[FAB-2498] Fix Panic upon Recover (CouchdB)

If peers starts up and there is no CouchDB state database,
there is a nil pointer panic due to nil savepoint.

This changeset fixes it by returning nil height
when there is nil savepont.  Nil height for savepoint
will trigger full state db recovery upon peer startup.

Added test to ensure nil height is returned in these cases.

Ensured that leveldb and couchdb behave consistently now.

Tested recovery on both leveldb and couchdb.

Change-Id: I0f2f2f89d7d3176fcf4a560d20665bd59c4d8a5d
Signed-off-by: denyeart <enyeart@us.ibm.com>

core/ledger/kvledger/txmgmt/statedb/commontests/test_common.go

@@ -30,6 +30,11 @@ func TestBasicRW(t *testing.T, dbProvider statedb.VersionedDBProvider) {
 	db, err := dbProvider.GetDBHandle("testbasicrw")
 	testutil.AssertNoError(t, err, "")
 
+	// Test that savepoint is nil for a new state db
+	sp, err := db.GetLatestSavePoint()
+	testutil.AssertNoError(t, err, "Error upon GetLatestSavePoint()")
+	testutil.AssertNil(t, sp)
+
 	// Test retrieval of non-existent key - returns nil rather than error
 	// For more details see https://github.com/hyperledger-archives/fabric/issues/936.
 	val, err := db.GetState("ns", "key1")
@@ -54,7 +59,7 @@ func TestBasicRW(t *testing.T, dbProvider statedb.VersionedDBProvider) {
 	vv, _ = db.GetState("ns2", "key4")
 	testutil.AssertEquals(t, vv, &vv4)
 
-	sp, err := db.GetLatestSavePoint()
+	sp, err = db.GetLatestSavePoint()
 	testutil.AssertNoError(t, err, "")
 	testutil.AssertEquals(t, sp, savePoint)
 }

core/ledger/kvledger/txmgmt/statedb/statecouchdb/statecouchdb.go

@@ -277,9 +277,6 @@ func (vdb *VersionedDB) ApplyUpdates(batch *statedb.UpdateBatch, height *version
 					attachment.AttachmentBytes = vv.Value
 					attachment.ContentType = "application/octet-stream"
 					attachment.Name = binaryWrapper
-
-					attachments := []couchdb.Attachment{}
-					attachments = append(attachments, *attachment)
 					couchDoc.Attachments = append(couchDoc.Attachments, *attachment)
 					couchDoc.JSONValue = addVersionAndChainCodeID(nil, ns, vv.Version)
 				}
@@ -398,19 +395,19 @@ func (vdb *VersionedDB) GetLatestSavePoint() (*version.Height, error) {
 	couchDoc, _, err := vdb.db.ReadDoc(savepointDocID)
 	if err != nil {
 		logger.Errorf("Failed to read savepoint data %s\n", err.Error())
-		return &version.Height{BlockNum: 0, TxNum: 0}, err
+		return nil, err
 	}
 
-	// ReadDoc() not found (404) will result in nil response, in these cases return height 0
-	if couchDoc.JSONValue == nil {
-		return &version.Height{BlockNum: 0, TxNum: 0}, nil
+	// ReadDoc() not found (404) will result in nil response, in these cases return height nil
+	if couchDoc == nil || couchDoc.JSONValue == nil {
+		return nil, nil
 	}
 
 	savepointDoc := &couchSavepointData{}
 	err = json.Unmarshal(couchDoc.JSONValue, &savepointDoc)
 	if err != nil {
 		logger.Errorf("Failed to unmarshal savepoint data %s\n", err.Error())
-		return &version.Height{BlockNum: 0, TxNum: 0}, err
+		return nil, err
 	}
 
 	return &version.Height{BlockNum: savepointDoc.BlockNum, TxNum: savepointDoc.TxNum}, nil

core/ledger/kvledger/txmgmt/statedb/statecouchdb/statecouchdb_test.go

@@ -33,9 +33,12 @@ func TestMain(m *testing.M) {
 
 	//call a helper method to load the core.yaml, will be used to detect if CouchDB is enabled
 	ledgertestutil.SetupCoreYAMLConfig("./../../../../../../peer")
+	viper.Set("peer.fileSystemPath", "/tmp/fabric/ledgertests/kvledger/txmgmt/statedb/statecouchdb")
 	viper.Set("ledger.state.stateDatabase", "CouchDB")
+
+	// both vagrant and CI have couchdb configured at host "couchdb"
 	viper.Set("ledger.state.couchDBConfig.couchDBAddress", "couchdb:5984")
-	viper.Set("peer.fileSystemPath", "/tmp/fabric/ledgertests/kvledger/txmgmt/statedb/statecouchdb")
+
 	result := m.Run()
 	viper.Set("ledger.state.stateDatabase", "goleveldb")
 	os.Exit(result)

core/ledger/kvledger/txmgmt/txmgr/commontests/pkg_test.go

@@ -113,7 +113,8 @@ func (env *couchDBLockBasedEnv) getName() string {
 
 func (env *couchDBLockBasedEnv) init(t *testing.T) {
 	viper.Set("peer.fileSystemPath", testFilesystemPath)
-	viper.Set("ledger.state.couchDBConfig.couchDBAddress", "127.0.0.1:5984")
+	// both vagrant and CI have couchdb configured at host "couchdb"
+	viper.Set("ledger.state.couchDBConfig.couchDBAddress", "couchdb:5984")
 	testDBEnv := statecouchdb.NewTestVDBEnv(t)
 	testDB, err := testDBEnv.DBProvider.GetDBHandle(couchTestChainID)
 	testutil.AssertNoError(t, err, "")

peer/core.yaml

@@ -211,9 +211,9 @@ peer:
             Hash: SHA2
             Security: 256
             # Location of Key Store, can be subdirectory of SbftLocal.DataDir
-            FileKeyStore: 
+            FileKeyStore:
                 # If "", defaults to 'mspConfigPath'/keystore
-                KeyStore: 
+                KeyStore:
 
     # Path on the file system where peer will find MSP local configurations
     mspConfigPath: msp/sampleconfig