fs/multipart: Append multipart parts in a proper Go routine in background. (#3282)
Krishna Srinivas
8 years ago
committed by
Harshavardhana
parent
38537c7df2
commit
afa4c7c3ef
@ -0,0 +1,210 @@ |
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/* |
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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 cmd |
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import ( |
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"errors" |
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"reflect" |
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"sync" |
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"time" |
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) |
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// Error sent by appendParts go-routine when there are holes in parts.
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// For ex. let's say client uploads part-2 before part-1 in which case we
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// can not append and have to wait till part-1 is uploaded. Hence we return
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// this error. Currently this error is not used in the caller.
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var errPartsMissing = errors.New("required parts missing") |
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// Error sent when appendParts go-routine has waited long enough and timedout.
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var errAppendPartsTimeout = errors.New("appendParts goroutine timeout") |
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// Timeout value for the appendParts go-routine.
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var appendPartsTimeout = 24 * 60 * 60 * time.Second |
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// Holds a map of uploadID->appendParts go-routine
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type backgroundAppend struct { |
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infoMap map[string]bgAppendPartsInfo |
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sync.Mutex |
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} |
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// Input to the appendParts go-routine
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type bgAppendPartsInput struct { |
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meta fsMetaV1 // list of parts that need to be appended
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errCh chan error // error sent by appendParts go-routine
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} |
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// Identifies an appendParts go-routine.
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type bgAppendPartsInfo struct { |
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inputCh chan bgAppendPartsInput |
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timeoutCh chan struct{} // closed by appendParts go-routine when it timesout
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endCh chan struct{} // closed after complete/abort of upload to end the appendParts go-routine
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} |
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// Called after a part is uploaded so that it can be appended in the background.
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func (b *backgroundAppend) append(disk StorageAPI, bucket, object, uploadID string, meta fsMetaV1) { |
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b.Lock() |
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info, ok := b.infoMap[uploadID] |
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if !ok { |
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// Corresponding appendParts go-routine was not found, create a new one. Would happen when the first
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// part of a multipart upload is uploaded.
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inputCh := make(chan bgAppendPartsInput) |
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timeoutCh := make(chan struct{}) |
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endCh := make(chan struct{}) |
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info = bgAppendPartsInfo{inputCh, timeoutCh, endCh} |
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b.infoMap[uploadID] = info |
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go b.appendParts(disk, bucket, object, uploadID, info) |
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} |
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b.Unlock() |
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go func() { |
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errCh := make(chan error) |
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// send input in a goroutine as send on the inputCh can block if appendParts go-routine
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// is busy appending a part.
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select { |
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case <-info.timeoutCh: |
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// This is to handle a rare race condition where we found info in b.infoMap
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// but soon after that appendParts go-routine timed out.
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case info.inputCh <- bgAppendPartsInput{meta, errCh}: |
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// Receive the error so that the appendParts go-routine does not block on send.
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// But the error received is ignored as fs.PutObjectPart() would have already
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// returned success to the client.
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<-errCh |
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} |
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}() |
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} |
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// Called on complete-multipart-upload. Returns nil if the required parts have been appended.
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func (b *backgroundAppend) complete(disk StorageAPI, bucket, object, uploadID string, meta fsMetaV1) error { |
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b.Lock() |
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info, ok := b.infoMap[uploadID] |
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b.Unlock() |
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if !ok { |
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return errPartsMissing |
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} |
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errCh := make(chan error) |
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select { |
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case <-info.timeoutCh: |
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// This is to handle a rare race condition where we found info in b.infoMap
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// but soon after that appendParts go-routine timedouted out.
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return errAppendPartsTimeout |
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case info.inputCh <- bgAppendPartsInput{meta, errCh}: |
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} |
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err := <-errCh |
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b.remove(uploadID) |
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return err |
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} |
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// Called after complete-multipart-upload or abort-multipart-upload so that the appendParts go-routine is not left dangling.
