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tso: introduce the AllocatorManager (#2859)
Signed-off-by: JmPotato <[email protected]>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,199 @@ | ||
| // Copyright 2020 TiKV Project Authors. | ||
| // | ||
| // 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, | ||
| // See the License for the specific language governing permissions and | ||
| // limitations under the License. | ||
|
|
||
| package tso | ||
|
|
||
| import ( | ||
| "context" | ||
| "fmt" | ||
| "path" | ||
| "sync" | ||
| "time" | ||
|
|
||
| "github.com/pingcap/kvproto/pkg/pdpb" | ||
| "github.com/pingcap/log" | ||
| "github.com/tikv/pd/pkg/errs" | ||
| "github.com/tikv/pd/server/election" | ||
| "go.etcd.io/etcd/clientv3" | ||
| "go.etcd.io/etcd/embed" | ||
| "go.uber.org/zap" | ||
| ) | ||
|
|
||
| // GlobalDCLocation is the Global TSO Allocator's dc-location label. | ||
| const GlobalDCLocation = "global" | ||
|
|
||
| type allocatorGroup struct { | ||
| dcLocation string | ||
| // allocator's parent ctx and cancel function, which is to | ||
| // control the allocator's behavior in AllocatorDaemon and | ||
| // pass the cancel signal to its parent as soon as possible | ||
| // since it is critical to let parent goroutine know whether | ||
| // the allocator is still able to work well. | ||
| parentCtx context.Context | ||
| parentCancel context.CancelFunc | ||
| // For the Global TSO Allocator, leadership is a PD leader's | ||
| // leadership, and for the Local TSO Allocator, leadership | ||
| // is a DC-level certificate to allow an allocator to generate | ||
| // TSO for local transactions in its DC. | ||
| leadership *election.Leadership | ||
| allocator Allocator | ||
| // the flag indicates whether this allocator is initialized | ||
| isInitialized bool | ||
| } | ||
|
|
||
| // AllocatorManager is used to manage the TSO Allocators a PD server holds. | ||
| // It is in charge of maintaining TSO allocators' leadership, checking election | ||
| // priority, and forwarding TSO allocation requests to correct TSO Allocators. | ||
| type AllocatorManager struct { | ||
| sync.RWMutex | ||
| wg sync.WaitGroup | ||
| // There are two kinds of TSO Allocators: | ||
| // 1. Global TSO Allocator, as a global single point to allocate | ||
| // TSO for global transactions, such as cross-region cases. | ||
| // 2. Local TSO Allocator, servers for DC-level transactions. | ||
| // dc-location/global (string) -> TSO Allocator | ||
| allocatorGroups map[string]*allocatorGroup | ||
| // etcd and its client | ||
| etcd *embed.Etcd | ||
| client *clientv3.Client | ||
| // tso config | ||
| rootPath string | ||
| saveInterval time.Duration | ||
| maxResetTSGap func() time.Duration | ||
| } | ||
|
|
||
| // NewAllocatorManager creates a new TSO Allocator Manager. | ||
| func NewAllocatorManager(etcd *embed.Etcd, client *clientv3.Client, rootPath string, saveInterval time.Duration, maxResetTSGap func() time.Duration) *AllocatorManager { | ||
| allocatorManager := &AllocatorManager{ | ||
| allocatorGroups: make(map[string]*allocatorGroup), | ||
| etcd: etcd, | ||
| client: client, | ||
| rootPath: rootPath, | ||
| saveInterval: saveInterval, | ||
| maxResetTSGap: maxResetTSGap, | ||
| } | ||
| return allocatorManager | ||
| } | ||
|
|
||
| func (am *AllocatorManager) getAllocatorPath(dcLocation string) string { | ||
| // For backward compatibility, the global timestamp's store path will still use the old one | ||
| if dcLocation == GlobalDCLocation { | ||
| return am.rootPath | ||
| } | ||
| return path.Join(am.rootPath, dcLocation) | ||
| } | ||
|
|
||
| // SetUpAllocator is used to set up an allocator, which will initialize the allocator and put it into allocator daemon. | ||
