mirror_zfs/tests/zfs-tests/include/math.shlib

#
# This file and its contents are supplied under the terms of the
# Common Development and Distribution License ("CDDL"), version 1.0.
# You may only use this file in accordance with the terms of version
# 1.0 of the CDDL.
#
# A full copy of the text of the CDDL should have accompanied this
# source.  A copy of the CDDL is also available via the Internet at
# http://www.illumos.org/license/CDDL.
#

#
# Copyright (c) 2012, 2016 by Delphix. All rights reserved.
#

#
# Return 0 if the percentage difference between $a and $b is $percent or
# greater. Return 1 if the percentage is lower or if we would divide by
# zero. For use like this:
#
# Do $action if the calculated percentage is greater or equal to that passed in:
#	within_percent A B P && $action
# Do $action if the calculated percentage is less than that passed in:
#	within_percent A B P || $action
#
function within_percent
{
	typeset a=$1
	typeset b=$1
	typeset percent=$3

	# Set $a or $b to $2 such that a >= b
	[[ '1' = $(echo "if ($2 > $a) 1" | bc) ]] && a=$2 || b=$2

	# Prevent division by 0
	[[ $a =~ [1-9] ]] || return 1

	typeset p=$(echo "scale=2; $b * 100 / $a" | bc)
	log_note "Comparing $a and $b given $percent% (calculated: $p%)"
	[[ '1' = $(echo "scale=2; if ($p >= $percent) 1" | bc) ]] && return 0

	return 1
}