Add cache preloading functionality

README.md

@@ -1,7 +1,7 @@
 # Nginx Helper #
 [![Project Status: Active – The project has reached a stable, usable state and is being actively developed.](https://www.repostatus.org/badges/latest/active.svg)](https://www.repostatus.org/#active)
 
-**Contributors:** rtcamp, rahul286, saurabhshukla, manishsongirkar36, faishal, desaiuditd, darren-slatten, jk3us, daankortenbach, telofy, pjv, llonchj, jinnko, weskoop, bcole808, gungeekatx, rohanveer, chandrapatel, gagan0123, ravanh, michaelbeil, samedwards, niwreg, entr, nuvoPoint, iam404, rittesh.patel, vishalkakadiya, BhargavBhandari90, vincent-lu, murrayjbrown, bryant1410, 1gor, matt-h, pySilver, johan-chassaing, dotsam, sanketio, petenelson, nathanielks, rigagoogoo, dslatten, jinschoi, kelin1003, vaishuagola27, rahulsprajapati, Joel-James, utkarshpatel, gsayed786, shashwatmittal, sudhiryadav, thrijith, stayallive, jaredwsmith, abhijitrakas, umeshnevase, sid177, souptik, arafatkn, subscriptiongroup, akrocks
+**Contributors:** rtcamp, rahul286, saurabhshukla, manishsongirkar36, faishal, desaiuditd, darren-slatten, jk3us, daankortenbach, telofy, pjv, llonchj, jinnko, weskoop, bcole808, gungeekatx, rohanveer, chandrapatel, gagan0123, ravanh, michaelbeil, samedwards, niwreg, entr, nuvoPoint, iam404, rittesh.patel, vishalkakadiya, BhargavBhandari90, vincent-lu, murrayjbrown, bryant1410, 1gor, matt-h, pySilver, johan-chassaing, dotsam, sanketio, petenelson, nathanielks, rigagoogoo, dslatten, jinschoi, kelin1003, vaishuagola27, rahulsprajapati, Joel-James, utkarshpatel, gsayed786, shashwatmittal, sudhiryadav, thrijith, stayallive, jaredwsmith, abhijitrakas, umeshnevase, sid177, souptik, arafatkn, subscriptiongroup, akrocks, Vedant-Gandhi
 
 **Tags:** nginx, cache, purge, nginx map, nginx cache, maps, fastcgi, proxy, redis, redis-cache, rewrite, permalinks
 

admin/class-nginx-helper-admin.php

@@ -278,6 +278,8 @@ public function nginx_helper_default_settings() {
 			'redis_prefix'                     => 'nginx-cache:',
 			'purge_url'                        => '',
 			'redis_enabled_by_constant'        => 0,
+            'preload_cache'                    => 0,
+            'is_cache_preloaded'               => 0
 		);
 
 	}
@@ -775,5 +777,100 @@ public function purge_all() {
 	public function display_notices() {
 		echo '<div class="updated"><p>' . esc_html__( 'Purge initiated', 'nginx-helper' ) . '</p></div>';
 	}
+
+	/**
+	 * Preloads the cache for the website.
+	 *
+	 * @return void
+	 */
+	public function preload_cache() {
+		$is_cache_preloaded    = $this->options['is_cache_preloaded'];
+		$preload_cache_enabled = $this->options['preload_cache'];
+
+		if ( $preload_cache_enabled && false === boolval( $is_cache_preloaded ) ) {
+			$this->options['is_cache_preloaded'] = true;
+
+			update_site_option( 'rt_wp_nginx_helper_options', $this->options );
+			$this->preload_cache_from_sitemap();
+		}
+	}
+
+	/**
+	 * This function preloads the cache from sitemap url.
+	 *
+	 * @return void
+	 */
+	private function preload_cache_from_sitemap() {
+
+        $sitemap_urls = $this->get_index_sitemap_urls();
+        $all_urls     = array();
+
+		foreach ( $sitemap_urls as $sitemap_url ) {
+			$urls = $this->extract_sitemap_urls( $sitemap_url );
+            $all_urls = array_merge( $all_urls, $urls );
+        }
+
+		$args = array(
+			'timeout'   => 1,
+			'blocking'  => false,
+			'sslverify' => false,
+		);
+
+		foreach ( $all_urls as $url ) {
+			wp_remote_get( esc_url_raw( $url ), $args );
+		}
+
+	}
+
+	/**
+	 * Fetches all the sitemap urls for the site.
+	 *
+	 * @return array
+	 */
+	private function get_index_sitemap_urls() {
+		$sitemaps = wp_sitemaps_get_server()->index->get_sitemap_list();
+		$urls     = array();
+		foreach ( $sitemaps as $sitemap ) {
+			$urls[] = $sitemap['loc'];
+		}
+		return $urls;
+	}
+
+	/**
+	 * Parse sitemap content and extract all URLs.
+	 *
+	 * @param string $sitemap_url The URL of the sitemap.
+	 * @return array|WP_Error An array of URLs or WP_Error on failure.
+	 */
+	private function extract_sitemap_urls( $sitemap_url ) {
+		$response = wp_remote_get( $sitemap_url );
+
+		$urls = array();
+
+		if ( is_wp_error( $response ) ) {
+			return $urls;
+		}
+
+		$sitemap_content = wp_remote_retrieve_body( $response );
+
+		libxml_use_internal_errors( true );
+		$xml = simplexml_load_string( $sitemap_content );
+
+		if ( false === $xml ) {
+			return new WP_Error( 'sitemap_parse_error', esc_html__( 'Failed to parse the sitemap XML', 'nginx-helper' ) );
+		}
+
+		$urls = array();
+
+		if ( $xml === false ) {
+			return $urls;
+		}
+
+		foreach ( $xml->url as $url ) {
+			$urls[] = (string) $url->loc;
+		}
+
+		return $urls;
+	}
 
 }

admin/partials/nginx-helper-general-options.php

@@ -40,6 +40,7 @@
 	'purge_page_on_deleted_comment',
 	'purge_feeds',
 	'smart_http_expire_form_nonce',
+    'preload_cache',
 );
 
 $all_inputs = array();
@@ -126,6 +127,12 @@
 						<label for="enable_purge"><?php esc_html_e( 'Enable Purge', 'nginx-helper' ); ?></label>
 					</td>
 				</tr>
+                <tr valign="top">
+                    <td>
+                        <input type="checkbox" value="1" id="preload_cache" name="preload_cache" <?php checked( $nginx_helper_settings['preload_cache'], 1 ); ?> />
+                        <label for="preload_cache"><?php esc_html_e( 'Preload Cache', 'nginx-helper' ); ?></label>
+                    </td>
+                </tr>
 			</table>
 		</div> <!-- End of .inside -->
 	</div>

includes/class-nginx-helper.php

@@ -227,6 +227,9 @@ private function define_admin_hooks() {
 
 		// expose action to allow other plugins to purge the cache.
 		$this->loader->add_action( 'rt_nginx_helper_purge_all', $nginx_purger, 'purge_all' );
+
+		// add action to preload the cache
+		$this->loader->add_action( 'admin_init', $nginx_helper_admin, 'preload_cache' );
 	}
 
 	/**