all repos — cgit @ f5069d88dff7a7ed2f4665904b03e906cca75a7c

a hyperfast web frontend for git written in c 

Fix cache algorithm loophole

This closes the door for unneccessary calls to cgit_fill_cache().

Noticed by Linus.

Signed-off-by: Lars Hjemli <hjemli@gmail.com>
Lars Hjemli hjemli@gmail.com
Mon, 11 Dec 2006 09:57:58 +0100
commit

f5069d88dff7a7ed2f4665904b03e906cca75a7c

parent

76827d8679d1d2bd46e8cddf7da2ce4178e1d676

3 files changed, 16 insertions(+), 11 deletions(-)

jump to
M cache.c → cache.c 
@@ -10,7 +10,7 @@ #include "cgit.h"
 
 const int NOLOCK = -1;
 
-int cache_lookup(struct cacheitem *item)
+void cache_prepare(struct cacheitem *item)
 {
 	if (!cgit_query_repo) {
 		item->name = xstrdup(fmt("%s/index.html", cgit_cache_root));

@@ -30,6 +30,10 @@ item->ttl = cgit_cache_static_ttl;
 		else
 			item->ttl = cgit_cache_repo_ttl;
 	}
+}
+
+int cache_exist(struct cacheitem *item)
+{
 	if (stat(item->name, &item->st)) {
 		item->st.st_mtime = 0;
 		return 0;
M cgit.c → cgit.c 
@@ -465,20 +465,20 @@ }
 
 static void cgit_refresh_cache(struct cacheitem *item)
 {
+	cache_prepare(item);
  top:
-	if (!cache_lookup(item)) {
-		if (cache_lock(item)) {
-			cgit_fill_cache(item);
-			cache_unlock(item);
-		} else {
+	if (!cache_exist(item)) {
+		if (!cache_lock(item)) {
 			sched_yield();
 			goto top;
 		}
-	} else if (cache_expired(item)) {
-		if (cache_lock(item)) {
+		if (!cache_exist(item))
+			cgit_fill_cache(item);
+		cache_unlock(item);
+	} else if (cache_expired(item) && cache_lock(item)) {
+		if (cache_expired(item))
 			cgit_fill_cache(item);
-			cache_unlock(item);
-		}
+		cache_unlock(item);
 	}
 }
M cgit.h → cgit.h 
@@ -56,9 +56,10 @@
 
 extern int cgit_read_config(const char *filename, configfn fn);
 
-extern int cache_lookup(struct cacheitem *item);
+extern void cache_prepare(struct cacheitem *item);
 extern int cache_lock(struct cacheitem *item);
 extern int cache_unlock(struct cacheitem *item);
+extern int cache_exist(struct cacheitem *item);
 extern int cache_expired(struct cacheitem *item);
 
 #endif /* CGIT_H */