class-cache.php

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<?php

/**
 * Handle caching using transients for GravityView
 */
class GravityView_Cache {

    /** @deprecated 2.14 - use BLOCKLIST_OPTION_NAME instead! */
    const BLACKLIST_OPTION_NAME = 'gravityview_cache_blocklist';

    const BLOCKLIST_OPTION_NAME = 'gravityview_cache_blocklist';

    /**
     * Form ID, or array of Form IDs
     *
     * @var mixed
     */
    protected $form_ids;

    /**
     * Extra request parameters used to generate the query. This is used to generate the unique transient key.
     *
     * @var array
     */
    protected $args;

    /**
     * The transient key used to store the cached item. 45 characters long.
     *
     * @var string
     */
    private $key = '';

    /**
     * Whether to use the cache or not. Set in {@see use_cache()}.
     *
     * @var null|boolean $use_cache
     */
    private $use_cache = null;

    /**
     *
     * @param array|int $form_ids Form ID or array of form IDs used in a request
     * @param array $args Extra request parameters used to generate the query. This is used to generate the unique transient key.
     */
    function __construct( $form_ids = NULL, $args = array() ) {

        $this->add_hooks();

        if ( ! is_null( $form_ids ) ) {

            $this->form_ids = $form_ids;

            $this->args = $args;

            $this->set_key();
        }
    }

    /**
     * Add actions for clearing out caches when entries are updated.
     */
    function add_hooks() {

        // Schedule cleanup of expired transients
        add_action( 'wp', array( $this, 'schedule_transient_cleanup' ) );

        // Hook in to the scheduled cleanup, if scheduled
        add_action( 'gravityview-expired-transients', array( $this, 'delete_expired_transients' ) );

        // Trigger this when you need to prevent any results from being cached with forms that have been modified
        add_action( 'gravityview_clear_form_cache', array( $this, 'blocklist_add' ) );

        /**
         * @since 1.14
         */
        add_action( 'gravityview_clear_entry_cache', array( $this, 'entry_property_changed' ) );

        add_action( 'gform_after_update_entry', array( $this, 'entry_updated' ), 10, 2 );

        add_action( 'gform_entry_created', array( $this, 'entry_created' ), 10, 2 );

        add_action( 'gform_post_add_entry', array( $this, 'entry_added' ), 10, 2 );

        add_action( 'gform_post_update_entry_property', array( $this, 'entry_property_changed' ), 10, 4 );

        add_action( 'gform_delete_lead', array( $this, 'entry_property_changed' ), 10 );

    }

    /**
     * Force refreshing a cache when an entry is deleted.
     *
     * The `gform_delete_lead` action is called before the lead is deleted; we fetch the entry to find out the form ID so it can be added to the blocklist.
     *
     * @since  1.5.1
     *
     * @param  int $lead_id Entry ID
     * @param  string $property_value Previous value of the lead status passed by gform_update_status hook
     * @param  string $previous_value Previous value of the lead status passed by gform_update_status hook
     *
     * @return void
     */
    public function entry_status_changed( $lead_id, $property_value = '', $previous_value = '' ) {

        $entry = GFAPI::get_entry( $lead_id );

        if ( is_wp_error( $entry ) ) {

            gravityview()->log->error( 'Could not retrieve entry {entry_id} to delete it: {error}', array( 'entry_id' => $lead_id, 'error' => $entry->get_error_message() ) );

            return;
        }

        gravityview()->log->debug( 'adding form {form_id} to blocklist because entry #{lead_id} was deleted', array( 'form_id' => $entry['form_id'], 'entry_id' => $lead_id, 'data' => array( 'value' => $property_value, 'previous' => $previous_value ) ) );

        $this->blocklist_add( $entry['form_id'] );
    }

    /**
     * Force refreshing a cache when an entry is deleted.
     *
     * The `gform_delete_lead` action is called before the lead is deleted; we fetch the entry to find out the form ID so it can be added to the blocklist.
     *
     * @since  2.16.3
     *
     * @param int    $lead_id        The Entry ID.
     * @param string $property_name  The property that was updated.
     * @param string $property_value The new value of the property that was updated.
     * @param string $previous_value The previous property value before the update.
     *
     * @return void
     */
    public function entry_property_changed( $lead_id, $property_name = '', $property_value = '', $previous_value = '' ) {