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func (b *backgroundAppend) remove(uploadID string) { |
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b.Lock() |
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defer b.Unlock() |
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info, ok := b.infoMap[uploadID] |
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if !ok { |
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return |
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} |
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delete(b.infoMap, uploadID) |
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close(info.endCh) |
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} |
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// This is run as a go-routine that appends the parts in the background.
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func (b *backgroundAppend) appendParts(disk StorageAPI, bucket, object, uploadID string, info bgAppendPartsInfo) { |
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// Holds the list of parts that is already appended to the "append" file.
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appendMeta := fsMetaV1{} |
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for { |
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select { |
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case input := <-info.inputCh: |
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// We receive on this channel when new part gets uploaded or when complete-multipart sends
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// a value on this channel to confirm if all the required parts are appended.
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meta := input.meta |
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for { |
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// Append should be done such a way that if part-3 and part-2 is uploaded before part-1, we
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// wait till part-1 is uploaded after which we append part-2 and part-3 as well in this for-loop.
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part, appendNeeded := partToAppend(meta, appendMeta) |
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if !appendNeeded { |
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if reflect.DeepEqual(meta.Parts, appendMeta.Parts) { |
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// Sending nil is useful so that the complete-multipart-upload knows that
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// all the required parts have been appended.
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input.errCh <- nil |
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} else { |
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// Sending error is useful so that complete-multipart-upload can fall-back to
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// its own append process.
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input.errCh <- errPartsMissing |
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} |
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break |
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} |
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if err := appendPart(disk, bucket, object, uploadID, part); err != nil { |
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input.errCh <- err |
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break |
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} |
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appendMeta.AddObjectPart(part.Number, part.Name, part.ETag, part.Size) |
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} |
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case <-info.endCh: |
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// Either complete-multipart-upload or abort-multipart-upload closed endCh to end the appendParts go-routine.
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appendFilePath := getFSAppendDataPath(uploadID) |
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disk.DeleteFile(bucket, appendFilePath) |
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return |
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case <-time.After(appendPartsTimeout): |
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// Timeout the goroutine to garbage collect its resources. This would happen if the client initiates
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// a multipart upload and does not complete/abort it.
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b.Lock() |
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delete(b.infoMap, uploadID) |
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b.Unlock() |
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// Delete the temporary append file as well.
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appendFilePath := getFSAppendDataPath(uploadID) |
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disk.DeleteFile(bucket, appendFilePath) |
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close(info.timeoutCh) |
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} |
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} |
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} |
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// Appends the "part" to the append-file inside "tmp/" that finally gets moved to the actual location
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// upon complete-multipart-upload.
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func appendPart(disk StorageAPI, bucket, object, uploadID string, part objectPartInfo) error { |
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partPath := pathJoin(mpartMetaPrefix, bucket, object, uploadID, part.Name) |
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appendFilePath := getFSAppendDataPath(uploadID) |
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offset := int64(0) |
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totalLeft := part.Size |
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buf := make([]byte, readSizeV1) |
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for totalLeft > 0 { |
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curLeft := int64(readSizeV1) |
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if totalLeft < readSizeV1 { |
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curLeft = totalLeft |
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} |
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var n int64 |
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n, err := disk.ReadFile(minioMetaBucket, partPath, offset, buf[:curLeft]) |
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if err != nil { |
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// Check for EOF/ErrUnexpectedEOF not needed as it should never happen as we know
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// the exact size of the file and hence know the size of buf[]
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// EOF/ErrUnexpectedEOF indicates that the length of file was shorter than part.Size and
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// hence considered as an error condition.
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disk.DeleteFile(bucket, appendFilePath) |
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return err |
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} |
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if err = disk.AppendFile(minioMetaBucket, appendFilePath, buf[:n]); err != nil { |
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disk.DeleteFile(bucket, appendFilePath) |
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return err |
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} |
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offset += n |
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totalLeft -= n |
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} |
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return nil |
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} |
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