Module: ProcessStarter

Defined in:
lib/process_starter.rb

Constant Summary collapse

WINRUN =

run in windows?

(RUBY_PLATFORM =~ /mswin|mingw/) ? true : false
HAVE_SPAWN =

have Ruby 1.9 spawn method

defined?(spawn) ? true : false
HAVE_POSIX_SPAWN =

loaded posix/spawn lib

defined?(POSIX::Spawn::spawn) ? true : false

Class Attribute Summary collapse

Class Method Summary collapse

Class Attribute Details

.allowed_methods ⇒ Object

Returns the value of attribute allowed_methods.



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# File 'lib/process_starter.rb', line 17

def allowed_methods
  @allowed_methods
end

Class Method Details

.close_io(do_close = false, debug = false) ⇒ Object

find all opened io descriptors in current process without FD_CLOEXEC flag (auto close on exec/system/spawn) based on close_io from: daemons.rubyforge.org/Daemonize.html



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# File 'lib/process_starter.rb', line 94

def self.close_io( do_close=false, debug = false )
  close_them = []
  # Make sure all input/output streams are closed
  puts "close_io: Part I" if debug
  # Part I: close all IO objects (except for STDIN/STDOUT/STDERR)
  ObjectSpace.each_object(IO) do |io|
    unless [STDIN, STDOUT, STDERR].include?(io)
      begin
#        puts "os #{io.to_i}, and="
#        puts io.fcntl(Fcntl::F_GETFD) & Fcntl::FD_CLOEXEC
        if (not io.closed?) and (io.fcntl(Fcntl::F_GETFD) & Fcntl::FD_CLOEXEC) == 0
          close_them << io.to_i
          puts "Closing #{io.inspect}" if debug
          io.close if do_close
        end
      rescue ::Exception
      end
    end
  end
#  puts close_them.inspect

puts "close_io: Part II" if debug
  # Make sure all input/output streams are closed
  # Part II: close all file decriptors (except for STDIN/STDOUT/STDERR)
  ios = Array.new(8192) {|i| IO.for_fd(i) rescue nil}.compact
  ios.each do |io|
    puts io.to_i if debug
    next if io.fileno < 3
    puts "checking flag" if debug
    r = begin; io.fcntl(Fcntl::F_GETFD) & Fcntl::FD_CLOEXEC != 0 rescue false; end
    puts if debug
#      puts io.fcntl(Fcntl::F_GETFD) & Fcntl::FD_CLOEXEC
#      next if (io.fcntl(Fcntl::F_GETFD) & Fcntl::FD_CLOEXEC != 0)
    next if r
#    puts "adding"
    close_them << io.to_i
    if do_close
      puts "Closing #{io.inspect}" if debug
      io.close  ### rescue nil -- DO NOT need to have rescue here, because if we cannot close - it is some kind of exception which need to be tracked
    end
  end
#  puts close_them.inspect

  close_them.uniq
end

.log(m) ⇒ Object 



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# File 'lib/process_starter.rb', line 23

def self.log(m)
  defined?(RAILS_DEFAULT_LOGGER) ? RAILS_DEFAULT_LOGGER.info(m) : puts(m)
end

.start(s, allowed_methods = nil) ⇒ Object

Starts the process not waiting for it’s finish, so child process run in parralel not inheritting file descriptors, so it finds and closes all opened handels works in windows and linux



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# File 'lib/process_starter.rb', line 31

def self.start(s, allowed_methods = nil )
  allowed_methods ||= self.allowed_methods

  log "********* ProcessStarter.start INVOKING EXTERNAL COMMAND #{s}, WINRUN IS #{WINRUN}, HAVE_POSIX_SPAWN IS #{HAVE_POSIX_SPAWN}, HAVE_SPAWN is #{HAVE_SPAWN}, allowed_methods are #{allowed_methods.inspect}"
  if WINRUN
#      if s.index("'")
#        s = s.gsub("'","\\'")
#      end    
    @@have_psexec ||= allowed_methods.include?(:psexec) ? ((`psexec /?` rescue "") =~ /computer/ ? 2 : 1) : -1
    if @@have_psexec == 2 and allowed_methods.include?(:psexec)
      log "starting using psexec"
      # -d = detach (nowait)
      # -w = current working directory
      r = system("psexec -d -w #{Dir.pwd} #{s}")
    else
      log "starting using START cmd /c (inherits descriptors (?) - THIS IS BAD, PLEASE DOWNLOAD and COPY PSEXEC TO AVAILABLE 'PATH')"
      # CANNOT call close_io here, because it will close descriptors in current (parent) process
      # close_io(true,true)
      system("start /b cmd /c #{s}")
    end
  else
    log "Executing in Linux style"

    # fix "s" for stdin, stdout, stderr
    nilport = WINRUN ? "NUL" : "/dev/null"
    # not specified stdin?
    if not s =~ /</
      s = s + " <#{nilport}"
    end
    # not specified both stdout and stderr?
    if not s =~ />/
      s = s + " >#{nilport} 2>#{nilport}"
    end
    # not specified stderr?
    if not s =~ /2>/
      s = s + " 2>#{nilport}"
    end
    # we omit the case: "program 2>nil", which specifies that stdout is not redirected, which means that 
    # if user specify 2>, he is clever, and has to specify 1> too.

    if HAVE_POSIX_SPAWN and allowed_methods.include?(:posix_spawn)
      close_them = Hash[ close_io().map {|x| [x, :close]} ]
      log "POSIX::Spawn::spawn with close descriptors: #{close_them.inspect}"
      Process.detach POSIX::Spawn::spawn( s, close_them) 
    elsif HAVE_SPAWN and allowed_methods.include?(:spawn)
      # we hope on http://www.ruby-doc.org/core-1.9.3/Process.html#method-c-spawn
      # [close_others => true] option
      # TODO: check it
      log "Ruby 1.9 spawn"
      Process.detach spawn( s ) 
    else
      log "fork{ close_io; exec }"
      Process.detach fork {
        close_io(true)
        exec(s)
      } 
    end
  end
end