FAB-1291: Couch support for doing a savepoint.

Added two functions in couchdb_txmgr.go, recordSavepoint is unexported and called during commit
go record a savepoint into couch. GetBlockNumFromSavepoint should be used during recovery to
get the block number associated with the savepoint

Added similar methods to goleveldb txmgr implementation

Added unit test function to xxx_txmgmt_test.go

Change-Id: Id2860232632d29cbe753b2840a625c34e541f2d9
Signed-off-by: Balaji Viswanathan <[email protected]>

Author: bviswana101

core/ledger/kvledger/txmgmt/couchdbtxmgmt/couchdb_txmgmt_test.go

@@ -106,3 +106,33 @@ func TestDatabaseAutoCreate(t *testing.T) {
 	}
 
 }
+
+//TestSavepoint tests the recordSavepoint and GetBlockNumfromSavepoint methods for recording and reading a savepoint document
+func TestSavepoint(t *testing.T) {
+
+	//Only run the tests if CouchDB is explitily enabled in the code,
+	//otherwise CouchDB may not be installed and all the tests would fail
+	//TODO replace this with external config property rather than config within the code
+	if ledgerconfig.IsCouchDBEnabled() == true {
+
+		env := newTestEnv(t)
+
+		txMgr := NewCouchDBTxMgr(env.conf,
+			env.couchDBAddress,    //couchDB Address
+			env.couchDatabaseName, //couchDB db name
+			env.couchUsername,     //enter couchDB id
+			env.couchPassword)     //enter couchDB pw
+
+		// record savepoint
+		txMgr.blockNum = 5
+		err := txMgr.recordSavepoint()
+		testutil.AssertNoError(t, err, fmt.Sprintf("Error when saving recordpoint data"))
+
+		// read the savepoint
+		blockNum, err := txMgr.GetBlockNumFromSavepoint()
+		testutil.AssertNoError(t, err, fmt.Sprintf("Error when saving recordpoint data"))
+		testutil.AssertEquals(t, txMgr.blockNum, blockNum)
+
+		txMgr.Shutdown()
+	}
+}

core/ledger/kvledger/txmgmt/couchdbtxmgmt/couchdb_txmgr.go

@@ -17,6 +17,8 @@ limitations under the License.
 package couchdbtxmgmt
 
 import (
+	"encoding/json"
+	"errors"
 	"sync"
 
 	"github.com/golang/protobuf/proto"
@@ -48,6 +50,15 @@ type updateSet struct {
 	m map[string]*versionedValue
 }
 
+// Savepoint docid (key) for couchdb
+const savepointDocID = "statedb_savepoint"
+
+// Savepoint data for couchdb
+type couchSavepointData struct {
+	BlockNum  uint64 `json:"BlockNum"`
+	UpdateSeq string `json:"UpdateSeq"`
+}
+
 func newUpdateSet() *updateSet {
 	return &updateSet{make(map[string]*versionedValue)}
 }
@@ -72,6 +83,7 @@ type CouchDBTxMgr struct {
 	updateSet    *updateSet
 	commitRWLock sync.RWMutex
 	couchDB      *couchdb.CouchDBConnectionDef // COUCHDB new properties for CouchDB
+	blockNum     uint64                        // block number corresponding to updateSet
 }
 
 // CouchConnection provides connection info for CouchDB
@@ -119,6 +131,7 @@ func (txmgr *CouchDBTxMgr) ValidateAndPrepare(block *common.Block) (*common.Bloc
 	invalidTxs := []*pb.InvalidTransaction{}
 	var valid bool
 	txmgr.updateSet = newUpdateSet()
+	txmgr.blockNum = block.Header.Number
 	logger.Debugf("Validating a block with [%d] transactions", len(block.Data.Data))
 	for txIndex, envBytes := range block.Data.Data {
 		// extract actions from the envelope message
@@ -159,6 +172,7 @@ func (txmgr *CouchDBTxMgr) ValidateAndPrepare(block *common.Block) (*common.Bloc
 				Transaction: &pb.Transaction{ /* FIXME */ }, Cause: pb.InvalidTransaction_RWConflictDuringCommit})
 		}
 	}
+
 	logger.Debugf("===COUCHDB=== Exiting CouchDBTxMgr.ValidateAndPrepare()")
 	return block, invalidTxs, nil
 }
@@ -258,13 +272,87 @@ func (txmgr *CouchDBTxMgr) Commit() error {
 
