Caching now supports expiry

Fixes #23

includes/cache.php

@@ -1,12 +1,8 @@
 <?php
 /**
- * Contextual Related Posts Cache interface.
+ * Cache interface.
  *
- * @package   Contextual_Related_Posts
- * @author    Ajay D'Souza
- * @license   GPL-2.0+
- * @link      https://webberzone.com
- * @copyright 2009-2020 Ajay D'Souza
+ * @package WHEREGO
  */
 
 // If this file is called directly, abort.
@@ -21,52 +17,16 @@
  */
 function wherego_ajax_clearcache() {
 
-	global $wpdb;
-
-	$counter = array();
-
-	$meta_keys = wherego_cache_get_keys();
-	$error     = false;
-
-	foreach ( $meta_keys as $meta_key ) {
-
-		$count = $wpdb->query( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching
-			$wpdb->prepare(
-				"
-				DELETE FROM {$wpdb->postmeta}
-				WHERE meta_key = %s
-				",
-				$meta_key
+	wherego_cache_delete();
+	exit(
+		wp_json_encode(
+			array(
+				'success' => 1,
+				'message' => __( 'Cache cleared', 'where-did-they-go-from-here' ),
 			)
-		);
-
-		if ( false === $count ) {
-			$error = true;
-		} else {
-			$counter[] = $count;
-		}
-	}
+		)
+	);
 
-	/**** Did an error occur? */
-	if ( $error ) {
-		exit(
-			wp_json_encode(
-				array(
-					'success' => 0,
-					'message' => __( 'An error occurred clearing the cache. Please contact your site administrator.\n\nError message:\n', 'where-did-they-go-from-here' ) . $wpdb->print_error(),
-				)
-			)
-		);
-	} else {    // No error, return the number of.
-		exit(
-			wp_json_encode(
-				array(
-					'success' => 1,
-					'message' => ( array_sum( $counter ) ) . __( ' cached row(s) cleared', 'where-did-they-go-from-here' ),
-				)
-			)
-		);
-	}
 }
 add_action( 'wp_ajax_wherego_clear_cache', 'wherego_ajax_clearcache' );
 
@@ -77,8 +37,10 @@ function wherego_ajax_clearcache() {
  * @since 2.4.0
  *
  * @param array $meta_keys Array of meta keys that hold the cache.
+ * @return int Number of keys deleted.
  */
 function wherego_cache_delete( $meta_keys = array() ) {
+	$loop = 0;
 
 	$default_meta_keys = wherego_cache_get_keys();
 
@@ -89,8 +51,13 @@ function wherego_cache_delete( $meta_keys = array() ) {
 	}
 
 	foreach ( $meta_keys as $meta_key ) {
-		delete_post_meta_by_key( $meta_key );
+		$del_meta = delete_wherego_cache_by_key( $meta_key );
+		if ( $del_meta ) {
+			$loop++;
+		}
 	}
+
+	return $loop;
 }
 
 
@@ -99,10 +66,10 @@ function wherego_cache_delete( $meta_keys = array() ) {
  *
  * @since 2.4.0
  *
- * @param mixed $post_id Post ID.
+ * @param int $post_id Post ID. Optional.
  * @return array Array of _wherego_cache keys.
  */
-function wherego_cache_get_keys( $post_id = null ) {
+function wherego_cache_get_keys( $post_id = 0 ) {
 	global $wpdb;
 
 	$keys = array();
@@ -111,9 +78,10 @@ function wherego_cache_get_keys( $post_id = null ) {
 		SELECT meta_key
 		FROM {$wpdb->postmeta}
 		WHERE `meta_key` LIKE '_wherego_cache_%'
+		AND `meta_key` NOT LIKE '_wherego_cache_expires_%'
 	";
 
-	if ( is_int( $post_id ) ) {
+	if ( $post_id > 0 ) {
 		$sql .= $wpdb->prepare( ' AND `post_id` = %d ', $post_id );
 	}
 
