append_entries.go

package raft

import (
	"io"
	"io/ioutil"

	"github.com/gogo/protobuf/proto"
	"github.com/goraft/raft/protobuf"
)

// The request sent to a server to append entries to the log.
type AppendEntriesRequest struct {
	Term         uint64 // Leader Server 当前 term
	PrevLogIndex uint64 // 根据 preLogIndex 在 server log entries 中获得 log entry 的 index & term
	PrevLogTerm  uint64
	CommitIndex  uint64 // Leader Server 的 commited Index
	LeaderName   string
	Entries      []*protobuf.LogEntry // 需要应用 log entries 列表,不超过阈值 maxLogEntriesPerRequest
}

// The response returned from a server appending entries to the log.
type AppendEntriesResponse struct {
	pb     *protobuf.AppendEntriesResponse
	peer   string
	append bool
}

// Creates a new AppendEntries request.
func newAppendEntriesRequest(term uint64, prevLogIndex uint64, prevLogTerm uint64,
	commitIndex uint64, leaderName string, entries []*LogEntry) *AppendEntriesRequest {
	pbEntries := make([]*protobuf.LogEntry, len(entries))

	for i := range entries {
		pbEntries[i] = entries[i].pb
	}

	return &AppendEntriesRequest{
		Term:         term,
		PrevLogIndex: prevLogIndex,
		PrevLogTerm:  prevLogTerm,
		CommitIndex:  commitIndex,
		LeaderName:   leaderName,
		Entries:      pbEntries,
	}
}

// Encodes the AppendEntriesRequest to a buffer. Returns the number of bytes
// written and any error that may have occurred.
func (req *AppendEntriesRequest) Encode(w io.Writer) (int, error) {
	pb := &protobuf.AppendEntriesRequest{
		Term:         proto.Uint64(req.Term),
		PrevLogIndex: proto.Uint64(req.PrevLogIndex),
		PrevLogTerm:  proto.Uint64(req.PrevLogTerm),
		CommitIndex:  proto.Uint64(req.CommitIndex),
		LeaderName:   proto.String(req.LeaderName),
		Entries:      req.Entries,
	}

	p, err := proto.Marshal(pb)
	if err != nil {
		return -1, err
	}

	return w.Write(p)
}

// Decodes the AppendEntriesRequest from a buffer. Returns the number of bytes read and
// any error that occurs.
func (req *AppendEntriesRequest) Decode(r io.Reader) (int, error) {
	data, err := ioutil.ReadAll(r)

	if err != nil {
		return -1, err
	}

	pb := new(protobuf.AppendEntriesRequest)
	if err := proto.Unmarshal(data, pb); err != nil {
		return -1, err
	}

	req.Term = pb.GetTerm()
	req.PrevLogIndex = pb.GetPrevLogIndex()
	req.PrevLogTerm = pb.GetPrevLogTerm()
	req.CommitIndex = pb.GetCommitIndex()
	req.LeaderName = pb.GetLeaderName()
	req.Entries = pb.GetEntries()

	return len(data), nil
}

// Creates a new AppendEntries response.
func newAppendEntriesResponse(term uint64, success bool, index uint64, commitIndex uint64) *AppendEntriesResponse {
	pb := &protobuf.AppendEntriesResponse{
		Term:        proto.Uint64(term),
		Index:       proto.Uint64(index),
		Success:     proto.Bool(success),
		CommitIndex: proto.Uint64(commitIndex),
	}

	return &AppendEntriesResponse{
		pb: pb,
	}
}

func (aer *AppendEntriesResponse) Index() uint64 {
	return aer.pb.GetIndex()
}

func (aer *AppendEntriesResponse) CommitIndex() uint64 {
	return aer.pb.GetCommitIndex()
}

func (aer *AppendEntriesResponse) Term() uint64 {
	return aer.pb.GetTerm()
}

func (aer *AppendEntriesResponse) Success() bool {
	return aer.pb.GetSuccess()
}

// Encodes the AppendEntriesResponse to a buffer. Returns the number of bytes
// written and any error that may have occurred.
func (resp *AppendEntriesResponse) Encode(w io.Writer) (int, error) {
	b, err := proto.Marshal(resp.pb)
	if err != nil {
		return -1, err
	}

	return w.Write(b)
}

// Decodes the AppendEntriesResponse from a buffer. Returns the number of bytes read and
// any error that occurs.
func (resp *AppendEntriesResponse) Decode(r io.Reader) (int, error) {
	data, err := ioutil.ReadAll(r)
	if err != nil {
		return -1, err
	}

	resp.pb = new(protobuf.AppendEntriesResponse)
	if err := proto.Unmarshal(data, resp.pb); err != nil {
		return -1, err
	}

	return len(data), nil
}