minio/cmd/xl-v1-utils.go
Harshavardhana 155a90403a fs/erasure: Rename meta 'md5Sum' as 'etag'. (#4319)
This PR also does backend format change to 1.0.1
from 1.0.0.  Backward compatible changes are still
kept to read the 'md5Sum' key. But all new objects
will be stored with the same details under 'etag'.

Fixes #4312
2017-05-14 12:05:51 -07:00

392 lines
12 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 cmd
import (
"errors"
"hash/crc32"
"path"
"sync"
"time"
"github.com/tidwall/gjson"
)
// Returns number of errors that occurred the most (incl. nil) and the
// corresponding error value. N B when there is more than one error value that
// occurs maximum number of times, the error value returned depends on how
// golang's map orders keys. This doesn't affect correctness as long as quorum
// value is greater than or equal to simple majority, since none of the equally
// maximal values would occur quorum or more number of times.
func reduceErrs(errs []error, ignoredErrs []error) (maxCount int, maxErr error) {
errorCounts := make(map[error]int)
errs = errorsCause(errs)
for _, err := range errs {
if isErrIgnored(err, ignoredErrs...) {
continue
}
errorCounts[err]++
}
max := 0
for err, count := range errorCounts {
switch {
case max < count:
max = count
maxErr = err
// Prefer `nil` over other error values with the same
// number of occurrences.
case max == count && err == nil:
maxErr = err
}
}
return max, maxErr
}
// reduceQuorumErrs behaves like reduceErrs by only for returning
// values of maximally occurring errors validated against a generic
// quorum number can be read or write quorum depending on usage.
// additionally a special error is provided as well to be returned
// in case quorum is not satisfied.
func reduceQuorumErrs(errs []error, ignoredErrs []error, quorum int, quorumErr error) (maxErr error) {
maxCount, maxErr := reduceErrs(errs, ignoredErrs)
if maxErr == nil && maxCount >= quorum {
// Success in quorum.
return nil
}
if maxErr != nil && maxCount >= quorum {
// Errors in quorum.
return traceError(maxErr, errs...)
}
// No quorum satisfied.
maxErr = traceError(quorumErr, errs...)
return
}
// reduceReadQuorumErrs behaves like reduceErrs but only for returning
// values of maximally occurring errors validated against readQuorum.
func reduceReadQuorumErrs(errs []error, ignoredErrs []error, readQuorum int) (maxErr error) {
return reduceQuorumErrs(errs, ignoredErrs, readQuorum, errXLReadQuorum)
}
// reduceWriteQuorumErrs behaves like reduceErrs but only for returning
// values of maximally occurring errors validated against writeQuorum.
func reduceWriteQuorumErrs(errs []error, ignoredErrs []error, writeQuorum int) (maxErr error) {
return reduceQuorumErrs(errs, ignoredErrs, writeQuorum, errXLWriteQuorum)
}
// Similar to 'len(slice)' but returns the actual elements count
// skipping the unallocated elements.
func diskCount(disks []StorageAPI) int {
diskCount := 0
for _, disk := range disks {
if disk == nil {
continue
}
diskCount++
}
return diskCount
}
// hashOrder - hashes input key to return returns consistent
// hashed integer slice. Returned integer order is salted
// with an input key. This results in consistent order.
// NOTE: collisions are fine, we are not looking for uniqueness
// in the slices returned.
func hashOrder(key string, cardinality int) []int {
if cardinality < 0 {
// Returns an empty int slice for negative cardinality.
return nil
}
nums := make([]int, cardinality)
keyCrc := crc32.Checksum([]byte(key), crc32.IEEETable)
start := int(uint32(keyCrc)%uint32(cardinality)) | 1
for i := 1; i <= cardinality; i++ {
nums[i-1] = 1 + ((start + i) % cardinality)
}
return nums
}
func parseXLStat(xlMetaBuf []byte) (statInfo, error) {
// obtain stat info.
stat := statInfo{}
// fetching modTime.
modTime, err := time.Parse(time.RFC3339, gjson.GetBytes(xlMetaBuf, "stat.modTime").String())
if err != nil {
return statInfo{}, err
}
stat.ModTime = modTime
// obtain Stat.Size .