| func (am *AllocatorManager) SetUpAllocator(parentCtx context.Context, parentCancel context.CancelFunc, dcLocation string, leadership *election.Leadership) error { | ||
| am.Lock() | ||
| defer am.Unlock() | ||
| switch dcLocation { | ||
| case GlobalDCLocation: | ||
| am.allocatorGroups[dcLocation] = &allocatorGroup{ | ||
| dcLocation: dcLocation, | ||
| parentCtx: parentCtx, | ||
| parentCancel: parentCancel, | ||
| leadership: leadership, | ||
| allocator: NewGlobalTSOAllocator(leadership, am.getAllocatorPath(dcLocation), am.saveInterval, am.maxResetTSGap), | ||
| } | ||
| if err := am.allocatorGroups[dcLocation].allocator.Initialize(); err != nil { | ||
| return err | ||
| } | ||
| am.allocatorGroups[dcLocation].isInitialized = true | ||
| default: | ||
| // Todo: set up a Local TSO Allocator | ||
| } | ||
| return nil | ||
| } | ||
|
|
||
| // GetAllocator get the allocator by dc-location. | ||
| func (am *AllocatorManager) GetAllocator(dcLocation string) (Allocator, error) { | ||
| am.RLock() | ||
| defer am.RUnlock() | ||
| allocatorGroup, exist := am.allocatorGroups[dcLocation] | ||
| if !exist { | ||
| return nil, errs.ErrGetAllocator.FastGenByArgs(fmt.Sprintf("%s allocator not found", dcLocation)) | ||
| } | ||
| return allocatorGroup.allocator, nil | ||
| } | ||
|
|
||
| func (am *AllocatorManager) getAllocatorGroups() []*allocatorGroup { | ||
| am.RLock() | ||
| defer am.RUnlock() | ||
| allocatorGroups := make([]*allocatorGroup, 0, len(am.allocatorGroups)) | ||
| for _, ag := range am.allocatorGroups { | ||
| allocatorGroups = append(allocatorGroups, ag) | ||
| } | ||
| return allocatorGroups | ||
| } | ||
|
|
||
| // AllocatorDaemon is used to update every allocator's TSO. | ||
| func (am *AllocatorManager) AllocatorDaemon(serverCtx context.Context) { | ||
| tsTicker := time.NewTicker(UpdateTimestampStep) | ||
| defer tsTicker.Stop() | ||
|
|
||
| for { | ||
| select { | ||
| case <-tsTicker.C: | ||
| // Collect all dc-locations first | ||
| allocatorGroups := am.getAllocatorGroups() | ||
| // Update each allocator concurrently | ||
| for _, ag := range allocatorGroups { | ||
| // Filter allocators without leadership and uninitialized | ||
| if ag.isInitialized && ag.leadership.Check() { | ||
| am.wg.Add(1) | ||
| go am.updateAllocator(ag) | ||
| } | ||
| } | ||
| am.wg.Wait() | ||
| case <-serverCtx.Done(): | ||
| return | ||
| } | ||
| } | ||
| } | ||
|
|
||
| // updateAllocator is used to update the allocator in the group. | ||
| func (am *AllocatorManager) updateAllocator(ag *allocatorGroup) { | ||
| defer am.wg.Done() | ||
| select { | ||
| case <-ag.parentCtx.Done(): | ||
| // Need to initialize first before next use | ||
| ag.isInitialized = false | ||
| // Resetting the allocator will clear TSO in memory | ||
| ag.allocator.Reset() | ||
| return | ||
| default: | ||
| } | ||
| if !ag.leadership.Check() { | ||
| log.Info("allocator doesn't campaign leadership yet", zap.String("dc-location", ag.dcLocation)) | ||
| time.Sleep(200 * time.Millisecond) | ||
| return | ||
| } | ||
| if err := ag.allocator.UpdateTSO(); err != nil { | ||
| log.Warn("failed to update allocator's timestamp", zap.String("dc-location", ag.dcLocation), zap.Error(err)) | ||
| ag.parentCancel() | ||
| return | ||
| } | ||
| } | ||
|
|
||
| // HandleTSORequest forwards TSO allocation requests to correct TSO Allocators. | ||
| func (am *AllocatorManager) HandleTSORequest(dcLocation string, count uint32) (pdpb.Timestamp, error) { | ||
| am.RLock() | ||
| defer am.RUnlock() | ||
| allocatorGroup, exist := am.allocatorGroups[dcLocation] | ||
| if !exist { | ||
| err := errs.ErrGetAllocator.FastGenByArgs(fmt.Sprintf("%s allocator not found, generate timestamp failed", dcLocation)) | ||
| return pdpb.Timestamp{}, err | ||
| } | ||
| return allocatorGroup.allocator.GenerateTSO(count) | ||
| } |
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