fetch_rss( string $url ): MagpieRSS|false

Compatibility

Present in every tracked release (6.7.7 to 7.1.0), and compiles on PHP 7.4 through 8.6-dev.

Parameters

$urlstring

URL to retrieve feed.

Return value

MagpieRSS|false

MagpieRSS object on success, false on failure.

Performance profile

How much work a call to fetch_rss() does, and what it touches: the algorithmic scaling, the Zend instruction count per call across PHP versions, the hooks it hands control to, and the core code that calls it. Measured from the compiled opcodes, not a stopwatch, so every number is identical on any machine running the same PHP version, and every function in core is ranked by cost.

Cost class

Expensive

Reaches an outbound HTTP request via wp_safe_remote_request().

Scaling

Constant

No loop in the body: the same number of instructions runs whatever you pass in.

Instructions

6–96

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 156.

Plugin surface

None

Nothing here hands control to plugin code.

Called by

2

2 places in core call this, so the cost is paid more often than your own code shows.

What it touches

• httpoutbound HTTP requestwp_safe_remote_request()one call below fetch_rss()

Further down the call graph this can also reach hook. That is the worst case, several calls deep and usually down an error path, not what a normal call pays.

What one call costs · 117 distinct outcomes

One number would be a lie: the work depends on which branch runs. These are every distinct cost fetch_rss() can have, taken from its control-flow graph on PHP 8.5.

Uses · 5

• init()Set up constants with default values, unless user overrides.
• _fetch_remote_file()Retrieve URL headers and content using WP HTTP Request API.
• is_success()
• _response_to_rss()Retrieve
• RSSCache::__construct()PHP5 constructor.

Used by · 2

• get_rss()Display RSS items in HTML list items.
• wp_rss()Display all RSS items in a HTML ordered list.

Source code

View on Trac ↗View on GitHub ↗

412function fetch_rss ($url) {413	// initialize constants414	init();415 416	if ( !isset($url) ) {417		// error("fetch_rss called without a url");418		return false;419	}420 421	// if cache is disabled422	if ( !MAGPIE_CACHE_ON ) {423		// fetch file, and parse it424		$resp = _fetch_remote_file( $url );425		if ( is_success( $resp->status ) ) {426			return _response_to_rss( $resp );427		}428		else {429			// error("Failed to fetch $url and cache is off");430			return false;431		}432	}433	// else cache is ON434	else {435		// Flow436		// 1. check cache437		// 2. if there is a hit, make sure it's fresh438		// 3. if cached obj fails freshness check, fetch remote439		// 4. if remote fails, return stale object, or error440 441		$cache = new RSSCache( MAGPIE_CACHE_DIR, MAGPIE_CACHE_AGE );442 443		if (MAGPIE_DEBUG and $cache->ERROR) {444			debug($cache->ERROR, E_USER_WARNING);445		}446 447		$cache_status 	 = 0;		// response of check_cache448		$request_headers = array(); // HTTP headers to send with fetch449		$rss 			 = 0;		// parsed RSS object450		$errormsg		 = 0;		// errors, if any451 452		if (!$cache->ERROR) {453			// return cache HIT, MISS, or STALE454			$cache_status = $cache->check_cache( $url );455		}456 457		// if object cached, and cache is fresh, return cached obj458		if ( $cache_status == 'HIT' ) {459			$rss = $cache->get( $url );460			if ( isset($rss) and $rss ) {461				$rss->from_cache = 1;462				if ( MAGPIE_DEBUG > 1) {463				debug("MagpieRSS: Cache HIT", E_USER_NOTICE);464			}465				return $rss;466			}467		}468 469		// else attempt a conditional get470 471		// set up headers472		if ( $cache_status == 'STALE' ) {473			$rss = $cache->get( $url );474			if ( isset($rss->etag) and $rss->last_modified ) {475				$request_headers['If-None-Match'] = $rss->etag;476				$request_headers['If-Last-Modified'] = $rss->last_modified;477			}478		}479 480		$resp = _fetch_remote_file( $url, $request_headers );481 482		if (isset($resp) and $resp) {483			if ($resp->status == '304' ) {484				// we have the most current copy485				if ( MAGPIE_DEBUG > 1) {486					debug("Got 304 for $url");487				}488				// reset cache on 304 (at minutillo insistent prodding)489				$cache->set($url, $rss);490				return $rss;491			}

Changelog

Introduced in 1.5.0. Unchanged from 6.7.7 through 7.1.0.

1. 6.7.7
2. 6.8.8
3. 6.9.7
4. 7.0.4
5. 7.1.0

Signature, return type and hooks compared across 5 parsed releases.

About this page

Parsed data

Generated from the wordpress-develop 7.0.4 tag, from src/wp-includes/rss.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.

Corrections

Something wrong on this page? Report it and it gets fixed in the next regeneration.