minio/cmd/xl-v1-object.go
Harshavardhana 15b4c49621 fs/xl: Simplify bucket metadata reading. (#3486)
ObjectLayer GetObject() now returns the entire object
if starting offset is 0 and length is negative. This
also allows to simplify handler layer code where
we always had to use GetObjectInfo() before proceeding
to read bucket metadata files examples `policy.json`.

This also reduces one additional call overhead.
2016-12-21 11:29:32 -08:00

616 lines
19 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 (
"crypto/md5"
"encoding/hex"
"hash"
"io"
"path"
"strings"
"sync"
"time"
"github.com/minio/minio/pkg/bpool"
"github.com/minio/minio/pkg/mimedb"
"github.com/minio/minio/pkg/objcache"
"github.com/minio/sha256-simd"
)
// list all errors which can be ignored in object operations.
var objectOpIgnoredErrs = []error{
errDiskNotFound,
errDiskAccessDenied,
errFaultyDisk,
errFaultyRemoteDisk,
}
/// Object Operations
// GetObject - reads an object erasured coded across multiple
// disks. Supports additional parameters like offset and length
// which is synonymous with HTTP Range requests.
//
// startOffset indicates the location at which the client requested
// object to be read at. length indicates the total length of the
// object requested by client.
func (xl xlObjects) GetObject(bucket, object string, startOffset int64, length int64, writer io.Writer) error {
if err := checkGetObjArgs(bucket, object); err != nil {
return err
}
// Start offset cannot be negative.
if startOffset < 0 {
return traceError(errUnexpected)
}
// Writer cannot be nil.
if writer == nil {
return traceError(errUnexpected)
}
// Read metadata associated with the object from all disks.
metaArr, errs := readAllXLMetadata(xl.storageDisks, bucket, object)
// Do we have read quorum?
if !isDiskQuorum(errs, xl.readQuorum) {
return traceError(InsufficientReadQuorum{}, errs...)
}
if reducedErr := reduceReadQuorumErrs(errs, objectOpIgnoredErrs, xl.readQuorum); reducedErr != nil {
return toObjectErr(reducedErr, bucket, object)
}
// List all online disks.
onlineDisks, modTime := listOnlineDisks(xl.storageDisks, metaArr, errs)
// Pick latest valid metadata.
xlMeta, err := pickValidXLMeta(metaArr, modTime)
if err != nil {
return err
}
// Reorder online disks based on erasure distribution order.
onlineDisks = getOrderedDisks(xlMeta.Erasure.Distribution, onlineDisks)
// Reorder parts metadata based on erasure distribution order.
metaArr = getOrderedPartsMetadata(xlMeta.Erasure.Distribution, metaArr)
// For negative length read everything.
if length < 0 {
length = xlMeta.Stat.Size - startOffset
}
// Reply back invalid range if the input offset and length fall out of range.
if startOffset > xlMeta.Stat.Size || startOffset+length > xlMeta.Stat.Size {
return traceError(InvalidRange{startOffset, length, xlMeta.Stat.Size})
}
// Get start part index and offset.
partIndex, partOffset, err := xlMeta.ObjectToPartOffset(startOffset)
if err != nil {
return traceError(InvalidRange{startOffset, length, xlMeta.Stat.Size})
}
// Get last part index to read given length.
lastPartIndex, _, err := xlMeta.ObjectToPartOffset(startOffset + length - 1)
if err != nil {
return traceError(InvalidRange{startOffset, length, xlMeta.Stat.Size})
}
// Save the writer.
mw := writer
// Object cache enabled block.
if xlMeta.Stat.Size > 0 && xl.objCacheEnabled {
// Validate if we have previous cache.
var cachedBuffer io.ReadSeeker
cachedBuffer, err = xl.objCache.Open(path.Join(bucket, object), modTime)
if err == nil { // Cache hit.
// Advance the buffer to offset as if it was read.
if _, err = cachedBuffer.Seek(startOffset, 0); err != nil { // Seek to the offset.
return traceError(err)
}
// Write the requested length.
if _, err = io.CopyN(writer, cachedBuffer, length); err != nil {
return traceError(err)
}
return nil
} // Cache miss.
