Add ExportConfigHistory() API to confighistoryDB (#1288)

This commit adds ExportConfigHistory() API to the
confighistoryDB retriever. It utilizes snapshot file
writer to dump keys & values stored in the
confighistoryDB to a snapshot file.

Signed-off-by: senthil <cendhu@gmail.com>

core/ledger/confighistory/db_helper.go

@@ -18,6 +18,7 @@ import (
 const (
 	keyPrefix     = "s"
 	separatorByte = byte(0)
+	nsStopper     = byte(1)
 )
 
 type compositeKey struct {
@@ -99,6 +100,14 @@ func (d *db) entryAt(blockNum uint64, ns, key string) (*compositeKV, error) {
 	return &compositeKV{k, v}, nil
 }
 
+func (d *db) getNamespaceIterator(ns string) *leveldbhelper.Iterator {
+	nsStartKey := []byte(keyPrefix + ns)
+	nsStartKey = append(nsStartKey, separatorByte)
+	nsEndKey := []byte(keyPrefix + ns)
+	nsEndKey = append(nsEndKey, nsStopper)
+	return d.GetIterator(nsStartKey, nsEndKey)
+}
+
 func encodeCompositeKey(ns, key string, blockNum uint64) []byte {
 	b := []byte(keyPrefix + ns)
 	b = append(b, separatorByte)

core/ledger/confighistory/db_helper_test.go

@@ -12,6 +12,7 @@ import (
 	"os"
 	"testing"
 
+	"github.com/hyperledger/fabric/common/ledger/util/leveldbhelper"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -66,6 +67,50 @@ func TestQueries(t *testing.T) {
 	checkEntryAt(t, "testcase-query10", db, "ns1", "key1", 45, nil)
 }
 
+func TestGetNamespaceIterator(t *testing.T) {
+	testDBPath := "/tmp/fabric/core/ledger/confighistory"
+	provider, err := newDBProvider(testDBPath)
+	require.NoError(t, err)
+	defer deleteTestPath(t, testDBPath)
+
+	db := provider.getDB("ledger1")
+	nsItr1 := db.getNamespaceIterator("ns1")
+	require.NoError(t, nsItr1.Error())
+	defer nsItr1.Release()
+	verifyNsEntries(t, nsItr1, nil)
+
+	sampleData := []*compositeKV{
+		{&compositeKey{ns: "ns1", key: "key1", blockNum: 40}, []byte("val1_40")}, // index 0
+		{&compositeKey{ns: "ns1", key: "key1", blockNum: 30}, []byte("val1_30")}, // index 1
+		{&compositeKey{ns: "ns1", key: "key1", blockNum: 20}, []byte("val1_20")}, // index 2
+		{&compositeKey{ns: "ns2", key: "key1", blockNum: 50}, []byte("val1_50")}, // index 3
+		{&compositeKey{ns: "ns2", key: "key1", blockNum: 20}, []byte("val1_20")}, // index 4
+		{&compositeKey{ns: "ns2", key: "key1", blockNum: 10}, []byte("val1_10")}, // index 5
+	}
+	populateDBWithSampleData(t, db, sampleData)
+
+	nsItr2 := db.getNamespaceIterator("ns1")
+	require.NoError(t, nsItr2.Error())
+	defer nsItr2.Release()
+	verifyNsEntries(t, nsItr2, sampleData[:3])
+
+	nsItr3 := db.getNamespaceIterator("ns2")
+	require.NoError(t, nsItr3.Error())
+	defer nsItr3.Release()
+	verifyNsEntries(t, nsItr3, sampleData[3:])
+}
+
+func verifyNsEntries(t *testing.T, nsItr *leveldbhelper.Iterator, expectedEntries []*compositeKV) {
+	var retrievedEntries []*compositeKV
+	for nsItr.Next() {
+		require.NoError(t, nsItr.Error())
+		key := decodeCompositeKey(nsItr.Key())
+		val := make([]byte, len(nsItr.Value()))
+		copy(val, nsItr.Value())
+		retrievedEntries = append(retrievedEntries, &compositeKV{key, val})
+	}
+	require.Equal(t, expectedEntries, retrievedEntries)
+}
 func populateDBWithSampleData(t *testing.T, db *db, sampledata []*compositeKV) {
 	batch := newBatch()
 	for _, data := range sampledata {

core/ledger/confighistory/mgr.go

@@ -8,12 +8,15 @@ package confighistory
 
 import (
 	"fmt"
+	"hash"
+	"path"
 
 	"github.com/golang/protobuf/proto"
 	"github.com/hyperledger/fabric-protos-go/common"
 	"github.com/hyperledger/fabric-protos-go/ledger/rwset/kvrwset"
 	"github.com/hyperledger/fabric-protos-go/peer"
 	"github.com/hyperledger/fabric/common/flogging"
+	"github.com/hyperledger/fabric/common/ledger/snapshot"
 	"github.com/hyperledger/fabric/core/ledger"
 	"github.com/pkg/errors"
 )
@@ -22,12 +25,15 @@ var logger = flogging.MustGetLogger("confighistory")
 
 const (
 	collectionConfigNamespace = "lscc" // lscc namespace was introduced in version 1.2 and we continue to use this in order to be compatible with existing data
+	snapshotFileFormat        = byte(1)
+	snapshotDataFileName      = "confighistory.data"
+	snapshotMetadataFileName  = "confighistory.metadata"
 )
 
 // Mgr should be registered as a state listener. The state listener builds the history and retriever helps in querying the history
 type Mgr interface {
 	ledger.StateListener
-	GetRetriever(ledgerID string, ledgerInfoRetriever LedgerInfoRetriever) ledger.ConfigHistoryRetriever
+	GetRetriever(ledgerID string, ledgerInfoRetriever LedgerInfoRetriever) *Retriever
 	Close()
 }
 
