#!/bin/bash
# Copyright (c) 2000-2020 Synology Inc. All rights reserved.

if [ -z "$__INCLUDE_PARALLEL__" ]; then
__INCLUDE_PARALLEL__=defined


ParallelAvailable() {
	# only check sem existance once.
	if [ -z "$__PARALLEL_AVAILABLE" ]; then
		which sem &>/dev/null
		__PARALLEL_AVAILABLE=$?

		if [ $__PARALLEL_AVAILABLE -eq 0 ]; then
			SEM_OPTION="--gnu"

			if [ -z "$SEM_VERSION" ]; then
				SEM_VERSION="$(parallel --version | grep -E "parallel [0-9]+" | awk '{print $NF;}')"
			fi
			if [ "$SEM_VERSION" -ge 20131122 ]; then
				SEM_OPTION="$SEM_OPTION --no-notice"
			fi
		fi
	fi

	return $__PARALLEL_AVAILABLE
}

ParallelCheckEnvironment() {
	# User has disabled parallel function.
	if [ "$__Parallel_enable" == false ]; then
		return 0
	fi
	if ! ParallelAvailable; then
		echo "******************************************************************" 1>&2
		echo "Warning: Cannot found sem command in your system." 1>&2
		echo "Please install parallel package on your build system to enable parallel function." 1>&2
		echo 1>&2
		echo "Ubuntu: apt-get install parallel" 1>&2
		echo "Arch: pacman -S parallel" 1>&2
		echo "******************************************************************" 1>&2

		return 1
	fi
	return 0
}

ParallelEnable() {
	if ! ParallelAvailable; then
		__Parallel_enable=false
		return 1
	fi


	__Parallel_enable=true
	return 0
}

ParallelDisable() {
	__Parallel_enable=false
	return 0
}

__Parallel_id() {
	echo "$$"
}

__ParallelRunCond() {
	ParallelAvailable && ${__Parallel_enable:-true}
}

ParallelInit() {
	if __ParallelRunCond; then
		ParallelCleanSemaphore
		trap "NoticeGandalf update_abort && ParallelCleanSemaphore" HUP TERM
		trap "NoticeGandalf update_abort && ParallelCleanSemaphore 130" INT
		trap "ParallelCleanSemaphore" EXIT
	fi
}

ParallelExecute() {
	if __ParallelRunCond; then
		sem $SEM_OPTION --id "$(__Parallel_id)" -j "${PARALLEL_JOBS:-+0}" "$@"
	else
		"$@"
	fi
}

ParallelWait() {
	if __ParallelRunCond; then
		sem $SEM_OPTION --wait --id "$(__Parallel_id)"
	fi
}

ParallelCleanSemaphore() {
	local return_value="$1"

	if __ParallelRunCond; then
		rm -rf ~/.parallel/semaphores/id-$(__Parallel_id)
	fi

	if [ -n "$return_value" ]; then
		exit "$return_value"
	fi
}

fi