@@ -151,5 +119,146 @@ function wherego_cache_delete_by_post( $post_id = null ) {
 		$flag[] = delete_post_meta( $post_id, $meta_key );
 	}
 	return wp_json_encode( $flag );
+}
+
+/**
+ * Get the meta key based on a list of parameters.
+ *
+ * @since 2.4.0
+ *
+ * @param mixed $attr Array of attributes typically.
+ * @return string Cache meta key
+ */
+function wherego_cache_get_key( $attr ) {
+
+	$meta_key = md5( wp_json_encode( $attr ) );
+
+	return $meta_key;
+}
+
+/**
+ * Sets/updates the value of the WZP cache for a post.
+ *
+ * @since 3.0.0
+ *
+ * @param int    $post_id    Post ID.
+ * @param string $key        WZP Cache key.
+ * @param mixed  $value      Metadata value. Must be serializable if non-scalar.
+ * @param int    $expiration Time until expiration in seconds. Default WZP_CACHE_TIME (one week if not overridden).
+ * @return int|bool Meta ID if the key didn't exist, true on successful update,
+ *                  false on failure or if the value passed to the function
+ *                  is the same as the one that is already in the database.
+ */
+function set_wherego_cache( $post_id, $key, $value, $expiration = WZP_CACHE_TIME ) {
+
+	$expiration = (int) $expiration;
+
+	/**
+	 * Filters the expiration for a WZP Cache key before its value is set.
+	 *
+	 * The dynamic portion of the hook name, `$key`, refers to the WZP Cache key.
+	 *
+	 * @since 3.0.0
+	 *
+	 * @param int    $expiration Time until expiration in seconds. Use 0 for no expiration.
+	 * @param int    $post_id    Post ID.
+	 * @param string $key        WZP Cache key name.
+	 * @param mixed  $value      New value of WZP Cache key.
+	 */
+	$expiration = apply_filters( "wherego_cache_time_{$key}", $expiration, $post_id, $key, $value );
+
+	$meta_key      = '_wherego_cache_' . $key;
+	$cache_expires = '_wherego_cache_expires_' . $key;
 
+	$updated = update_post_meta( $post_id, $meta_key, $value, '' );
+	update_post_meta( $post_id, $cache_expires, time() + $expiration, '' );
+
+	return $updated;
+}
+
+/**
+ * Get the value of the WZP cache for a post.
+ *
+ * @since 3.0.0
+ *
+ * @param int    $post_id Post ID.
+ * @param string $key     WZP Cache key.
+ * @return mixed Value of the WZP cache or false if invalid, expired or unavailable.
+ */
+function get_wherego_cache( $post_id, $key ) {
+	$meta_key      = '_wherego_cache_' . $key;
+	$cache_expires = '_wherego_cache_expires_' . $key;
+
+	$value = get_post_meta( $post_id, $meta_key, true );
+
+	if ( ! WZP_CACHE_TIME ) {
+		return $value;
+	}
+
+	if ( $value ) {
+		$expires = (int) get_post_meta( $post_id, $cache_expires, true );
+		if ( $expires < time() || empty( $expires ) ) {
+			delete_wherego_cache( $post_id, $meta_key );
+			return false;
+		} else {
+			return $value;
+		}
+	} else {
+		return false;
+	}
+}
+
+
+/**
+ * Delete the value of the WZP cache for a post.
+ *
+ * @since 3.0.0
+ *
+ * @param int    $post_id Post ID.
+ * @param string $key     WZP Cache key.
+ * @return bool True on success, False on failure.
+ */
+function delete_wherego_cache( $post_id, $key ) {
+	$meta_key      = '_wherego_cache_' . $key;
+	$cache_expires = '_wherego_cache_expires_' . $key;
+
+	$result = delete_post_meta( $post_id, $meta_key );
+	if ( $result ) {
+		delete_post_meta( $post_id, $cache_expires );
+	}
+
+	return $result;
+}
+
+
+/**
+ * Delete the value of the WZP cache by cache key.
+ *
+ * @since 3.0.0
+ *
+ * @param string $key WZP Cache key.
+ * @return bool True on success, False on failure.
+ */
+function delete_wherego_cache_by_key( $key ) {
+	$key           = str_replace( '_wherego_cache_expires_', '', $key );
+	$key           = str_replace( '_wherego_cache_', '', $key );
+	$meta_key      = '_wherego_cache_' . $key;
+	$cache_expires = '_wherego_cache_expires_' . $key;
+
+	$result = delete_post_meta_by_key( $meta_key );
+	delete_post_meta_by_key( $cache_expires );
+
+	return $result;
+}
+
+/**
+ * Adds a clear cache button to the settings screen.
+ *
+ * @since 3.0.0
+ */
+function wherego_cache_button() {
+	?>
+	<input type="button" name="cache_clear" id="cache_clear"  value="<?php esc_attr_e( 'Clear cache', 'where-did-they-go-from-here' ); ?>" class="button button-secondary delete" onclick="return wheregoClearCache();" />
+	<?php
 }
+add_action( 'wherego_settings_form_buttons', 'wherego_cache_button' );

