add really fast track cache script

webroot/imgf.php

@@ -0,0 +1,60 @@
+<?php
+/**
+ * Fast track cache, read entries from the cache before processing image
+ * the ordinary way.
+ */
+ // Include debug functions
+function debug($msg)
+{
+    $file = "/tmp/cimage";
+    if (!is_writable($file)) {
+        return;
+    }
+    $msg .= ":" . count(get_included_files());
+    $msg .= ":" . round(memory_get_peak_usage()/1024/1024, 3) . "MB";
+    $msg .= ":" . (string) round((microtime(true) - $_SERVER['REQUEST_TIME_FLOAT']), 6) . "ms";
+    file_put_contents($file, "$msg\n", FILE_APPEND);
+}
+
+
+
+$query = $_GET;
+
+// Remove parts from querystring that should not be part of filename
+$clear = array("nc", "no-cache");
+foreach ($clear as $value) {
+    unset($query[$value]);
+}
+
+arsort($query);
+$queryAsString = http_build_query($query);
+
+$filename = md5($queryAsString);
+if (is_readable($filename)) {
+    $item = json_decode(file_get_contents($filename), true);
+
+    if (is_readable($item["source"])) {
+        foreach ($item["header"] as $value) {
+            header($value);
+        }
+
+        if (isset($_SERVER["HTTP_IF_MODIFIED_SINCE"])
+            && strtotime($_SERVER["HTTP_IF_MODIFIED_SINCE"]) == $item["last-modified"]) {
+            header("HTTP/1.0 304 Not Modified");
+            debug("really fast track 304");
+            exit;
+        }
+
+        foreach ($item["header-output"] as $value) {
+            header($value);
+        }
+
+        readfile($item["source"]);
+        debug("really fast track 200");
+        exit;
+    }
+}
+
+
+// No fast track cache, proceed as usual
+include __DIR__ . "/img.php";