#!/usr/bin/env ruby
#
# built-in
#
  require 'optparse'
  require 'logger'
#
# http://raa.ruby-lang.org/project/lockfile/
#
  require 'lockfile'

  class Main
#--{{{
    VERSION = Lockfile::VERSION 

    USAGE = 
#--{{{
  <<-usage
  NAME
    rlock v#{ VERSION }

  SYNOPSIS
    rlock [options]+ lockfile [program [args]+ | -- program options+ [args]+]

  DESCRIPTTION
    rlock creates NFS safe lockfiles.  it can optionally run a program while
    holding the lock, ensuring lockfile removal on program exit.  if a program
    is specified to be run rlock will spawn a background thread to kept the
    lockfile 'fresh' by touching it at a regular interval.  in this way a lease
    is maintained on the lockfile and other processes attempting to obtain the
    lock can determine that it is in use.  see the '--refresh' option for how to
    control the touch interval.  any other process trying to obtain a lock will
    automatically remove a stale lockfile; a stale lockfile is one that is older
    than a certain age.  this age be controled via the '--max_age' option.

  ENVIRONMENT
    LOCKFILE_DEBUG=1 
      causes internal actions of the library to be shown on STDERR 

  DIAGNOSTICS
   rlock attempts to exit with the status of 'program' except where it
   cannot due to exceptional conditions.  in addition the message 

    'RLOCK SUBCOMMAND FAILURE' 
    
    will be printed on STDERR if 'program' exits with non-zero status.

   success => $? == 0
   failure => $? != 0

  AUTHOR
   ara.t.howard@gmail.com

  BUGS
    1 < bugno && bugno < 42

  OPTIONS
  usage
#--}}}

    EXAMPLES =
#--{{{
  <<-examples
  EXAMPLES

    0) simple usage - create lockfile in an atomic fashion (obtain a lock) 

      ~ > rlock lockfile

    1) safe usage - create a lockfile, execute a command, and remove lockfile

      ~ > rlock lockfile ls lockfile

    2) same as above, but logging verbose messages 

      ~ > rlock -v4 lockfile ls lockfile
   
    3) same as above, but logging verbose messages and showing actions internal
    to lockfile library

      ~ > rlock -v4 -d lockfile ls lockfile

    4) same as above

      ~ > LOCKFILE_DEBUG=1 rlock -v4 lockfile ls lockfile

    5) same as above

      ~ > export LOCKFILE_DEBUG=1
      ~ > rlock -v4 lockfile ls lockfile

    6) you need to tell the option parser to stop parsing rlock options if you
    intend to pass options to 'program' 

      ~ > rlock -v4 -d lockfile -- ls -ltar lockfile

       without the '--' rlock would consume the '-ltar' option as one of
       it's own.

    7) lock lockfile and exec 'program' - remove the lockfile if it is older
    than 4242 seconds

      ~ > rlock --max_age=4242 lockfile program 

    8) lock lockfile and exec 'program' - remove the lockfile if it is older
    than 4242 seconds, set the refresh rate to be 8 seconds.

      ~ > rlock --max_age=4242 --refresh=8 lockfile program 

    9) same as above, but fail if lockfile cannot be obtained within 1 minute

      ~ > rlock --max_age=4242 --refresh=8 --timeout=60 lockfile program 

    10) lockfile creation involves making some temporary files.  normally these
    are cleaned up unless rlock is killed with 'kill -9'.  these temp files are
    normally 'sweeped' - searched for and removed - unless the '--dont_sweep'
    option is given.  note that sweeping can remove ONLY old temp files created
    by the same host since there is otherwise no way to tell if the offending
    process is still running.

    lock lockfile and run program - do not do any sweeping

      ~ > rlock --dont_sweep lockfile program 

  examples
#--}}}

    EXIT_SUCCESS = 0
    EXIT_FAILURE = 1

    attr :argv
    attr :op
    attr :logger
    attr :config

    def initialize argv = ARGV
#--{{{
      @argv = mcp argv
      parse_opts
      if @opt_version
        puts Main::VERSION
        exit EXIT_SUCCESS
      end
      if @opt_help
        usage
        exit EXIT_SUCCESS
      end
      parse_argv
      run
#--}}}
    end
    def run
#--{{{
      init_logging

      debug{ "lockpath <#{ @lockpath }>" }

      opts = {}
      options = 
        %w(retries max_age sleep_inc min_sleep max_sleep suspend timeout refresh poll_retries poll_max_sleep)
      options.each do |opt|
        #if((val = eval("opt_#{ opt }")))
        if(send("opt_#{ opt }?"))
          val = send "opt_#{ opt }"
          begin
            val = (opts[opt] = String === val ? Integer(val) : val)
            logger.debug{ "<#{ opt }> <#{ val.inspect }>" }
          rescue
            logger.fatal{ "illegal value <#{ val.inspect }> for opt <#{ opt }>" }
            exit EXIT_FAILURE
          end
        end
      end

      opts['debug'] = true if opt_debug

      begin
        case @argv.size
          when 0
            opts['dont_clean'] = true
            logger.debug{ "opts <#{ opts.inspect }>" }
            logger.debug{ "aquiring lock <#{ @lockpath }>..." }
          #
          # simple usage - just create the lockfile with opts
          #
            lockfile = ::Lockfile.new @lockpath, opts
            lockfile.lock

