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minio/cmd/xl-v1-healing-common.go

192 lines
5.8 KiB

/*
* Minio Cloud Storage, (C) 2016, 2017 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 "time"
// commonTime returns a maximally occurring time from a list of time.
func commonTime(modTimes []time.Time) (modTime time.Time, count int) {
var maxima int // Counter for remembering max occurrence of elements.
timeOccurenceMap := make(map[time.Time]int)
// Ignore the uuid sentinel and count the rest.
for _, time := range modTimes {
if time == timeSentinel {
continue
}
timeOccurenceMap[time]++
}
// Find the common cardinality from previously collected
// occurrences of elements.
for time, count := range timeOccurenceMap {
if count == maxima && time.After(modTime) {
maxima = count
modTime = time
} else if count > maxima {
maxima = count
modTime = time
}
}
// Return the collected common uuid.
return modTime, maxima
}
// Beginning of unix time is treated as sentinel value here.
var timeSentinel = time.Unix(0, 0).UTC()
// Boot modTimes up to disk count, setting the value to time sentinel.
func bootModtimes(diskCount int) []time.Time {
modTimes := make([]time.Time, diskCount)
// Boots up all the modtimes.
for i := range modTimes {
modTimes[i] = timeSentinel
}
return modTimes
}
// Extracts list of times from xlMetaV1 slice and returns, skips
// slice elements which have errors. As a special error
// errFileNotFound is treated as a initial good condition.
func listObjectModtimes(partsMetadata []xlMetaV1, errs []error) (modTimes []time.Time) {
modTimes = bootModtimes(len(partsMetadata))
// Set a new time value, specifically set when
// error == errFileNotFound (this is needed when this is a
// fresh PutObject).
timeNow := time.Now().UTC()
for index, metadata := range partsMetadata {
if errs[index] == nil {
// Once the file is found, save the uuid saved on disk.
modTimes[index] = metadata.Stat.ModTime
} else if errs[index] == errFileNotFound {
// Once the file is not found then the epoch is current time.
modTimes[index] = timeNow
}
}
return modTimes
}
// Returns slice of online disks needed.
// - slice returing readable disks.
// - modTime of the Object
func listOnlineDisks(disks []StorageAPI, partsMetadata []xlMetaV1, errs []error) (onlineDisks []StorageAPI, modTime time.Time) {
onlineDisks = make([]StorageAPI, len(disks))
// List all the file commit ids from parts metadata.
modTimes := listObjectModtimes(partsMetadata, errs)
// Reduce list of UUIDs to a single common value.
modTime, _ = commonTime(modTimes)
// Create a new online disks slice, which have common uuid.
for index, t := range modTimes {
if t == modTime {
onlineDisks[index] = disks[index]
} else {
onlineDisks[index] = nil
}
}
return onlineDisks, modTime
}
// Return disks with the outdated or missing object.
func outDatedDisks(disks []StorageAPI, partsMetadata []xlMetaV1, errs []error) (outDatedDisks []StorageAPI) {
outDatedDisks = make([]StorageAPI, len(disks))
latestDisks, _ := listOnlineDisks(disks, partsMetadata, errs)
for index, disk := range latestDisks {
if errorCause(errs[index]) == errFileNotFound {
outDatedDisks[index] = disks[index]
continue
}
if errs[index] != nil {
continue
}
if disk == nil {
outDatedDisks[index] = disks[index]
}
}
return outDatedDisks
}
// Returns if the object should be healed.
func xlShouldHeal(partsMetadata []xlMetaV1, errs []error) bool {
modTime, _ := commonTime(listObjectModtimes(partsMetadata, errs))
for index := range partsMetadata {
if errs[index] == errDiskNotFound {
continue
}
if errs[index] != nil {
return true
}
if modTime != partsMetadata[index].Stat.ModTime {
return true
}
}
return false
}
// xlHealStat - returns a structure which describes how many data,
// parity erasure blocks are missing and if it is possible to heal
// with the blocks present.
func xlHealStat(xl xlObjects, partsMetadata []xlMetaV1, errs []error) HealInfo {
// Less than quorum erasure coded blocks of the object have the same create time.
// This object can't be healed with the information we have.
modTime, count := commonTime(listObjectModtimes(partsMetadata, errs))
if count < xl.readQuorum {
return HealInfo{
Status: quorumUnavailable,
MissingDataCount: 0,
MissingPartityCount: 0,
}
}
// If there isn't a valid xlMeta then we can't heal the object.
xlMeta, err := pickValidXLMeta(partsMetadata, modTime)
if err != nil {
return HealInfo{
Status: corrupted,
MissingDataCount: 0,
MissingPartityCount: 0,
}
}
// Compute heal statistics like bytes to be healed, missing
// data and missing parity count.
missingDataCount := 0
missingParityCount := 0
for i, err := range errs {
// xl.json is not found, which implies the erasure
// coded blocks are unavailable in the corresponding disk.
// First half of the disks are data and the rest are parity.
if realErr := errorCause(err); realErr == errFileNotFound || realErr == errDiskNotFound {
if xlMeta.Erasure.Distribution[i]-1 < xl.dataBlocks {
missingDataCount++
} else {
missingParityCount++
}
}
}
// This object can be healed. We have enough object metadata
// to reconstruct missing erasure coded blocks.
return HealInfo{
Status: canHeal,
MissingDataCount: missingDataCount,
MissingPartityCount: missingParityCount,
}
}