Contents

#!/bin/bash
# Grzegorz Wierzowiecki
# "mutex_dir.sh"
# GNU GPL or BSD - as you like
# Script inspiered by:
# http://www.bash-hackers.org/wiki/doku.php/howto/mutex

function print_help(){
  cat << HELP_INFO
Usage:
$0 lock lock-dir calling_app_pid
$0 unlock lock-dir
Return:
0 - on success
1 - on general fail
2 - when locking failed
3 - when received signal
HELP_INFO
  exit
}

# lock dirs/files
lock_dir="$2"
app_pid="$3"
pid_file="${lock_dir}/pid"
user_file="${lock_dir}/user"

# exit codes
ENO_SUCCESS=0
ENO_GENERAL=1
ENO_LOCKFAIL=2
ENO_RECVSIG=3

function lock(){
  if ! kill -0 $app_pid &>/dev/null; then
    echo 'Calling app pid (='$app_pid')is not responding.'
    return 1
  fi
  local lock_dir="$1"
  if mkdir "${lock_dir}" &>/dev/null; then
    # lock succeeded, store the PID
    echo "$app_pid" >"${pid_file}"
    # Dump the user having this lock in another file
    echo "${SUDO_USER}" >"${user_file}"
    return ${ENO_SUCCESS}
  else
    # lock failed, now check if the other PID is alive
    other_pid="$(cat "${pid_file}" 2>/dev/null)"
    if [ $? != 0 ]; then
      # Pid file does not exists - propably directory is beeing deleted
      return ${ENO_LOCKFAIL}
    fi
    if ! kill -0 $other_pid &>/dev/null; then
      # lock is stale, remove it and restart
      unlock "$lock_dir"
      lock "$lock_dir"
      return $?
    else
      # lock is valid and OTHERPID is active - exit, we're locked!
      #echo "lock failed, PID ${OTHERPID} is active" >&2
      return ${ENO_LOCKFAIL}
    fi
  fi
  return 0
}

function unlock(){
  rm -r "$1" &>/dev/null
  return $?
}

case "$1" in
  lock) lock "$lock_dir" ; exit $? ;;
  unlock) unlock "$lock_dir"; exit $? ;;
  *) print_help ;;
esac

Version data entries

67 entries across 67 versions & 1 rubygems

Version	Path
hybrid_platforms_conductor-32.7.0	lib/hybrid_platforms_conductor/mutex_dir
hybrid_platforms_conductor-32.6.0	lib/hybrid_platforms_conductor/mutex_dir
hybrid_platforms_conductor-32.5.0	lib/hybrid_platforms_conductor/mutex_dir
hybrid_platforms_conductor-32.4.2	lib/hybrid_platforms_conductor/mutex_dir
hybrid_platforms_conductor-32.4.1	lib/hybrid_platforms_conductor/mutex_dir
hybrid_platforms_conductor-32.4.0	lib/hybrid_platforms_conductor/mutex_dir
hybrid_platforms_conductor-32.3.6	lib/hybrid_platforms_conductor/mutex_dir