tunables:

* add CACHE_MAX_DAYS as a tunable generic expiry interval for various cached files
* add some comments to tunables in functions.php
* rename _MIN_CACHE_FILE_SIZE to MIN_CACHE_FILE_SIZE
* respect MIN_CACHE_FILE_SIZE setting in a few more places where content is cached

classes/rssutils.php

@@ -1152,7 +1152,7 @@ class RSSUtils {
 				if (!file_exists($local_filename)) {
 					$file_content = fetch_file_contents($src);
 
-					if ($file_content && strlen($file_content) > _MIN_CACHE_FILE_SIZE) {
+					if ($file_content && strlen($file_content) > MIN_CACHE_FILE_SIZE) {
 						file_put_contents($local_filename, $file_content);
 					}
 				} else {
@@ -1186,7 +1186,7 @@ class RSSUtils {
 				if (!file_exists($local_filename)) {
 					$file_content = fetch_file_contents($src);
 
-					if ($file_content && strlen($file_content) > _MIN_CACHE_FILE_SIZE) {
+					if ($file_content && strlen($file_content) > MIN_CACHE_FILE_SIZE) {
 						file_put_contents($local_filename, $file_content);
 					}
 				} else {
@@ -1243,7 +1243,7 @@ class RSSUtils {
 
 				if ($files) {
 					foreach ($files as $file) {
-						if (time() - filemtime($file) > 86400*7) {
+						if (time() - filemtime($file) > 86400*CACHE_MAX_DAYS) {
 							unlink($file);
 
 							++$num_deleted;

include/functions.php

@@ -30,17 +30,12 @@
 
 	/**
 	 * Define a constant if not already defined
-	 *
-	 * @param string $name The constant name.
-	 * @param mixed $value The constant value.
-	 * @access public
-	 * @return boolean True if defined successfully or not.
 	 */
 	function define_default($name, $value) {
 		defined($name) or define($name, $value);
 	}
 
-	///// Some defaults that you can override in config.php //////
+	/* Some tunables you can override in config.php using define():	*/
 
 	define_default('FEED_FETCH_TIMEOUT', 45);
 	// How may seconds to wait for response when requesting feed from a site
@@ -52,12 +47,18 @@
 	define_default('FILE_FETCH_CONNECT_TIMEOUT', 15);
 	// How many seconds to wait for initial response from website when
 	// fetching files from remote sites
-
-	// feed updating stuff
 	define_default('DAEMON_UPDATE_LOGIN_LIMIT', 30);
+	// stop updating feeds if users haven't logged in for X days
 	define_default('DAEMON_FEED_LIMIT', 500);
+	// feed limit for one update batch
 	define_default('DAEMON_SLEEP_INTERVAL', 120);
-	define_default('_MIN_CACHE_FILE_SIZE', 1024);
+	// default sleep interval between feed updates (sec)
+	define_default('MIN_CACHE_FILE_SIZE', 1024);
+	// do not cache files smaller than that (bytes)
+	define_default('CACHE_MAX_DAYS', 7);
+	// max age in days for various automatically cached (temporary) files
+
+	/* tunables end here */
 
 	if (DB_TYPE == "pgsql") {
 		define('SUBSTRING_FOR_DATE', 'SUBSTRING_FOR_DATE');

plugins/af_zz_imgproxy/init.php

@@ -69,7 +69,7 @@ class Af_Zz_ImgProxy extends Plugin {
 
 				$disable_cache = $this->host->get($this, "disable_cache");
 
-				if (!$disable_cache) {
+				if (!$disable_cache && strlen($data) > MIN_CACHE_FILE_SIZE) {
 					if (file_put_contents($local_filename, $data)) {
 						$mimetype = mime_content_type($local_filename);
 						header("Content-type: $mimetype");

plugins/cache_starred_images/init.php

@@ -209,7 +209,7 @@ class Cache_Starred_Images extends Plugin implements IHandler {
 				if (!file_exists($local_filename)) {
 					$file_content = fetch_file_contents($src);
 
-					if ($file_content && strlen($file_content) > 0) {
+					if ($file_content && strlen($file_content) > MIN_CACHE_FILE_SIZE) {
 						file_put_contents($local_filename, $file_content);
 						$success = true;
 					}