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router.go
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router.go
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// Copyright 2016 CodisLabs. All Rights Reserved.
// Licensed under the MIT (MIT-LICENSE.txt) license.
package proxy
import (
"sync"
"time"
"github.com/CodisLabs/codis/pkg/models"
"github.com/CodisLabs/codis/pkg/utils/errors"
"github.com/CodisLabs/codis/pkg/utils/log"
"github.com/CodisLabs/codis/pkg/utils/redis"
)
const MaxSlotNum = models.MaxSlotNum
//存储了集群中所有的sharedBackendConnPool和slot
//用于将redis请求转发给相应的slot进行处理
type Router struct {
mu sync.RWMutex
pool struct {
// 后端与redis通信的链接池 主从
primary *sharedBackendConnPool
replica *sharedBackendConnPool
}
// key对应的槽
slots [MaxSlotNum]Slot
config *Config
online bool
closed bool
}
func NewRouter(config *Config) *Router {
s := &Router{config: config}
s.pool.primary = newSharedBackendConnPool(config, config.BackendPrimaryParallel)
s.pool.replica = newSharedBackendConnPool(config, config.BackendReplicaParallel)
for i := range s.slots {
s.slots[i].id = i
s.slots[i].method = &forwardSync{}
}
return s
}
func (s *Router) Start() {
s.mu.Lock()
defer s.mu.Unlock()
if s.closed {
return
}
s.online = true
}
func (s *Router) Close() {
s.mu.Lock()
defer s.mu.Unlock()
if s.closed {
return
}
s.closed = true
for i := range s.slots {
s.fillSlot(&models.Slot{Id: i}, false, nil)
}
}
func (s *Router) GetSlots() []*models.Slot {
s.mu.RLock()
defer s.mu.RUnlock()
slots := make([]*models.Slot, MaxSlotNum)
for i := range s.slots {
slots[i] = s.slots[i].snapshot()
}
return slots
}
func (s *Router) GetSlot(id int) *models.Slot {
s.mu.RLock()
defer s.mu.RUnlock()
if id < 0 || id >= MaxSlotNum {
return nil
}
slot := &s.slots[id]
return slot.snapshot()
}
func (s *Router) HasSwitched() bool {
s.mu.RLock()
defer s.mu.RUnlock()
for i := range s.slots {
if s.slots[i].switched {
return true
}
}
return false
}
var (
ErrClosedRouter = errors.New("use of closed router")
ErrInvalidSlotId = errors.New("use of invalid slot id")
ErrInvalidMethod = errors.New("use of invalid forwarder method")
)
func (s *Router) FillSlot(m *models.Slot) error {
s.mu.Lock()
defer s.mu.Unlock()
// 参数校验
// 准备根据之前的1024个models.Slot,创建1024个/pkg/proxy/slots.go中的Slot
if s.closed {
return ErrClosedRouter
}
if m.Id < 0 || m.Id >= MaxSlotNum {
return ErrInvalidSlotId
}
var method forwardMethod
switch m.ForwardMethod {
default:
return ErrInvalidMethod
case models.ForwardSync:
method = &forwardSync{}
case models.ForwardSemiAsync:
method = &forwardSemiAsync{}
}
s.fillSlot(m, false, method)
return nil
}
func (s *Router) KeepAlive() error {
s.mu.RLock()
defer s.mu.RUnlock()
if s.closed {
return ErrClosedRouter
}
s.pool.primary.KeepAlive()
s.pool.replica.KeepAlive()
return nil
}
func (s *Router) isOnline() bool {
return s.online && !s.closed
}
//将某个request分发给各个具体的slot进行处理的方法主要有三个,都是由Router来完成:
//根据key进行转发
func (s *Router) dispatch(r *Request) error {
hkey := getHashKey(r.Multi, r.OpStr)
var id = Hash(hkey) % MaxSlotNum
slot := &s.slots[id]
//将请求分发到相应的slot
return slot.forward(r, hkey)
}
//将request发到指定slot
func (s *Router) dispatchSlot(r *Request, id int) error {
if id < 0 || id >= MaxSlotNum {
return ErrInvalidSlotId
}
slot := &s.slots[id]
return slot.forward(r, nil)
}
//这个直接指明了redis服务器地址的请求,如果找不到就返回false
func (s *Router) dispatchAddr(r *Request, addr string) bool {
