FAB-1172 - Advanced simulation functions for CouchDB

Added implementations for the following:

    QueryExecutor.GetStateRangeScanIterator()
    QueryExecutor.GetStateMultipleKeys()
    TxSimulator.DeleteState()
    TxSimulator.SetStateMultipleKeys()

Unit testing was extended for the range query in couchdb.go

Additional unit testing for simulation functions will be added
following a refactoring of unit tests for goleveldb.

Change-Id: Id0907ace75767fe4b296f16c10d18693718d790f
Signed-off-by: Chris Elder <[email protected]>

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

@@ -39,12 +39,27 @@ func (q *CouchDBQueryExecutor) GetState(ns string, key string) ([]byte, error) {
 
 // GetStateMultipleKeys implements method in interface `ledger.QueryExecutor`
 func (q *CouchDBQueryExecutor) GetStateMultipleKeys(namespace string, keys []string) ([][]byte, error) {
-	return nil, errors.New("Not yet implemented")
+	var results [][]byte
+	var value []byte
+	var err error
+	for _, key := range keys {
+		value, err = q.GetState(namespace, key)
+		if err != nil {
+			return nil, err
+		}
+		results = append(results, value)
+	}
+	return results, nil
 }
 
 // GetStateRangeScanIterator implements method in interface `ledger.QueryExecutor`
 func (q *CouchDBQueryExecutor) GetStateRangeScanIterator(namespace string, startKey string, endKey string) (ledger.ResultsIterator, error) {
-	return nil, errors.New("Not yet implemented")
+	//q.checkDone()
+	scanner, err := q.txmgr.getCommittedRangeScanner(namespace, startKey, endKey)
+	if err != nil {
+		return nil, err
+	}
+	return &qKVItr{scanner}, nil
 }
 
 // GetTransactionsForKey - implements method in interface `ledger.QueryExecutor`
@@ -61,3 +76,25 @@ func (q *CouchDBQueryExecutor) ExecuteQuery(query string) (ledger.ResultsIterato
 func (q *CouchDBQueryExecutor) Done() {
 	//TODO - acquire lock when constructing and release the lock here
 }
+
+type qKVItr struct {
+	s *kvScanner
+}
+
+// Next implements Next() method in ledger.ResultsIterator
+func (itr *qKVItr) Next() (ledger.QueryResult, error) {
+	committedKV, err := itr.s.next()
+	if err != nil {
+		return nil, err
+	}
+	if committedKV == nil {
+		return nil, nil
+	}
+
+	return &ledger.KV{Key: committedKV.key, Value: committedKV.value}, nil
+}
+
+// Close implements Close() method in ledger.ResultsIterator
+func (itr *qKVItr) Close() {
+	itr.s.close()
+}

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

@@ -20,6 +20,7 @@ import (
 	"errors"
 	"reflect"
 
+	"github.com/hyperledger/fabric/core/ledger"
 	"github.com/hyperledger/fabric/core/ledger/kvledger/txmgmt"
 	logging "github.com/op/go-logging"
 )
@@ -108,6 +109,16 @@ func (s *CouchDBTxSimulator) GetState(ns string, key string) ([]byte, error) {
 	return value, nil
 }
 
+// GetStateRangeScanIterator implements method in interface `ledger.QueryExecutor`
+func (s *CouchDBTxSimulator) GetStateRangeScanIterator(namespace string, startKey string, endKey string) (ledger.ResultsIterator, error) {
+	//s.checkDone()
+	scanner, err := s.txmgr.getCommittedRangeScanner(namespace, startKey, endKey)
+	if err != nil {
+		return nil, err
+	}
+	return &sKVItr{scanner, s}, nil
+}
+
 // SetState implements method in interface `ledger.TxSimulator`
 func (s *CouchDBTxSimulator) SetState(ns string, key string, value []byte) error {
 	logger.Debugf("===COUCHDB=== Entering CouchDBTxSimulator.SetState()")
@@ -190,7 +201,12 @@ func (s *CouchDBTxSimulator) GetTxSimulationResults() ([]byte, error) {
 
 // SetStateMultipleKeys implements method in interface `ledger.TxSimulator`
 func (s *CouchDBTxSimulator) SetStateMultipleKeys(namespace string, kvs map[string][]byte) error {
-	return errors.New("Not yet implemented")
+	for k, v := range kvs {
+		if err := s.SetState(namespace, k, v); err != nil {
+			return err
+		}
+	}
+	return nil
 }
 
