* bring back cache-busting for feed icons based on timestamp

 * DiskCache: use singleton pattern to create less cache object instances
 * DiskCache: implement ETag

10 files changed, 43 insertions, 31 deletions

diff --git a/classes/article.php b/classes/article.php
index 1d441dee2..609ddeebe 100755
--- a/classes/article.php
+++ b/classes/article.php
@@ -447,7 +447,7 @@ class Article extends Handler_Protected {
 
 		$rv = [];
 
-		$cache = new DiskCache("images");
+		$cache = DiskCache::instance("images");
 
 		foreach ($encs as $enc) {
 			$cache_key = sha1($enc->content_url);
@@ -640,7 +640,7 @@ class Article extends Handler_Protected {
 				$article_stream = UrlHelper::rewrite_relative($site_url, $article_stream);
 		}
 
-		$cache = new DiskCache("images");
+		$cache = DiskCache::instance("images");
 
 		if ($article_image && $cache->exists(sha1($article_image)))
 			$article_image = $cache->get_url(sha1($article_image));
diff --git a/classes/counters.php b/classes/counters.php
index 9699cb97c..48b7264dd 100644
--- a/classes/counters.php
+++ b/classes/counters.php
@@ -187,9 +187,9 @@ class Counters {
 			$last_updated = TimeHelper::make_local_datetime($line['last_updated'], false);
 
 			if (Feeds::_has_icon($id)) {
-				$has_img = filemtime(Feeds::_get_icon_file($id));
+				$ts = filemtime(Feeds::_get_icon_file($id));
 			} else {
-				$has_img = false;
+				$ts = 0;
 			}
 
 			// hide default un-updated timestamp i.e. 1970-01-01 (?) -fox
@@ -201,7 +201,7 @@ class Counters {
 				"updated" => $last_updated,
 				"counter" => (int) $line["count"],
 				"markedcounter" => (int) $line["count_marked"],
-				"has_img" => (int) $has_img
+				"ts" => (int) $ts
 			];
 
 			$cv["error"] = $line["last_error"];
diff --git a/classes/diskcache.php b/classes/diskcache.php
index bf7031587..96c826728 100644
--- a/classes/diskcache.php
+++ b/classes/diskcache.php
@@ -3,6 +3,8 @@ class DiskCache implements Cache_Adapter {
 	/** @var Cache_Adapter $adapter */
 	private $adapter;
 
+	private static $instances = [];
+
 	/**
 	 * https://stackoverflow.com/a/53662733
 	 *
@@ -195,6 +197,13 @@ class DiskCache implements Cache_Adapter {
 		'text/x-scriptzsh'                                                          => 'zsh'
 	];
 
+	public static function instance(string $dir) : DiskCache {
+		if ((self::$instances[$dir] ?? null) == null)
+			self::$instances[$dir] = new self($dir);
+
+		return self::$instances[$dir];
+	}
+
 	public function __construct(string $dir) {
 		foreach (PluginHost::getInstance()->get_plugins() as $n => $p) {
 			if (implements_interface($p, "Cache_Adapter")) {
@@ -302,9 +311,10 @@ class DiskCache implements Cache_Adapter {
 			return false;
 		}
 
-		$gmt_modified = gmdate("D, d M Y H:i:s", (int)$this->get_mtime($filename)) . " GMT";
+		$file_mtime = $this->get_mtime($filename);
+		$gmt_modified = gmdate("D, d M Y H:i:s", (int)$file_mtime) . " GMT";
 
-		if (($_SERVER['HTTP_IF_MODIFIED_SINCE'] ?? '') == $gmt_modified) {
+		if (($_SERVER['HTTP_IF_MODIFIED_SINCE'] ?? '') == $gmt_modified || ($_SERVER['HTTP_IF_NONE_MATCH'] ?? '') == $file_mtime) {
 			header('HTTP/1.1 304 Not Modified');
 			return false;
 		}
@@ -339,7 +349,8 @@ class DiskCache implements Cache_Adapter {
 
 		header("Expires: $stamp_expires", true);
 		header("Last-Modified: $gmt_modified", true);
-		header("Cache-Control: public");
+		header("Cache-Control: no-cache");
+		header("ETag: $file_mtime");
 
 		header_remove("Pragma");
 
@@ -378,7 +389,7 @@ class DiskCache implements Cache_Adapter {
 		$doc = new DOMDocument();
 		if (@$doc->loadHTML('<?xml encoding="UTF-8">' . $res)) {
 			$xpath = new DOMXPath($doc);
-			$cache = new DiskCache("images");
+			$cache = DiskCache::instance("images");
 