        $entry = GFAPI::get_entry( $lead_id );

        if ( is_wp_error( $entry ) ) {

            gravityview()->log->error( 'Could not retrieve entry {entry_id} during cache clearing: {error}', array(
                'entry_id' => $lead_id,
                'error'    => $entry->get_error_message()
            ) );

            return;
        }

        gravityview()->log->debug( 'adding form {form_id} to blocklist because the {property_name} property was updated for entry #{lead_id}', array(
            'form_id'  => $entry['form_id'],
            'entry_id' => $lead_id,
            'data'     => array(
                'value'    => $property_value,
                'previous' => $previous_value,
                'property_name' => $property_name,
            )
        ) );

        $this->blocklist_add( $entry['form_id'] );
    }

    /**
     * When an entry is updated, add the entry's form to the cache blocklist
     *
     * @param  array $form GF form array
     * @param  int $lead_id Entry ID
     *
     * @return void
     */
    public function entry_updated( $form, $lead_id ) {

        gravityview()->log->debug(' adding form {form_id} to blocklist because entry #{entry_id} was updated', array( 'form_id' => $form['id'], 'entry_id' => $lead_id ) );

        $this->blocklist_add( $form['id'] );
    }

    /**
     * When an entry is created, add the entry's form to the cache blocklist
     *
     * We don't want old caches; when an entry is added, we want to clear the cache.
     *
     * @param  array $entry GF entry array
     * @param  array $form GF form array
     *
     * @return void
     */
    public function entry_created( $entry, $form ) {

        gravityview()->log->debug( 'adding form {form_id} to blocklist because entry #{entry_id} was created', array( 'form_id' => $form['id'], 'entry_id' => $entry['id'] ) );

        $this->blocklist_add( $form['id'] );
    }

    /**
     * Clear the cache when entries are added via GFAPI::add_entry().
     *
     * @param array $entry The GF Entry array
     * @param array $form  The GF Form array
     *
     * @return void
     */
    public function entry_added( $entry, $form ) {
        if ( is_wp_error( $entry ) ) {
            return;
        }

        gravityview()->log->debug( 'adding form {form_id} to blocklist because entry #{entry_id} was added', array( 'form_id' => $form['id'], 'entry_id' => $entry['id'] ) );

        $this->blocklist_add( $form['id'] );
    }

    /**
     * Calculate the prefix based on the Form IDs
     *
     * @param  int|array $form_ids Form IDs to generate prefix for
     *
     * @return string           Prefix for the cache string used in set_key()
     */
    protected function get_cache_key_prefix( $form_ids = NULL ) {

        if ( is_null( $form_ids ) ) {
            $form_ids = $this->form_ids;
        }

        // Normally just one form, but supports multiple forms
        //
        // Array of IDs 12, 5, 14 would result in `f:12-f:5-f:14`
        $forms = 'f:' . implode( '-f:', (array) $form_ids );

        // Prefix for transient keys
        // Now the prefix would be: `gv-cache-f:12-f:5-f:14-`
        return 'gv-cache-' . $forms . '-';

    }

    /**
     * Set the transient key based on the form IDs and the arguments passed to the class
     */
    protected function set_key() {

        // Don't set key if no forms have been set.
        if ( empty( $this->form_ids ) ) {
            return;
        }

        $key = $this->get_cache_key_prefix() . sha1( serialize( $this->args ) );

        // The transient name column can handle up to 64 characters.
        // The `_transient_timeout_` prefix that is prepended to the string is 11 characters.
        // 64 - 19 = 45
        // We make sure the key isn't too long or else WP doesn't store data.
        $this->key = substr( $key, 0, 45 );
    }

    /**
     * Allow public access to get transient key
     *
     * @return string Transient key
     */
    public function get_key() {
        return $this->key;
    }

