Add NATS Ack/Nak to nats jetstream V3 Finish

Signed-off-by: stephen-totty-hpe <stephen.totty@hpe.com>

protocol/nats_jetstream/v3/message.go

@@ -17,6 +17,7 @@ import (
 	"github.com/cloudevents/sdk-go/v2/binding"
 	"github.com/cloudevents/sdk-go/v2/binding/format"
 	"github.com/cloudevents/sdk-go/v2/binding/spec"
+	"github.com/cloudevents/sdk-go/v2/protocol"
 )
 
 const (
@@ -105,6 +106,35 @@ func (m *Message) ReadBinary(ctx context.Context, encoder binding.BinaryWriter)
 
 // Finish *must* be called when message from a Receiver can be forgotten by the receiver.
 func (m *Message) Finish(err error) error {
+	// Ack and Nak first checks to see if the message has been acknowleged
+	// and if Ack/Nak was done, it immediately returns an error without applying any logic to the message on the server.
+	// Nak will only be sent if the error given is explictly a NACK error(protocol.ResultNACK).
+	// AckPolicy effects if an explict Ack/Nak is needed.
+	// AckExplicit: The default policy. Each individual message must be acknowledged.
+	// 		Recommended for most reliability and functionality.
+	// AckNone: No acknowledgment needed; the server assumes acknowledgment on delivery.
+	// AckAll: Acknowledge only the last message received in a series; all previous messages are automatically acknowledged.
+	// 		Will acknowledge all pending messages for all subscribers for Pull Consumer.
+	// see: github.com/nats-io/nats.go/jetstream/ConsumerConfig.AckPolicy
+	if m.Msg == nil {
+		return nil
+	}
+	if protocol.IsNACK(err) {
+		if err = m.Msg.Nak(); err != jetstream.ErrMsgAlreadyAckd {
+			return err
+		}
+	}
+	if protocol.IsACK(err) {
+		if err = m.Msg.Ack(); err != jetstream.ErrMsgAlreadyAckd {
+			return err
+		}
+	}
+
+	// In the case that we receive an unknown error, the behavior of whether the message is Ack/Nak
+	// will be based on the consumer configuration.  There are several options such as:
+	// AckPolicy, AckWait, MaxDeliver, MaxAckPending
+	// that determine how messages would be redelivered by the server.
+	// [consumers configuration]: https://docs.nats.io/nats-concepts/jetstream/consumers#configuration
 	return nil
 }
 

protocol/nats_jetstream/v3/message_test.go

@@ -9,11 +9,13 @@ import (
 	"bytes"
 	"context"
 	"encoding/json"
+	"errors"
 	"reflect"
 	"testing"
 
 	"github.com/cloudevents/sdk-go/v2/binding/spec"
 	bindingtest "github.com/cloudevents/sdk-go/v2/binding/test"
+	"github.com/cloudevents/sdk-go/v2/protocol"
 
 	"github.com/cloudevents/sdk-go/v2/binding"
 	"github.com/cloudevents/sdk-go/v2/test"
@@ -23,11 +25,17 @@ import (
 
 type jetStreamMsg struct {
 	jetstream.Msg
-	msg *nats.Msg
+	msg        *nats.Msg
+	ackCalled  bool
+	ackErr     error
+	nackCalled bool
+	nackErr    error
 }
 
 func (j *jetStreamMsg) Data() []byte         { return j.msg.Data }
 func (j *jetStreamMsg) Headers() nats.Header { return j.msg.Header }
+func (j *jetStreamMsg) Ack() error           { j.ackCalled = true; return j.ackErr }
+func (j *jetStreamMsg) Nak() error           { j.nackCalled = true; return j.nackErr }
 