s.mu.RLock()
defer s.mu.RUnlock()
if bc := s.pool.primary.Get(addr).BackendConn(r.Database, r.Seed16(), false); bc != nil {
bc.PushBack(r)
return true
}
if bc := s.pool.replica.Get(addr).BackendConn(r.Database, r.Seed16(), false); bc != nil {
bc.PushBack(r)
return true
}
return false
}
//这个阶段主要是初始化槽/ 或者dashboard重新迁移了槽 刷新映射关系
//初始化之后 每个slot都被分配了相应的backendConn,只不过此时每个backendConn都为空
func (s *Router) fillSlot(m *models.Slot, switched bool, method forwardMethod) {
slot := &s.slots[m.Id]
// 将slot的lock.hold属性设为true,并加锁
// 等后端命令执行完之后这里的线程会被唤醒 继续进行更新映射关系
slot.blockAndWait()
// reset
// 清空models.Slot里面的backendConn
// 这里的bc就是我们之前提到过的处理redis请求的sharedBackendConn 第一次进来的时候,backend为空,这里直接返回
slot.backend.bc.Release()
slot.backend.bc = nil
slot.backend.id = 0
slot.migrate.bc.Release()
slot.migrate.bc = nil
slot.migrate.id = 0
for i := range slot.replicaGroups {
for _, bc := range slot.replicaGroups[i] {
bc.Release()
}
}
slot.replicaGroups = nil
//false
slot.switched = switched
//初始阶段addr和from都是空字符串
//这里的addr就是迁移出的后端redis地址
if addr := m.BackendAddr; len(addr) != 0 {
// 创建后端的链接 通过codis-server地址获取SharedBackendConn
// 从Router的primary sharedBackendConnPool中取出addr对应的sharedBackendConn,如果没有就新建并放入,也相当于初始化了
slot.backend.bc = s.pool.primary.Retain(addr)
slot.backend.id = m.BackendAddrGroupId
}
if from := m.MigrateFrom; len(from) != 0 {
slot.migrate.bc = s.pool.primary.Retain(from)
slot.migrate.id = m.MigrateFromGroupId
}
if !s.config.BackendPrimaryOnly {
for i := range m.ReplicaGroups {
var group []*sharedBackendConn
for _, addr := range m.ReplicaGroups[i] {
group = append(group, s.pool.replica.Retain(addr))
}
if len(group) == 0 {
continue
}
slot.replicaGroups = append(slot.replicaGroups, group)
}
}
if method != nil {
slot.method = method
}
if !m.Locked {
slot.unblock()
}
if !s.closed {
if slot.migrate.bc != nil {
if switched {
log.Warnf("fill slot %04d, backend.addr = %s, migrate.from = %s, locked = %t, +switched",
slot.id, slot.backend.bc.Addr(), slot.migrate.bc.Addr(), slot.lock.hold)
} else {
log.Warnf("fill slot %04d, backend.addr = %s, migrate.from = %s, locked = %t",
slot.id, slot.backend.bc.Addr(), slot.migrate.bc.Addr(), slot.lock.hold)
}
} else {
if switched {
log.Warnf("fill slot %04d, backend.addr = %s, locked = %t, +switched",
slot.id, slot.backend.bc.Addr(), slot.lock.hold)
} else {
log.Warnf("fill slot %04d, backend.addr = %s, locked = %t",
slot.id, slot.backend.bc.Addr(), slot.lock.hold)
}
}
}
}
func (s *Router) SwitchMasters(masters map[int]string) error {
s.mu.Lock()
defer s.mu.Unlock()
if s.closed {
return ErrClosedRouter
}
cache := &redis.InfoCache{
Auth: s.config.ProductAuth, Timeout: time.Millisecond * 100,
}
for i := range s.slots {
s.trySwitchMaster(i, masters, cache)
}
return nil
}
func (s *Router) trySwitchMaster(id int, masters map[int]string, cache *redis.InfoCache) {
var switched bool
var m = s.slots[id].snapshot()
hasSameRunId := func(addr1, addr2 string) bool {
if addr1 != addr2 {
rid1 := cache.GetRunId(addr1)
rid2 := cache.GetRunId(addr2)
return rid1 != "" && rid1 == rid2
}
return true
}
if addr := masters[m.BackendAddrGroupId]; addr != "" {
if !hasSameRunId(addr, m.BackendAddr) {
m.BackendAddr, switched = addr, true
}
}
if addr := masters[m.MigrateFromGroupId]; addr != "" {
if !hasSameRunId(addr, m.MigrateFrom) {
m.MigrateFrom, switched = addr, true
}
}
if switched {
s.fillSlot(m, true, nil)
}
}