Add defensive copy of objects in InMemBucket (#42)

Add locking and return a copy of the internally stored objects in InMemBucket. This fixes a race condition that can be triggered if the result of `.Objects()` is read while another goroutine modifies the objects (such as uploading a new file). Noticed in grafana/mimir#4021 Signed-off-by: Nick Pillitteri <[email protected]> Co-authored-by: Matej Gera <[email protected]>
thanos-io · Jan 31, 2023 · ae1c52a · ae1c52a
1 parent 3cac994
commit ae1c52a
Showing 1 changed file with 10 additions and 2 deletions.
diff --git a/inmem.go b/inmem.go
@@ -34,10 +34,18 @@ func NewInMemBucket() *InMemBucket {
 	}
 }
 
-// Objects returns internally stored objects.
+// Objects returns a copy of the internally stored objects.
 // NOTE: For assert purposes.
 func (b *InMemBucket) Objects() map[string][]byte {
-	return b.objects
+	b.mtx.RLock()
+	defer b.mtx.RUnlock()
+
+	objs := make(map[string][]byte)
+	for k, v := range b.objects {
+		objs[k] = v
+	}
+
+	return objs
 }
 
 // Iter calls f for each entry in the given directory. The argument to f is the full