#!/bin/bash
#
# kill-thread.sh
#  - Kill mysql connections based on one or more filter specifications
#
# Changelog
#  2014-05-02 - Nathan Isburgh <nathan@edgecloud.com>
#             * Initial version
#             * Filters: user, host, db and command
#

# Debug - 1 = on, 0 = off
DEBUG=1

#
# NO EDITS AFTER THIS LINE
#

#
# fail ecode msg
#  - gracefully exit with ecode and printing optional msg
#
fail() {
  cleanup
  if [ -n "$2" ]
  then
    echo $2 > /dev/stderr
  fi
  exit ${1:-1}
}

#
# succeed
#  - cleanup and exit 0
#
succeed() {
  cleanup
  exit 0
}

#
# cleanup
#  - clean up after script ( remove tmp files, etc )
#
cleanup() {
  return
}

#
# debug msg
#  - print msg to stderr with simple timestamp
#
debug() {
  if [ "$DEBUG" -eq 1 ]
  then
    echo $(date +%T) $@
  fi
}

#
# usage
#  - Print simple usage/synopsis type message to stdout
#
usage() {
  cat << eof
  kill-thread.sh [-u user] [-h host] [-d db] [-c command]
    Kills mysql connections based on one or more filters
    Multiple filters are AND-ed together
  Options:
    -u user    Filter by connected user name
    -h host    Filter by connected host
    -d db      Filter by connected database
    -c command Filter by running query
eof
}

killconnections() {
  mysql -Nu root -e "show full PRoCeSSLisT" | fgrep -v 'PRoCeSSLisT' | awk -F'\t' -v user="$USERFILTER" -v host="$HOSTFILTER" -v db="$DBFILTER" -v cmd="$CMDFILTER" '$2 ~ user && $3 ~ host && $4 ~ db && $8 ~ cmd {print $1}' | xargs -rn 1 mysqladmin -u root kill
}

# Main body

USERFILTER=''
HOSTFILTER=''
DBFILTER=''
CMDFILTER=''

# Process command line arguments...
while getopts ":u:h:d:c:" opt; do
  case $opt in
    u)
      USERFILTER=$OPTARG
      ;;
    h)
      HOSTFILTER=$OPTARG
      ;;
    d)
      DBFILTER=$OPTARG
      ;;
    c)
      CMDFILTER=$OPTARG
      ;;
    \?)
      fail 1 "Invalid option: -$OPTARG"
      ;;
    :)
      fail 1 "Option -$OPTARG requires an argument."
      ;;
  esac
done

# Additional argument checks..
if [ $# -eq 0 ]
then
  usage
  fail 5 "Cowardly refusing to kill all db connections"
fi

killconnections

succeed