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a0635dcdd9
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
72 lines
2.3 KiB
Go
72 lines
2.3 KiB
Go
/*
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* Minio Cloud Storage, (C) 2016 Minio, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package main
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import (
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"path"
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"time"
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)
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// getLoadBalancedDisks - fetches load balanced (sufficiently randomized) disk slice.
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func (xl xlObjects) getLoadBalancedDisks() (disks []StorageAPI) {
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// Based on the random shuffling return back randomized disks.
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for _, i := range hashOrder(time.Now().UTC().String(), len(xl.storageDisks)) {
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disks = append(disks, xl.storageDisks[i-1])
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}
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return disks
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}
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// This function does the following check, suppose
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// object is "a/b/c/d", stat makes sure that objects ""a/b/c""
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// "a/b" and "a" do not exist.
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func (xl xlObjects) parentDirIsObject(bucket, parent string) bool {
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var isParentDirObject func(string) bool
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isParentDirObject = func(p string) bool {
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if p == "." {
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return false
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}
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if xl.isObject(bucket, p) {
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// If there is already a file at prefix "p" return error.
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return true
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}
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// Check if there is a file as one of the parent paths.
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return isParentDirObject(path.Dir(p))
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}
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return isParentDirObject(parent)
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}
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// isObject - returns `true` if the prefix is an object i.e if
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// `xl.json` exists at the leaf, false otherwise.
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func (xl xlObjects) isObject(bucket, prefix string) (ok bool) {
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for _, disk := range xl.getLoadBalancedDisks() {
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if disk == nil {
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continue
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}
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// Check if 'prefix' is an object on this 'disk', else continue the check the next disk
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_, err := disk.StatFile(bucket, path.Join(prefix, xlMetaJSONFile))
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if err == nil {
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return true
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}
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// Ignore for file not found, disk not found or faulty disk.
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if isErrIgnored(err, walkResultIgnoredErrs) {
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continue
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}
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errorIf(err, "Unable to stat a file %s/%s/%s", bucket, prefix, xlMetaJSONFile)
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} // Exhausted all disks - return false.
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return false
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}
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