set_transient( string $transient, mixed $value, int $expiration = 0 ): bool

Description

Compatibility

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

Parameters

$transientstring

Transient name. Expected to not be SQL-escaped.
Must be 172 characters or fewer in length.

$valuemixed

Transient value. Must be serializable if non-scalar.
Expected to not be SQL-escaped.

$expirationintoptional

Time until expiration in seconds. Default 0 (no expiration).Default: 0

Return value

bool

True if the value was set, false otherwise.

Performance profile

How much work a call to set_transient() 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

Moderate

Reads stored settings via get_option(), cached per request but not free on a cold cache.

Scaling

Constant

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

Instructions

34–97

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 132.

Plugin surface

5 hooks

Third-party callbacks on 'pre_set_transient_{$transient}', 'expiration_of_transient_{$transient}', 'set_transient_{$transient}' run inside this call, and their cost is not bounded by anything here.

Called by

22

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

What it touches

• transienttransientset_transient()this function does it
• hookthird-party callbacksapply_filters()called directly
• cacheobject cachewp_cache_set()called directly
• optionoption read or writeget_option()called directly
• serializeserialisationmaybe_unserialize()one call below set_transient()

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

What one call costs · 20 distinct outcomes

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

Hooks and filters fired · 5

5 hooks fire while set_transient() runs, in this order:

1. 1
   apply_filters( pre_set_transient_{$transient} )filterline 1526 (+17 into the body)

   Filters a specific transient before its value is set.

2. 2
   apply_filters( expiration_of_transient_{$transient} )filterline 1539 (+30 into the body)

   Filters the expiration for a transient before its value is set.

3. 3
   do_action( set_transient_{$transient} )actionline 1594 (+85 into the body)

   Fires after the value for a specific transient has been set.

4. 4
   do_action( set_transient )actionline 1605 (+96 into the body)

   Fires after the value for a transient has been set.

5. 5
   do_action( setted_transient )action_deprecatedline 1618 (+109 into the body)

   Fires after the transient is set.

Uses · 11

• apply_filters()Calls the callback functions that have been added to a filter hook.
• wp_using_ext_object_cache()Toggles `$_wp_using_ext_object_cache` on and off without directly touching global.
• wp_installing()Checks or sets whether WordPress is in "installation" mode.
• wp_cache_set()Saves the data to the cache.
• wp_prime_option_caches()Primes specific options into the cache with a single database query.
• get_option()Retrieves an option value based on an option name.
• add_option()Adds a new option.
• delete_option()Removes an option by name. Prevents removal of protected WordPress options.
• update_option()Updates the value of an option that was already added.
• do_action()Calls the callback functions that have been added to an action hook.
• do_action_deprecated()Fires functions attached to a deprecated action hook.

Used by · 22

• Featured_Content::get_featured_post_ids()Gets featured post IDs.
• RSSCache::set()
• WP_Automatic_Updater::has_fatal_error()Performs a loopback request to check for potential fatal errors.
• WP_Site_Health::wp_cron_scheduled_check()Runs the scheduled event to check and update the latest site health status for the website.
• WP_oEmbed_Controller::get_proxy_item()Callback for the proxy API endpoint.
• clean_dirsize_cache()Cleans directory size cache used by recurse_dirsize().
• install_themes_feature_list()Retrieves the list of WordPress theme features (aka theme tags).
• is_multi_author()Determines whether this site has more than one author.
• recurse_dirsize()Gets the size of a directory recursively.
• register_core_block_style_handles()Registers core block style handles.
• spawn_cron()Sends a request to run cron through HTTP request that doesn't halt page loading.
• twentyfifteen_categorized_blog()Determines whether blog/site has more than one category.

Source code

View on Trac ↗View on GitHub ↗

1509function set_transient( $transient, $value, $expiration = 0 ) {1510 1511	$expiration = (int) $expiration;1512 1513	/**1514	 * Filters a specific transient before its value is set.1515	 *1516	 * The dynamic portion of the hook name, `$transient`, refers to the transient name.1517	 *1518	 * @since 3.0.01519	 * @since 4.2.0 The `$expiration` parameter was added.1520	 * @since 4.4.0 The `$transient` parameter was added.1521	 *1522	 * @param mixed  $value      New value of transient.1523	 * @param int    $expiration Time until expiration in seconds.1524	 * @param string $transient  Transient name.1525	 */1526	$value = apply_filters( "pre_set_transient_{$transient}", $value, $expiration, $transient );1527 1528	/**1529	 * Filters the expiration for a transient before its value is set.1530	 *1531	 * The dynamic portion of the hook name, `$transient`, refers to the transient name.1532	 *1533	 * @since 4.4.01534	 *1535	 * @param int    $expiration Time until expiration in seconds. Use 0 for no expiration.1536	 * @param mixed  $value      New value of transient.1537	 * @param string $transient  Transient name.1538	 */1539	$expiration = apply_filters( "expiration_of_transient_{$transient}", $expiration, $value, $transient );1540 1541	if ( wp_using_ext_object_cache() || wp_installing() ) {1542		$result = wp_cache_set( $transient, $value, 'transient', $expiration );1543	} else {1544		$transient_timeout = '_transient_timeout_' . $transient;1545		$transient_option  = '_transient_' . $transient;1546		wp_prime_option_caches( array( $transient_option, $transient_timeout ) );1547 1548		if ( false === get_option( $transient_option ) ) {1549			$autoload = true;1550			if ( $expiration ) {1551				$autoload = false;1552				add_option( $transient_timeout, time() + $expiration, '', false );1553			}1554			$result = add_option( $transient_option, $value, '', $autoload );1555		} else {1556			/*1557			 * If expiration is requested, but the transient has no timeout option,1558			 * delete, then re-create transient rather than update.1559			 */1560			$update = true;1561 1562			if ( $expiration ) {1563				if ( false === get_option( $transient_timeout ) ) {1564					delete_option( $transient_option );1565					add_option( $transient_timeout, time() + $expiration, '', false );1566					$result = add_option( $transient_option, $value, '', false );1567					$update = false;1568				} else {1569					update_option( $transient_timeout, time() + $expiration );1570				}1571			}1572 1573			if ( $update ) {1574				$result = update_option( $transient_option, $value );1575			}1576		}1577	}1578 1579	if ( $result ) {1580 1581		/**1582		 * Fires after the value for a specific transient has been set.1583		 *1584		 * The dynamic portion of the hook name, `$transient`, refers to the transient name.1585		 *1586		 * @since 3.0.01587		 * @since 3.6.0 The `$value` and `$expiration` parameters were added.1588		 * @since 4.4.0 The `$transient` parameter was added.

Changelog

Introduced in 2.8.0. 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 6.9.7 tag, from src/wp-includes/option.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.