cleaning up changeset API

internal/datasourcev2/polling_data_source.go

@@ -148,7 +148,7 @@ func (pp *PollingProcessor) poll() error {
 		return err
 	}
 
-	payload := changeSet.Intent().Payloads[0]
+	payload := changeSet.IntentCode().Payload
 	switch payload.Code {
 	case fdv2proto.IntentTransferFull:
 		pp.dataDestination.SetBasis(changeSet.Changes(), changeSet.Selector(), true)

internal/datasourcev2/streaming_data_source.go

@@ -258,8 +258,7 @@ func (sp *StreamProcessor) consumeStream(stream *es.Stream, closeWhenReady chan<
 					break
 				}
 
-				// The Finish method guarantees that at least one payload is present.
-				payload := changeSet.Intent().Payloads[0]
+				payload := changeSet.IntentCode().Payload
 				switch payload.Code {
 				case fdv2proto.IntentTransferFull:
 					sp.dataDestination.SetBasis(changeSet.Changes(), changeSet.Selector(), true)

internal/fdv2proto/changeset.go

@@ -21,13 +21,13 @@ type Change struct {
 }
 
 type ChangeSet struct {
-	intent   ServerIntent
+	intentCode IntentCode
 	changes  []Change
 	selector Selector
 }
 
-func (c *ChangeSet) Intent() ServerIntent {
-	return c.intent
+func (c *ChangeSet) IntentCode() IntentCode{
+	return c.intentCode
 }
 
 func (c *ChangeSet) Changes() []Change {
@@ -49,16 +49,13 @@ func NewChangeSetBuilder() *ChangeSetBuilder {
 
 func (c *ChangeSetBuilder) NoChanges() *ChangeSet {
 	return &ChangeSet{
-		intent:   ServerIntent{Payloads: []Payload{{Code: IntentNone}}},
+		intentCode: IntentNone,
 		selector: NoSelector(),
 		changes:  nil,
 	}
 }
 
 func (c *ChangeSetBuilder) Start(intent ServerIntent) error {
-	if len(intent.Payloads) == 0 {
-		return errors.New("changeset: server-intent event has no payloads")
-	}
 	c.intent = &intent
 	c.changes = nil
 	return nil
@@ -71,11 +68,12 @@ func (c *ChangeSetBuilder) Finish(selector Selector) (*ChangeSet, error) {
 		return nil, errors.New("changeset: cannot complete without a server-intent")
 	}
 	changes := &ChangeSet{
-		intent:   *c.intent,
+		intentCode: c.intent.Payload.Code,
 		selector: selector,
 		changes:  c.changes,
 	}
 	c.changes = nil
+	c.intent.Payload.Code =
 	return changes, nil
 }
 

internal/fdv2proto/changeset_test.go

@@ -16,27 +16,15 @@ func TestChangeSetBuilder_MustStartToFinish(t *testing.T) {
 	_, err := builder.Finish(selector)
 	assert.Error(t, err)
 
-	assert.NoError(t, builder.Start(ServerIntent{Payloads: []Payload{{Code: IntentNone}}}))
+	assert.NoError(t, builder.Start(ServerIntent{Payload: Payload{Code: IntentNone}}))
 
 	_, err = builder.Finish(selector)
 	assert.NoError(t, err)
 }
 
-func TestChangeSetBuilder_MustHaveAtLeastOnePayload(t *testing.T) {
-	builder := NewChangeSetBuilder()
-	err := builder.Start(ServerIntent{})
-	assert.Error(t, err)
-
-	err = builder.Start(ServerIntent{Payloads: []Payload{{Code: IntentNone}}})
-	assert.NoError(t, err)
-
-	err = builder.Start(ServerIntent{Payloads: []Payload{{Code: IntentNone}, {Code: IntentNone}, {Code: IntentNone}}})
-	assert.NoError(t, err)
-}
-
 func TestChangeSetBuilder_Changes(t *testing.T) {
 	builder := NewChangeSetBuilder()
-	err := builder.Start(ServerIntent{Payloads: []Payload{{Code: IntentTransferChanges}}})
+	err := builder.Start(ServerIntent{Payload: Payload{Code: IntentTransferChanges}})
 	assert.NoError(t, err)
 
 	builder.AddPut("foo", "bar", 1, []byte("baz"))
@@ -52,12 +40,17 @@ func TestChangeSetBuilder_Changes(t *testing.T) {
 	assert.Equal(t, Change{Action: ChangeTypePut, Kind: "foo", Key: "bar", Version: 1, Object: []byte("baz")}, changes[0])
 	assert.Equal(t, Change{Action: ChangeTypeDelete, Kind: "foo", Key: "bar", Version: 1}, changes[1])
 
-	assert.Equal(t, IntentTransferChanges, changeSet.Intent().Payloads[0].Code)
+	assert.Equal(t, IntentTransferChanges, changeSet.IntentCode().Payload.Code)
 	assert.Equal(t, selector, changeSet.Selector())
 
 }
 
-func TestChangeSetBuilder_ImplicitXferChanges(t *testing.T) {
+// After receiving an intent, the SDK may receive 1 or more objects before receiving a payload-transferred.
+// At that point, LaunchDarkly may send more objects followed by another payload-transferred. These objects
+// should be regarded as part of an implicit "xfer-changes" intent, even though the server doesn't actually send one.
+// If the server intends to use an xfer-full instead (for efficiency or other reasons), it will need to explicitly
+// send one.
+func TestChangeSetBuilder_ImplicitIntentXferChanges(t *testing.T) {
 
 }
 
@@ -66,11 +59,10 @@ func TestChangeSetBuilder_NoChanges(t *testing.T) {
 	changeSet := builder.NoChanges()
 	assert.NotNil(t, changeSet)
 
-	intent := changeSet.Intent()
+	intent := changeSet.IntentCode()
 	assert.NotNil(t, intent)
 
-	assert.NotEmpty(t, intent.Payloads)
-	assert.Equal(t, IntentNone, intent.Payloads[0].Code)
+	assert.Equal(t, IntentNone, intent.Payload.Code)
 
 	assert.False(t, changeSet.Selector().IsDefined())
 	assert.Equal(t, NoSelector(), changeSet.Selector())