package concurrency
import (
"fmt"
v3 "github.com/coreos/etcd/clientv3"
"github.com/coreos/etcd/mvcc/mvccpb"
"golang.org/x/net/context"
)
func waitDelete(ctx context.Context, client *v3.Client, key string, rev int64) error {
cctx, cancel := context.WithCancel(ctx)
defer cancel()
var wr v3.WatchResponse
wch := client.Watch(cctx, key, v3.WithRev(rev))
for wr = range wch {
for _, ev := range wr.Events {
if ev.Type == mvccpb.DELETE {
return nil
} } }if err := wr.Err(); err != nil {
return err
}if err := ctx.Err(); err != nil {
return err
}return fmt.Errorf("lost watcher waiting for delete")
}
// waitDeletes efficiently waits until all keys matching the prefix and no greater
// than the create revision.
func waitDeletes(ctx context.Context, client *v3.Client, pfx string, maxCreateRev int64) error {
getOpts := append(v3.WithLastCreate(), v3.WithMaxCreateRev(maxCreateRev))
for {
resp, err := client.Get(ctx, pfx, getOpts...)
if err != nil {
return err
}if len(resp.Kvs) == 0 {
return nil
}lastKey := string(resp.Kvs[0].Key)
if err = waitDelete(ctx, client, lastKey, resp.Header.Revision); err != nil {
return err
} }}
原文：http://www.cnblogs.com/zhangboyu/p/7452710.html