github.com/slspeek/camlistore_namedsearch@v0.0.0-20140519202248-ed6f70f7721a/pkg/blobserver/s3/enumerate.go (about)

     1  /*
     2  Copyright 2011 Google Inc.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8       http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package s3
    18  
    19  import (
    20  	"log"
    21  
    22  	"camlistore.org/pkg/blob"
    23  	"camlistore.org/pkg/blobserver"
    24  	"camlistore.org/pkg/context"
    25  )
    26  
    27  var _ blobserver.MaxEnumerateConfig = (*s3Storage)(nil)
    28  
    29  func (sto *s3Storage) MaxEnumerate() int { return 1000 }
    30  
    31  // marker returns the string lexically greater than the provided s
    32  // with the same length as s.
    33  func nextStr(s string) string {
    34  	if s == "" {
    35  		return s
    36  	}
    37  	b := []byte(s)
    38  	i := len(b)
    39  	for i > 0 {
    40  		i--
    41  		b[i]++
    42  		if b[i] != 0 {
    43  			break
    44  		}
    45  	}
    46  	return string(b)
    47  }
    48  
    49  func (sto *s3Storage) EnumerateBlobs(ctx *context.Context, dest chan<- blob.SizedRef, after string, limit int) (err error) {
    50  	defer close(dest)
    51  	if faultEnumerate.FailErr(&err) {
    52  		return
    53  	}
    54  	startAt := after
    55  	if _, ok := blob.Parse(after); ok {
    56  		startAt = nextStr(after)
    57  	}
    58  	objs, err := sto.s3Client.ListBucket(sto.bucket, startAt, limit)
    59  	if err != nil {
    60  		log.Printf("s3 ListBucket: %v", err)
    61  		return err
    62  	}
    63  	for _, obj := range objs {
    64  		if obj.Key == after {
    65  			continue
    66  		}
    67  		br, ok := blob.Parse(obj.Key)
    68  		if !ok {
    69  			continue
    70  		}
    71  		select {
    72  		case dest <- blob.SizedRef{Ref: br, Size: uint32(obj.Size)}:
    73  		case <-ctx.Done():
    74  			return context.ErrCanceled
    75  		}
    76  	}
    77  	return nil
    78  }