threaded delta search: proper locking for cache accounting

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin-pack-objects.c b/builtin-pack-objects.c
index e091bcbda9233f8b1bfe25f6aa4d702614d42435..b126fc8e727f8f9670ba85d9a5bf498f1baf5dfc 100644 (file)
--- a/builtin-pack-objects.c
+++ b/builtin-pack-objects.c
@@ -1301,6 +1301,10 @@ static pthread_mutex_t read_mutex = PTHREAD_MUTEX_INITIALIZER;
 #define read_lock()            pthread_mutex_lock(&read_mutex)
 #define read_unlock()          pthread_mutex_unlock(&read_mutex)
 
+static pthread_mutex_t cache_mutex = PTHREAD_MUTEX_INITIALIZER;
+#define cache_lock()           pthread_mutex_lock(&cache_mutex)
+#define cache_unlock()         pthread_mutex_unlock(&cache_mutex)
+
 static pthread_mutex_t progress_mutex = PTHREAD_MUTEX_INITIALIZER;
 #define progress_lock()                pthread_mutex_lock(&progress_mutex)
 #define progress_unlock()      pthread_mutex_unlock(&progress_mutex)
@@ -1309,6 +1313,8 @@ static pthread_mutex_t progress_mutex = PTHREAD_MUTEX_INITIALIZER;
 
 #define read_lock()            0
 #define read_unlock()          0
+#define cache_lock()           0
+#define cache_unlock()         0
 #define progress_lock()                0
 #define progress_unlock()      0
 
@@ -1423,17 +1429,27 @@ static int try_delta(struct unpacked *trg, struct unpacked *src,
        trg_entry->delta_size = delta_size;
        trg->depth = src->depth + 1;
 
+       /*
+        * Handle memory allocation outside of the cache
+        * accounting lock.  Compiler will optimize the strangeness
+        * away when THREADED_DELTA_SEARCH is not defined.
+        */
+       if (trg_entry->delta_data)
+               free(trg_entry->delta_data);
+       cache_lock();
        if (trg_entry->delta_data) {
                delta_cache_size -= trg_entry->delta_size;
-               free(trg_entry->delta_data);
                trg_entry->delta_data = NULL;
        }
-
        if (delta_cacheable(src_size, trg_size, delta_size)) {
-               trg_entry->delta_data = xrealloc(delta_buf, delta_size);
                delta_cache_size += trg_entry->delta_size;
-       } else
+               cache_unlock();
+               trg_entry->delta_data = xrealloc(delta_buf, delta_size);
+       } else {
+               cache_unlock();
                free(delta_buf);
+       }
+
        return 1;
 }