// For unknown error, return and error out.
if err != objcache.ErrKeyNotFoundInCache {
return traceError(err)
} // Cache has not been found, fill the cache.
// Cache is only set if whole object is being read.
if startOffset == 0 && length == xlMeta.Stat.Size {
// Proceed to set the cache.
var newBuffer io.WriteCloser
// Create a new entry in memory of length.
newBuffer, err = xl.objCache.Create(path.Join(bucket, object), length)
if err == nil {
// Create a multi writer to write to both memory and client response.
mw = io.MultiWriter(newBuffer, writer)
defer newBuffer.Close()
}
// Ignore error if cache is full, proceed to write the object.
if err != nil && err != objcache.ErrCacheFull {
// For any other error return here.
return toObjectErr(traceError(err), bucket, object)
}
}
}
totalBytesRead := int64(0)
chunkSize := getChunkSize(xlMeta.Erasure.BlockSize, xlMeta.Erasure.DataBlocks)
pool := bpool.NewBytePool(chunkSize, len(onlineDisks))
// Read from all parts.
for ; partIndex <= lastPartIndex; partIndex++ {
if length == totalBytesRead {
break
}
// Save the current part name and size.
partName := xlMeta.Parts[partIndex].Name
partSize := xlMeta.Parts[partIndex].Size
readSize := partSize - partOffset
// readSize should be adjusted so that we don't write more data than what was requested.
if readSize > (length - totalBytesRead) {
readSize = length - totalBytesRead
}
// Get the checksums of the current part.
checkSums := make([]string, len(onlineDisks))
var ckSumAlgo string
for index, disk := range onlineDisks {
// Disk is not found skip the checksum.
if disk == nil {
checkSums[index] = ""
continue
}
ckSumInfo := metaArr[index].Erasure.GetCheckSumInfo(partName)
checkSums[index] = ckSumInfo.Hash
// Set checksum algo only once, while it is possible to have
// different algos per block because of our `xl.json`.
// It is not a requirement, set this only once for all the disks.
if ckSumAlgo != "" {
ckSumAlgo = ckSumInfo.Algorithm
}
}
// Start erasure decoding and writing to the client.
n, err := erasureReadFile(mw, onlineDisks, bucket, pathJoin(object, partName), partOffset, readSize, partSize, xlMeta.Erasure.BlockSize, xlMeta.Erasure.DataBlocks, xlMeta.Erasure.ParityBlocks, checkSums, ckSumAlgo, pool)
if err != nil {
errorIf(err, "Unable to read %s of the object `%s/%s`.", partName, bucket, object)
return toObjectErr(err, bucket, object)
}
// Track total bytes read from disk and written to the client.
totalBytesRead += n
// partOffset will be valid only for the first part, hence reset it to 0 for
// the remaining parts.
partOffset = 0
} // End of read all parts loop.
// Return success.
return nil
}
// GetObjectInfo - reads object metadata and replies back ObjectInfo.
func (xl xlObjects) GetObjectInfo(bucket, object string) (ObjectInfo, error) {
if err := checkGetObjArgs(bucket, object); err != nil {
return ObjectInfo{}, err
}
info, err := xl.getObjectInfo(bucket, object)
if err != nil {
return ObjectInfo{}, toObjectErr(err, bucket, object)
}
return info, nil
}
// getObjectInfo - wrapper for reading object metadata and constructs ObjectInfo.
func (xl xlObjects) getObjectInfo(bucket, object string) (objInfo ObjectInfo, err error) {
// returns xl meta map and stat info.
xlStat, xlMetaMap, err := xl.readXLMetaStat(bucket, object)
if err != nil {
// Return error.
return ObjectInfo{}, err
}
objInfo = ObjectInfo{
IsDir: false,
Bucket: bucket,
Name: object,
Size: xlStat.Size,
ModTime: xlStat.ModTime,
MD5Sum: xlMetaMap["md5Sum"],
ContentType: xlMetaMap["content-type"],
ContentEncoding: xlMetaMap["content-encoding"],
}
// md5Sum has already been extracted into objInfo.MD5Sum. We
// need to remove it from xlMetaMap to avoid it from appearing as
// part of response headers. e.g, X-Minio-* or X-Amz-*.
delete(xlMetaMap, "md5Sum")
objInfo.UserDefined = xlMetaMap
return objInfo, nil
}
func undoRename(disks []StorageAPI, srcBucket, srcEntry, dstBucket, dstEntry string, isPart bool, errs []error) {
var wg = &sync.WaitGroup{}
// Undo rename object on disks where RenameFile succeeded.
