From 1cde7b06bca43c17e2fb279d95f72ba598d86f49 Mon Sep 17 00:00:00 2001
From: Simon Rettberg
Date: Wed, 8 Feb 2023 15:54:42 +0100
Subject: [dozmod] Try to avoid race condition, output slow dmsd download

---
 modules-available/dozmod/api.inc.php | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/modules-available/dozmod/api.inc.php b/modules-available/dozmod/api.inc.php
index c71ea946..6b9d68c8 100644
--- a/modules-available/dozmod/api.inc.php
+++ b/modules-available/dozmod/api.inc.php
@@ -34,7 +34,10 @@ function cache_key_to_filename($key)
 function cache_put($key, $value)
 {
 	$filename = cache_key_to_filename($key);
-	file_put_contents($filename, $value);
+	// Try to avoid another client concurrently accessing the cache seeing an empty file
+	$tmp = $filename . '-' . mt_rand();
+	file_put_contents($tmp, $value);
+	rename($tmp, $filename);
 }
 
 function cache_has($key)
@@ -179,7 +182,12 @@ function getListForLocations($locationIds, $raw)
 	if ($examMode) {
 		$url .= '&exams';
 	}
+	$t = microtime(true);
 	$value = Download::asString($url, 60, $code);
+	$t = microtime(true) - $t;
+	if ($t > 5) {
+		error_log("Download of lecture list took $t ($code)");
+	}
 	if ($value === false || $code < 200 || $code > 299)
 		return false;
 	cache_put($rawKey, $value);
@@ -207,7 +215,12 @@ function _getVmData($lecture_uuid, $subResource = false)
 	if ($subResource !== false) {
 		$url .= '/' . $subResource;
 	}
+	$t = microtime(true);
 	$response = Download::asString($url, 60, $code);
+	$t = microtime(true) - $t;
+	if ($t > 5) {
+		error_log("Download of $subResource took $t ($code)");
+	}
 	if ($code < 200 || $code > 299)
 		return (int)$code;
 	return $response;
-- 
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