2

测试代码

func Test_watch(t *testing.T) {
    ec, _ := NewEtcdClient([]string{"http://127.0.0.1:2379"})
    cli := ec.getEtcdAPI()
    go func() {
        watcher := cli.Watcher("/a", &client.WatcherOptions{
            Recursive: true,
        })
        for {
            resp, err := watcher.Next(context.Background())
            fmt.Println(resp)
            fmt.Println(err)
        }
    }()
    cli.Set(context.Background(), "/a/b", "a-b", &client.SetOptions{})
    time.Sleep(1 * time.Second)
    cli.Set(context.Background(), "/a/b/c", "a-b-c", &client.SetOptions{})
    time.Sleep(1 * time.Second)
    cli.Set(context.Background(), "/a/d", "a-d", &client.SetOptions{})
    time.Sleep(1 * time.Second)
    cli.Delete(context.Background(), "/a/b/c", &client.DeleteOptions{})
    time.Sleep(1 * time.Second)
    cli.Delete(context.Background(), "/a/b", &client.DeleteOptions{})
    time.Sleep(1 * time.Second)
}

结果是

{"action":"set","node":{"key":"/a/b","value":"a-b","modifiedIndex":479128,"createdIndex":479128},"prevNode":{"key":"/a/b","value":"a-b","modifiedIndex":479126,"createdIndex":479126}}
&{set {Key: /a/b, CreatedIndex: 479128, ModifiedIndex: 479128, TTL: 0} {Key: /a/b, CreatedIndex: 479126, ModifiedIndex: 479126, TTL: 0} 479127}
<nil>

{"action":"set","node":{"key":"/a/d","value":"a-d","modifiedIndex":479129,"createdIndex":479129},"prevNode":{"key":"/a/d","value":"a-d","modifiedIndex":479127,"createdIndex":479127}}
&{set {Key: /a/d, CreatedIndex: 479129, ModifiedIndex: 479129, TTL: 0} {Key: /a/d, CreatedIndex: 479127, ModifiedIndex: 479127, TTL: 0} 479128}
<nil>

{"action":"delete","node":{"key":"/a/b","modifiedIndex":479130,"createdIndex":479128},"prevNode":{"key":"/a/b","value":"a-b","modifiedIndex":479128,"createdIndex":479128}}
&{delete {Key: /a/b, CreatedIndex: 479128, ModifiedIndex: 479130, TTL: 0} {Key: /a/b, CreatedIndex: 479128, ModifiedIndex: 479128, TTL: 0} 479129}
<nil>

结论是

  • etcd 的 directory 类型节点可以通过设置recursive=True,watch其直接儿子的新增和删除

  • 孙子节点的新增和删除无法被感知

  • 没有加recursive=True无法感知其儿子的新增和删除

  • 新增和删除的节点会在watch消息里给出,无需再去用get拉取内容。也就是watch给的是类似binlog的增量同步消息

  • 依赖watch来增量同步,需要保证watch不丢掉中间改动。这个可以通过WatcherOptions上的AfterIndex属性来实现,Index就是etcd node的版本。etcd v2 只有节点级别的版本,v3 才有全仓库的版本。


taowen
4.1k 声望1.4k 粉丝

Go开发者们请加入我们,滴滴出行平台技术部 taowen@didichuxing.com


引用和评论

0 条评论