stream_sum

Documentation

Index

• Constants
• Variables
• func ChunkMappingKey(m message.Message, b []byte) []byte
• func FillPRNG(b []byte) []byte
• func NewChunkMapping(ctx context.Context, jc pb.JournalClient) (message.MappingFunc, error)
• type Chunk
• type StreamID
  • func NewStreamID() StreamID
• type Sum
  • func (s *Sum) Update(chunk Chunk) (done bool, err error)

Constants

const SumsJournal pb.Journal = "examples/stream-sum/sums"

Variables

var SumsMapping message.MappingFunc = func(msg message.Message) (pb.Journal, message.Framing, error) {
	return SumsJournal, message.JSONFraming, nil
}

Functions

func ChunkMappingKey

func ChunkMappingKey(m message.Message, b []byte) []byte

func FillPRNG

func FillPRNG(b []byte) []byte

FillPRNG generates fast but high-quality random entropy into the provided byte slice.

func NewChunkMapping

func NewChunkMapping(ctx context.Context, jc pb.JournalClient) (message.MappingFunc, error)

Types

type Chunk

type Chunk struct {
	ID    StreamID // Unique ID of the stream.
	SeqNo int      // Monotonic sequence number. One begins a new stream under this unique StreamID.
	Data  []byte   // Raw data included in the Value. If empty, this is the stream's final chunk.
}

Chunk is an ordered slice of stream content.

type StreamID

type StreamID [16]byte

StreamID uniquely identifies a stream.

func NewStreamID

func NewStreamID() StreamID

NewStreamID returns a new, globally unique StreamID.

type Sum

type Sum struct {
	ID    StreamID // Unique ID of the stream.
	SeqNo int      // SeqNo of last Chunk summed.
	Value uint64   // Computed sum through SeqNo.
}

Sum represents a partial or final CRC64 sum of a stream.

func (*Sum) Update

func (s *Sum) Update(chunk Chunk) (done bool, err error)

Update folds a Chunk into this Sum, returning whether this is the last Chunk of the Stream. Update requires that SeqNo be totally ordered, however replays of previous SeqNo are ignored.