lib.sh

#!/usr/bin/env bash

# lib.sh -- common functions for use by cake-autorate.sh
#
# This file is part of cake-autorate.

__set_e=0
if [[ ! ${-} =~ e ]]
then
    set -e
    __set_e=1
fi

if [[ -z ${__sleep_fd:-} ]]
then
	exec {__sleep_fd}<> <(:)
fi

typeof() 
{
	# typeof -- returns the type of a variable

	local type_sig
	type_sig=$(declare -p "${1}" 2>/dev/null)
	if [[ "${type_sig}" =~ "declare --" ]]
	then
		str_type "${1}"
	elif [[ "${type_sig}" =~ "declare -a" ]]
	then
		printf "array"
	elif [[ "${type_sig}" =~ "declare -A" ]]
	then
		printf "map"
	else
		printf "none"
	fi
}

str_type() 
{
	# str_type -- returns the type of a string

	local -n str=${1}

	if [[ "${str}" =~ ^[0-9]+$ ]]
	then
		printf "integer"
	elif [[ "${str}" =~ ^[0-9]*\.[0-9]+$ ]]
	then
		printf "float"
	elif [[ "${str}" =~ ^-[0-9]+$ ]]
	then
		printf "negative-integer"
	elif [[ "${str}" =~ ^-[0-9]*\.[0-9]+$ ]]
	then
		printf "negative-float"
	else
		# technically not validated, user is just trusted to call
		# this function with valid strings
		printf "string"
	fi
}

sleep_s()
{
	# Calling the external sleep binary could be rather slow,
	# especially as it is called very frequently and typically on mediocre hardware.
	#
	# bash's loadable sleep module is not typically available
	# in OpenWRT and most embedded systems, and use of the bash
	# read command with a timeout offers performance that is
	# at least on a par with bash's sleep module.
	#
	# For benchmarks, check the following links:
	# - https://github.com/lynxthecat/cake-autorate/issues/174#issuecomment-1460057382
	# - https://github.com/lynxthecat/cake-autorate/issues/174#issuecomment-1460074498

	# ${1} = sleep_duration_s (seconds, e.g. 0.5, 1 or 1.5)

	read -r -t "${1}" -u "${__sleep_fd}" || :
}

sleep_us()
{
	# ${1} = sleep_duration_us (microseconds)

	printf -v sleep_duration_s %.1f "${1}e-6"
	read -r -t "${sleep_duration_s}" -u "${__sleep_fd}" || :
}

sleep_remaining_tick_time()
{
	# sleeps until the end of the tick duration

	# ${1} = t_start_us (microseconds)
	# ${2} = tick_duration_us (microseconds)

	# shellcheck disable=SC2154
	((
		sleep_duration_us=${1} + ${2} - ${EPOCHREALTIME/.},
		sleep_duration_us < 0 && (sleep_duration_us=0)
	))

	printf -v sleep_duration_s %.1f "${sleep_duration_us}e-6"
	read -r -t "${sleep_duration_s}" -u "${__sleep_fd}" || :
}

randomize_array()
{
	# randomize the order of the elements of an array

	local -n array=${1}

	subset=("${array[@]}")
	array=()
	for ((set=${#subset[@]}; set>0; set--))
	do
		idx=$((RANDOM%set))
		array+=("${subset[idx]}")
		unset "subset[idx]"
		subset=("${subset[@]}")
	done
}

terminate()
{
	# Send regular kill to processes and monitor terminations;
	# return as soon as all of the active processes terminate;
	# if any processes remain active after timeout (defaults to one second),
	# then kill with fire using kill -9;
	# and, finally, call wait on all processes to reap any zombie processes.

	local pids=${1} timeout_ms=${2:-1000}

	read -r -a pids <<< "${pids}"

	kill "${pids[@]}" 2> /dev/null

	for ((i=0; i<timeout_ms; i+=100))
	do
		for process in "${!pids[@]}"
		do
			kill -0 "${pids[${process}]}" 2> /dev/null || unset "pids[${process}]"
		done
		[[ "${pids[*]}" ]] || return
		sleep_s 0.1
	done

	kill -9 "${pids[@]}" 2> /dev/null
}

if (( __set_e == 1 ))
then
    set +e
fi
unset __set_e