// If srcEntry/dstEntry are objects then add a trailing slash to copy
// over all the parts inside the object directory
if !isPart {
srcEntry = retainSlash(srcEntry)
dstEntry = retainSlash(dstEntry)
}
for index, disk := range disks {
if disk == nil {
continue
}
// Undo rename object in parallel.
wg.Add(1)
go func(index int, disk StorageAPI) {
defer wg.Done()
if errs[index] != nil {
return
}
_ = disk.RenameFile(dstBucket, dstEntry, srcBucket, srcEntry)
}(index, disk)
}
wg.Wait()
}
// rename - common function that renamePart and renameObject use to rename
// the respective underlying storage layer representations.
func rename(disks []StorageAPI, srcBucket, srcEntry, dstBucket, dstEntry string, isPart bool, quorum int) error {
// Initialize sync waitgroup.
var wg = &sync.WaitGroup{}
// Initialize list of errors.
var errs = make([]error, len(disks))
if !isPart {
dstEntry = retainSlash(dstEntry)
srcEntry = retainSlash(srcEntry)
}
// Rename file on all underlying storage disks.
for index, disk := range disks {
if disk == nil {
errs[index] = errDiskNotFound
continue
}
wg.Add(1)
go func(index int, disk StorageAPI) {
defer wg.Done()
err := disk.RenameFile(srcBucket, srcEntry, dstBucket, dstEntry)
if err != nil && err != errFileNotFound {
errs[index] = traceError(err)
}
}(index, disk)
}
// Wait for all renames to finish.
wg.Wait()
// We can safely allow RenameFile errors up to len(xl.storageDisks) - xl.writeQuorum
// otherwise return failure. Cleanup successful renames.
if !isDiskQuorum(errs, quorum) {
// Undo all the partial rename operations.
undoRename(disks, srcBucket, srcEntry, dstBucket, dstEntry, isPart, errs)
return traceError(errXLWriteQuorum)
}
return reduceWriteQuorumErrs(errs, objectOpIgnoredErrs, quorum)
}
// renamePart - renames a part of the source object to the destination
// across all disks in parallel. Additionally if we have errors and do
// not have a readQuorum partially renamed files are renamed back to
// its proper location.
func renamePart(disks []StorageAPI, srcBucket, srcPart, dstBucket, dstPart string, quorum int) error {
isPart := true
return rename(disks, srcBucket, srcPart, dstBucket, dstPart, isPart, quorum)
}
// renameObject - renames all source objects to destination object
// across all disks in parallel. Additionally if we have errors and do
// not have a readQuorum partially renamed files are renamed back to
// its proper location.
func renameObject(disks []StorageAPI, srcBucket, srcObject, dstBucket, dstObject string, quorum int) error {
isPart := false
return rename(disks, srcBucket, srcObject, dstBucket, dstObject, isPart, quorum)
}
// PutObject - creates an object upon reading from the input stream
// until EOF, erasure codes the data across all disk and additionally
// writes `xl.json` which carries the necessary metadata for future
// object operations.
func (xl xlObjects) PutObject(bucket string, object string, size int64, data io.Reader, metadata map[string]string, sha256sum string) (objInfo ObjectInfo, err error) {
if err = checkPutObjectArgs(bucket, object, xl); err != nil {
return ObjectInfo{}, err
}
// No metadata is set, allocate a new one.
if metadata == nil {
metadata = make(map[string]string)
}
uniqueID := mustGetUUID()
tempErasureObj := path.Join(uniqueID, "part.1")
tempObj := uniqueID
// Initialize md5 writer.
md5Writer := md5.New()
writers := []io.Writer{md5Writer}
var sha256Writer hash.Hash
if sha256sum != "" {
sha256Writer = sha256.New()
writers = append(writers, sha256Writer)
}
// Proceed to set the cache.
