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
}

#
# Return 0 if value is within +/-tolerance of target.
# Return 1 if value exceeds our tolerance.
# For use like this:
#
# Do $action if value is within the tolerance from target passed in:
#	within_tolerance VAL TAR TOL && $action
# Do $action if value surpasses the tolerance from target passed in:
#	within_tolerance VAL TAR TOL || $action
#
function within_tolerance #value #target #tolerance
{
	typeset val=$1
	typeset target=$2
	typeset tol=$3

	typeset diff=$((abs(val - target)))
	log_note "Checking if $val is within +/-$tol of $target (diff: $diff)"
	((diff <= tol)) && return 0

	return 1
}

#
# Return 0 if the human readable string of the form <value>[suffix] can
# be converted to bytes.  Allow suffixes are shown in the table below.
#
function to_bytes
{
	typeset size=$1
	typeset value=$(echo "$size" | grep -o '[0-9]\+')

	case $size in
		*PB|*pb|*P|*p)	factor='1024^5'	;;
		*TB|*tb|*T|*t)	factor='1024^4'	;;
		*GB|*gb|*G|*g)	factor='1024^3'	;;
		*MB|*mb|*M|*m)	factor='1024^2'	;;
		*KB|*kb|*K|*k)	factor='1024^1'	;;
		*B|*b)		factor='1024^0'	;;
		*[!0-9.]*)	return 1 ;;
		*)		factor='1024^0'	;;
	esac

	echo "$value * ($factor)" | bc

	return 0
}

#
# Verify $a is equal to $b, otherwise raise an error specifying
# the $type of values being compared
#
function verify_eq # <a> <b> <type>
{
	typeset a=$1
	typeset b=$2
	typeset type=$3

	if [[ $a -ne $b ]]; then
		log_fail "Compared $type should be equal: $a != $b"
	fi
}

#
# Verify $a is not equal to $b, otherwise raise an error specifying
# the $type of values being compared
#
function verify_ne # <a> <b> <type>
{
	typeset a=$1
	typeset b=$2
	typeset type=$3

	if [[ $a -eq $b ]]; then
		log_fail "Compared $type should be not equal: $a == $b"
	fi
}

# A simple function to get a random number between two bounds (inclusive)
#
# Probably not the most efficient for large ranges, but it's okay.
#
# Note since we're using $RANDOM, 32767 is the largest number we
# can accept as the upper bound.
#
# $1 lower bound
# $2 upper bound
function random_int_between
{
	typeset -i min=$1
	typeset -i max=$2
	typeset -i rand=0

	while [[ $rand -lt $min ]] ; do
		rand=$(( $RANDOM % $max + 1))
	done

	echo $rand
}