265 lines
6.8 KiB
Go
265 lines
6.8 KiB
Go
/*
|
|
Copyright 2014 CoreOS, Inc.
|
|
|
|
Licensed under the Apache License, Version 2.0 (the "License");
|
|
you may not use this file except in compliance with the License.
|
|
You may obtain a copy of the License at
|
|
|
|
http://www.apache.org/licenses/LICENSE-2.0
|
|
|
|
Unless required by applicable law or agreed to in writing, software
|
|
distributed under the License is distributed on an "AS IS" BASIS,
|
|
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
See the License for the specific language governing permissions and
|
|
limitations under the License.
|
|
*/
|
|
|
|
package raft
|
|
|
|
import (
|
|
"fmt"
|
|
"log"
|
|
|
|
pb "github.com/coreos/etcd/raft/raftpb"
|
|
)
|
|
|
|
type raftLog struct {
|
|
ents []pb.Entry
|
|
unstable uint64
|
|
committed uint64
|
|
applied uint64
|
|
offset uint64
|
|
snapshot pb.Snapshot
|
|
}
|
|
|
|
func newLog() *raftLog {
|
|
return &raftLog{
|
|
ents: make([]pb.Entry, 1),
|
|
unstable: 0,
|
|
committed: 0,
|
|
applied: 0,
|
|
}
|
|
}
|
|
|
|
func (l *raftLog) load(ents []pb.Entry) {
|
|
if l.offset != ents[0].Index {
|
|
panic("entries loaded don't match offset index")
|
|
}
|
|
l.ents = ents
|
|
l.unstable = l.offset + uint64(len(ents))
|
|
}
|
|
|
|
func (l *raftLog) String() string {
|
|
return fmt.Sprintf("offset=%d committed=%d applied=%d len(ents)=%d", l.offset, l.committed, l.applied, len(l.ents))
|
|
}
|
|
|
|
// maybeAppend returns (0, false) if the entries cannot be appended. Otherwise,
|
|
// it returns (last index of new entries, true).
|
|
func (l *raftLog) maybeAppend(index, logTerm, committed uint64, ents ...pb.Entry) (lastnewi uint64, ok bool) {
|
|
lastnewi = index + uint64(len(ents))
|
|
if l.matchTerm(index, logTerm) {
|
|
from := index + 1
|
|
ci := l.findConflict(from, ents)
|
|
switch {
|
|
case ci == 0:
|
|
case ci <= l.committed:
|
|
panic("conflict with committed entry")
|
|
default:
|
|
l.append(ci-1, ents[ci-from:]...)
|
|
}
|
|
tocommit := min(committed, lastnewi)
|
|
// if toCommit > commitIndex, set commitIndex = toCommit
|
|
if l.committed < tocommit {
|
|
l.committed = tocommit
|
|
}
|
|
return lastnewi, true
|
|
}
|
|
return 0, false
|
|
}
|
|
|
|
func (l *raftLog) append(after uint64, ents ...pb.Entry) uint64 {
|
|
l.ents = append(l.slice(l.offset, after+1), ents...)
|
|
l.unstable = min(l.unstable, after+1)
|
|
return l.lastIndex()
|
|
}
|
|
|
|
// findConflict finds the index of the conflict.
|
|
// It returns the first pair of conflicting entries between the existing
|
|
// entries and the given entries, if there are any.
|
|
// If there is no conflicting entries, and the existing entries contains
|
|
// all the given entries, zero will be returned.
|
|
// If there is no conflicting entries, but the given entries contains new
|
|
// entries, the index of the first new entry will be returned.
|
|
// An entry is considered to be conflicting if it has the same index but
|
|
// a different term.
|
|
// The first entry MUST have an index equal to the argument 'from'.
|
|
// The index of the given entries MUST be continuously increasing.
|
|
func (l *raftLog) findConflict(from uint64, ents []pb.Entry) uint64 {
|
|
// TODO(xiangli): validate the index of ents
|
|
for i, ne := range ents {
|
|
if oe := l.at(from + uint64(i)); oe == nil || oe.Term != ne.Term {
|
|
return from + uint64(i)
|
|
}
|
|
}
|
|
return 0
|
|
}
|
|
|
|
func (l *raftLog) unstableEnts() []pb.Entry {
|
|
ents := l.slice(l.unstable, l.lastIndex()+1)
|
|
if ents == nil {
|
|
return nil
|
|
}
|
|
cpy := make([]pb.Entry, len(ents))
|
|
copy(cpy, ents)
|
|
return cpy
|
|
}
|
|
|
|
// nextEnts returns all the available entries for execution.
|
|
// If applied is smaller than the index of snapshot, it returns all committed
|
|
// entries after the index of snapshot.