 	}
 
+	// Record a savepoint
+	err := txmgr.recordSavepoint()
+	if err != nil {
+		logger.Errorf("===COUCHDB=== Error during recordSavepoint: %s\n", err.Error())
+		return err
+	}
+
 	logger.Debugf("===COUCHDB=== Exiting CouchDBTxMgr.Commit()")
 	return nil
 }
 
+// recordSavepoint Record a savepoint in statedb.
+// Couch parallelizes writes in cluster or sharded setup and ordering is not guaranteed.
+// Hence we need to fence the savepoint with sync. So ensure_full_commit is called before AND after writing savepoint document
+// TODO: Optimization - merge 2nd ensure_full_commit with savepoint by using X-Couch-Full-Commit header
+func (txmgr *CouchDBTxMgr) recordSavepoint() error {
+	var err error
+	var savepointDoc couchSavepointData
+	// ensure full commit to flush all changes until now to disk
+	dbResponse, err := txmgr.couchDB.EnsureFullCommit()
+	if err != nil || dbResponse.Ok != true {
+		logger.Errorf("====COUCHDB==== Failed to perform full commit\n")
+		return errors.New("Failed to perform full commit")
+	}
+
+	// construct savepoint document
+	// UpdateSeq would be useful if we want to get all db changes since a logical savepoint
+	dbInfo, _, err := txmgr.couchDB.GetDatabaseInfo()
+	if err != nil {
+		logger.Errorf("====COUCHDB==== Failed to get DB info %s\n", err.Error())
+		return err
+	}
+	savepointDoc.BlockNum = txmgr.blockNum
+	savepointDoc.UpdateSeq = dbInfo.UpdateSeq
+
+	savepointDocJSON, err := json.Marshal(savepointDoc)
+	if err != nil {
+		logger.Errorf("====COUCHDB==== Failed to create savepoint data %s\n", err.Error())
+		return err
+	}
+
+	// SaveDoc using couchdb client and use JSON format
+	_, err = txmgr.couchDB.SaveDoc(savepointDocID, "", savepointDocJSON, nil)
+	if err != nil {
+		logger.Errorf("====CouchDB==== Failed to save the savepoint to DB %s\n", err.Error())
+	}
+
+	// ensure full commit to flush savepoint to disk
+	dbResponse, err = txmgr.couchDB.EnsureFullCommit()
+	if err != nil || dbResponse.Ok != true {
+		logger.Errorf("====COUCHDB==== Failed to perform full commit\n")
+		return errors.New("Failed to perform full commit")
+	}
+	return nil
+}
+
+// GetBlockNumFromSavepoint Reads the savepoint from database and returns the corresponding block number.
+// If no savepoint is found, it returns 0
+func (txmgr *CouchDBTxMgr) GetBlockNumFromSavepoint() (uint64, error) {
+	var err error
+	savepointJSON, _, err := txmgr.couchDB.ReadDoc(savepointDocID)
+	if err != nil {
+		// TODO: differentiate between 404 and some other error code
+		logger.Errorf("====COUCHDB==== Failed to read savepoint data %s\n", err.Error())
+		return 0, err
+	}
+
+	savepointDoc := &couchSavepointData{}
+	err = json.Unmarshal(savepointJSON, &savepointDoc)
+	if err != nil {
+		logger.Errorf("====COUCHDB==== Failed to read savepoint data %s\n", err.Error())
+		return 0, err
+	}
+
+	return savepointDoc.BlockNum, nil
+}
+
 // Rollback implements method in interface `txmgmt.TxMgr`
 func (txmgr *CouchDBTxMgr) Rollback() {
 	txmgr.updateSet = nil
+	txmgr.blockNum = 0
 }
 