stat.Size = gjson.GetBytes(xlMetaBuf, "stat.size").Int()
return stat, nil
}
func parseXLVersion(xlMetaBuf []byte) string {
return gjson.GetBytes(xlMetaBuf, "version").String()
}
func parseXLFormat(xlMetaBuf []byte) string {
return gjson.GetBytes(xlMetaBuf, "format").String()
}
func parseXLRelease(xlMetaBuf []byte) string {
return gjson.GetBytes(xlMetaBuf, "minio.release").String()
}
func parseXLErasureInfo(xlMetaBuf []byte) erasureInfo {
erasure := erasureInfo{}
erasureResult := gjson.GetBytes(xlMetaBuf, "erasure")
// parse the xlV1Meta.Erasure.Distribution.
disResult := erasureResult.Get("distribution").Array()
distribution := make([]int, len(disResult))
for i, dis := range disResult {
distribution[i] = int(dis.Int())
}
erasure.Distribution = distribution
erasure.Algorithm = erasureResult.Get("algorithm").String()
erasure.DataBlocks = int(erasureResult.Get("data").Int())
erasure.ParityBlocks = int(erasureResult.Get("parity").Int())
erasure.BlockSize = erasureResult.Get("blockSize").Int()
erasure.Index = int(erasureResult.Get("index").Int())
// Pare xlMetaV1.Erasure.Checksum array.
checkSumsResult := erasureResult.Get("checksum").Array()
checkSums := make([]checkSumInfo, len(checkSumsResult))
for i, checkSumResult := range checkSumsResult {
checkSum := checkSumInfo{}
checkSum.Name = checkSumResult.Get("name").String()
checkSum.Algorithm = checkSumResult.Get("algorithm").String()
checkSum.Hash = checkSumResult.Get("hash").String()
checkSums[i] = checkSum
}
erasure.Checksum = checkSums
return erasure
}
func parseXLParts(xlMetaBuf []byte) []objectPartInfo {
// Parse the XL Parts.
partsResult := gjson.GetBytes(xlMetaBuf, "parts").Array()
partInfo := make([]objectPartInfo, len(partsResult))
for i, p := range partsResult {
info := objectPartInfo{}
info.Number = int(p.Get("number").Int())
info.Name = p.Get("name").String()
info.ETag = p.Get("etag").String()
info.Size = p.Get("size").Int()
partInfo[i] = info
}
return partInfo
}
func parseXLMetaMap(xlMetaBuf []byte) map[string]string {
// Get xlMetaV1.Meta map.
metaMapResult := gjson.GetBytes(xlMetaBuf, "meta").Map()
metaMap := make(map[string]string)
for key, valResult := range metaMapResult {
metaMap[key] = valResult.String()
}
return metaMap
}
// Constructs XLMetaV1 using `gjson` lib to retrieve each field.
func xlMetaV1UnmarshalJSON(xlMetaBuf []byte) (xlMetaV1, error) {
xlMeta := xlMetaV1{}
// obtain version.
xlMeta.Version = parseXLVersion(xlMetaBuf)
// obtain format.
xlMeta.Format = parseXLFormat(xlMetaBuf)
// Parse xlMetaV1.Stat .
stat, err := parseXLStat(xlMetaBuf)
if err != nil {
return xlMetaV1{}, err
}
xlMeta.Stat = stat
// parse the xlV1Meta.Erasure fields.
xlMeta.Erasure = parseXLErasureInfo(xlMetaBuf)
// Parse the XL Parts.
xlMeta.Parts = parseXLParts(xlMetaBuf)
// Get the xlMetaV1.Realse field.
xlMeta.Minio.Release = parseXLRelease(xlMetaBuf)
// parse xlMetaV1.
xlMeta.Meta = parseXLMetaMap(xlMetaBuf)
return xlMeta, nil
}
// read xl.json from the given disk, parse and return xlV1MetaV1.Parts.
func readXLMetaParts(disk StorageAPI, bucket string, object string) ([]objectPartInfo, error) {
// Reads entire `xl.json`.
xlMetaBuf, err := disk.ReadAll(bucket, path.Join(object, xlMetaJSONFile))
if err != nil {
return nil, traceError(err)
}
// obtain xlMetaV1{}.Partsusing `github.com/tidwall/gjson`.
xlMetaParts := parseXLParts(xlMetaBuf)
return xlMetaParts, nil
}
// read xl.json from the given disk and parse xlV1Meta.Stat and xlV1Meta.Meta using gjson.
func readXLMetaStat(disk StorageAPI, bucket string, object string) (statInfo, map[string]string, error) {
// Reads entire `xl.json`.
xlMetaBuf, err := disk.ReadAll(bucket, path.Join(object, xlMetaJSONFile))
if err != nil {
return statInfo{}, nil, traceError(err)
}
// obtain version.
