/*
* 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"
"io"
"os"
"reflect"
"sync"
"time"
)
// Error sent by appendParts go-routine when there are holes in parts.
// For ex. let's say client uploads part-2 before part-1 in which case we
// can not append and have to wait till part-1 is uploaded. Hence we return
// this error. Currently this error is not used in the caller.
var errPartsMissing = errors.New("required parts missing")
// Error sent when appendParts go-routine has waited long enough and timedout.
var errAppendPartsTimeout = errors.New("appendParts go-routine timeout")
// Timeout value for the appendParts go-routine.
var appendPartsTimeout = 24 * 60 * 60 * time.Second // 24 Hours.
// Holds a map of uploadID->appendParts go-routine
type backgroundAppend struct {
sync.Mutex
infoMap map[string]bgAppendPartsInfo
appendFile io.WriteCloser
}
// Input to the appendParts go-routine
type bgAppendPartsInput struct {
meta fsMetaV1 // list of parts that need to be appended
errCh chan error // error sent by appendParts go-routine
}
// Identifies an appendParts go-routine.
type bgAppendPartsInfo struct {
inputCh chan bgAppendPartsInput
timeoutCh chan struct{} // closed by appendParts go-routine when it timesout
abortCh chan struct{} // closed after abort of upload to end the appendParts go-routine
completeCh chan struct{} // closed after complete of upload to end the appendParts go-routine
}
// Called after a part is uploaded so that it can be appended in the background.
func (fs fsObjects) append(bucket, object, uploadID string, meta fsMetaV1) chan error {
fs.bgAppend.Lock()
info, ok := fs.bgAppend.infoMap[uploadID]
if !ok {
// Corresponding appendParts go-routine was not found, create a new one. Would happen when the first
// part of a multipart upload is uploaded.
inputCh := make(chan bgAppendPartsInput)
timeoutCh := make(chan struct{})
abortCh := make(chan struct{})
completeCh := make(chan struct{})
info = bgAppendPartsInfo{inputCh, timeoutCh, abortCh, completeCh}
fs.bgAppend.infoMap[uploadID] = info
go fs.appendParts(bucket, object, uploadID, info)
}
fs.bgAppend.Unlock()
errCh := make(chan error)
go func() {
// send input in a goroutine as send on the inputCh can block if appendParts go-routine
// is busy appending a part.
select {
case <-info.timeoutCh:
// This is to handle a rare race condition where we found info in b.infoMap
// but soon after that appendParts go-routine timed out.
errCh <- errAppendPartsTimeout
case info.inputCh <- bgAppendPartsInput{meta, errCh}:
}
}()
return errCh
}
// Called on complete-multipart-upload. Returns nil if the required parts have been appended.
func (fs *fsObjects) complete(bucket, object, uploadID string, meta fsMetaV1) error {
fs.bgAppend.Lock()
defer fs.bgAppend.Unlock()
info, ok := fs.bgAppend.infoMap[uploadID]
delete(fs.bgAppend.infoMap, uploadID)
if !ok {
return errPartsMissing
}
errCh := make(chan error)
select {
case <-info.timeoutCh:
// This is to handle a rare race condition where we found info in b.infoMap
// but soon after that appendParts go-routine timedouted out.
return errAppendPartsTimeout
case info.inputCh <- bgAppendPartsInput{meta, errCh}:
}
err := <-errCh
close(info.completeCh)
return err
}
// Called after complete-multipart-upload or abort-multipart-upload so that the appendParts go-routine is not left dangling.
func (fs fsObjects) abort(uploadID string) {
fs.bgAppend.Lock()
defer fs.bgAppend.Unlock()
info, ok := fs.bgAppend.infoMap[uploadID]
if !ok {
return
}
delete(fs.bgAppend.infoMap, uploadID)
info.abortCh <- struct{}{}
}
// This is run as a go-routine that appends the parts in the background.
func (fs fsObjects) appendParts(bucket, object, uploadID string, info bgAppendPartsInfo) {
appendPath := pathJoin(fs.fsPath, minioMetaTmpBucket, fs.fsUUID, uploadID)
// Holds the list of parts that is already appended to the "append" file.
appendMeta := fsMetaV1{}
// Allocate staging read buffer.
buf := make([]byte, readSizeV1)
for {
select {
case input := <-info.inputCh:
// We receive on this channel when new part gets uploaded or when complete-multipart sends
// a value on this channel to confirm if all the required parts are appended.
meta := input.meta
for {
// Append should be done such a way that if part-3 and part-2 is uploaded before part-1, we
// wait till part-1 is uploaded after which we append part-2 and part-3 as well in this for-loop.
part, appendNeeded := partToAppend(meta, appendMeta)
if !appendNeeded {
if reflect.DeepEqual(meta.Parts, appendMeta.Parts) {
// Sending nil is useful so that the complete-multipart-upload knows that
// all the required parts have been appended.
input.errCh <- nil
} else {
// Sending error is useful so that complete-multipart-upload can fall-back to
// its own append process.
input.errCh <- errPartsMissing
}
break
}
if err := fs.appendPart(bucket, object, uploadID, part, buf); err != nil {
fsRemoveFile(appendPath)
appendMeta.Parts = nil
input.errCh <- err
break
}
appendMeta.AddObjectPart(part.Number, part.Name, part.ETag, part.Size)
}
case <-info.abortCh:
// abort-multipart-upload closed abortCh to end the appendParts go-routine.
fsRemoveFile(appendPath)
// So that any racing PutObjectPart does not leave a dangling go-routine.
close(info.timeoutCh)
return
case <-info.completeCh:
// complete-multipart-upload closed completeCh to end the appendParts go-routine.
close(info.timeoutCh) // So that any racing PutObjectPart does not leave a dangling go-routine.
return
case <-time.After(appendPartsTimeout):
// Timeout the goroutine to garbage collect its resources. This would happen if the client initiates
// a multipart upload and does not complete/abort it.
fs.bgAppend.Lock()
delete(fs.bgAppend.infoMap, uploadID)
fs.bgAppend.Unlock()
// Delete the temporary append file as well.
fsRemoveFile(appendPath)
close(info.timeoutCh)
return
}
}
}
// Appends the "part" to the append-file inside "tmp/" that finally gets moved to the actual location
// upon complete-multipart-upload.
func (fs fsObjects) appendPart(bucket, object, uploadID string, part objectPartInfo, buf []byte) error {
partPath := pathJoin(fs.fsPath, minioMetaMultipartBucket, bucket, object, uploadID, part.Name)
offset := int64(0)
// Read each file part to start writing to the temporary concatenated object.
file, size, err := fsOpenFile(partPath, offset)
if err != nil {
if err == errFileNotFound {
return errPartsMissing
}
return err
}
defer file.Close()
tmpObjPath := pathJoin(fs.fsPath, minioMetaTmpBucket, fs.fsUUID, uploadID)
// No need to hold a lock, this is a unique file and will be only written
// to one one process per uploadID per minio process.
wfile, err := os.OpenFile(preparePath(tmpObjPath), os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0666)
if err != nil {
return err
}
defer wfile.Close()
// Fallocate more space as we concatenate.
if err = fsFAllocate(int(wfile.Fd()), 0, size); err != nil {
return err
}
_, err = io.CopyBuffer(wfile, file, buf)
return err
}