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|
package sarama
import "fmt"
const (
unknownRecords = iota
legacyRecords
defaultRecords
magicOffset = 16
magicLength = 1
)
// Records implements a union type containing either a RecordBatch or a legacy MessageSet.
type Records struct {
recordsType int
MsgSet *MessageSet
RecordBatch *RecordBatch
}
func newLegacyRecords(msgSet *MessageSet) Records {
return Records{recordsType: legacyRecords, MsgSet: msgSet}
}
func newDefaultRecords(batch *RecordBatch) Records {
return Records{recordsType: defaultRecords, RecordBatch: batch}
}
// setTypeFromFields sets type of Records depending on which of MsgSet or RecordBatch is not nil.
// The first return value indicates whether both fields are nil (and the type is not set).
// If both fields are not nil, it returns an error.
func (r *Records) setTypeFromFields() (bool, error) {
if r.MsgSet == nil && r.RecordBatch == nil {
return true, nil
}
if r.MsgSet != nil && r.RecordBatch != nil {
return false, fmt.Errorf("both MsgSet and RecordBatch are set, but record type is unknown")
}
r.recordsType = defaultRecords
if r.MsgSet != nil {
r.recordsType = legacyRecords
}
return false, nil
}
func (r *Records) encode(pe packetEncoder) error {
if r.recordsType == unknownRecords {
if empty, err := r.setTypeFromFields(); err != nil || empty {
return err
}
}
switch r.recordsType {
case legacyRecords:
if r.MsgSet == nil {
return nil
}
return r.MsgSet.encode(pe)
case defaultRecords:
if r.RecordBatch == nil {
return nil
}
return r.RecordBatch.encode(pe)
}
return fmt.Errorf("unknown records type: %v", r.recordsType)
}
func (r *Records) setTypeFromMagic(pd packetDecoder) error {
magic, err := magicValue(pd)
if err != nil {
return err
}
r.recordsType = defaultRecords
if magic < 2 {
r.recordsType = legacyRecords
}
return nil
}
func (r *Records) decode(pd packetDecoder) error {
if r.recordsType == unknownRecords {
if err := r.setTypeFromMagic(pd); err != nil {
return err
}
}
switch r.recordsType {
case legacyRecords:
r.MsgSet = &MessageSet{}
return r.MsgSet.decode(pd)
case defaultRecords:
r.RecordBatch = &RecordBatch{}
return r.RecordBatch.decode(pd)
}
return fmt.Errorf("unknown records type: %v", r.recordsType)
}
func (r *Records) numRecords() (int, error) {
if r.recordsType == unknownRecords {
if empty, err := r.setTypeFromFields(); err != nil || empty {
return 0, err
}
}
switch r.recordsType {
case legacyRecords:
if r.MsgSet == nil {
return 0, nil
}
return len(r.MsgSet.Messages), nil
case defaultRecords:
if r.RecordBatch == nil {
return 0, nil
}
return len(r.RecordBatch.Records), nil
}
return 0, fmt.Errorf("unknown records type: %v", r.recordsType)
}
func (r *Records) isPartial() (bool, error) {
if r.recordsType == unknownRecords {
if empty, err := r.setTypeFromFields(); err != nil || empty {
return false, err
}
}
switch r.recordsType {
case unknownRecords:
return false, nil
case legacyRecords:
if r.MsgSet == nil {
return false, nil
}
return r.MsgSet.PartialTrailingMessage, nil
case defaultRecords:
if r.RecordBatch == nil {
return false, nil
}
return r.RecordBatch.PartialTrailingRecord, nil
}
return false, fmt.Errorf("unknown records type: %v", r.recordsType)
}
func (r *Records) isControl() (bool, error) {
if r.recordsType == unknownRecords {
if empty, err := r.setTypeFromFields(); err != nil || empty {
return false, err
}
}
switch r.recordsType {
case legacyRecords:
return false, nil
case defaultRecords:
if r.RecordBatch == nil {
return false, nil
}
return r.RecordBatch.Control, nil
}
return false, fmt.Errorf("unknown records type: %v", r.recordsType)
}
func (r *Records) isOverflow() (bool, error) {
if r.recordsType == unknownRecords {
if empty, err := r.setTypeFromFields(); err != nil || empty {
return false, err
}
}
switch r.recordsType {
case unknownRecords:
return false, nil
case legacyRecords:
if r.MsgSet == nil {
return false, nil
}
return r.MsgSet.OverflowMessage, nil
case defaultRecords:
return false, nil
}
return false, fmt.Errorf("unknown records type: %v", r.recordsType)
}
func magicValue(pd packetDecoder) (int8, error) {
dec, err := pd.peek(magicOffset, magicLength)
if err != nil {
return 0, err
}
return dec.getInt8()
}
func (r *Records) getControlRecord() (ControlRecord, error) {
if r.RecordBatch == nil || len(r.RecordBatch.Records) <= 0 {
return ControlRecord{}, fmt.Errorf("cannot get control record, record batch is empty")
}
firstRecord := r.RecordBatch.Records[0]
controlRecord := ControlRecord{}
err := controlRecord.decode(&realDecoder{raw: firstRecord.Key}, &realDecoder{raw: firstRecord.Value})
if err != nil {
return ControlRecord{}, err
}
return controlRecord, nil
}
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