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minio/cmd/erasure-common.go

108 lines
3.4 KiB

/*
* MinIO Cloud Storage, (C) 2016-2020 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 cmd
import (
"context"
"path"
"github.com/minio/minio/pkg/sync/errgroup"
)
func (er erasureObjects) getLoadBalancedLocalDisks() (newDisks []StorageAPI) {
disks := er.getDisks()
// Based on the random shuffling return back randomized disks.
for _, i := range hashOrder(UTCNow().String(), len(disks)) {
if disks[i-1] != nil && disks[i-1].IsLocal() {
newDisks = append(newDisks, disks[i-1])
}
}
return newDisks
}
// getLoadBalancedNDisks - fetches load balanced (sufficiently randomized) disk slice with N disks online
func (er erasureObjects) getLoadBalancedNDisks(ndisks int) (newDisks []StorageAPI) {
disks := er.getLoadBalancedDisks()
for _, disk := range disks {
if disk == nil {
continue
}
newDisks = append(newDisks, disk)
ndisks--
if ndisks == 0 {
break
}
}
return
}
// getLoadBalancedDisks - fetches load balanced (sufficiently randomized) disk slice.
func (er erasureObjects) getLoadBalancedDisks() (newDisks []StorageAPI) {
disks := er.getDisks()
// Based on the random shuffling return back randomized disks.
for _, i := range hashOrder(UTCNow().String(), len(disks)) {
newDisks = append(newDisks, disks[i-1])
}
return newDisks
}
// 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 (er erasureObjects) parentDirIsObject(ctx context.Context, bucket, parent string) bool {
var isParentDirObject func(string) bool
isParentDirObject = func(p string) bool {
if p == "." || p == SlashSeparator {
return false
}
if er.isObject(ctx, bucket, p) {
// If there is already a file at prefix "p", return true.
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.meta` exists at the leaf, false otherwise.
func (er erasureObjects) isObject(ctx context.Context, bucket, prefix string) (ok bool) {
storageDisks := er.getDisks()
g := errgroup.WithNErrs(len(storageDisks))
for index := range storageDisks {
index := index
g.Go(func() error {
if storageDisks[index] == nil {
return errDiskNotFound
}
// Check if 'prefix' is an object on this 'disk', else continue the check the next disk
return storageDisks[index].CheckFile(ctx, bucket, prefix)
}, index)
}
// NOTE: Observe we are not trying to read `xl.meta` and figure out the actual
// quorum intentionally, but rely on the default case scenario. Actual quorum
// verification will happen by top layer by using getObjectInfo() and will be
// ignored if necessary.
readQuorum := getReadQuorum(len(storageDisks))
return reduceReadQuorumErrs(ctx, g.Wait(), objectOpIgnoredErrs, readQuorum) == nil
}