xlVersion := parseXLVersion(xlMetaBuf)
// obtain format.
xlFormat := parseXLFormat(xlMetaBuf)
// Validate if the xl.json we read is sane, return corrupted format.
if !isXLMetaValid(xlVersion, xlFormat) {
// For version mismatchs and unrecognized format, return corrupted format.
return statInfo{}, nil, traceError(errCorruptedFormat)
}
// obtain xlMetaV1{}.Meta using `github.com/tidwall/gjson`.
xlMetaMap := parseXLMetaMap(xlMetaBuf)
// obtain xlMetaV1{}.Stat using `github.com/tidwall/gjson`.
xlStat, err := parseXLStat(xlMetaBuf)
if err != nil {
return statInfo{}, nil, traceError(err)
}
// Return structured `xl.json`.
return xlStat, xlMetaMap, nil
}
// readXLMeta reads `xl.json` and returns back XL metadata structure.
func readXLMeta(disk StorageAPI, bucket string, object string) (xlMeta xlMetaV1, err error) {
// Reads entire `xl.json`.
xlMetaBuf, err := disk.ReadAll(bucket, path.Join(object, xlMetaJSONFile))
if err != nil {
return xlMetaV1{}, traceError(err)
}
// obtain xlMetaV1{} using `github.com/tidwall/gjson`.
xlMeta, err = xlMetaV1UnmarshalJSON(xlMetaBuf)
if err != nil {
return xlMetaV1{}, traceError(err)
}
// Return structured `xl.json`.
return xlMeta, nil
}
// Reads all `xl.json` metadata as a xlMetaV1 slice.
// Returns error slice indicating the failed metadata reads.
func readAllXLMetadata(disks []StorageAPI, bucket, object string) ([]xlMetaV1, []error) {
errs := make([]error, len(disks))
metadataArray := make([]xlMetaV1, len(disks))
var wg = &sync.WaitGroup{}
// Read `xl.json` parallelly across disks.
for index, disk := range disks {
if disk == nil {
errs[index] = errDiskNotFound
continue
}
wg.Add(1)
// Read `xl.json` in routine.
go func(index int, disk StorageAPI) {
defer wg.Done()
var err error
metadataArray[index], err = readXLMeta(disk, bucket, object)
if err != nil {
errs[index] = err
return
}
}(index, disk)
}
// Wait for all the routines to finish.
wg.Wait()
// Return all the metadata.
return metadataArray, errs
}
// Return shuffled partsMetadata depending on distribution.
func shufflePartsMetadata(partsMetadata []xlMetaV1, distribution []int) (shuffledPartsMetadata []xlMetaV1) {
if distribution == nil {
return partsMetadata
}
shuffledPartsMetadata = make([]xlMetaV1, len(partsMetadata))
// Shuffle slice xl metadata for expected distribution.
for index := range partsMetadata {
blockIndex := distribution[index]
shuffledPartsMetadata[blockIndex-1] = partsMetadata[index]
}
return shuffledPartsMetadata
}
// shuffleDisks - shuffle input disks slice depending on the
// erasure distribution. return shuffled slice of disks with
// their expected distribution.
func shuffleDisks(disks []StorageAPI, distribution []int) (shuffledDisks []StorageAPI) {
if distribution == nil {
return disks
}
shuffledDisks = make([]StorageAPI, len(disks))
// Shuffle disks for expected distribution.
for index := range disks {
blockIndex := distribution[index]
shuffledDisks[blockIndex-1] = disks[index]
}
return shuffledDisks
}
// Errors specifically generated by getPartSizeFromIdx function.
var (
errPartSizeZero = errors.New("Part size cannot be zero")
errPartSizeIndex = errors.New("Part index cannot be smaller than 1")
)
// getPartSizeFromIdx predicts the part size according to its index. It also
// returns -1 when totalSize is also -1.
func getPartSizeFromIdx(totalSize int64, partSize int64, partIndex int) (int64, error) {
if partSize == 0 {
return 0, traceError(errPartSizeZero)
}
if partIndex < 1 {
return 0, traceError(errPartSizeIndex)
}
switch totalSize {
case -1, 0:
return totalSize, nil
}
// Compute the total count of parts
partsCount := totalSize/partSize + 1
// Return the part's size
switch {
case int64(partIndex) < partsCount:
return partSize, nil
case int64(partIndex) == partsCount:
// Size of last part
return totalSize % partSize, nil
default:
return 0, nil
}
}