    /**
     * Get the blocklist array.
     *
     * @since 2.16.3
     *
     * @return array
     */
    private function blocklist_get() {
        $blocklist = get_option( self::BLOCKLIST_OPTION_NAME, array() );

        return array_map( 'intval', (array) $blocklist );
    }

    /**
     * Add form IDs to a "blocklist" to force the cache to be refreshed
     *
     * @param  int|array $form_ids Form IDs to force to be updated
     *
     * @return boolean           False if value was not updated and true if value was updated.
     */
    public function blocklist_add( $form_ids ) {

        $blocklist = $this->blocklist_get();

        $form_ids = is_array( $form_ids ) ? $form_ids : array( $form_ids );

        $form_ids = array_map( 'intval', $form_ids );

        // Add the passed form IDs
        $blocklist = array_merge( (array) $blocklist, $form_ids );

        // Don't duplicate
        $blocklist = array_unique( $blocklist );

        // Remove empty items from blocklist
        $blocklist = array_filter( $blocklist );

        $updated = update_option( self::BLOCKLIST_OPTION_NAME, $blocklist );

        if ( false !== $updated ) {
            gravityview()->log->debug( 'Added form IDs to cache blocklist', array( 'data' => array(
                '$form_ids'  => $form_ids,
                '$blocklist' => $blocklist
            ) ) );
        }

        return $updated;
    }

    /**
     * @deprecated 2.14 {@see GravityView_Cache::blocklist_add()}
     *
     * @param  int|array $form_ids Form IDs to force to be updated
     *
     * @return bool Whether the removal was successful
     */
    public function blacklist_add( $form_ids ) {
        _deprecated_function( __METHOD__, '2.14', 'GravityView_Cache::blocklist_add()' );
        return $this->blocklist_remove( $form_ids );
    }

    /**
     * Remove Form IDs from blocklist
     *
     * @param  int|array $form_ids Form IDs to remove
     *
     * @return bool Whether the removal was successful
     */
    public function blocklist_remove( $form_ids ) {

        $blocklist = get_option( self::BLOCKLIST_OPTION_NAME, array() );

        $updated_list = array_diff( $blocklist, (array) $form_ids );

        gravityview()->log->debug( 'Removing form IDs from cache blocklist', array( 'data' => array(
            '$form_ids'     => $form_ids,
            '$blocklist'    => $blocklist,
            '$updated_list' => $updated_list
        ) ) );

        return update_option( self::BLOCKLIST_OPTION_NAME, $updated_list );
    }

    /**
     * @deprecated 2.14 {@see GravityView_Cache::blocklist_remove()}
     *
     * @param  int|array $form_ids Form IDs to add
     *
     * @return bool Whether the removal was successful
     */
    public function blacklist_remove( $form_ids ) {
        _deprecated_function( __METHOD__, '2.14', 'GravityView_Cache::blocklist_remove()' );
        return $this->blocklist_remove( $form_ids );
    }

    /**
     * Is a form ID in the cache blocklist?
     *
     * @param  int|array $form_ids Form IDs to check if in blocklist
     *
     * @deprecated 2.14 Use {@see GravityView_Cache::in_blocklist()}
     *
     * @return bool
     */
    public function in_blacklist( $form_ids = NULL ) {
        _deprecated_function( __METHOD__, '2.14', 'GravityView_Cache::in_blocklist()' );
        return $this->in_blocklist( $form_ids );
    }

    /**
     * Is a form ID in the cache blocklist
     *
     * @param  int|array $form_ids Form IDs to check if in blocklist
     *
     * @return bool
     */
    public function in_blocklist( $form_ids = NULL ) {

        $blocklist = $this->blocklist_get();

        // Use object var if exists
        $form_ids = is_null( $form_ids ) ? $this->form_ids : $form_ids;

        if ( empty( $form_ids ) ) {

            gravityview()->log->debug( 'Did not add form to blocklist; empty form ID', array( 'data' => $form_ids ) );

            return false;
        }

        foreach ( (array) $form_ids as $form_id ) {

            if ( in_array( (int) $form_id, $blocklist, true ) ) {

                gravityview()->log->debug( 'Form #{form_id} is in the cache blocklist', array( 'form_id' => $form_id ) );

                return true;
            }
        }

        return false;
    }


    /**
     * Get transient result
     *
     * @param  string $key Transient key to fetch
     *
     * @return mixed      False: Not using cache or cache was a WP_Error object; NULL: no results found; Mixed: cache value
     */
    public function get( $key = null ) {

