#!/usr/bin/sh
#
#!ident @(#) parallel.sh 1.1 (Cyrille.Lefevre-lists%nospam@laposte.net.invalid) Mon Jun 28 17:42:42     2010
# supprimer "%nospam" et ".invalid" pour me repondre.
# remove "%nospam" and ".invalid" to answer me.
#
# Copyright (c) 2010 Cyrille Lefevre. All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
#
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
#    notice, this list of conditions and the following disclaimer in
#    the documentation and/or other materials provided with the
#    distribution.
# 3. The name of the authors and contributors may not be used to
#    endorse or promote products derived from this software without
#    specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS''
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
# TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
# PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS
# OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
# USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
# OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
# SUCH DAMAGE.

function loop {
	typeset maxpid=$1
	typeset pid= newpids=
	typeset -i sleep=0
	while (( npid >= maxpid )); do
		newpids= sleep=1
		for pid in ${pids}; do
			if kill -0 "${pid}" 2> /dev/null; then
				newpids="${newpids} ${pid}"
			else
				sleep=0
				(( npid -= 1 ))
				wait "${pid}"
				echo "${pid}: done"
			fi
		done
		pids=${newpids}
		(( sleep != 0 )) && sleep 1
	done
}

function parallel {
	typeset ncpu=$1 nice=$2
	shift 2
	typeset -i npid=0
	typeset pids=
	while read -r; do
		case ${REPLY} in
		''|'#'*)
			continue
			;;
		ncpu=*|nice=*)
			echo ${REPLY}
			eval ${REPLY}
			continue 
			;;
		rset)
			echo rset
			ncpu=${_ncpu}
			continue 
			;;
		wait)
			echo wait
			loop 1
			continue 
			;;
		esac
		loop "${ncpu}"
		${REPLY} &
		(( npid += 1 ))
		pids="${pids} $!"
		[[ -n ${nice} && ${nice} != 0 ]] && sleep 1 && renice ${nice} $!
		echo "$!: $REPLY"
	done
	loop 1
}

_ncpu=$1
if (( ${_ncpu:-0} < 1 )); then
	case $(uname) in
	AIX)
		_ncpu=$(LC_ALL=C lsdev -c processor | grep -c Avail)
		;;
	Darwin)
		#noht#_ncpu=$(sysctl -n hw.physicalcpu)
		_ncpu=$(sysctl -n hw.availcpu) # was logicalcpu
		;;
	FreeBSD)
		_ncpu=$(sysctl -n hw.ncpu)
		;;
	HP-UX)
		_ncpu=$(ioscan -fkC processor | grep -c processor)
		;;
	CYGWIN*)
		# _ncpu=${NUMBER_OF_PROCESSORS}
		_ncpu=$(grep -c processor /proc/cpuinfo)
		;;
	Linux)
		#noht#_ncpu=$(grep 'physical id' /proc/cpuinfo | sort -u | wc -l)
		_ncpu=$(grep -c processor /proc/cpuinfo)
		;;
	SunOS)
		_ncpu=$(LC_ALL=C psrinfo -v | grep -c on-line)
		;;
	esac
fi

_coef=$2
if (( ${_coef:-0} > 1 )); then
	(( _ncpu *= _coef ))
fi

_nice=$3

_time0=${SECONDS}
parallel ${_ncpu:-1} ${_nice:-0} "$@"
(( _time0 -= -${SECONDS} ))
echo elapsed: ${_time0}