includes/main.php

@@ -39,7 +39,7 @@ function get_wherego( $args = array() ) {
 	if ( ! empty( $args['cache'] ) && ! ( is_preview() || is_admin() || ( defined( 'REST_REQUEST' ) && REST_REQUEST ) ) ) {
 		$meta_key = wherego_cache_get_key( $args );
 
-		$output = get_post_meta( $post->ID, $meta_key, true );
+		$output = get_wherego_cache( $post->ID, $meta_key );
 		if ( $output ) {
 			/** This filter has been defined in main.php */
 			return apply_filters( 'get_wherego', $output, $args );
@@ -175,7 +175,7 @@ function get_wherego( $args = array() ) {
 
 	// Support caching to speed up retrieval.
 	if ( ! empty( $args['cache'] ) && ! ( is_preview() || is_admin() || ( defined( 'REST_REQUEST' ) && REST_REQUEST ) ) ) {
-		update_post_meta( $post->ID, $meta_key, $output, '' );
+		set_wherego_cache( $post->ID, $meta_key, $output );
 	}
 
 	/**
@@ -384,18 +384,3 @@ function wherego_get_style() {
 	 */
 	return apply_filters( 'wherego_get_style', $style, $wherego_style, $thumb_width, $thumb_height );
 }
-
-/**
- * Get the meta key based on a list of parameters.
- *
- * @since 2.4.0
- *
- * @param array $attr   Array of attributes.
- * @return string Cache meta key
- */
-function wherego_cache_get_key( $attr ) {
-
-	$meta_key = '_wherego_cache_' . md5( wp_json_encode( $attr ) );
-
-	return $meta_key;
-}

readme.txt

@@ -106,6 +106,7 @@ You can also use this function to display posts on any type of page generated by
 	* Support for PolyLang and WPML
 
 * Enhancements:
+    * Improved caching with inbuilt expiry. Use WZP_CACHE_TIME in your wp-config.php to set how long the cache should be set for. Default is one week. Setting it to `false` will disable expiry
 	* Upgraded post thumbnail handling: Select the thumbnail size. The plugin will also check for site icons before the default thumbnail is selected
 	* Upgraded settings to new Settings_API class
 	* Grid thumbnail style has been redone to use CSS grid and flexbox. Please pick the correct thumbnail size in the Thumbnail settings

uninstall.php

@@ -45,7 +45,8 @@ function wherego_delete_data() {
 		"
 		DELETE FROM {$wpdb->postmeta}
 		WHERE meta_key LIKE 'wheredidtheycomefrom'
-	"
+		OR `meta_key` LIKE '_wherego_cache_%'
+		"
 	);
 
 	delete_option( 'ald_wherego_settings' );

where-did-they-go-from-here.php

@@ -62,6 +62,17 @@
 	define( 'WHEREGO_PLUGIN_URL', plugin_dir_url( WHEREGO_PLUGIN_FILE ) );
 }
 
+/**
+ * Cache expiration time.
+ *
+ * @since 3.0.0
+ *
+ * @var int Cache time. Default is one week.
+ */
+if ( ! defined( 'WZP_CACHE_TIME' ) ) {
+	define( 'WZP_CACHE_TIME', WEEK_IN_SECONDS );
+}
+
 /*
  *----------------------------------------------------------------------------
  * Includes