        $key = is_null( $key ) ? $this->key : $key;

        if ( ! $this->use_cache() ) {

            gravityview()->log->debug( 'Not using cached results because of GravityView_Cache->use_cache() results' );

            return false;
        }

        gravityview()->log->debug( 'Fetching request with transient key {key}', array( 'key' => $key ) );

        $result = get_transient( $key );

        if ( is_wp_error( $result ) ) {

            gravityview()->log->debug( 'Fetching request resulted in error:', array( 'data' => $result ) );

            return false;

        } elseif ( $result ) {

            gravityview()->log->debug( 'Cached results found for transient key {key}', array( 'key' => $key ) );

            return $result;
        }

        gravityview()->log->debug( 'No cached results found for transient key {key}', array( 'key' => $key ) );

        return NULL;
    }

    /**
     * Cache content as a transient.
     *
     * Cache time defaults to 1 day.
     *
     * @since 2.16 Added $cache_time parameter to allow overriding the default cache time.
     *
     * @param mixed $content The content to cache.
     * @param string $filter_name Name used to modify the cache time. Will be set to `gravityview_cache_time_{$filter_name}`.
     * @param int|null $expiration Cache time in seconds. If not set, DAYS_IN_SECONDS will be used.
     *
     * @return bool If $content is not set, false. Otherwise, returns true if transient was set and false if not.
     */
    public function set( $content, $filter_name = '', $expiration = null ) {

        // Don't cache empty results
        if ( ! empty( $content ) ) {

            $expiration = ! is_int( $expiration ) ? DAY_IN_SECONDS : $expiration;

            /**
             * @filter `gravityview_cache_time_{$filter_name}` Modify the cache time for a type of cache
             * @param int $time_in_seconds Default: `DAY_IN_SECONDS`
             */
            $expiration = (int) apply_filters( 'gravityview_cache_time_' . $filter_name, $expiration );

            gravityview()->log->debug( 'Setting cache with transient key {key} for {expiration} seconds', array( 'key' => $this->key, 'expiration' => $expiration ) );

            $transient_was_set = set_transient( $this->key, $content, $expiration );

            if ( ! $transient_was_set && $this->use_cache() ) {
                gravityview()->log->error( 'Transient was not set for this key: ' . $this->key );
            }

            return $transient_was_set;
        }

        gravityview()->log->debug( 'Cache not set; content is empty' );

        return false;
    }

    /**
     * Delete cached transients based on form IDs
     *
     * @todo Use REGEX to match forms when array of form IDs is passed, instead of using a simple LIKE
     * @todo  Rate limit deleting to prevent abuse
     *
     * @param  int|array $form_ids Form IDs to delete
     *
     * @return void
     */
    public function delete( $form_ids = NULL ) {
        global $wpdb;

        // Use object var if exists
        $form_ids = is_null( $form_ids ) ? $this->form_ids : $form_ids;

        if ( empty( $form_ids ) ) {
            gravityview()->log->debug( 'Did not delete cache; empty form IDs' );

            return;
        }

        foreach ( (array) $form_ids as $form_id ) {

            $key = '_transient_gv-cache-';

            $key = $wpdb->esc_like( $key );

            $form_id = intval( $form_id );

            // Find the transients containing this form
            $key = "$key%f:$form_id-%"; // \_transient\_gv-cache-%f:1-% for example
            $sql = $wpdb->prepare( "SELECT option_name FROM {$wpdb->options} WHERE `option_name` LIKE %s", $key );

            foreach ( ( $transients = $wpdb->get_col( $sql ) ) as $transient ) {
                // We have to delete it via the API to make sure the object cache is updated appropriately
                delete_transient( preg_replace( '#^_transient_#', '', $transient ) );
            }

            gravityview()->log->debug( 'Deleting cache for form #{form_id}', array( 'form_id' => $form_id, 'data' => array(
                $sql,
                sprintf( 'Deleted results: %d', count( $transients ) )
            ) ) );
        }

    }

    /**
     * Schedule expired transient cleanup twice a day.
     *
     * Can be overruled by the `gravityview_cleanup_transients` filter (returns boolean)
     *
     * @return void
     */
    public function schedule_transient_cleanup() {

