From 35c0fe47238d00f90f2b50e12656bfd65a149ced Mon Sep 17 00:00:00 2001
From: Joshua Ramon Enslin <joshua@museum-digital.de>
Date: Tue, 1 Dec 2020 00:05:59 +0100
Subject: [PATCH] Require cached contents in MD_STD_CACHE to be 3 chars long

An empty json array is 2 chars long
---
 MD_STD_CACHE.php | 45 +++++++++++++++++++++++++++++++++------------
 1 file changed, 33 insertions(+), 12 deletions(-)

diff --git a/MD_STD_CACHE.php b/MD_STD_CACHE.php
index ce35550..89639e2 100644
--- a/MD_STD_CACHE.php
+++ b/MD_STD_CACHE.php
@@ -16,6 +16,27 @@ final class MD_STD_CACHE {
     /** @var integer */
     public static int $redis_port = 6379;
 
+    /**
+     * Shutdown function for caching contents of output buffer.
+     *
+     * @param string  $redisKey Key to cache by in redis.
+     * @param integer $expiry   Expiration time in seconds.
+     *
+     * @return void
+     */
+    public static function shutdown_cache_through_redis(string $redisKey, int $expiry = 3600):void {
+
+        $outputT = trim(MD_STD::minimizeHTMLString(MD_STD::ob_get_clean()));
+        echo $outputT;
+
+        $redis = new Redis();
+        $redis->connect(self::$redis_host, self::$redis_port, 1, NULL, 0, 0, ['auth' => [MD_CONF::$redis_pw]]);
+        $redis->set($redisKey, $outputT);
+        $redis->expire($redisKey, $expiry);
+        $redis->close();
+
+    }
+
     /**
      * Caches and serves a page through redis. Should be called at the start
      * of the script generating a page.
@@ -34,26 +55,26 @@ final class MD_STD_CACHE {
             ob_start();
 
             if (($redisResult = $redis->get($redisKey))) {
-                $redis->close();
-                return $redisResult;
+
+                if (strlen($redisResult) > 3) {
+                    $redis->close();
+                    return $redisResult;
+                }
+                else {
+                    register_shutdown_function(function(string $redisKey, int $expiry = 3600) :void {
+                        self::shutdown_cache_through_redis($redisKey, $expiry);
+                    }, $redisKey);
+                }
+
             }
             else {
 
                 register_shutdown_function(function(string $redisKey, int $expiry = 3600) :void {
-
-                    $outputT = MD_STD::minimizeHTMLString(MD_STD::ob_get_clean());
-                    echo $outputT;
-
-                    $redis = new Redis();
-                    $redis->connect(self::$redis_host, self::$redis_port, 1, NULL, 0, 0, ['auth' => [MD_CONF::$redis_pw]]);
-                    $redis->set($redisKey, $outputT);
-                    $redis->expire($redisKey, $expiry);
-                    $redis->close();
+                    self::shutdown_cache_through_redis($redisKey, $expiry);
                 }, $redisKey);
 
             }
 
-            $redis->close();
         }
         $redis->close();