forked from absolute8511/ZanRedisDB
/
message_queue.go
151 lines (138 loc) · 3.36 KB
/
message_queue.go
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// Copyright 2017-2019 Lei Ni (nilei81@gmail.com)
//
// 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 (
"sync"
"github.com/youzan/ZanRedisDB/raft/raftpb"
)
// MessageQueue is the queue used to hold Raft messages.
type MessageQueue struct {
size uint64
ch chan struct{}
left []raftpb.Message
right []raftpb.Message
snapshot []raftpb.Message
leftInWrite bool
stopped bool
idx uint64
oldIdx uint64
cycle uint64
lazyFreeCycle uint64
mu sync.Mutex
}
// NewMessageQueue creates a new MessageQueue instance.
func NewMessageQueue(size uint64, ch bool, lazyFreeCycle uint64) *MessageQueue {
q := &MessageQueue{
size: size,
lazyFreeCycle: lazyFreeCycle,
left: make([]raftpb.Message, size),
right: make([]raftpb.Message, size),
snapshot: make([]raftpb.Message, 0),
}
if ch {
q.ch = make(chan struct{}, 1)
}
return q
}
// Close closes the queue so no further messages can be added.
func (q *MessageQueue) Close() {
q.mu.Lock()
defer q.mu.Unlock()
q.stopped = true
}
// Notify notifies the notification channel listener that a new message is now
// available in the queue.
func (q *MessageQueue) Notify() {
if q.ch != nil {
select {
case q.ch <- struct{}{}:
default:
}
}
}
// Ch returns the notification channel.
func (q *MessageQueue) Ch() <-chan struct{} {
return q.ch
}
func (q *MessageQueue) targetQueue() []raftpb.Message {
var t []raftpb.Message
if q.leftInWrite {
t = q.left
} else {
t = q.right
}
return t
}
// Add adds the specified message to the queue.
func (q *MessageQueue) Add(msg raftpb.Message) (bool, bool) {
q.mu.Lock()
if q.idx >= q.size {
q.mu.Unlock()
return false, q.stopped
}
if q.stopped {
q.mu.Unlock()
return false, true
}
w := q.targetQueue()
w[q.idx] = msg
q.idx++
q.mu.Unlock()
return true, false
}
// AddSnapshot adds the specified snapshot to the queue.
func (q *MessageQueue) AddSnapshot(msg raftpb.Message) bool {
if msg.Type != raftpb.MsgSnap {
panic("not a snapshot message")
}
q.mu.Lock()
defer q.mu.Unlock()
if q.stopped {
return false
}
q.snapshot = append(q.snapshot, msg)
return true
}
func (q *MessageQueue) gc() {
if q.lazyFreeCycle > 0 {
oldq := q.targetQueue()
if q.lazyFreeCycle == 1 {
for i := uint64(0); i < q.oldIdx; i++ {
oldq[i].Entries = nil
}
} else if q.cycle%q.lazyFreeCycle == 0 {
for i := uint64(0); i < q.size; i++ {
oldq[i].Entries = nil
}
}
}
}
// Get returns everything current in the queue.
func (q *MessageQueue) Get() []raftpb.Message {
q.mu.Lock()
defer q.mu.Unlock()
q.cycle++
sz := q.idx
q.idx = 0
t := q.targetQueue()
q.leftInWrite = !q.leftInWrite
q.gc()
q.oldIdx = sz
if len(q.snapshot) == 0 {
return t[:sz]
}
ssm := q.snapshot
q.snapshot = make([]raftpb.Message, 0)
return append(ssm, t[:sz]...)
}