count-filter-calls.php

<?php
/**
 * Plugin Name:       Count Filter Calls
 * Plugin URI:        https://gist.github.com/afragen/a8a89888c60c4836a21667531469c7a9
 * Description:       Count number of times certain filters are called and cumulative time spent for the call with almost no computing done.
 * Version:           0.3
 * Author:            Andy Fragen
 * License:           MIT
 * Requires at least: 5.2
 * Requires PHP:      7.0
 * Gist Plugin URI:   https://gist.github.com/afragen/a8a89888c60c4836a21667531469c7a9
 */

/*
 * Exit if called directly.
 * PHP version check and exit.
 */
if ( ! defined( 'WPINC' ) ) {
	die;
}

global $count_pre, $count_site, $time_pre, $time_site;

add_filter(
	'pre_set_site_transient_update_plugins',
	function() {
		$start = microtime( true );
		global $count_pre, $time_pre;
		$count_pre++;
		$time_pre = $time_pre + ( microtime( true ) - $start );
	}
);

// get_site_transient() called for every plugin row.
add_filter(
	'site_transient_update_plugins',
	function() {
		$start = microtime( true );
		global $count_site, $time_site;
		$count_site++;
		$time_site = $time_site + ( microtime( true ) - $start );
	}
);

add_action(
	'shutdown',
	function() {
		global $pagenow, $count_pre, $count_site, $time_pre, $time_site;
		if ( ! empty( $count_pre ) && ! empty( $count_site ) ) {
			error_log( $pagenow . ':pre_set_site_transient_update_plugins: ' . $count_pre . ' calls - ' . number_format( $time_pre, 6 ) . ' seconds (cumulative time)' );
			error_log( $pagenow . ':site_transient_update_plugins: ' . $count_site . ' calls - ' . number_format( $time_site, 6 ) . ' seconds (cumulative time)' );
		}
	}
);