Class: Slave::LifeLine

Inherits:
Object
  • Object
show all
Defined in:
lib/slave.rb,
lib/slave-1.2.1.rb

Overview

the LifeLine class is used to communitacte between child and parent processes and to prevent child processes from ever becoming zombies or otherwise abandoned by their parents. the basic concept is that a socket pair is setup between child and parent. the child process, because it is a Slave, sets up a handler such that, should it’s socket ever grow stale, will exit the process. this class replaces the HeartBeat class from previous Slave versions.

Constant Summary collapse

FDS =

–{{{

ThreadSafeHash.new
DELEGATED = 
%w( puts gets read write close flush each )

Instance Method Summary collapse

Constructor Details

#initialize ⇒ LifeLine

Returns a new instance of LifeLine.



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# File 'lib/slave.rb', line 175

def initialize
  @pair = Socket.pair(Socket::AF_UNIX, Socket::SOCK_STREAM, 0)
  @owner = Process.pid
  @pid = nil
  @socket = nil
  @object_id = object_id

  @fds = @pair.map{|s| s.fileno}
  oid, fds = @object_id, @fds
  FDS[oid] = fds 
  ObjectSpace.define_finalizer(self){ FDS.delete oid } 
end

Instance Method Details

#catch(*ignored) ⇒ Object 



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# File 'lib/slave.rb', line 201

def catch(*ignored)
  raise if owner?
  @pair[0].close
  @pair[0] = nil
  @pid = Process.pid
  @socket = @pair[-1]
  @socket.sync = true
  close_unused_sockets_after_forking
end

#cling(&b) ⇒ Object 



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# File 'lib/slave.rb', line 268

def cling &b
  on_cut{ begin; b.call if b; ensure; Kernel.exit; end }.join
end

#close_unused_sockets_after_forking ⇒ Object 



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# File 'lib/slave.rb', line 211

def close_unused_sockets_after_forking
  begin
    to_delete = []
    begin
      FDS.each do |oid, fds|
        next if oid == @object_id
        begin
          IO.for_fd(fds.first).close
        rescue Exception => e
          STDERR.puts "#{ e.message } (#{ e.class })\n#{ e.backtrace.join 10.chr }"
        ensure
          to_delete << oid
        end
      end
    ensure
      FDS.ex{ to_delete.each{|oid| FDS.delete oid rescue 42} }
    end
    GC.start
  rescue Exception => e
    42
  end
end

#cut ⇒ Object Also known as: release 



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# File 'lib/slave.rb', line 234

def cut
  raise unless owner?
  raise unless @socket
  @socket.close rescue nil
  FDS.delete object_id
end

#on_cut(&b) ⇒ Object 



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# File 'lib/slave.rb', line 253

def on_cut &b
  at_exit{ begin; b.call; ensure; b = nil; end if b}
  Thread.new(Thread.current){|current|
    Thread.current.abort_on_exception = true
    begin
      each{|*a|}
    rescue Exception
      current.raise $!
      42
    ensure
      begin; b.call; ensure; b = nil; end if b
    end
  }
end

#owner? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/slave.rb', line 188

def owner?
  Process.pid == @owner
end

#throw(*ignored) ⇒ Object 



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# File 'lib/slave.rb', line 192

def throw(*ignored)
  raise unless owner?
  @pair[-1].close
  @pair[-1] = nil
  @pid = Process.pid
  @socket = @pair[0]
  @socket.sync = true
end