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https://github.com/talent-plan/tinykv.git
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5e089a2cd1
Signed-off-by: Connor <zbk602423539@gmail.com> Co-authored-by: Nick Cameron <nrc@ncameron.org> Co-authored-by: linning <linningde25@gmail.com> Co-authored-by: YangKeao <keao.yang@yahoo.com> Co-authored-by: andylokandy <andylokandy@hotmail.com> Co-authored-by: Iosmanthus Teng <myosmanthustree@gmail.com>
117 lines
2.8 KiB
Go
117 lines
2.8 KiB
Go
// Copyright 2016 PingCAP, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package id
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import (
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"path"
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"sync"
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"github.com/pingcap-incubator/tinykv/scheduler/pkg/etcdutil"
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"github.com/pingcap-incubator/tinykv/scheduler/pkg/typeutil"
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"github.com/pingcap-incubator/tinykv/scheduler/server/kv"
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"github.com/pingcap/log"
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"github.com/pkg/errors"
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"go.etcd.io/etcd/clientv3"
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"go.uber.org/zap"
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)
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// Allocator is the allocator to generate unique ID.
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type Allocator interface {
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Alloc() (uint64, error)
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}
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const allocStep = uint64(1000)
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// AllocatorImpl is used to allocate ID.
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type AllocatorImpl struct {
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mu sync.Mutex
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base uint64
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end uint64
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client *clientv3.Client
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rootPath string
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member string
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}
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// NewAllocatorImpl creates a new IDAllocator.
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func NewAllocatorImpl(client *clientv3.Client, rootPath string, member string) *AllocatorImpl {
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return &AllocatorImpl{client: client, rootPath: rootPath, member: member}
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}
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// Alloc returns a new id.
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func (alloc *AllocatorImpl) Alloc() (uint64, error) {
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alloc.mu.Lock()
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defer alloc.mu.Unlock()
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if alloc.base == alloc.end {
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end, err := alloc.generate()
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if err != nil {
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return 0, err
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}
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alloc.end = end
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alloc.base = alloc.end - allocStep
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}
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alloc.base++
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return alloc.base, nil
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}
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func (alloc *AllocatorImpl) generate() (uint64, error) {
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key := alloc.getAllocIDPath()
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value, err := etcdutil.GetValue(alloc.client, key)
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if err != nil {
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return 0, err
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}
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var (
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cmp clientv3.Cmp
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end uint64
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)
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if value == nil {
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// create the key
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cmp = clientv3.Compare(clientv3.CreateRevision(key), "=", 0)
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} else {
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// update the key
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end, err = typeutil.BytesToUint64(value)
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if err != nil {
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return 0, err
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}
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cmp = clientv3.Compare(clientv3.Value(key), "=", string(value))
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}
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end += allocStep
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value = typeutil.Uint64ToBytes(end)
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txn := kv.NewSlowLogTxn(alloc.client)
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leaderPath := path.Join(alloc.rootPath, "leader")
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t := txn.If(append([]clientv3.Cmp{cmp}, clientv3.Compare(clientv3.Value(leaderPath), "=", alloc.member))...)
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resp, err := t.Then(clientv3.OpPut(key, string(value))).Commit()
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if err != nil {
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return 0, err
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}
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if !resp.Succeeded {
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return 0, errors.New("generate id failed, we may not leader")
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}
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log.Info("idAllocator allocates a new id", zap.Uint64("alloc-id", end))
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return end, nil
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}
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func (alloc *AllocatorImpl) getAllocIDPath() string {
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return path.Join(alloc.rootPath, "alloc_id")
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}
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