 			$entries = $xpath->query('(//img[@src]|//source[@src|@srcset]|//video[@poster|@src])');
 
diff --git a/classes/feeds.php b/classes/feeds.php
index d34a23e4b..382d8dbf8 100755
--- a/classes/feeds.php
+++ b/classes/feeds.php
@@ -1163,7 +1163,7 @@ class Feeds extends Handler_Protected {
 	}
 
 	static function _get_icon_file(int $feed_id): string {
-		$favicon_cache = new DiskCache('feed-icons');
+		$favicon_cache = DiskCache::instance('feed-icons');
 
 		return $favicon_cache->get_full_path((string)$feed_id);
 	}
@@ -1182,7 +1182,7 @@ class Feeds extends Handler_Protected {
 	}
 
 	static function _has_icon(int $feed_id): bool {
-		$favicon_cache = new DiskCache('feed-icons');
+		$favicon_cache = DiskCache::instance('feed-icons');
 
 		return $favicon_cache->exists((string)$feed_id);
 	}
diff --git a/classes/handler/public.php b/classes/handler/public.php
index b848b15fe..190c806be 100755
--- a/classes/handler/public.php
+++ b/classes/handler/public.php
@@ -759,7 +759,7 @@ class Handler_Public extends Handler {
 		// we do not allow files with extensions at the moment
 		$filename = str_replace(".", "", $filename);
 
-		$cache = new DiskCache($cache_dir);
+		$cache = DiskCache::instance($cache_dir);
 
 		if ($cache->exists($filename)) {
 			$cache->send($filename);
@@ -771,7 +771,7 @@ class Handler_Public extends Handler {
 
 	function feed_icon() : void {
 		$id = (int)$_REQUEST['id'];
-		$cache = new DiskCache('feed-icons');
+		$cache = DiskCache::instance('feed-icons');
 
 		if ($cache->exists((string)$id)) {
 			$cache->send((string)$id);
diff --git a/classes/pref/feeds.php b/classes/pref/feeds.php
index 067b8225e..a9ae91979 100755
--- a/classes/pref/feeds.php
+++ b/classes/pref/feeds.php
@@ -455,7 +455,7 @@ class Pref_Feeds extends Handler_Protected {
 	function removeIcon(): void {
 		$feed_id = (int) $_REQUEST["feed_id"];
 
-		$cache = new DiskCache('feed-icons');
+		$cache = DiskCache::instance('feed-icons');
 
 		$feed = ORM::for_table('ttrss_feeds')
 			->where('owner_uid', $_SESSION['uid'])
@@ -487,7 +487,7 @@ class Pref_Feeds extends Handler_Protected {
 		if ($feed && $tmp_file && move_uploaded_file($_FILES['icon_file']['tmp_name'], $tmp_file)) {
 			if (filesize($tmp_file) < Config::get(Config::MAX_FAVICON_FILE_SIZE)) {
 
-				$cache = new DiskCache('feed-icons');
+				$cache = DiskCache::instance('feed-icons');
 
 				if ($cache->put((string)$feed_id, file_get_contents($tmp_file))) {
 
@@ -514,7 +514,8 @@ class Pref_Feeds extends Handler_Protected {
 		if (file_exists($tmp_file))
 			unlink($tmp_file);
 
-		print json_encode(['rc' => $rc, 'icon_url' => Feeds::_get_icon($feed_id)]);
+		print json_encode(['rc' => $rc, 'icon_url' =>
+			Feeds::_get_icon($feed_id) . "?ts=" . time() ]);
 	}
 
 	function editfeed(): void {
@@ -1188,7 +1189,7 @@ class Pref_Feeds extends Handler_Protected {
 
 			$pdo->commit();
 
-			$favicon_cache = new DiskCache('feed-icons');
+			$favicon_cache = DiskCache::instance('feed-icons');
 
 			if ($favicon_cache->exists((string)$id))
 				$favicon_cache->remove((string)$id);
diff --git a/classes/rssutils.php b/classes/rssutils.php
index 9d9b335c6..561171d09 100755
--- a/classes/rssutils.php
+++ b/classes/rssutils.php
@@ -37,7 +37,7 @@ class RSSUtils {
 		$pdo = Db::pdo();
 		$sth = $pdo->prepare("SELECT id FROM ttrss_feeds WHERE id = ?");
 
-		$cache = new DiskCache('feed-icons');
+		$cache = DiskCache::instance('feed-icons');
 
 		if ($cache->is_writable()) {
 			$dh = opendir($cache->get_full_path(""));
@@ -348,7 +348,7 @@ class RSSUtils {
 		$pdo = Db::pdo();
 
 		/** @var DiskCache $cache */
-		$cache = new DiskCache('feeds');
+		$cache = DiskCache::instance('feeds');
 
 		if (Config::get(Config::DB_TYPE) == "pgsql") {
 			$favicon_interval_qpart = "favicon_last_checked < NOW() - INTERVAL '12 hour'";
@@ -606,7 +606,7 @@ class RSSUtils {
 				$feed_obj->favicon_last_checked = Db::NOW();
 				$feed_obj->save();
 
