minio/xl-v1-common.go
Harshavardhana a1a667ae5d xl: Change fileMetadata to xlMetadata. (#1404)
Finalized backend format

```
{
    "version": "1.0.0",
    "stat": {
        "size": 24256,
        "modTime": "2016-04-28T00:11:37.843Z"
    },
    "erasure": {
        "data": 5,
        "parity": 5,
        "blockSize": 4194304
    ],
    "minio": {
        "release": "RELEASE.2016-04-28T00-09-47Z"
    }
}
```
2016-04-28 19:27:02 -07:00

182 lines
5.5 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 main
import (
"errors"
slashpath "path"
"path/filepath"
"github.com/Sirupsen/logrus"
)
// Get the highest integer from a given integer slice.
func highestInt(intSlice []int64) (highestInteger int64) {
highestInteger = int64(0)
for _, integer := range intSlice {
if highestInteger < integer {
highestInteger = integer
}
}
return highestInteger
}
// Extracts file versions from partsMetadata slice and returns version slice.
func listFileVersions(partsMetadata []xlMetaV1, errs []error) (versions []int64, err error) {
versions = make([]int64, len(partsMetadata))
for index, metadata := range partsMetadata {
if errs[index] == nil {
versions[index] = metadata.Stat.Version
} else {
versions[index] = -1
}
}
return versions, nil
}
// Returns slice of online disks needed.
// - slice returing readable disks.
// - xlMetaV1
// - bool value indicating if healing is needed.
// - error if any.
func (xl XL) listOnlineDisks(volume, path string) (onlineDisks []StorageAPI, mdata xlMetaV1, heal bool, err error) {
partsMetadata, errs := xl.getPartsMetadata(volume, path)
notFoundCount := 0
// FIXME: take care of the situation when a disk has failed and been removed
// by looking at the error returned from the fs layer. fs-layer will have
// to return an error indicating that the disk is not available and should be
// different from ErrNotExist.
for _, err := range errs {
if err == errFileNotFound {
notFoundCount++
// If we have errors with file not found greater than allowed read
// quorum we return err as errFileNotFound.
if notFoundCount > len(xl.storageDisks)-xl.readQuorum {
return nil, xlMetaV1{}, false, errFileNotFound
}
}
}
highestVersion := int64(0)
onlineDisks = make([]StorageAPI, len(xl.storageDisks))
// List all the file versions from partsMetadata list.
versions, err := listFileVersions(partsMetadata, errs)
if err != nil {
log.WithFields(logrus.Fields{
"volume": volume,
"path": path,
}).Errorf("Extracting file versions failed with %s", err)
return nil, xlMetaV1{}, false, err
}
// Get highest file version.
highestVersion = highestInt(versions)
// Pick online disks with version set to highestVersion.
onlineDiskCount := 0
for index, version := range versions {
if version == highestVersion {
mdata = partsMetadata[index]
onlineDisks[index] = xl.storageDisks[index]
onlineDiskCount++
} else {
onlineDisks[index] = nil
}
}
// If online disks count is lesser than configured disks, most
// probably we need to heal the file, additionally verify if the
// count is lesser than readQuorum, if not we throw an error.
if onlineDiskCount < len(xl.storageDisks) {
// Online disks lesser than total storage disks, needs to be
// healed. unless we do not have readQuorum.
heal = true
// Verify if online disks count are lesser than readQuorum
// threshold, return an error if yes.
if onlineDiskCount < xl.readQuorum {
log.WithFields(logrus.Fields{
"volume": volume,
"path": path,
"onlineDiskCount": onlineDiskCount,
"readQuorumCount": xl.readQuorum,
}).Errorf("%s", errReadQuorum)
return nil, xlMetaV1{}, false, errReadQuorum
}
}
return onlineDisks, mdata, heal, nil
}
// Get xl.json metadata as a map slice.
// Returns error slice indicating the failed metadata reads.
// Read lockNS() should be done by caller.
func (xl XL) getPartsMetadata(volume, path string) ([]xlMetaV1, []error) {
errs := make([]error, len(xl.storageDisks))
metadataArray := make([]xlMetaV1, len(xl.storageDisks))
xlMetaV1FilePath := slashpath.Join(path, xlMetaV1File)
for index, disk := range xl.storageDisks {
offset := int64(0)
metadataReader, err := disk.ReadFile(volume, xlMetaV1FilePath, offset)
if err != nil {
errs[index] = err
continue
}
defer metadataReader.Close()
metadata, err := xlMetaV1Decode(metadataReader)
if err != nil {
// Unable to parse xl.json, set error.
errs[index] = err
continue
}
metadataArray[index] = metadata
}
return metadataArray, errs
}
// Writes/Updates `xl.json` for given file. updateParts carries
// index of disks where `xl.json` needs to be updated.
//
// Returns collection of errors, indexed in accordance with input
// updateParts order.
// Write lockNS() should be done by caller.
func (xl XL) setPartsMetadata(volume, path string, metadata xlMetaV1, updateParts []bool) []error {
xlMetaV1FilePath := filepath.Join(path, xlMetaV1File)
errs := make([]error, len(xl.storageDisks))
for index := range updateParts {
errs[index] = errors.New("Metadata not updated")
}
for index, shouldUpdate := range updateParts {
if !shouldUpdate {
continue
}
writer, err := xl.storageDisks[index].CreateFile(volume, xlMetaV1FilePath)
errs[index] = err
if err != nil {
continue
}
err = metadata.Write(writer)
if err != nil {
errs[index] = err
safeCloseAndRemove(writer)
continue
}
writer.Close()
}
return errs
}