key.go

Documentation: go.etcd.io/etcd/client/v3/concurrency

     1  // Copyright 2016 The etcd Authors
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package concurrency
    16  
    17  import (
    18  	"context"
    19  	"fmt"
    20  
    21  	pb "go.etcd.io/etcd/api/v3/etcdserverpb"
    22  	"go.etcd.io/etcd/api/v3/mvccpb"
    23  	v3 "go.etcd.io/etcd/client/v3"
    24  )
    25  
    26  func waitDelete(ctx context.Context, client *v3.Client, key string, rev int64) error {
    27  	cctx, cancel := context.WithCancel(ctx)
    28  	defer cancel()
    29  
    30  	var wr v3.WatchResponse
    31  	wch := client.Watch(cctx, key, v3.WithRev(rev))
    32  	for wr = range wch {
    33  		for _, ev := range wr.Events {
    34  			if ev.Type == mvccpb.DELETE {
    35  				return nil
    36  			}
    37  		}
    38  	}
    39  	if err := wr.Err(); err != nil {
    40  		return err
    41  	}
    42  	if err := ctx.Err(); err != nil {
    43  		return err
    44  	}
    45  	return fmt.Errorf("lost watcher waiting for delete")
    46  }
    47  
    48  // waitDeletes efficiently waits until all keys matching the prefix and no greater
    49  // than the create revision.
    50  func waitDeletes(ctx context.Context, client *v3.Client, pfx string, maxCreateRev int64) (*pb.ResponseHeader, error) {
    51  	getOpts := append(v3.WithLastCreate(), v3.WithMaxCreateRev(maxCreateRev))
    52  	for {
    53  		resp, err := client.Get(ctx, pfx, getOpts...)
    54  		if err != nil {
    55  			return nil, err
    56  		}
    57  		if len(resp.Kvs) == 0 {
    58  			return resp.Header, nil
    59  		}
    60  		lastKey := string(resp.Kvs[0].Key)
    61  		if err = waitDelete(ctx, client, lastKey, resp.Header.Revision); err != nil {
    62  			return nil, err
    63  		}
    64  	}
    65  }
    66
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