 var (
 	outBinaryMessage = bindingtest.MockBinaryMessage{
@@ -190,3 +198,116 @@ func TestGetExtension(t *testing.T) {
 		})
 	}
 }
+
+func TestFinish(t *testing.T) {
+	type args struct {
+		err    error
+		ackErr error
+		nakErr error
+	}
+	type wants struct {
+		err        error
+		ackCalled  bool
+		nackCalled bool
+	}
+	tests := []struct {
+		name  string
+		args  args
+		wants wants
+	}{
+		{
+			name: "nil error given",
+			args: args{
+				err: nil,
+			},
+			wants: wants{
+				err:        nil,
+				ackCalled:  true,
+				nackCalled: false,
+			},
+		},
+		{
+			name: "ACK error given",
+			args: args{
+				err: protocol.ResultACK,
+			},
+			wants: wants{
+				err:        nil,
+				ackCalled:  true,
+				nackCalled: false,
+			},
+		},
+		{
+			name: "NACK error given",
+			args: args{
+				err: protocol.ResultNACK,
+			},
+			wants: wants{
+				err:        nil,
+				ackCalled:  false,
+				nackCalled: true,
+			},
+		},
+		{
+			name: "unknown error given",
+			args: args{
+				err: errors.New("unknown"),
+			},
+			wants: wants{
+				err:        nil,
+				ackCalled:  false,
+				nackCalled: false,
+			},
+		},
+		{
+			name: "jetstream.ErrMsgAlreadyAckd error returned from Ack",
+			args: args{
+				err:    protocol.ResultACK,
+				ackErr: jetstream.ErrMsgAlreadyAckd,
+			},
+			wants: wants{
+				err:        nil,
+				ackCalled:  true,
+				nackCalled: false,
+			},
+		},
+		{
+			name: "jetstream.ErrMsgAlreadyAckd error returned from Nak",
+			args: args{
+				err:    protocol.ResultNACK,
+				nakErr: jetstream.ErrMsgAlreadyAckd,
+			},
+			wants: wants{
+				err:        nil,
+				ackCalled:  false,
+				nackCalled: true,
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			binaryReceiverMessage.ackCalled = false
+			binaryReceiverMessage.ackErr = tt.args.ackErr
+			binaryReceiverMessage.nackCalled = false
+			binaryReceiverMessage.nackErr = tt.args.nakErr
+			message := NewMessage(binaryReceiverMessage)
+			if message == nil {
+				t.Errorf("Error in NewMessage!")
+			}
+			gotErr := message.Finish(tt.args.err)
+			if gotErr != tt.wants.err {
+				t.Errorf("ExpectedErr %s, while got %s", tt.wants.err, gotErr)
+			}
+			var mockMessage *jetStreamMsg
+			if message != nil {
+				mockMessage = message.Msg.(*jetStreamMsg)
+			}
+			if mockMessage.ackCalled != tt.wants.ackCalled {
+				t.Errorf("ExpectedAck %t, while got %t", tt.wants.ackCalled, mockMessage.ackCalled)
+			}
+			if mockMessage.nackCalled != tt.wants.nackCalled {
+				t.Errorf("ExpectedNack %t, while got %t", tt.wants.nackCalled, mockMessage.nackCalled)
+			}
+		})
+	}
+}

protocol/nats_jetstream/v3/options.go

@@ -42,7 +42,7 @@ func WithConnection(conn *nats.Conn) ProtocolOption {
 // WithJetStreamOptions sets jetstream options used in the protocol sender and receiver
 func WithJetStreamOptions(jetStreamOpts []jetstream.JetStreamOpt) ProtocolOption {
 	return func(p *Protocol) error {
-		p.jetSteamOpts = jetStreamOpts
+		p.jetStreamOpts = jetStreamOpts
 		return nil
 	}
 }

protocol/nats_jetstream/v3/options_test.go

@@ -474,7 +474,7 @@ func TestWithJetStreamOptions(t *testing.T) {
 			wants: wants{
 				err: nil,
 				protocol: &Protocol{
-					jetSteamOpts: jetStreamOpts,
+					jetStreamOpts: jetStreamOpts,
 				},
 			},
 		},

protocol/nats_jetstream/v3/protocol.go

@@ -29,8 +29,8 @@ type Protocol struct {
 	natsOpts []nats.Option
 
 	// jetstream options
-	jetSteamOpts []jetstream.JetStreamOpt
-	jetStream    jetstream.JetStream
+	jetStreamOpts []jetstream.JetStreamOpt
+	jetStream     jetstream.JetStream
 
 	// receiver
 	incoming              chan msgErr
@@ -76,7 +76,7 @@ func New(ctx context.Context, opts ...ProtocolOption) (*Protocol, error) {
 		}
 	}
 
-	if p.jetStream, errConnection = jetstream.New(p.conn, p.jetSteamOpts...); errConnection != nil {
+	if p.jetStream, errConnection = jetstream.New(p.conn, p.jetStreamOpts...); errConnection != nil {
 		return nil, errConnection
 	}