#!/bin/sh

# Reads filenames on stdin, xz-compresses each in place.

# Not optimal for "compress relatively few, large files" scenario!

# How many xz's to run in parallel:

procgroup=""

while test "$#" != 0; do

	# Get it from -jNUM

	N="${1#-j}"

	if test "$N" = "$1"; then

		# Not -j<something> - warn and ignore

		echo "parallel_xz: warning: unrecognized argument: '$1'"

	else

		procgroup="$N"

	fi

	shift

done

#This seems to cause problems with large numbers

if (( $procgroup > 6 )); then

	procgroup=6

fi

# If told to use only one cpu:

test "$procgroup" || exec xargs -r xz

test "$procgroup" = 1 && exec xargs -r xz

# xz has some startup cost. If files are really small,

# this cost might be significant. To combat this,

# process several files (in sequence) by each xz process via -n 16:

exec xargs -r -n 16 -P $procgroup xz