var newBuffer io.WriteCloser
// If caching is enabled, proceed to set the cache.
if size > 0 && xl.objCacheEnabled {
// PutObject invalidates any previously cached object in memory.
xl.objCache.Delete(path.Join(bucket, object))
// Create a new entry in memory of size.
newBuffer, err = xl.objCache.Create(path.Join(bucket, object), size)
if err == nil {
// Create a multi writer to write to both memory and client response.
writers = append(writers, newBuffer)
}
// Ignore error if cache is full, proceed to write the object.
if err != nil && err != objcache.ErrCacheFull {
// For any other error return here.
return ObjectInfo{}, toObjectErr(traceError(err), bucket, object)
}
}
mw := io.MultiWriter(writers...)
// Limit the reader to its provided size if specified.
var limitDataReader io.Reader
if size > 0 {
// This is done so that we can avoid erroneous clients sending
// more data than the set content size.
limitDataReader = io.LimitReader(data, size)
} else {
// else we read till EOF.
limitDataReader = data
}
// Tee reader combines incoming data stream and md5, data read from input stream is written to md5.
teeReader := io.TeeReader(limitDataReader, mw)
// Initialize xl meta.
xlMeta := newXLMetaV1(object, xl.dataBlocks, xl.parityBlocks)
onlineDisks := getOrderedDisks(xlMeta.Erasure.Distribution, xl.storageDisks)
// Delete temporary object in the event of failure. If
// PutObject succeeded there would be no temporary object to
// delete.
defer xl.deleteObject(minioMetaTmpBucket, tempObj)
if size > 0 {
for _, disk := range onlineDisks {
if disk != nil {
actualSize := xl.sizeOnDisk(size, xlMeta.Erasure.BlockSize, xlMeta.Erasure.DataBlocks)
disk.PrepareFile(minioMetaTmpBucket, tempErasureObj, actualSize)
}
}
}
// Erasure code data and write across all disks.
sizeWritten, checkSums, err := erasureCreateFile(onlineDisks, minioMetaTmpBucket, tempErasureObj, teeReader, xlMeta.Erasure.BlockSize, xlMeta.Erasure.DataBlocks, xlMeta.Erasure.ParityBlocks, bitRotAlgo, xl.writeQuorum)
if err != nil {
return ObjectInfo{}, toObjectErr(err, minioMetaTmpBucket, tempErasureObj)
}
// Should return IncompleteBody{} error when reader has fewer bytes
// than specified in request header.
if sizeWritten < size {
return ObjectInfo{}, traceError(IncompleteBody{})
}
// For size == -1, perhaps client is sending in chunked encoding
// set the size as size that was actually written.
if size == -1 {
size = sizeWritten
}
// Save additional erasureMetadata.
modTime := time.Now().UTC()
newMD5Hex := hex.EncodeToString(md5Writer.Sum(nil))
// Update the md5sum if not set with the newly calculated one.
if len(metadata["md5Sum"]) == 0 {
metadata["md5Sum"] = newMD5Hex
}
// Guess content-type from the extension if possible.
if metadata["content-type"] == "" {
if objectExt := path.Ext(object); objectExt != "" {
if content, ok := mimedb.DB[strings.ToLower(strings.TrimPrefix(objectExt, "."))]; ok {
metadata["content-type"] = content.ContentType
}
}
}
// md5Hex representation.
md5Hex := metadata["md5Sum"]
if md5Hex != "" {
if newMD5Hex != md5Hex {
// Returns md5 mismatch.
return ObjectInfo{}, traceError(BadDigest{md5Hex, newMD5Hex})
}
}
if sha256sum != "" {
newSHA256sum := hex.EncodeToString(sha256Writer.Sum(nil))
if newSHA256sum != sha256sum {
return ObjectInfo{}, traceError(SHA256Mismatch{})
}
}
// Check if an object is present as one of the parent dir.
