#!/usr/bin/env bash
################################################################################
#  Copyright 2023 Ververica Inc.
#
#  Licensed under the Apache License, Version 2.0 (the "License");
#  you may not use this file except in compliance with the License.
#  You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
#  Unless required by applicable law or agreed to in writing, software
#  distributed under the License is distributed on an "AS IS" BASIS,
#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#  See the License for the specific language governing permissions and
# limitations under the License.
################################################################################

#
# This file contains a watchdog tool to monitor a task and potentially kill it after
# not producing any output for $MAX_NO_OUTPUT seconds.
#

# Number of seconds w/o output before printing a stack trace and killing the watched process
MAX_NO_OUTPUT=${MAX_NO_OUTPUT:-900}

# Number of seconds to sleep before checking the output again
SLEEP_TIME=${SLEEP_TIME:-20}

# Internal fields
CMD_OUT="/tmp/watchdog.out"
CMD_PID="/tmp/watchdog.pid"
CMD_EXIT="/tmp/watchdog.exit"


# =============================================
# Utility functions
# ============================================= 

max_of() {
  local max number

  max="$1"

  for number in "${@:2}"; do
    if ((number > max)); then
      max="$number"
    fi
  done

  printf '%d\n' "$max"
}

# Returns the highest modification time out of $CMD_OUT (which is the command output file)
# and any file(s) named "mvn-*.log" (which are logging files created by Flink's tests)
mod_time () {
	CMD_OUT_MOD_TIME=`stat -c "%Y" $CMD_OUT`
	ADDITIONAL_FILES_MOD_TIMES=`stat -c "%Y" $WATCHDOG_ADDITIONAL_MONITORING_FILES 2> /dev/null`
	echo `max_of $CMD_OUT_MOD_TIME $ADDITIONAL_FILES_MOD_TIMES`
}

the_time() {
	echo `date +%s`
}

# watchdog process

watchdog () {
	touch $CMD_OUT

	while true; do
		sleep $SLEEP_TIME

		time_diff=$((`the_time` - `mod_time`))

		if [ $time_diff -ge $MAX_NO_OUTPUT ]; then
			echo "=============================================================================="
			echo "Process produced no output for ${MAX_NO_OUTPUT} seconds."
			echo "=============================================================================="

			# run timeout callback
			$CALLBACK_ON_TIMEOUT

			echo "Killing process with pid=$(<$CMD_PID) and all descendants"
			pkill -P $(<$CMD_PID) # kill descendants
			kill $(<$CMD_PID) # kill process itself

			exit 1
		fi
	done
}


# =============================================
# main function
# =============================================

# entrypoint
function run_with_watchdog() {
	local cmd="$1"
	local CALLBACK_ON_TIMEOUT="$2"

	watchdog &
	WD_PID=$!
	echo "STARTED watchdog (${WD_PID})."

	echo "RUNNING '${cmd}'."

	# Run $CMD and pipe output to $CMD_OUT for the watchdog. The PID is written to $CMD_PID to
	# allow the watchdog to kill $CMD if it is not producing any output anymore. $CMD_EXIT contains
	# the exit code. This is important for CI build life-cycle (success/failure).
	( $cmd & PID=$! ; echo $PID >&3 ; wait $PID ; echo $? >&4 ) 3>$CMD_PID 4>$CMD_EXIT | tee $CMD_OUT

	EXIT_CODE=$(<$CMD_EXIT)

	echo "Process exited with EXIT CODE: ${EXIT_CODE}."

	# Make sure to kill the watchdog in any case after $CMD has completed
	echo "Trying to KILL watchdog (${WD_PID})."
	( kill $WD_PID 2>&1 ) > /dev/null

	rm $CMD_PID
	rm $CMD_EXIT

	return $EXIT_CODE
}