 // CopyState implements method in interface `ledger.TxSimulator`
@@ -202,3 +218,34 @@ func (s *CouchDBTxSimulator) CopyState(sourceNamespace string, targetNamespace s
 func (s *CouchDBTxSimulator) ExecuteUpdate(query string) error {
 	return errors.New("Not supported by KV data model")
 }
+
+type sKVItr struct {
+	scanner   *kvScanner
+	simulator *CouchDBTxSimulator
+}
+
+// Next implements Next() method in ledger.ResultsIterator
+// Returns the next item in the result set. The `QueryResult` is expected to be nil when
+// the iterator gets exhausted
+func (itr *sKVItr) Next() (ledger.QueryResult, error) {
+	committedKV, err := itr.scanner.next()
+	if err != nil {
+		return nil, err
+	}
+	if committedKV == nil {
+		return nil, nil
+	}
+
+	// Get existing cache for RW at the namespace of the result set if it exists.  If none exists, then create it.
+	nsRWs := itr.simulator.getOrCreateNsRWHolder(itr.scanner.namespace)
+	nsRWs.readMap[committedKV.key] = &kvReadCache{
+		&txmgmt.KVRead{Key: committedKV.key, Version: committedKV.version}, committedKV.value}
+
+	return &ledger.KV{Key: committedKV.key, Value: committedKV.value}, nil
+}
+
+// Close implements Close() method in ledger.ResultsIterator
+// which releases resources occupied by the iterator.
+func (itr *sKVItr) Close() {
+	itr.scanner.close()
+}

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

@@ -17,6 +17,7 @@ limitations under the License.
 package couchdbtxmgmt
 
 import (
+	"bytes"
 	"encoding/json"
 	"errors"
 	"sync"
@@ -36,6 +37,8 @@ import (
 
 var logger = logging.MustGetLogger("couchdbtxmgmt")
 
+var compositeKeySep = []byte{0x00}
+
 // Conf - configuration for `CouchDBTxMgr`
 type Conf struct {
 	DBPath string
@@ -383,6 +386,22 @@ func (txmgr *CouchDBTxMgr) getCommittedValueAndVersion(ns string, key string) ([
 	return docBytes, ver, nil
 }
 
+//getCommittedRangeScanner contructs composite start and end keys based on the namespace then calls the CouchDB range scanner
+func (txmgr *CouchDBTxMgr) getCommittedRangeScanner(namespace string, startKey string, endKey string) (*kvScanner, error) {
+	var compositeStartKey []byte
+	var compositeEndKey []byte
+	if startKey != "" {
+		compositeStartKey = constructCompositeKey(namespace, startKey)
+	}
+	if endKey != "" {
+		compositeEndKey = constructCompositeKey(namespace, endKey)
+	}
+
+	queryResult, _ := txmgr.couchDB.ReadDocRange(string(compositeStartKey), string(compositeEndKey), 1000, 0)
+
+	return newKVScanner(namespace, *queryResult), nil
+}
+
 func encodeValue(value []byte, version uint64) []byte {
 	versionBytes := proto.EncodeVarint(version)
 	deleteMarker := 0
@@ -409,7 +428,50 @@ func decodeValue(encodedValue []byte) ([]byte, uint64) {
 
 func constructCompositeKey(ns string, key string) []byte {
 	compositeKey := []byte(ns)
-	compositeKey = append(compositeKey, byte(0))
+	compositeKey = append(compositeKey, compositeKeySep...)
 	compositeKey = append(compositeKey, []byte(key)...)
 	return compositeKey
 }
+
+func splitCompositeKey(compositeKey []byte) (string, string) {
+	split := bytes.SplitN(compositeKey, compositeKeySep, 2)
+	return string(split[0]), string(split[1])
+}
+
+type kvScanner struct {
+	cursor    int
+	namespace string
+	results   []couchdb.QueryResult
+}
+
+type committedKV struct {
+	key     string
+	version *version.Height
+	value   []byte
+}
+
+func newKVScanner(namespace string, queryResults []couchdb.QueryResult) *kvScanner {
+	return &kvScanner{-1, namespace, queryResults}
+}
+
+func (scanner *kvScanner) next() (*committedKV, error) {
+
+	scanner.cursor++
+
+	if scanner.cursor >= len(scanner.results) {
+		return nil, nil
+	}
+
+	selectedValue := scanner.results[scanner.cursor]
+
+	_, key := splitCompositeKey([]byte(selectedValue.ID))
+
+	//TODO - change hardcoded version when version support is available in CouchDB
+	return &committedKV{key, version.NewHeight(1, 1), selectedValue.Value}, nil
+
+}
+
+func (scanner *kvScanner) close() {
+
+	scanner = nil
+}