|
|
func (l *raftLog) nextEnts() (ents []pb.Entry) {
|
|
off := max(l.applied, l.snapshot.Index)
|
|
if l.committed > off {
|
|
return l.slice(off+1, l.committed+1)
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func (l *raftLog) appliedTo(i uint64) {
|
|
if i == 0 {
|
|
return
|
|
}
|
|
if l.committed < i || i < l.applied {
|
|
log.Panicf("applied[%d] is out of range [prevApplied(%d), committed(%d)]", i, l.applied, l.committed)
|
|
}
|
|
l.applied = i
|
|
}
|
|
|
|
func (l *raftLog) stableTo(i uint64) {
|
|
l.unstable = i + 1
|
|
}
|
|
|
|
func (l *raftLog) lastIndex() uint64 { return uint64(len(l.ents)) - 1 + l.offset }
|
|
|
|
func (l *raftLog) lastTerm() uint64 { return l.term(l.lastIndex()) }
|
|
|
|
func (l *raftLog) term(i uint64) uint64 {
|
|
if e := l.at(i); e != nil {
|
|
return e.Term
|
|
}
|
|
return 0
|
|
}
|
|
|
|
func (l *raftLog) entries(i uint64) []pb.Entry {
|
|
// never send out the first entry
|
|
// first entry is only used for matching
|
|
// prevLogTerm
|
|
if i == l.offset {
|
|
panic("cannot return the first entry in log")
|
|
}
|
|
return l.slice(i, l.lastIndex()+1)
|
|
}
|
|
|
|
// isUpToDate determines if the given (lastIndex,term) log is more up-to-date
|
|
// by comparing the index and term of the last entries in the existing logs.
|
|
// If the logs have last entries with different terms, then the log with the
|
|
// later term is more up-to-date. If the logs end with the same term, then
|
|
// whichever log has the larger lastIndex is more up-to-date. If the logs are
|
|
// the same, the given log is up-to-date.
|
|
func (l *raftLog) isUpToDate(lasti, term uint64) bool {
|
|
return term > l.lastTerm() || (term == l.lastTerm() && lasti >= l.lastIndex())
|
|
}
|
|
|
|
func (l *raftLog) matchTerm(i, term uint64) bool {
|
|
if e := l.at(i); e != nil {
|
|
return e.Term == term
|
|
}
|
|
return false
|
|
}
|
|
|
|
func (l *raftLog) maybeCommit(maxIndex, term uint64) bool {
|
|
if maxIndex > l.committed && l.term(maxIndex) == term {
|
|
l.committed = maxIndex
|
|
return true
|
|
}
|
|
return false
|
|
}
|
|
|
|
// compact compacts all log entries until i.
|
|
// It removes the log entries before i, exclusive.
|
|
// i must be not smaller than the index of the first entry
|
|
// and not greater than the index of the last entry.
|
|
// the number of entries after compaction will be returned.
|
|
func (l *raftLog) compact(i uint64) uint64 {
|
|
if l.isOutOfAppliedBounds(i) {
|
|
panic(fmt.Sprintf("compact %d out of bounds [%d:%d]", i, l.offset, l.applied))
|
|
}
|
|
l.ents = l.slice(i, l.lastIndex()+1)
|
|
l.unstable = max(i+1, l.unstable)
|
|
l.offset = i
|
|
return uint64(len(l.ents))
|
|
}
|
|
|
|
func (l *raftLog) snap(d []byte, index, term uint64, nodes []uint64) {
|
|
l.snapshot = pb.Snapshot{
|
|
Data: d,
|
|
Nodes: nodes,
|
|
Index: index,
|
|
Term: term,
|
|
}
|
|
}
|
|
|
|
func (l *raftLog) restore(s pb.Snapshot) {
|
|
l.ents = []pb.Entry{{Term: s.Term}}
|
|
l.unstable = s.Index + 1
|
|
l.committed = s.Index
|
|
l.offset = s.Index
|
|
l.snapshot = s
|
|
}
|
|
|
|
func (l *raftLog) at(i uint64) *pb.Entry {
|
|
if l.isOutOfBounds(i) {
|
|
return nil
|
|
}
|
|
return &l.ents[i-l.offset]
|
|
}
|
|
|
|
// slice returns a slice of log entries from lo through hi-1, inclusive.
|
|
func (l *raftLog) slice(lo uint64, hi uint64) []pb.Entry {
|
|
if lo >= hi {
|
|
return nil
|
|
}
|
|
if l.isOutOfBounds(lo) || l.isOutOfBounds(hi-1) {
|
|
return nil
|
|
}
|
|
return l.ents[lo-l.offset : hi-l.offset]
|
|
}
|
|
|
|
func (l *raftLog) isOutOfBounds(i uint64) bool {
|
|
if i < l.offset || i > l.lastIndex() {
|
|
return true
|
|
}
|
|
return false
|
|
}
|
|
|
|
func (l *raftLog) isOutOfAppliedBounds(i uint64) bool {
|
|
if i < l.offset || i > l.applied {
|
|
return true
|
|
}
|
|
return false
|
|
}
|
|
|
|
func min(a, b uint64) uint64 {
|
|
if a > b {
|
|
return b
|
|
}
|
|
return a
|
|
}
|
|
|
|
func max(a, b uint64) uint64 {
|
|
if a > b {
|
|
return a
|
|
}
|
|
return b
|
|
}
|