@@ -105,8 +111,8 @@ func (m *mgr) HandleStateUpdates(trigger *ledger.StateUpdateTrigger) error {
 }
 
 // GetRetriever returns an implementation of `ledger.ConfigHistoryRetriever` for the given ledger id.
-func (m *mgr) GetRetriever(ledgerID string, ledgerInfoRetriever LedgerInfoRetriever) ledger.ConfigHistoryRetriever {
-	return &retriever{
+func (m *mgr) GetRetriever(ledgerID string, ledgerInfoRetriever LedgerInfoRetriever) *Retriever {
+	return &Retriever{
 		ledgerInfoRetriever:    ledgerInfoRetriever,
 		ledgerID:               ledgerID,
 		deployedCCInfoProvider: m.ccInfoProvider,
@@ -119,15 +125,15 @@ func (m *mgr) Close() {
 	m.dbProvider.Close()
 }
 
-type retriever struct {
+type Retriever struct {
 	ledgerInfoRetriever    LedgerInfoRetriever
 	ledgerID               string
 	deployedCCInfoProvider ledger.DeployedChaincodeInfoProvider
 	dbHandle               *db
 }
 
 // MostRecentCollectionConfigBelow implements function from the interface ledger.ConfigHistoryRetriever
-func (r *retriever) MostRecentCollectionConfigBelow(blockNum uint64, chaincodeName string) (*ledger.CollectionConfigInfo, error) {
+func (r *Retriever) MostRecentCollectionConfigBelow(blockNum uint64, chaincodeName string) (*ledger.CollectionConfigInfo, error) {
 	compositeKV, err := r.dbHandle.mostRecentEntryBelow(blockNum, collectionConfigNamespace, constructCollectionConfigKey(chaincodeName))
 	if err != nil {
 		return nil, err
@@ -141,7 +147,7 @@ func (r *retriever) MostRecentCollectionConfigBelow(blockNum uint64, chaincodeNa
 }
 
 // CollectionConfigAt implements function from the interface ledger.ConfigHistoryRetriever
-func (r *retriever) CollectionConfigAt(blockNum uint64, chaincodeName string) (*ledger.CollectionConfigInfo, error) {
+func (r *Retriever) CollectionConfigAt(blockNum uint64, chaincodeName string) (*ledger.CollectionConfigInfo, error) {
 	info, err := r.ledgerInfoRetriever.GetBlockchainInfo()
 	if err != nil {
 		return nil, err
@@ -163,7 +169,67 @@ func (r *retriever) CollectionConfigAt(blockNum uint64, chaincodeName string) (*
 	return constructCollectionConfigInfo(compositeKV, implicitColls)
 }
 
-func (r *retriever) getImplicitCollection(chaincodeName string) ([]*peer.StaticCollectionConfig, error) {
+// ExportConfigHistory exports configuration history from the confighistoryDB to
+// a file. Currently, we store only one type of configuration in the db, i.e.,
+// private data collection configuration.
+// We write the full key and value stored in the database as is to the file.
+// Though we could decode the key and write a proto message with exact ns, key,
+// block number, and collection config, we store the full key and value to avoid
+// unnecessary encoding and decoding of proto messages.
+// The key format stored in db is "s" + ns + byte(0) + key + "~collection" + byte(0)
+// + blockNum. As we store the key as is, we store 13 extra bytes. For a million
+// records, it would add only 12 MB overhead. Note that the protobuf also adds some
+// extra bytes. Further, the collection config namespace is not expected to have
+// millions of entries.
+func (r *Retriever) ExportConfigHistory(dir string, hasher hash.Hash) (map[string][]byte, error) {
+	dataFileWriter, err := snapshot.CreateFile(path.Join(dir, snapshotDataFileName), snapshotFileFormat, hasher)
+	if err != nil {
+		return nil, err
+	}
+	defer dataFileWriter.Close()
+
+	nsItr := r.dbHandle.getNamespaceIterator(collectionConfigNamespace)
+	if err := nsItr.Error(); err != nil {
+		return nil, errors.Wrap(err, "internal leveldb error while obtaining db iterator")
+
+	}
+	defer nsItr.Release()
+	var numCollectionConfigs uint64 = 0
+	for nsItr.Next() {
+		if err := nsItr.Error(); err != nil {
+			return nil, errors.Wrap(err, "internal leveldb error while iterating for collection config history")
+		}
+		if err := dataFileWriter.EncodeBytes(nsItr.Key()); err != nil {
+			return nil, err
+		}
+		if err := dataFileWriter.EncodeBytes(nsItr.Value()); err != nil {
+			return nil, err
+		}
+		numCollectionConfigs++
+	}
+	dataHash, err := dataFileWriter.Done()
+	if err != nil {
+		return nil, err
+	}
+
+	hasher.Reset()
+	metadataFileWriter, err := snapshot.CreateFile(path.Join(dir, snapshotMetadataFileName), snapshotFileFormat, hasher)
+	if err != nil {
+		return nil, err
+	}
+	defer metadataFileWriter.Close()
+	if err = metadataFileWriter.EncodeUVarint(numCollectionConfigs); err != nil {
+		return nil, err
+	}
+	metadataHash, err := metadataFileWriter.Done()
+
+	return map[string][]byte{
+		snapshotDataFileName:     dataHash,
+		snapshotMetadataFileName: metadataHash,
+	}, nil
+}
+
+func (r *Retriever) getImplicitCollection(chaincodeName string) ([]*peer.StaticCollectionConfig, error) {
 	qe, err := r.ledgerInfoRetriever.NewQueryExecutor()
 	if err != nil {
 		return nil, err