// -- FIXME. (needs a new kind of lock).
if xl.parentDirIsObject(bucket, path.Dir(object)) {
return ObjectInfo{}, toObjectErr(traceError(errFileAccessDenied), bucket, object)
}
// Rename if an object already exists to temporary location.
newUniqueID := mustGetUUID()
if xl.isObject(bucket, object) {
// Delete the temporary copy of the object that existed before this PutObject request.
defer xl.deleteObject(minioMetaTmpBucket, newUniqueID)
// NOTE: Do not use online disks slice here.
// The reason is that existing object should be purged
// regardless of `xl.json` status and rolled back in case of errors.
err = renameObject(xl.storageDisks, bucket, object, minioMetaTmpBucket, newUniqueID, xl.writeQuorum)
if err != nil {
return ObjectInfo{}, toObjectErr(err, bucket, object)
}
}
// Fill all the necessary metadata.
xlMeta.Meta = metadata
xlMeta.Stat.Size = size
xlMeta.Stat.ModTime = modTime
// Add the final part.
xlMeta.AddObjectPart(1, "part.1", newMD5Hex, xlMeta.Stat.Size)
partsMetadata := make([]xlMetaV1, len(xl.storageDisks))
// Update `xl.json` content on each disks.
for index := range partsMetadata {
partsMetadata[index] = xlMeta
partsMetadata[index].Erasure.AddCheckSumInfo(checkSumInfo{
Name: "part.1",
Hash: checkSums[index],
Algorithm: bitRotAlgo,
})
}
// Write unique `xl.json` for each disk.
if err = writeUniqueXLMetadata(onlineDisks, minioMetaTmpBucket, tempObj, partsMetadata, xl.writeQuorum); err != nil {
return ObjectInfo{}, toObjectErr(err, bucket, object)
}
// Rename the successfully written temporary object to final location.
err = renameObject(onlineDisks, minioMetaTmpBucket, tempObj, bucket, object, xl.writeQuorum)
if err != nil {
return ObjectInfo{}, toObjectErr(err, bucket, object)
}
// Once we have successfully renamed the object, Close the buffer which would
// save the object on cache.
if size > 0 && xl.objCacheEnabled && newBuffer != nil {
newBuffer.Close()
}
objInfo = ObjectInfo{
IsDir: false,
Bucket: bucket,
Name: object,
Size: xlMeta.Stat.Size,
ModTime: xlMeta.Stat.ModTime,
MD5Sum: xlMeta.Meta["md5Sum"],
ContentType: xlMeta.Meta["content-type"],
ContentEncoding: xlMeta.Meta["content-encoding"],
UserDefined: xlMeta.Meta,
}
return objInfo, nil
}
// deleteObject - wrapper for delete object, deletes an object from
// all the disks in parallel, including `xl.json` associated with the
// object.
func (xl xlObjects) deleteObject(bucket, object string) error {
// Initialize sync waitgroup.
var wg = &sync.WaitGroup{}
// Initialize list of errors.
var dErrs = make([]error, len(xl.storageDisks))
for index, disk := range xl.storageDisks {
if disk == nil {
dErrs[index] = traceError(errDiskNotFound)
continue
}
wg.Add(1)
go func(index int, disk StorageAPI) {
defer wg.Done()
err := cleanupDir(disk, bucket, object)
if err != nil && errorCause(err) != errVolumeNotFound {
dErrs[index] = err
}
}(index, disk)
}
// Wait for all routines to finish.
wg.Wait()
// Do we have write quorum?
if !isDiskQuorum(dErrs, xl.writeQuorum) {
// Return errXLWriteQuorum if errors were more than allowed write quorum.
return traceError(errXLWriteQuorum)
}
return nil
}
// DeleteObject - deletes an object, this call doesn't necessary reply
// any error as it is not necessary for the handler to reply back a
// response to the client request.
func (xl xlObjects) DeleteObject(bucket, object string) (err error) {
if err = checkDelObjArgs(bucket, object); err != nil {
return err
}
// Validate object exists.
if !xl.isObject(bucket, object) {
return traceError(ObjectNotFound{bucket, object})
} // else proceed to delete the object.
// Delete the object on all disks.
err = xl.deleteObject(bucket, object)
if err != nil {
return toObjectErr(err, bucket, object)
}
if xl.objCacheEnabled {
// Delete from the cache.
xl.objCache.Delete(pathJoin(bucket, object))
}
// Success.
return nil
}