[FAB-9817] Use Tx-simulator after obtaining results

In the current implementation, a transaction simulator instance
releases itself (as an caution for optimization) when the caller
has obtained the simulation results. The assumption was that this
will be the last step in using the simulator.

However, now there is a situation where gossip would need to obtain the simulation
results and based on the private data present in the simulation results, it will use
the simulator to fetch the collection configurations.

This CR removes this self-release behavior. Also, a test is added to
make sure that the previously obtained rwset are not affected by
further data operations on the simulator.

Change-Id: Ic5664cd8d4536b31c603154ede573bbf3c095e76
Signed-off-by: manish <manish.sethi@gmail.com>

Author: manish-sethi

core/ledger/kvledger/txmgmt/txmgr/lockbasedtxmgr/lockbased_tx_simulator.go

@@ -125,7 +125,6 @@ func (s *lockBasedTxSimulator) ExecuteQueryOnPrivateData(namespace, collection,
 // GetTxSimulationResults implements method in interface `ledger.TxSimulator`
 func (s *lockBasedTxSimulator) GetTxSimulationResults() (*ledger.TxSimulationResults, error) {
 	logger.Debugf("Simulation completed, getting simulation results")
-	s.Done()
 	if s.helper.err != nil {
 		return nil, s.helper.err
 	}

core/ledger/kvledger/txmgmt/txmgr/lockbasedtxmgr/txmgr_test.go

@@ -6,6 +6,8 @@ SPDX-License-Identifier: Apache-2.0
 package lockbasedtxmgr
 
 import (
+	"bytes"
+	"encoding/gob"
 	"encoding/json"
 	"fmt"
 	"testing"
@@ -72,6 +74,63 @@ func testTxSimulatorWithNoExistingData(t *testing.T, env testEnv) {
 	assert.Nil(t, simulationResults.PvtSimulationResults)
 }
 
+func TestTxSimulatorGetResults(t *testing.T) {
+	testEnv := testEnvsMap[levelDBtestEnvName]
+	testEnv.init(t, "testLedger", nil)
+	defer testEnv.cleanup()
+	var err error
+
+	// Create a simulator and get/set keys in one namespace "ns1"
+	simulator, _ := testEnv.getTxMgr().NewTxSimulator("test_txid1")
+	simulator.GetState("ns1", "key1")
+	simulator.GetPrivateData("ns1", "coll1", "key1")
+	simulator.SetState("ns1", "key1", []byte("value1"))
+	// get simulation results and verify that this contains rwset only for one namespace
+	simulationResults1, err := simulator.GetTxSimulationResults()
+	assert.Equal(t, 1, len(simulationResults1.PubSimulationResults.NsRwset))
+	// clone freeze simulationResults1
+	buff1 := new(bytes.Buffer)
+	assert.NoError(t, gob.NewEncoder(buff1).Encode(simulationResults1))
+	frozenSimulationResults1 := &ledger.TxSimulationResults{}
+	assert.NoError(t, gob.NewDecoder(buff1).Decode(&frozenSimulationResults1))
+
+	// use the same simulator after obtaining the simulaiton results by get/set keys in one more namespace "ns2"
+	simulator.GetState("ns2", "key2")
+	simulator.GetPrivateData("ns2", "coll2", "key2")
+	simulator.SetState("ns2", "key2", []byte("value2"))
+	// get simulation results and verify that this contains rwset for both the namespaces "ns1" and "ns2"
+	simulationResults2, err := simulator.GetTxSimulationResults()
+	assert.Equal(t, 2, len(simulationResults2.PubSimulationResults.NsRwset))
+	// clone freeze simulationResults2
+	buff2 := new(bytes.Buffer)
+	assert.NoError(t, gob.NewEncoder(buff2).Encode(simulationResults2))
+	frozenSimulationResults2 := &ledger.TxSimulationResults{}
+	assert.NoError(t, gob.NewDecoder(buff2).Decode(&frozenSimulationResults2))
+
+	// use the same simulator further to operate on different keys in the namespcace "ns1"
+	simulator.GetState("ns1", "key3")
+	simulator.GetPrivateData("ns1", "coll3", "key3")
+	simulator.SetState("ns1", "key3", []byte("value3"))
+	// get simulation results and verify that this contains rwset for both the namespaces "ns1" and "ns2"
+	simulationResults3, err := simulator.GetTxSimulationResults()
+	assert.Equal(t, 2, len(simulationResults3.PubSimulationResults.NsRwset))
+
+	// Now, verify that the simulator operations did not have an effect on privously obtained results
+	assert.Equal(t, frozenSimulationResults1, simulationResults1)
+	assert.Equal(t, frozenSimulationResults2, simulationResults2)
+
+	// Call 'Done' and all the data get/set operations after calling 'Done' should fail.
+	simulator.Done()
+	_, err = simulator.GetState("ns3", "key3")
+	assert.Errorf(t, err, "An error is expected when using simulator to get/set data after calling `Done` function()")
+	err = simulator.SetState("ns3", "key3", []byte("value3"))
+	assert.Errorf(t, err, "An error is expected when using simulator to get/set data after calling `Done` function()")
+	_, err = simulator.GetPrivateData("ns3", "coll3", "key3")
+	assert.Errorf(t, err, "An error is expected when using simulator to get/set data after calling `Done` function()")
+	err = simulator.SetPrivateData("ns3", "coll3", "key3", []byte("value3"))
+	assert.Errorf(t, err, "An error is expected when using simulator to get/set data after calling `Done` function()")
+}
+
 func TestTxSimulatorWithExistingData(t *testing.T) {
 	for _, testEnv := range testEnvs {
 		t.Run(testEnv.getName(), func(t *testing.T) {