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cherry pick tikv#3305 to release-2.1
Signed-off-by: ti-srebot <ti-srebot@pingcap.com>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,118 @@ | ||
| // Copyright 2016 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. | ||
|
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| package id | ||
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| import ( | ||
| "path" | ||
| "sync" | ||
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| "github.com/pingcap/log" | ||
| "github.com/tikv/pd/pkg/errs" | ||
| "github.com/tikv/pd/pkg/etcdutil" | ||
| "github.com/tikv/pd/pkg/typeutil" | ||
| "github.com/tikv/pd/server/kv" | ||
| "go.etcd.io/etcd/clientv3" | ||
| "go.uber.org/zap" | ||
| ) | ||
|
|
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| // Allocator is the allocator to generate unique ID. | ||
| type Allocator interface { | ||
| Alloc() (uint64, error) | ||
| } | ||
|
|
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| const allocStep = uint64(1000) | ||
|
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| // AllocatorImpl is used to allocate ID. | ||
| type AllocatorImpl struct { | ||
| mu sync.Mutex | ||
| base uint64 | ||
| end uint64 | ||
|
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| client *clientv3.Client | ||
| rootPath string | ||
| member string | ||
| } | ||
|
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| // NewAllocatorImpl creates a new IDAllocator. | ||
| func NewAllocatorImpl(client *clientv3.Client, rootPath string, member string) *AllocatorImpl { | ||
| return &AllocatorImpl{client: client, rootPath: rootPath, member: member} | ||
| } | ||
|
|
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| // Alloc returns a new id. | ||
| func (alloc *AllocatorImpl) Alloc() (uint64, error) { | ||
| alloc.mu.Lock() | ||
| defer alloc.mu.Unlock() | ||
|
|
||
| if alloc.base == alloc.end { | ||
| err := alloc.Generate() | ||
| if err != nil { | ||
| return 0, err | ||
| } | ||
|
|
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| alloc.base = alloc.end - allocStep | ||
| } | ||
|
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| alloc.base++ | ||
|
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| return alloc.base, nil | ||
| } | ||
|
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| // Generate synchronizes and generates id range. | ||
| func (alloc *AllocatorImpl) Generate() error { | ||
| key := alloc.getAllocIDPath() | ||
| value, err := etcdutil.GetValue(alloc.client, key) | ||
| if err != nil { | ||
| return err | ||
| } | ||
|
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| var ( | ||
| cmp clientv3.Cmp | ||
| end uint64 | ||
| ) | ||
|
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| if value == nil { | ||
| // create the key | ||
| cmp = clientv3.Compare(clientv3.CreateRevision(key), "=", 0) | ||
| } else { | ||
| // update the key | ||
| end, err = typeutil.BytesToUint64(value) | ||
| if err != nil { | ||
| return err | ||
| } | ||
|
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| cmp = clientv3.Compare(clientv3.Value(key), "=", string(value)) | ||
| } | ||
|
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| end += allocStep | ||
| value = typeutil.Uint64ToBytes(end) | ||
| txn := kv.NewSlowLogTxn(alloc.client) | ||
| leaderPath := path.Join(alloc.rootPath, "leader") | ||
| t := txn.If(append([]clientv3.Cmp{cmp}, clientv3.Compare(clientv3.Value(leaderPath), "=", alloc.member))...) | ||
| resp, err := t.Then(clientv3.OpPut(key, string(value))).Commit() | ||
| if err != nil { | ||
| return errs.ErrEtcdTxn.Wrap(err).GenWithStackByArgs() | ||
| } | ||
| if !resp.Succeeded { | ||
| return errs.ErrEtcdTxn.FastGenByArgs() | ||
| } | ||
|
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| log.Info("idAllocator allocates a new id", zap.Uint64("alloc-id", end)) | ||
| idGauge.WithLabelValues("idalloc").Set(float64(end)) | ||
| alloc.end = end | ||
| return nil | ||
| } | ||
|
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| func (alloc *AllocatorImpl) getAllocIDPath() string { | ||
| return path.Join(alloc.rootPath, "alloc_id") | ||
| } |
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