backend: skip *bolt.DB.Size call when nil

integration/v3_maintenance_test.go

@@ -0,0 +1,49 @@
+// Copyright 2016 The etcd Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package integration
+
+import (
+	"testing"
+	"time"
+
+	"google.golang.org/grpc"
+
+	pb "github.com/coreos/etcd/etcdserver/etcdserverpb"
+	"github.com/coreos/etcd/pkg/testutil"
+	"golang.org/x/net/context"
+)
+
+// TestV3MaintenanceHashInflight ensures inflight Hash call
+// to embedded being-stopped EtcdServer does not trigger panic.
+func TestV3MaintenanceHashInflight(t *testing.T) {
+	defer testutil.AfterTest(t)
+	clus := NewClusterV3(t, &ClusterConfig{Size: 1})
+	defer clus.Terminate(t)
+
+	cli := clus.RandClient()
+	mvc := toGRPC(cli).Maintenance
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
+
+	donec := make(chan struct{})
+	go func() {
+		defer close(donec)
+		mvc.Hash(ctx, &pb.HashRequest{}, grpc.FailFast(false))
+	}()
+
+	clus.Members[0].s.HardStop()
+	cancel()
+
+	<-donec
+}

mvcc/backend/batch_tx.go

@@ -162,7 +162,20 @@ func (t *batchTx) commit(stop bool) {
 		if t.pending == 0 && !stop {
 			t.backend.mu.RLock()
 			defer t.backend.mu.RUnlock()
-			atomic.StoreInt64(&t.backend.size, t.tx.Size())
+
+			// batchTx.commit(true) calls *bolt.Tx.Commit, which
+			// initializes *bolt.Tx.db and *bolt.Tx.meta as nil,
+			// and subsequent *bolt.Tx.Size() call panics.
+			//
+			// This nil pointer reference panic happens when:
+			//   1. batchTx.commit(false) from newBatchTx
+			//   2. batchTx.commit(true) from stopping backend
+			//   3. batchTx.commit(false) from inflight mvcc Hash call
+			//
+			// Check if db is nil to prevent this panic
+			if t.tx.DB() != nil {
+				atomic.StoreInt64(&t.backend.size, t.tx.Size())
+			}
 			return
 		}
 		start := time.Now()

mvcc/kvstore_test.go

@@ -532,6 +532,20 @@ func newTestKeyBytes(rev revision, tombstone bool) []byte {
 	return bytes
 }
 
+// TestStoreHashAfterForceCommit ensures that later Hash call to
+// closed backend with ForceCommit does not panic.
+func TestStoreHashAfterForceCommit(t *testing.T) {
+	be, tmpPath := backend.NewDefaultTmpBackend()
+	kv := NewStore(be, &lease.FakeLessor{}, nil)
+	defer os.Remove(tmpPath)
+
+	// as in EtcdServer.HardStop
+	kv.Close()
+	be.Close()
+
+	kv.Hash()
+}
+
 func newFakeStore() *store {
 	b := &fakeBackend{&fakeBatchTx{
 		Recorder:   &testutil.RecorderBuffered{},