        /**
         * @filter `gravityview_cleanup_transients` Override GravityView cleanup of transients by setting this to false
         * @param boolean $cleanup Whether to run the GravityView auto-cleanup of transients. Default: `true`
         */
        $cleanup = apply_filters( 'gravityview_cleanup_transients', true );

        if ( ! $cleanup ) {
            return;
        }

        if ( ! wp_next_scheduled( 'gravityview-expired-transients' ) ) {
            wp_schedule_event( time(), 'daily', 'gravityview-expired-transients' );
        }
    }

    /**
     * Delete expired transients.
     *
     * The code is copied from the Delete Expired Transients, with slight modifications to track # of results and to get the blog ID dynamically
     *
     * @see https://wordpress.org/plugins/delete-expired-transients/ Plugin where the code was taken from
     * @see  DelxtransCleaners::clearBlogExpired()
     * @return void
     */
    public function delete_expired_transients() {
        global $wpdb;

        // Added this line, which isn't in the plugin
        $blog_id = get_current_blog_id();

        $num_results = 0;

        // get current PHP time, offset by a minute to avoid clashes with other tasks
        $threshold = time() - 60;

        // get table name for options on specified blog
        $table = $wpdb->get_blog_prefix( $blog_id ) . 'options';

        // delete expired transients, using the paired timeout record to find them
        $sql = "
            delete from t1, t2
            using $table t1
            join $table t2 on t2.option_name = replace(t1.option_name, '_timeout', '')
            where (t1.option_name like '\_transient\_timeout\_%' or t1.option_name like '\_site\_transient\_timeout\_%')
            and t1.option_value < '$threshold'
        ";

        $num_results = $wpdb->query( $sql );

        // delete orphaned transient expirations
        // also delete NextGEN Gallery 2.x display cache timeout aliases
        $sql = "
            delete from $table
            where (
                   option_name like '\_transient\_timeout\_%'
                or option_name like '\_site\_transient\_timeout\_%'
                or option_name like 'displayed\_galleries\_%'
                or option_name like 'displayed\_gallery\_rendering\_%'
            )
            and option_value < '$threshold'
        ";

        $num_results += $wpdb->query( $sql );

        gravityview()->log->debug( 'Deleted {count} expired transient records from the database', array( 'count' => $num_results ) );
    }

    /**
     * Check whether to use cached results, if available
     *
     * If the user can edit posts, they are able to override whether to cache results by adding `cache` or `nocache` to the URL requested.
     *
     * @return boolean True: use cache; False: don't use cache
     */
    public function use_cache() {

        // Exit early if debugging (unless running PHPUnit)
        if ( defined( 'GRAVITYVIEW_DISABLE_CACHE' ) && GRAVITYVIEW_DISABLE_CACHE && ! ( defined('DOING_GRAVITYVIEW_TESTS' ) && DOING_GRAVITYVIEW_TESTS ) ) {
            return (boolean) apply_filters( 'gravityview_use_cache', false, $this );
        }

        // Only run once per instance.
        if ( ! is_null( $this->use_cache ) ) {
            return $this->use_cache;
        }

        $use_cache = true;

        if ( GVCommon::has_cap( 'edit_gravityviews' ) ) {

            if ( isset( $_GET['cache'] ) || isset( $_GET['nocache'] ) ) {

                gravityview()->log->debug( 'Not using cache: ?cache or ?nocache is in the URL' );

                $use_cache = false;
            }

        }

        // Has the form been flagged as having changed items in it?
        if ( ! $use_cache || $this->in_blocklist() ) {

            // Delete caches for all items with form IDs XYZ
            $this->delete( $this->form_ids );

            // Remove the form from
            $this->blocklist_remove( $this->form_ids );
        }

        /**
         * @filter `gravityview_use_cache` Modify whether to use the cache or not
         * @param  boolean $use_cache Previous setting
         * @param GravityView_Cache $this The GravityView_Cache object
         */
        $this->use_cache = (boolean) apply_filters( 'gravityview_use_cache', $use_cache, $this );

        return $this->use_cache;
    }

}

new GravityView_Cache;