 func (txmgr *CouchDBTxMgr) getCommitedVersion(ns string, key string) (*version.Height, error) {

core/ledger/kvledger/txmgmt/lockbasedtxmgmt/lockbased_txmgmt_test.go

@@ -18,6 +18,7 @@ package lockbasedtxmgmt
 
 import (
 	"fmt"
+	"math"
 	"testing"
 
 	"github.com/hyperledger/fabric/core/ledger"
@@ -67,9 +68,13 @@ func TestTxSimulatorWithExistingData(t *testing.T) {
 	testutil.AssertNoError(t, err, fmt.Sprintf("Error in validateTx(): %s", err))
 	testutil.AssertSame(t, isValid, true)
 	txMgr.addWriteSetToBatch(txRWSet, version.NewHeight(1, 1))
+	txMgr.blockNum = math.MaxUint64
 	err = txMgr.Commit()
 	testutil.AssertNoError(t, err, fmt.Sprintf("Error while calling commit(): %s", err))
 
+	blockNum, err := txMgr.GetBlockNumFromSavepoint()
+	testutil.AssertEquals(t, blockNum, txMgr.blockNum)
+
 	// simulate tx2 that make changes to existing data
 	s2, _ := txMgr.NewTxSimulator()
 	value, _ := s2.GetState("ns1", "key1")
@@ -258,7 +263,7 @@ func testIterator(t *testing.T, numKeys int, startKeyNum int, endKeyNum int) {
 		keyNum := begin + count
 		k := kv.(*ledger.KV).Key
 		v := kv.(*ledger.KV).Value
-		t.Logf("Retrieved k=%s, v=%s", k, v)
+		t.Logf("Retrieved k=%s, v=%s at count=%d start=%s end=%s", k, v, count, startKey, endKey)
 		testutil.AssertEquals(t, k, createTestKey(keyNum))
 		testutil.AssertEquals(t, v, createTestValue(keyNum))
 		count++

core/ledger/kvledger/txmgmt/lockbasedtxmgmt/lockbased_txmgr.go

@@ -18,6 +18,8 @@ package lockbasedtxmgmt
 
 import (
 	"bytes"
+	"encoding/binary"
+	"reflect"
 	"sync"
 
 	"github.com/hyperledger/fabric/core/ledger"
@@ -50,6 +52,9 @@ type updateSet struct {
 	m map[string]*versionedValue
 }
 
+// savepoint key
+const savepointKey = "savepoint"
+
 func newUpdateSet() *updateSet {
 	return &updateSet{make(map[string]*versionedValue)}
 }
@@ -73,6 +78,7 @@ type LockBasedTxMgr struct {
 	db           *db.DB
 	updateSet    *updateSet
 	commitRWLock sync.RWMutex
+	blockNum     uint64
 }
 
 // NewLockBasedTxMgr constructs a `LockBasedTxMgr`
@@ -102,6 +108,7 @@ func (txmgr *LockBasedTxMgr) ValidateAndPrepare(block *common.Block) (*common.Bl
 	invalidTxs := []*pb.InvalidTransaction{}
 	var valid bool
 	txmgr.updateSet = newUpdateSet()
+	txmgr.blockNum = block.Header.Number
 	logger.Debugf("Validating a block with [%d] transactions", len(block.Data.Data))
 	for txIndex, envBytes := range block.Data.Data {
 		// extract actions from the envelope message
@@ -203,6 +210,15 @@ func (txmgr *LockBasedTxMgr) Commit() error {
 			batch.Put([]byte(k), encodeValue(v.value, v.version))
 		}
 	}
+
+	// record the savepoint along with batch
+	if txmgr.blockNum != 0 {
+		savepointValue := make([]byte, reflect.TypeOf(txmgr.blockNum).Size())
+		binary.LittleEndian.PutUint64(savepointValue, txmgr.blockNum)
+		// Need a composite key for iterator to function correctly - use separator itself as special/hidden namespace
+		batch.Put(constructCompositeKey(string(compositeKeySep), savepointKey), savepointValue)
+	}
+
 	txmgr.commitRWLock.Lock()
 	defer txmgr.commitRWLock.Unlock()
 	defer func() { txmgr.updateSet = nil }()
@@ -212,9 +228,24 @@ func (txmgr *LockBasedTxMgr) Commit() error {
 	return nil
 }
 
