#!/bin/sh

# Ensure the Oregano browser_shell processes are kept at nice -5

keep_nice_value=-5
suppress_errors=0

log_error () {
  if [ "${suppress_errors}" -eq 0 ]; then
    echo "$1"
  fi
}

renice_oregano () {
  local oregano_browser_process="$(pgrep -f browser_shell.*file:///app/oregano)"
  local number_of_oreganos="$(echo "${oregano_browser_process}" | wc -w)"
  if [ "${number_of_oreganos}" -eq 0 ]; then
    log_error "Error keeping Oregano nice, Oregano is not running."
    return 1
  fi
  if [ "${number_of_oreganos}" -gt 1 ]; then
    log_error "Error keeping Oregano nice, more than one instance of Oregano is running."
    return 1
  fi
  local oregano_group_id
  oregano_group_id="$(cut -d ' ' -f 5 /proc/"${oregano_browser_process}"/stat)"
  if [ $? -ne 0 ]; then
    log_error "Error keeping Oregano nice, unable to get gpid for browser process "${oregano_browser_process}""
    return 1
  fi
  local oregano_browser_shells
  oregano_browser_shells="$(pgrep -g "${oregano_group_id}" -x browser_shell)"
  if [ $? -ne 0 ] || [ "$(echo "${oregano_browser_shells}" | wc -w)" -eq 0 ]; then
    log_error "Error keeping Oregano nice, unable to get Oregano browser_shell pids"
    return 1
  fi
  local renice_failed=0
  for i in $oregano_browser_shells; do
    local nice_value="$(cut -d ' ' -f 19 /proc/"${i}"/stat)"
    if [ "${nice_value}" -ne "${keep_nice_value}" ]; then
      renice -n ${keep_nice_value} ${i}
      if [ $? -ne 0 ]; then
        reniced_failed=1
      fi
    fi
  done
  if [ "${renice_failed}" -eq 1 ]; then
    log_error "Error keeping Oregano nice, renice failed."
    return 1
  fi
  return 0
}

renice_oregano_with_timeout () {
  # Retry timeout is 2 minutes
  local timeout=$((2 * 60))
  local sleep_time=10
  suppress_errors=0
  for i in $(seq 1 $((${timeout} / ${sleep_time}))); do
    renice_oregano
    if [ $? -eq 0 ]; then
      break;
    fi
    # Only log the first error so we don't spam the logs
    suppress_errors=1
    sleep "${sleep_time}"
  done
}

(
  while true; do
    wait-until-created /tmp/renice_oregano
    rm /tmp/renice_oregano
    renice_oregano_with_timeout
  done
) &

# To be extra sure we never run into the case where Oregano is not niced, have
# a fall back that checks every hour to ensure Oregano stays niced.
while true; do
  renice_oregano_with_timeout
  # Check every hour to ensure Oregano stays niced
  sleep $((60 * 60))
done