100 lines
2.2 KiB
Go
100 lines
2.2 KiB
Go
package raft
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import (
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"bytes"
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"code.google.com/p/goprotobuf/proto"
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"encoding/json"
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"fmt"
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"github.com/benbjohnson/go-raft/protobuf"
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"io"
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)
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// A log entry stores a single item in the log.
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type LogEntry struct {
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log *Log
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Index uint64
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Term uint64
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CommandName string
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Command []byte
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Position int64 // position in the log file
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commit chan bool
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}
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// Creates a new log entry associated with a log.
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func newLogEntry(log *Log, index uint64, term uint64, command Command) (*LogEntry, error) {
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var buf bytes.Buffer
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var commandName string
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if command != nil {
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commandName = command.CommandName()
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if encoder, ok := command.(CommandEncoder); ok {
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if err := encoder.Encode(&buf); err != nil {
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return nil, err
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}
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} else {
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json.NewEncoder(&buf).Encode(command)
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}
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}
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e := &LogEntry{
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log: log,
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Index: index,
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Term: term,
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CommandName: commandName,
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Command: buf.Bytes(),
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commit: make(chan bool, 5),
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}
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return e, nil
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}
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// Encodes the log entry to a buffer. Returns the number of bytes
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// written and any error that may have occurred.
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func (e *LogEntry) encode(w io.Writer) (int, error) {
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defer e.log.pBuffer.Reset()
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e.log.pLogEntry.Index = proto.Uint64(e.Index)
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e.log.pLogEntry.Term = proto.Uint64(e.Term)
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e.log.pLogEntry.CommandName = proto.String(e.CommandName)
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e.log.pLogEntry.Command = e.Command
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err := e.log.pBuffer.Marshal(e.log.pLogEntry)
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if err != nil {
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return -1, err
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}
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if _, err = fmt.Fprintf(w, "%8x\n", len(e.log.pBuffer.Bytes())); err != nil {
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return -1, err
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}
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return w.Write(e.log.pBuffer.Bytes())
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}
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// Decodes the log entry from a buffer. Returns the number of bytes read and
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// any error that occurs.
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func (e *LogEntry) decode(r io.Reader) (int, error) {
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var length int
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_, err := fmt.Fscanf(r, "%8x\n", &length)
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if err != nil {
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return -1, err
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}
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data := make([]byte, length)
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_, err = r.Read(data)
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if err != nil {
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return -1, err
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}
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pb := &protobuf.ProtoLogEntry{}
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if err = proto.Unmarshal(data, pb); err != nil {
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return -1, err
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}
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e.Term = pb.GetTerm()
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e.Index = pb.GetIndex()
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e.CommandName = pb.GetCommandName()
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e.Command = pb.Command
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return length, nil
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}
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