+// GetBlockNumFromSavepoint returns the block num recorded in savepoint,
+// returns 0 if NO savepoint is found
+func (txmgr *LockBasedTxMgr) GetBlockNumFromSavepoint() (uint64, error) {
+	var blockNum uint64
+	savepointValue, err := txmgr.db.Get(constructCompositeKey(string(compositeKeySep), savepointKey))
+	if err != nil {
+		return 0, err
+	}
+
+	// savepointValue is not encoded with version
+	blockNum = binary.LittleEndian.Uint64(savepointValue)
+	return blockNum, nil
+}
+
 // Rollback implements method in interface `txmgmt.TxMgr`
 func (txmgr *LockBasedTxMgr) Rollback() {
 	txmgr.updateSet = nil
+	txmgr.blockNum = 0
 }
 
 func (txmgr *LockBasedTxMgr) getCommitedVersion(ns string, key string) (*version.Height, error) {

core/ledger/util/couchdb/couchdb.go

@@ -230,6 +230,38 @@ func (dbclient *CouchDBConnectionDef) DropDatabase() (*DBOperationResponse, erro
 
 }
 
+// EnsureFullCommit calls _ensure_full_commit for explicit fsync
+func (dbclient *CouchDBConnectionDef) EnsureFullCommit() (*DBOperationResponse, error) {
+
+	logger.Debugf("===COUCHDB=== Entering EnsureFullCommit()")
+
+	url := fmt.Sprintf("%s/%s/_ensure_full_commit", dbclient.URL, dbclient.Database)
+
+	resp, _, err := dbclient.handleRequest(http.MethodPost, url, nil, "", "")
+	if err != nil {
+		logger.Errorf("====COUCHDB==== Failed to invoke _ensure_full_commit Error: %s\n", err.Error())
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	dbResponse := &DBOperationResponse{}
+	json.NewDecoder(resp.Body).Decode(&dbResponse)
+
+	if dbResponse.Ok == true {
+		logger.Debugf("===COUCHDB=== _ensure_full_commit database %s ", dbclient.Database)
+	}
+
+	logger.Debugf("===COUCHDB=== Exiting EnsureFullCommit()")
+
+	if dbResponse.Ok == true {
+
+		return dbResponse, nil
+
+	}
+
+	return dbResponse, fmt.Errorf("Error syncing database")
+}
+
 //SaveDoc method provides a function to save a document, id and byte array
 func (dbclient *CouchDBConnectionDef) SaveDoc(id string, rev string, bytesDoc []byte, attachments []Attachment) (string, error) {
 
@@ -497,7 +529,7 @@ func (dbclient *CouchDBConnectionDef) handleRequest(method, url string, data io.
 	}
 
 	//add content header for PUT
-	if method == http.MethodPut {
+	if method == http.MethodPut || method == http.MethodPost {
 
 		//If the multipartBoundary is not set, then this is a JSON and content-type should be set
 		//to application/json.   Else, this is contains an attachment and needs to be multipart
@@ -514,7 +546,7 @@ func (dbclient *CouchDBConnectionDef) handleRequest(method, url string, data io.
 	}
 
 	//add content header for PUT
-	if method == http.MethodPut {
+	if method == http.MethodPut || method == http.MethodPost {
 		req.Header.Set("Accept", "application/json")
 	}