X-Git-Url: http://git.vrable.net/?a=blobdiff_plain;f=bluesky%2Flog.c;h=cec46cb9a9aa90cc3a48f72cc8526ba4187f6817;hb=8ae6b69c5d727704d4414e370c165dd71668031c;hp=9b4b62bd416fb7edaa6bd5fa61cf1ff558e779f8;hpb=e6135fbeca4bbedd24b5f8c55fb765a97bdc78ad;p=bluesky.git

diff --git a/bluesky/log.c b/bluesky/log.c
index 9b4b62b..cec46cb 100644
--- a/bluesky/log.c
+++ b/bluesky/log.c
@@ -82,6 +82,7 @@ static void log_commit(BlueSkyLog *log)
         g_cond_signal(item->cond);
         g_mutex_unlock(item->lock);
         log->committed = g_slist_delete_link(log->committed, log->committed);
+        bluesky_cloudlog_unref(item);
         batchsize++;
     }
 
@@ -153,6 +154,7 @@ static gpointer log_thread(gpointer d)
         if ((item->location_flags | item->pending_write) & CLOUDLOG_JOURNAL) {
             g_mutex_unlock(item->lock);
             bluesky_cloudlog_unref(item);
+            g_atomic_int_add(&item->data_lock_count, -1);
             continue;
         }
 
@@ -199,6 +201,7 @@ static gpointer log_thread(gpointer d)
         offset += sizeof(header) + sizeof(footer) + item->data->len;
 
         log->committed  = g_slist_prepend(log->committed, item);
+        g_atomic_int_add(&item->data_lock_count, -1);
         g_mutex_unlock(item->lock);
 
         /* Force an if there are no other log items currently waiting to be
@@ -235,6 +238,7 @@ BlueSkyLog *bluesky_log_new(const char *log_directory)
 void bluesky_log_item_submit(BlueSkyCloudLog *item, BlueSkyLog *log)
 {
     bluesky_cloudlog_ref(item);
+    g_atomic_int_add(&item->data_lock_count, 1);
     g_async_queue_push(log->queue, item);
 }
 
@@ -282,10 +286,12 @@ BlueSkyRCStr *bluesky_log_map_object(BlueSkyLog *log,
         map = g_new0(BlueSkyMmap, 1);
 
         off_t length = lseek(fd, 0, SEEK_END);
+        map->log_seq = log_seq;
         map->addr = (const char *)mmap(NULL, length, PROT_READ, MAP_SHARED,
                                        fd, 0);
         map->len = length;
-        g_atomic_int_set(&map->refcount, 1);
+        map->log = log;
+        g_atomic_int_set(&map->refcount, 0);
 
         g_hash_table_insert(log->mmap_cache, GINT_TO_POINTER(log_seq), map);
 
@@ -296,3 +302,31 @@ BlueSkyRCStr *bluesky_log_map_object(BlueSkyLog *log,
 
     return bluesky_string_new_from_mmap(map, log_offset, log_size);
 }
+
+void bluesky_mmap_unref(BlueSkyMmap *mmap)
+{
+    if (mmap == NULL)
+        return;
+
+    if (g_atomic_int_dec_and_test(&mmap->refcount)) {
+        /* There is a potential race condition here: the BlueSkyLog contains a
+         * hash table of currently-existing BlueSkyMmap objects, which does not
+         * hold a reference.  Some other thread might grab a new reference to
+         * this object after reading it from the hash table.  So, before
+         * destruction we need to grab the lock for the hash table, then check
+         * the reference count again.  If it is still zero, we can proceed with
+         * object destruction. */
+        BlueSkyLog *log = mmap->log;
+        g_mutex_lock(log->mmap_lock);
+        if (g_atomic_int_get(&mmap->refcount) > 0) {
+            g_mutex_unlock(log->mmap_lock);
+            return;
+        }
+
+        g_hash_table_remove(log->mmap_cache, GINT_TO_POINTER(mmap->log_seq));
+        munmap((void *)mmap->addr, mmap->len);
+        g_free(mmap);
+        g_mutex_unlock(log->mmap_lock);
+    }
+}
+