#!/usr/bin/env bash
#
# RebuildQueue daemon control
# AUTHOR: Jay Allen, Endevver Consulting, http://www.jayallen.org
# $Id$

RQ=plugins/RebuildQueue/RebuildQueue

man() {
    cat <<EOU | ${PAGER:-less}
NAME
    $(basename $0) - RebuildQueue Daemon controller
SYNOPSIS
    Usage: $(basename $0) [-v] [-l LOG] [-w NUM] [-m MT_DIR] COMMAND

DESCRIPTION

    This script was developed to more easily start, stop and restart
    RebuildQueue in dameon mode providing you with the most common options
    which can be specified either by options flags or environment variables.

    While you could use the RebuildQueue.pl script itself, a few problems
    have been experienced (which haven't been tracked down yet) with it as
    the crontab bootstrapper:

        * Under certain circumstances, when RebuildQueue.pl is run from the
          crontab, it is not quitting as designed when another daemon with
          the same worker ID is already running.

        * A memory leak has been witnessed that occurs most often in
          long-running RebuildQueue daemons.

    Using the '$(basename $0) restart' properly kills the pre-existing
    RebuildQueue daemons before replacing them with new versions, killing
    two birds (and a few daemons) with one stone.

COMMANDS

    start
        Starts RebuildQueue in daemon mode launching as many workers as is
        specified by the -w flag. This is the default and is only needed if
        no other options are specified.

    stop
        Terminates all running RebuildQueue processes for the specified
        Movable Type installation. (Equivlent to 'kill -INT PIDs')

    restart
        Kills all running RebuildQueue processes before starting new
        processes.

    test
        Shows you the configuration that would be used by the script
        after processing all environment variables (see below) and 
        command-line options and exits.  If the -v flag is also specified
        the sequence of commands will also be shown with those filled 
        in values.

    help
        Displays this help documentation

OPTIONS

    -m, --mthome
        Specifies the absolute path to the Movable Type directory
        containing the RebuildQueue plugin. This can also be specified by
        the MT_HOME environment variable.

    -l, --log LOG
        Send output to the file LOG. If LOG is not an absolute path it will
        be written relative to your MT directory (e.g. logs/rebuild.log). If
        not specified, the output will be discarded (/dev/null). Can
        alternately be specified by the RQLOG environment variable.

    -w, --workers NN
        Number of RebuildQueue daemn workers to start. Default is 1.

    -v, --verbose
        By default, the script outputs nothing in the case it is succesful
        which is good for cron. This option turns on chattiness.

ENVIRONMENT

    If you prefer, the following environment variables can be set instead of
    specifying them on the command-line or in your crontab.

        MT_HOME
            Set to an absolute path. Equivalent to -m.

        RQLOG
            Set to either an absolute path or one relative to the MT
            directory. Equivalent to -l.

        RQWORKERS
            Set to the number of desired workers. Can optionally be set by
            the RQWORKERS environment variable. Equivalent to -w

    NOTE: Options specified on the command-line take precedence over these
    environment variables. This is useful if you run multiple installations
    and want to set defaults yet override others on a per-installation
    basis.

RETURN VALUES
     The test utility exits with one of the following values:

     0       expression evaluated to true.

     1       expression evaluated to false or expression was missing.

     >1      An error occurred.

DISCLAIMER
       The author of this utility will be held no responsibility for any damages and losses of data and/or files that may be caused by the use thereof.

       Use me at your own risk!

AUTHOR
       Jay Allen, Endevver Consulting, http://jayallen.org

COPYRIGHT
       Copyright 2008, Jay Allen

       This script is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

EOU
    exit 0
}

usage() {

    [[ -n "$1" ]] && local error=-1 && echo "Error: $1"
    cat <<EOU
Usage: $(basename $0) [-v] [-l LOG] [-w #] [-m DIR] COMMAND
Commands:
    start, stop, restart, test and help
Options:
    -m, --mthome DIR    RebuildQueue output log file
    -l, --log FILE      RebuildQueue output log file
    -w, --workers N     Number of RebuildQueue daemn workers to start
    -v, --verbose       Displays more information
EOU
    exit $error
}

dispatch() {
    while [ "$1" ]; do
        [ $VERBOSE ] && echo "$1"
        [ $TEST ] || eval "$1";
        shift;
    done
}

progress() {
    [ $VERBOSE ] || return
    while [ "$1" ]; do echo ">>> $1"; shift; done
}

parse_options() {
    [[ -z "$1" ]] && usage

    while [[ "$1" =~ ^(-|start|stop|restart|test|help) ]]; do
        case "${1//-/}" in
            m | mt       ) MT_HOME=$2; shift;;
            l | log      ) RQLOG=$2; shift;;
            w | workers  ) RQWORKERS=$2; shift;;
            v | verbose  ) VERBOSE=1;;
            help         ) man;;
            test         ) TEST=1;;
            start        ) START=1;;
            restart      ) START=1;STOP=1;;
            stop         ) STOP=1;;
            *) usage "Unknown option: $1";;
        esac 
        shift
    done

    [ "$MT_HOME" ]       || usage "MT home directory not specified"
    [ -d "$MT_HOME" ]    || usage "$MT_HOME not found or is not a directory"
    [ -e "$MT_HOME/$RQ.pl" ] || usage "$MT_HOME/$RQ.pl not found"
    [[ "${RQLOG:=/dev/null}" =~ ^/ ]] || RQLOG="$MT_HOME/$RQLOG"

    RQWORKERS=${RQWORKERS:-1}
    export MT_HOME=${MT_HOME%%/}
}

show_config() {
    echo "Using the following values:"
    for I in MT_HOME RQLOG RQWORKERS STOP START TEST VERBOSE; do
        printf "   %-10s %s\n" "$I:" "${!I}"
    done
}

stop() {
    if [[ $(ps ax  2>/dev/null) ]]; then
        psoptions="ax"    # BSD systems
    else
        psoptions="-ef"   # Other systems
    fi
    PSOUT="$(ps $psoptions | grep $MT_HOME/$RQ.pl | grep -v grep )"
    if [ "$PSOUT" ]; then
        PIDS=$(echo "$PSOUT" | awk {'print $1'} | xargs )
        progress "RebuildQueue processes to kill:"
        echo "$PSOUT"
        dispatch "kill -INT $PIDS"
    else
        progress "No RebuildQueue processes exist"
    fi
}

start() {
    progress "Starting $RQWORKERS RebuildQueue daemon processes"
    while [[ $RQWORKERS -gt 0 ]]; do
        dispatch "MT_HOME='$MT_HOME' nohup nice -n 15 $MT_HOME/$RQ.pl --daemonize  --worker $RQWORKERS >> $RQLOG 2>&1 &"
        RQWORKERS=$(($RQWORKERS-1))
    done
}

parse_options "$@"
[ $TEST ] && show_config
[[ -n "$STOP" || -n "$TEST" ]] && stop
[[ -n "$START" || -n "$TEST" ]] && start
progress "Done."
exit 0