WordPress at a glance
function is not described

wp_update_plugins() WP 2.3.0

Checks for available updates to plugins based on the latest versions hosted on WordPress.org.

Despite its name this function does not actually perform any updates, it only checks for available updates.

A list of all plugins installed is sent to WP, along with the site locale.

Checks against the WordPress server at api.wordpress.org. Will only check if WordPress isn't installing.

Hooks from the function
Return

null. Null. Nothing.

Usage

wp_update_plugins( $extra_stats );
$extra_stats(array)
Extra statistics to report to the WordPress.org API.

Notes

  • Global. String. $wp_version The WordPress version string.

Changelog

Since 2.3.0 Introduced.

Code of wp_update_plugins() WP 5.7

<?php
function wp_update_plugins( $extra_stats = array() ) {
	if ( wp_installing() ) {
		return;
	}

	// Include an unmodified $wp_version.
	require ABSPATH . WPINC . '/version.php';

	// If running blog-side, bail unless we've not checked in the last 12 hours.
	if ( ! function_exists( 'get_plugins' ) ) {
		require_once ABSPATH . 'wp-admin/includes/plugin.php';
	}

	$plugins      = get_plugins();
	$translations = wp_get_installed_translations( 'plugins' );

	$active  = get_option( 'active_plugins', array() );
	$current = get_site_transient( 'update_plugins' );

	if ( ! is_object( $current ) ) {
		$current = new stdClass;
	}

	$new_option               = new stdClass;
	$new_option->last_checked = time();

	$doing_cron = wp_doing_cron();

	// Check for update on a different schedule, depending on the page.
	switch ( current_filter() ) {
		case 'upgrader_process_complete':
			$timeout = 0;
			break;
		case 'load-update-core.php':
			$timeout = MINUTE_IN_SECONDS;
			break;
		case 'load-plugins.php':
		case 'load-update.php':
			$timeout = HOUR_IN_SECONDS;
			break;
		default:
			if ( $doing_cron ) {
				$timeout = 2 * HOUR_IN_SECONDS;
			} else {
				$timeout = 12 * HOUR_IN_SECONDS;
			}
	}

	$time_not_changed = isset( $current->last_checked ) && $timeout > ( time() - $current->last_checked );

	if ( $time_not_changed && ! $extra_stats ) {
		$plugin_changed = false;

		foreach ( $plugins as $file => $p ) {
			$new_option->checked[ $file ] = $p['Version'];

			if ( ! isset( $current->checked[ $file ] ) || (string) $current->checked[ $file ] !== (string) $p['Version'] ) {
				$plugin_changed = true;
			}
		}

		if ( isset( $current->response ) && is_array( $current->response ) ) {
			foreach ( $current->response as $plugin_file => $update_details ) {
				if ( ! isset( $plugins[ $plugin_file ] ) ) {
					$plugin_changed = true;
					break;
				}
			}
		}

		// Bail if we've checked recently and if nothing has changed.
		if ( ! $plugin_changed ) {
			return;
		}
	}

	// Update last_checked for current to prevent multiple blocking requests if request hangs.
	$current->last_checked = time();
	set_site_transient( 'update_plugins', $current );

	$to_send = compact( 'plugins', 'active' );

	$locales = array_values( get_available_languages() );

	/**
	 * Filters the locales requested for plugin translations.
	 *
	 * @since 3.7.0
	 * @since 4.5.0 The default value of the `$locales` parameter changed to include all locales.
	 *
	 * @param array $locales Plugin locales. Default is all available locales of the site.
	 */
	$locales = apply_filters( 'plugins_update_check_locales', $locales );
	$locales = array_unique( $locales );

	if ( $doing_cron ) {
		$timeout = 30;
	} else {
		// Three seconds, plus one extra second for every 10 plugins.
		$timeout = 3 + (int) ( count( $plugins ) / 10 );
	}

	$options = array(
		'timeout'    => $timeout,
		'body'       => array(
			'plugins'      => wp_json_encode( $to_send ),
			'translations' => wp_json_encode( $translations ),
			'locale'       => wp_json_encode( $locales ),
			'all'          => wp_json_encode( true ),
		),
		'user-agent' => 'WordPress/' . $wp_version . '; ' . home_url( '/' ),
	);

	if ( $extra_stats ) {
		$options['body']['update_stats'] = wp_json_encode( $extra_stats );
	}

	$url      = 'http://api.wordpress.org/plugins/update-check/1.1/';
	$http_url = $url;
	$ssl      = wp_http_supports( array( 'ssl' ) );

	if ( $ssl ) {
		$url = set_url_scheme( $url, 'https' );
	}

	$raw_response = wp_remote_post( $url, $options );

	if ( $ssl && is_wp_error( $raw_response ) ) {
		trigger_error(
			sprintf(
				/* translators: %s: Support forums URL. */
				__( 'An unexpected error occurred. Something may be wrong with WordPress.org or this server&#8217;s configuration. If you continue to have problems, please try the <a href="%s">support forums</a>.' ),
				__( 'https://wordpress.org/support/forums/' )
			) . ' ' . __( '(WordPress could not establish a secure connection to WordPress.org. Please contact your server administrator.)' ),
			headers_sent() || WP_DEBUG ? E_USER_WARNING : E_USER_NOTICE
		);
		$raw_response = wp_remote_post( $http_url, $options );
	}

	if ( is_wp_error( $raw_response ) || 200 !== wp_remote_retrieve_response_code( $raw_response ) ) {
		return;
	}

	$response = json_decode( wp_remote_retrieve_body( $raw_response ), true );

	foreach ( $response['plugins'] as &$plugin ) {
		$plugin = (object) $plugin;

		if ( isset( $plugin->compatibility ) ) {
			$plugin->compatibility = (object) $plugin->compatibility;

			foreach ( $plugin->compatibility as &$data ) {
				$data = (object) $data;
			}
		}
	}

	unset( $plugin, $data );

	foreach ( $response['no_update'] as &$plugin ) {
		$plugin = (object) $plugin;
	}

	unset( $plugin );

	if ( is_array( $response ) ) {
		$new_option->response     = $response['plugins'];
		$new_option->translations = $response['translations'];
		// TODO: Perhaps better to store no_update in a separate transient with an expiry?
		$new_option->no_update = $response['no_update'];
	} else {
		$new_option->response     = array();
		$new_option->translations = array();
		$new_option->no_update    = array();
	}

	set_site_transient( 'update_plugins', $new_option );
}