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minio/xl-v1-common.go

92 lines
2.7 KiB

/*
* 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 "path"
// getLoadBalancedQuorumDisks - fetches load balanced sufficiently
// randomized quorum disk slice.
func (xl xlObjects) getLoadBalancedQuorumDisks() (disks []StorageAPI) {
// It is okay to have readQuorum disks.
return xl.getLoadBalancedDisks()[:xl.readQuorum-1]
}
// getLoadBalancedDisks - fetches load balanced (sufficiently
// randomized) disk slice.
func (xl xlObjects) getLoadBalancedDisks() (disks []StorageAPI) {
// Based on the random shuffling return back randomized disks.
for _, i := range randInts(len(xl.storageDisks)) {
disks = append(disks, xl.storageDisks[i-1])
}
return disks
}
// This function does the following check, suppose
// object is "a/b/c/d", stat makes sure that objects ""a/b/c""
// "a/b" and "a" do not exist.
func (xl xlObjects) parentDirIsObject(bucket, parent string) bool {
var isParentDirObject func(string) bool
isParentDirObject = func(p string) bool {
if p == "." {
return false
}
if xl.isObject(bucket, p) {
// If there is already a file at prefix "p" return error.
return true
}
// Check if there is a file as one of the parent paths.
return isParentDirObject(path.Dir(p))
}
return isParentDirObject(parent)
}
// isObject - returns `true` if the prefix is an object i.e if
// `xl.json` exists at the leaf, false otherwise.
func (xl xlObjects) isObject(bucket, prefix string) bool {
for _, disk := range xl.getLoadBalancedQuorumDisks() {
if disk == nil {
continue
}
// Check if 'prefix' is an object in this 'disk', else continue the check with next disk
_, err := disk.StatFile(bucket, path.Join(prefix, xlMetaJSONFile))
if err != nil {
if err == errFileNotFound || err == errDiskNotFound {
continue
}
// TODO: log the error
} else {
return true
}
}
return false
}
// statPart - returns fileInfo structure for a successful stat on part file.
func (xl xlObjects) statPart(bucket, objectPart string) (fileInfo FileInfo, err error) {
for _, disk := range xl.getLoadBalancedQuorumDisks() {
if disk == nil {
continue
}
fileInfo, err = disk.StatFile(bucket, objectPart)
if err != nil {
return FileInfo{}, err
}
break
}
return fileInfo, nil
}