minio/xl-v1-list-objects.go
Harshavardhana a0635dcdd9 XL: Do not rely on getLoadBalancedQuorumDisks for NS consistency. (#2243)
The reason is any function relying on `getLoadBalancedQuorumDisks`
cannot possibly have an idempotent behavior.

The problem comes from given a set of N disks returning just a
shuffled N/2 disks.  In case of a scenario where we have N/2
number of failed disks, the returned value of `getLoadBalancedQuorumDisks`
is not equal to the same failed disks so essentially calls using such
disks might succeed or fail randomly at different intervals in time.

This proposal change is we move to `getLoadBalancedDisks()`
and use the shuffled N disks as a whole. Since most of the time we might
hit a good disk since we are not reducing our solution space. This
also provides consistent behavior for all the functions which rely
on shuffled disks.

Fixes #2242
2016-07-21 00:27:08 -07:00

164 lines
4.8 KiB
Go

/*
* Minio Cloud Storage, (C) 2016 Minio, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package main
import "strings"
// listObjects - wrapper function implemented over file tree walk.
func (xl xlObjects) listObjects(bucket, prefix, marker, delimiter string, maxKeys int) (ListObjectsInfo, error) {
// Default is recursive, if delimiter is set then list non recursive.
recursive := true
if delimiter == slashSeparator {
recursive = false
}
walkResultCh, endWalkCh := xl.listPool.Release(listParams{bucket, recursive, marker, prefix})
if walkResultCh == nil {
endWalkCh = make(chan struct{})
isLeaf := xl.isObject
listDir := listDirFactory(isLeaf, xl.getLoadBalancedDisks()...)
walkResultCh = startTreeWalk(bucket, prefix, marker, recursive, listDir, isLeaf, endWalkCh)
}
var objInfos []ObjectInfo
var eof bool
var nextMarker string
for i := 0; i < maxKeys; {
walkResult, ok := <-walkResultCh
if !ok {
// Closed channel.
eof = true
break
}
// For any walk error return right away.
if walkResult.err != nil {
// File not found is a valid case.
if walkResult.err == errFileNotFound {
return ListObjectsInfo{}, nil
}
return ListObjectsInfo{}, toObjectErr(walkResult.err, bucket, prefix)
}
entry := walkResult.entry
var objInfo ObjectInfo
if strings.HasSuffix(entry, slashSeparator) {
// Object name needs to be full path.
objInfo.Bucket = bucket
objInfo.Name = entry
objInfo.IsDir = true
} else {
// Set the Mode to a "regular" file.
var err error
objInfo, err = xl.getObjectInfo(bucket, entry)
if err != nil {
// Ignore errFileNotFound
if err == errFileNotFound {
errorIf(err, "Unable to get object info", bucket, entry)
continue
}
return ListObjectsInfo{}, toObjectErr(err, bucket, prefix)
}
}
nextMarker = objInfo.Name
objInfos = append(objInfos, objInfo)
i++
if walkResult.end == true {
eof = true
break
}
}
params := listParams{bucket, recursive, nextMarker, prefix}
if !eof {
xl.listPool.Set(params, walkResultCh, endWalkCh)
}
result := ListObjectsInfo{IsTruncated: !eof}
for _, objInfo := range objInfos {
result.NextMarker = objInfo.Name
if objInfo.IsDir {
result.Prefixes = append(result.Prefixes, objInfo.Name)
continue
}
result.Objects = append(result.Objects, ObjectInfo{
Name: objInfo.Name,
ModTime: objInfo.ModTime,
Size: objInfo.Size,
MD5Sum: objInfo.MD5Sum,
IsDir: false,
})
}
return result, nil
}
// ListObjects - list all objects at prefix, delimited by '/'.
func (xl xlObjects) ListObjects(bucket, prefix, marker, delimiter string, maxKeys int) (ListObjectsInfo, error) {
// Verify if bucket is valid.
if !IsValidBucketName(bucket) {
return ListObjectsInfo{}, BucketNameInvalid{Bucket: bucket}
}
// Verify if bucket exists.
if !xl.isBucketExist(bucket) {
return ListObjectsInfo{}, BucketNotFound{Bucket: bucket}
}
if !IsValidObjectPrefix(prefix) {
return ListObjectsInfo{}, ObjectNameInvalid{Bucket: bucket, Object: prefix}
}
// Verify if delimiter is anything other than '/', which we do not support.
if delimiter != "" && delimiter != slashSeparator {
return ListObjectsInfo{}, UnsupportedDelimiter{
Delimiter: delimiter,
}
}
// Verify if marker has prefix.
if marker != "" {
if !strings.HasPrefix(marker, prefix) {
return ListObjectsInfo{}, InvalidMarkerPrefixCombination{
Marker: marker,
Prefix: prefix,
}
}
}
// With max keys of zero we have reached eof, return right here.
if maxKeys == 0 {
return ListObjectsInfo{}, nil
}
// For delimiter and prefix as '/' we do not list anything at all
// since according to s3 spec we stop at the 'delimiter' along
// with the prefix. On a flat namespace with 'prefix' as '/'
// we don't have any entries, since all the keys are of form 'keyName/...'
if delimiter == slashSeparator && prefix == slashSeparator {
return ListObjectsInfo{}, nil
}
// Over flowing count - reset to maxObjectList.
if maxKeys < 0 || maxKeys > maxObjectList {
maxKeys = maxObjectList
}
// Initiate a list operation, if successful filter and return quickly.
listObjInfo, err := xl.listObjects(bucket, prefix, marker, delimiter, maxKeys)
if err == nil {
// We got the entries successfully return.
return listObjInfo, nil
}
// Return error at the end.
return ListObjectsInfo{}, toObjectErr(err, bucket, prefix)
}