      # wait for the parent to acknowledge receipt of the result.
      master_response = Marshal.load(@child_io)
    rescue EOFError
      nil
    rescue Exception => e
      puts "Exception encountered: #{e.inspect}\nbacktrace:\n#{e.backtrace * %(\n)}"
    end
    
    # terminate, skipping any at_exit blocks.
    exit!(0)
  end
  @child_io.close
end

Instance Method Details

#abortObject

abort the current running fork


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# File 'lib/spork/forker.rb', line 56

def abort
  if running?
    Process.kill(Signal.list['TERM'], @child_pid)
    @child_pid = nil
    true
  end
end

#resultObject

Wait for the fork to finish running, and then return its return value.

If the fork was aborted, then result returns nil.


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# File 'lib/spork/forker.rb', line 39

def result
  return unless running?
  result_thread = Thread.new do
    begin
      @result = Marshal.load(@server_io)
      Marshal.dump('ACK', @server_io)
    rescue ForkDiedException, EOFError
      @result = nil
    end
  end
  Process.wait(@child_pid)
  result_thread.raise(ForkDiedException) if @result.nil?
  @child_pid = nil
  @result
end

#running?Boolean

Returns:

  • (Boolean)

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# File 'lib/spork/forker.rb', line 64

def running?
  return false unless @child_pid
  Process.getpgid(@child_pid)
  true
rescue Errno::ESRCH
  false
end