            logger.debug{ "aquired lock <#{ @lockpath }>" }
          else
            logger.debug{ "opts <#{ opts.inspect }>" }
            logger.debug{ "aquiring lock <#{ @lockpath }>..." }
          #
          # block usage - create the lockfile with opts, run block, rm lockfile
          #
            status = 1

            lockfile = ::Lockfile.new @lockpath, opts

            lockfile.lock do
              logger.debug{ "aquired lock <#{ @lockpath }>" }
              logger.debug{ "cmd <#{ @argv.join ' ' }>" }
              v = nil
              begin
                v = $VERBOSE
                $VERBOSE = nil 
                STDOUT.flush
                STDERR.flush
                fork{ exec(*@argv) }
                pid, status = Process::wait2
              ensure
                $VERBOSE = v
              end
              logger.debug{ "status <#{ $? }>" }
            end

            status = status.exitstatus
            STDERR.puts "RLOCK SUBCOMMAND FAILURE" unless status == 0
            exit status
        end
      rescue => e
        logger.fatal{ e }
        exit EXIT_FAILURE
      end

      exit EXIT_SUCCESS
#--}}}
    end
    def parse_opts
#--{{{
      @op = OptionParser::new
      @op.banner = ''
      define_options
      @op.parse! argv

#--}}}
    end
    def parse_argv
#--{{{
      usage and exit EXIT_FAILURE if @argv.empty?
      @lockpath = @argv.shift
#--}}}
    end
    def define_options
#--{{{
      options = [
        ['--retries=n','-r', "default(#{ Lockfile.retries.inspect }) - (nil => forever)"],
        ['--max_age=n','-a', "default(#{ Lockfile.max_age.inspect })"],
        ['--sleep_inc=n','-s', "default(#{ Lockfile.sleep_inc.inspect })"],
        ['--max_sleep=n','-p', "default(#{ Lockfile.max_sleep.inspect })"],
        ['--min_sleep=n','-P', "default(#{ Lockfile.min_sleep.inspect })"],
        ['--suspend=n','-u', "default(#{ Lockfile.suspend.inspect })"],
        ['--timeout=n','-t', "default(#{ Lockfile.timeout.inspect }) - (nil => never)"],
        ['--refresh=n','-f', "default(#{ Lockfile.refresh.inspect })"],
        ['--debug','-d', "default(#{ Lockfile.debug.inspect })"],
        ['--poll_retries=n','-R', "default(#{ Lockfile.poll_retries.inspect })"],
        ['--poll_max_sleep=n','-S', "default(#{ Lockfile.poll_max_sleep.inspect })"],
        ['--dont_sweep','-w', "default(#{ Lockfile.dont_sweep.inspect })"],

        ['--version'],
        ['--verbosity=0-4|debug|info|warn|error|fatal','-v'],
        ['--log=path','-l'],
        ['--log_age=log_age'],
        ['--log_size=log_size'],
        ['--help','-h'],
      ]
      options.each do |option|
        opt = option.first.gsub(%r/(?:--)|(?:=.*$)/o,'').strip
        get, set = opt_attr opt
        value4 = lambda do |v|
          case v
            when NilClass, %r/^t|true$/i
              true
            when %r/^f|false$/i
              false
            when %r/^nil|nul|null$/i
              nil
            else
              v
          end
        end
        @op.def_option(*option) do |v|
          send set, value4[v]
        end
      end
#--}}}
    end
    %w(debug info warn error fatal).each do |m|
      eval "def #{ m }(*args,&block);@logger.#{ m }(*args,&block);end"
    end
    def init_logging
#--{{{
      if @opt_log_age
        @opt_log_age = @opt_log_age.to_i if @opt_log_age =~ /\d/
      end
      if @opt_log_size
        @opt_log_size = @opt_log_size.to_i if @opt_log_size =~ /\d/
      end
      $logger = @logger = Logger::new(@opt_log || STDERR, @opt_log_age, @opt_log_size)

      level = nil
      @opt_verbosity ||= 'info'
      @opt_verbosity =
        case @opt_verbosity
          when /^\s*(?:4|d|debug)\s*$/io
            level = 'Logging::DEBUG'
            4
          when /^\s*(?:3|i|info)\s*$/io
            level = 'Logging::INFO'
            3
          when /^\s*(?:2|w|warn)\s*$/io
            level = 'Logging::WARN'
            2
          when /^\s*(?:1|e|error)\s*$/io
            level = 'Logging::ERROR'
            1
          when /^\s*(?:0|f|fatal)\s*$/io
            level = 'Logging::FATAL'
            0
          else
            abort "illegal verbosity setting <#{ @opt_verbosity }>" 
        end
      @logger.level = 2 - ((@opt_verbosity % 5) - 2) 
#--}}}
    end
    def usage io = STDOUT
#--{{{
      io << USAGE
      io << "\n"
      io << @op
      io << "\n"
      io << EXAMPLES if defined? EXAMPLES
      self
#--}}}
    end
    def opt_attr opt
#--{{{
      query = "opt_#{ opt }?"
      get = "opt_#{ opt }"
      set = "#{ get }="
      code = <<-code
        class << self
          def #{ query }; defined? @#{ get }; end
          def #{ get }; defined?(@#{ get }) ? @#{ get } : nil; end
          def #{ set } value; @#{ get } = value; end
        end
      code
      instance_eval code 
      [get, set]
#--}}}
    end
    def mcp obj
#--{{{
      Marshal::load(Marshal::dump(obj))
#--}}}
    end
#--}}}
  end

  Main::new