Timestamp data

stamped-data.php

<?php
// mock get_option / update_option using global state
require_once( 'mock.php' );

/**
 * Timestamp a value.
 * update_option( $name, stamp( $value ) );
 *
 * @param int|null $timestamp now, or provided time() compatible timestamp.
 *
 * @return string JSON encoded stamped data.
 */
function stamp( mixed $value, int $timestamp = null ) : string {
	if ( is_null( $timestamp ) ) {
		$timestamp = time();
	}
	$a = [
		'ts' => $timestamp,
		'value' => $value,
	];

	return json_encode( $a );
}

/**
 * Return a stamped value.
 * [ $age, $value ] = stamped( get_option( $name, $default ) );
 *
 * @param string $json Data encoded by stamp().
 *
 * @return array [
 *  $age int Age in seconds.
 *  $value mixed Original data.
 * ]
 */
function stamped( string $json ) : array {
	$a = json_decode( $json, true );
	$a['age'] = time() - (int) $a['ts'];

	return [ $a['age'], $a['value'] ];
}

$name = 'test_data';
while ( true ) {
	$default = stamp( null, 0 );
	[ $age, $valued ] = stamped( get_option( $name, $default ) );
	printf( 'age: %d; value: %s' . PHP_EOL, $age, $valued );

	if ( $age > 13 ) {
		printf('> write(%d > %d)...' . PHP_EOL, $age, 13);
		$value =  random_int( 0, 1000 );
		update_option( $name, stamp( $value ) );
	}
	sleep( random_int( 1, 5 ) );
}

age: 1691923207; value:
> write(1691923207 > 13)...
age: 2; value: 136
age: 6; value: 136
age: 9; value: 136
age: 12; value: 136
age: 14; value: 136
> write(14 > 13)...
age: 3; value: 31
age: 5; value: 31
age: 10; value: 31
age: 14; value: 31
> write(14 > 13)...
age: 1; value: 827
age: 5; value: 827
age: 6; value: 827
^C