-				$favicon_cache = new DiskCache('feed-icons');
+				$favicon_cache = DiskCache::instance('feed-icons');
 
 				$favicon_modified = $favicon_cache->exists($feed) ? $favicon_cache->get_mtime($feed) : -1;
 
@@ -1320,7 +1320,7 @@ class RSSUtils {
 	 * @see FeedEnclosure
 	 */
 	static function cache_enclosures(array $enclosures, string $site_url): void {
-		$cache = new DiskCache("images");
+		$cache = DiskCache::instance("images");
 
 		if ($cache->is_writable()) {
 			foreach ($enclosures as $enc) {
@@ -1372,7 +1372,7 @@ class RSSUtils {
 
 	/* TODO: move to DiskCache? */
 	static function cache_media(string $html, string $site_url): void {
-		$cache = new DiskCache("images");
+		$cache = DiskCache::instance("images");
 
 		if ($html && $cache->is_writable()) {
 			$doc = new DOMDocument();
@@ -1695,7 +1695,7 @@ class RSSUtils {
 
 		$dh = opendir($old_dir);
 
-		$cache = new DiskCache('feed-icons');
+		$cache = DiskCache::instance('feed-icons');
 
 		if ($dh) {
 			while (($old_filename = readdir($dh)) !== false) {
@@ -1714,7 +1714,7 @@ class RSSUtils {
 	}
 
 	static function housekeeping_common(): void {
-		$cache = new DiskCache("");
+		$cache = DiskCache::instance("");
 		$cache->expire_all();
 
 		self::migrate_feed_icons();
@@ -1789,7 +1789,7 @@ class RSSUtils {
 				break;
 			}
 
-			$favicon_cache = new DiskCache('feed-icons');
+			$favicon_cache = DiskCache::instance('feed-icons');
 
 			if ($favicon_cache->is_writable()) {
 				Debug::log("favicon: $favicon_url looks valid, saving to cache", Debug::LOG_VERBOSE);
diff --git a/js/Feeds.js b/js/Feeds.js
index b3913b1f0..42641dc74 100644
--- a/js/Feeds.js
+++ b/js/Feeds.js
@@ -71,7 +71,7 @@ const	Feeds = {
 			const kind = elems[l].kind;
 			const ctr = parseInt(elems[l].counter);
 			const error = elems[l].error;
-			const has_img = elems[l].has_img;
+			const ts = elems[l].ts;
 			const updated = elems[l].updated;
 
 			if (id == "global-unread") {
@@ -98,9 +98,9 @@ const	Feeds = {
 				this.setValue(id, false, 'updated', updated);
 
 				if (id > 0) {
-					if (has_img) {
+					if (ts) {
 						this.setIcon(id, false,
-							App.getInitParam("icons_url") + '?' + dojo.objectToQuery({op: 'feed_icon', id: id}));
+							App.getInitParam("icons_url") + '?' + dojo.objectToQuery({op: 'feed_icon', id: id, ts: ts}));
 					} else {
 						this.setIcon(id, false, 'images/blank_icon.gif');
 					}
diff --git a/plugins/af_comics/filters/af_comics_gocomics_farside.php b/plugins/af_comics/filters/af_comics_gocomics_farside.php
index e4e230516..e2951eb36 100644
--- a/plugins/af_comics/filters/af_comics_gocomics_farside.php
+++ b/plugins/af_comics/filters/af_comics_gocomics_farside.php
@@ -50,7 +50,7 @@ class Af_Comics_Gocomics_FarSide extends Af_ComicFilter {
 					if ($content_node) {
 						$imgs = $xpath->query('//img[@data-src]', $content_node);
 
-						$cache = new DiskCache("images");
+						$cache = DiskCache::instance("images");
 
 						foreach ($imgs as $img) {
 							$image_url = $img->getAttribute('data-src');
diff --git a/plugins/cache_starred_images/init.php b/plugins/cache_starred_images/init.php
index daaab2dca..208eafde9 100755
--- a/plugins/cache_starred_images/init.php
+++ b/plugins/cache_starred_images/init.php
@@ -21,8 +21,8 @@ class Cache_Starred_Images extends Plugin {
 
 	function init($host) {
 		$this->host = $host;
-		$this->cache = new DiskCache("starred-images");
-		$this->cache_status = new DiskCache("starred-images.status-files");
+		$this->cache = DiskCache::instance("starred-images");
+		$this->cache_status = DiskCache::instance("starred-images.status-files");
 
 		if ($this->cache->make_dir())
 			chmod($this->cache->get_dir(), 0777);