#!/bin/sh
#
# Snapshot of the current GridEngine configuration using git for the
# backend storage and tracking mechanism.
#
# Should normally be called via a cronjob.
#
# Following Edward Dale's idea:
# http://scompt.com/blog/archives/2009/10/13/versioned-grid-engine-configuration
# but using git for the backend
#
# initialize:
#
# git --git-dir=$GIT_DIR init --bare --shared=world
#
# Note: we use Perl for inplace editing since some versions of sed have
#       problems with this task.
################################################################################
################################################################################
# CUSTOMIZE THESE SETTINGS TO MATCH YOUR REQUIREMENTS:

SGE_ROOT=/opt/grid
SGE_CELL=default
GIT_DIR=/data/cfd/share/git-repo/gridengine-config.git

#
# END OF CUSTOMIZE SETTINGS
################################################################################
################################################################################
Script=${0##.*/}
saveScript="$SGE_ROOT/util/upgrade_modules/save_sge_config.sh"
export SGE_ROOT SGE_CELL GIT_DIR

for i in git perl
do
    type $i >/dev/null 2>&1 || {
        echo "Error: $Script - no '$i' found"
        exit 1
    }
done

#------------------------------------------------------------------------------
usage() {
    while [ "$#" -ge 1 ]; do echo "$1"; shift; done
    cat<<USAGE

usage: ${0##*/} [OPTION | GIT_COMMAND]
options:
  -help     display this usage
  init      initialize git repo in $GIT_DIR

pass-through git commands:
  log       ls-files
  show      whatchanged

  Snapshot of the current GridEngine configuration using git for the
  backend storage and tracking mechanism.

* git repository stored here:
  $GIT_DIR

copyright (c) 2009-10 <Mark.Olesen@faurecia.com>

USAGE
    exit 1
}
#------------------------------------------------------------------------------
# parse options
while [ "$#" -gt 0 ]
do
    case "$1" in
    ( help | -h | -help )
        usage
        ;;
    ( init )
        shift
        if [ -d "$GIT_DIR" ]
        then
            echo "Error: $Script - $GIT_DIR already exists"
            exit 1
        else
            git --git-dir=$GIT_DIR init --bare --shared=world $@
            rc=$?

            # add a description for gitweb
            i="$GIT_DIR/description"
            if [ -f "$i" -a -w "$i" ]
            then
                echo "snapshot of the current GridEngine configuration" > $i
            fi
        fi
        exit $rc
        ;;
    ( log | ls-files | show | whatchanged )
        git --git-dir=$GIT_DIR $@
        exit $?
        ;;
    (*)
        usage "unknown option/argument: '$*'"
        ;;
    esac
done



[ -d "$GIT_DIR" ] || {
    echo "git repo: $GIT_DIR does not exist"
    exit 1
}


i="$SGE_ROOT/$SGE_CELL/common/settings.sh"
if [ -f "$i" -a -r "$i" ]
then
    . "$i"
else
    echo "cannot read $i"
    exit 1
fi

[ -f "$saveScript" -a -r "$saveScript" ] || {
    echo "cannot read $i"
    exit 1
}

# Create a fresh empty directory
# cannot use --tmpdir on older systems
tmpDir=$(mktemp -d "/tmp/sgeSaveConfig.XXXXXXXXXX")
trap "rm -rf $tmpDir 2>/dev/null; exit 0" EXIT TERM INT

[ -d "$tmpDir" ] || {
    echo "Error: temp dir '$tmpDir' does not exist"
    exit 1
}

$saveScript $tmpDir

#------------------------------------------------------------------------------
# cleanup
#
(
    cd $tmpDir || exit 1

    # all operations are now in the current directory
    GIT_WORK_TREE=.
    export GIT_WORK_TREE

    # minor error checking that the save script worked
    if [ -f backup_date -a -r backup_date ]
    then
        msg=$(cat backup_date)
    else
        echo "cannot read backup_date - $saveScript might have failed"
        exit 1
    fi


    # ignore accounting (too big)
    rm -f cell/accounting

    # ignore current users
    rm -f users/*

    # ignore current load_values for exec hosts
    perl -i -ne '/^load_values/ or print' execution/*

    # assign (consumable) complex_values to zero - otherwise we indirectly
    # track the external license usage when qlicserver is being used
    # also sort the complexes to avoid spurious changes
    perl -i -p -e 'if (/^complex_values/) { chomp; ' \
               -e 's/=\d+/=0/g; s/^(complex\S+\s+)//; ' \
               -e '$_ = $1 . join("," => sort split /,/) . "\n" }' \
               execution/global

    #
    # determine if the configuration changed
    #
    # this is fairly roundabout until we find a better way
    needsCommit=false

    if [ -n "$(git ls-files -d)" ]       # files deleted?
    then
        needsCommit=true
    elif [ -n "$(git ls-files -o)" ]     # files added?
    then
        needsCommit=true
    else
        # files modified?
        # do it the long way to ensure we also get staged modifications
        set -- $(git status | perl -ne 's/^#\s+modified:// and print')

        # changes in backup_date, jobseqnum etc alone are not enough
        # to warrant a commit
        while [ "$#" -ge 1 ]
        do
            case $1 in
            ( arseqnum | backup_date | jobseqnum )
                shift
                ;;
            (*)
                needsCommit=true
                break
                ;;
            esac
        done
    fi

    if [ "$needsCommit" = true ]
    then
        # register all new files
        git add .

        # commit everything
        git commit -a -m "$msg"
    else
        echo "no changes to be committed $msg"
    fi
)

exit 0
#------------------------------------------------------------------------------