mirror of
https://github.com/etcd-io/etcd.git
synced 2024-09-27 06:25:44 +00:00
111 lines
3.1 KiB
Go
111 lines
3.1 KiB
Go
// Copyright 2016 The etcd Authors
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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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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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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 mirror implements etcd mirroring operations.
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package mirror
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import (
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"github.com/coreos/etcd/clientv3"
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"golang.org/x/net/context"
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)
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const (
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batchLimit = 1000
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)
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// Syncer syncs with the key-value state of an etcd cluster.
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type Syncer interface {
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// SyncBase syncs the base state of the key-value state.
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// The key-value state are sent through the returned chan.
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SyncBase(ctx context.Context) (<-chan clientv3.GetResponse, chan error)
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// SyncUpdates syncs the updates of the key-value state.
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// The update events are sent through the returned chan.
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SyncUpdates(ctx context.Context) clientv3.WatchChan
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}
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// NewSyncer creates a Syncer.
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func NewSyncer(c *clientv3.Client, prefix string, rev int64) Syncer {
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return &syncer{c: c, prefix: prefix, rev: rev}
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}
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type syncer struct {
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c *clientv3.Client
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rev int64
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prefix string
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}
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func (s *syncer) SyncBase(ctx context.Context) (<-chan clientv3.GetResponse, chan error) {
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respchan := make(chan clientv3.GetResponse, 1024)
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errchan := make(chan error, 1)
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// if rev is not specified, we will choose the most recent revision.
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if s.rev == 0 {
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resp, err := s.c.Get(ctx, "foo")
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if err != nil {
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errchan <- err
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close(respchan)
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close(errchan)
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return respchan, errchan
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}
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s.rev = resp.Header.Revision
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}
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go func() {
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defer close(respchan)
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defer close(errchan)
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var key string
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opts := []clientv3.OpOption{clientv3.WithLimit(batchLimit), clientv3.WithRev(s.rev)}
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if len(s.prefix) == 0 {
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// If len(s.prefix) == 0, we will sync the entire key-value space.
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// We then range from the smallest key (0x00) to the end.
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opts = append(opts, clientv3.WithFromKey())
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key = "\x00"
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} else {
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// If len(s.prefix) != 0, we will sync key-value space with given prefix.
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// We then range from the prefix to the next prefix if exists. Or we will
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// range from the prefix to the end if the next prefix does not exists.
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opts = append(opts, clientv3.WithRange(clientv3.GetPrefixRangeEnd(s.prefix)))
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key = s.prefix
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}
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for {
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resp, err := s.c.Get(ctx, key, opts...)
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if err != nil {
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errchan <- err
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return
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}
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respchan <- (clientv3.GetResponse)(*resp)
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if !resp.More {
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return
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}
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// move to next key
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key = string(append(resp.Kvs[len(resp.Kvs)-1].Key, 0))
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}
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}()
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return respchan, errchan
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}
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func (s *syncer) SyncUpdates(ctx context.Context) clientv3.WatchChan {
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if s.rev == 0 {
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panic("unexpected revision = 0. Calling SyncUpdates before SyncBase finishes?")
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}
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return s.c.Watch(ctx, s.prefix, clientv3.WithPrefix(), clientv3.WithRev(s.rev+1))
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}
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