174 lines
4.7 KiB
Go
174 lines
4.7 KiB
Go
/*
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* Mini Object Storage, (C) 2014 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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// +build amd64
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package split
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import (
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"bufio"
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"bytes"
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"errors"
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"io"
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"io/ioutil"
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"os"
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"strconv"
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"strings"
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)
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// Message structure for results from the SplitStream goroutine
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type SplitMessage struct {
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Data []byte
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Err error
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}
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type JoinMessage struct {
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Reader io.Reader
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Length int64
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Err error
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}
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// SplitStream reads from io.Reader, splits the data into chunks, and sends
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// each chunk to the channel. This method runs until an EOF or error occurs. If
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// an error occurs, the method sends the error over the channel and returns.
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// Before returning, the channel is always closed.
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//
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// The user should run this as a gorountine and retrieve the data over the
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// channel.
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//
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// channel := make(chan SplitMessage)
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// go SplitStream(reader, chunkSize, channel)
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// for chunk := range channel {
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// log.Println(chunk.Data)
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// }
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func SplitStream(reader io.Reader, chunkSize uint64) <-chan SplitMessage {
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ch := make(chan SplitMessage)
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go splitStreamGoRoutine(reader, chunkSize, ch)
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return ch
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}
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func splitStreamGoRoutine(reader io.Reader, chunkSize uint64, ch chan SplitMessage) {
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// we read until EOF or another error
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var readError error
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// run this until an EOF or error occurs
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for readError == nil {
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// keep track of how much data has been read
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var totalRead uint64
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// Create a buffer to write the current chunk into
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var bytesBuffer bytes.Buffer
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bytesWriter := bufio.NewWriter(&bytesBuffer)
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// read a full chunk
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for totalRead < chunkSize && readError == nil {
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var currentRead int
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// if we didn't read a full chunk, we should attempt to read again.
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// We create a byte array representing how much space is left
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// unwritten in the given chunk
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chunk := make([]byte, chunkSize-totalRead)
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currentRead, readError = reader.Read(chunk)
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// keep track of how much we have read in total
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totalRead = totalRead + uint64(currentRead)
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// prune the array to only what has been read, write to chunk buffer
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chunk = chunk[0:currentRead]
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bytesWriter.Write(chunk)
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}
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// flush stream to underlying byte buffer
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bytesWriter.Flush()
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// if we have data available, send it over the channel
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if bytesBuffer.Len() != 0 {
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ch <- SplitMessage{bytesBuffer.Bytes(), nil}
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}
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}
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// if we have an error other than an EOF, send it over the channel
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if readError != io.EOF {
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ch <- SplitMessage{nil, readError}
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}
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// close the channel, signaling the channel reader that the stream is complete
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close(ch)
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}
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func JoinFiles(dirname string, inputPrefix string) io.Reader {
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reader, writer := io.Pipe()
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fileInfos, readError := ioutil.ReadDir(dirname)
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if readError != nil {
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writer.CloseWithError(readError)
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}
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var newfileInfos []os.FileInfo
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for _, fi := range fileInfos {
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if strings.Contains(fi.Name(), inputPrefix) == true {
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newfileInfos = append(newfileInfos, fi)
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}
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}
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if len(newfileInfos) == 0 {
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writer.CloseWithError(errors.New("no files found for given prefix"))
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}
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go joinFilesGoRoutine(newfileInfos, writer)
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return reader
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}
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func joinFilesGoRoutine(fileInfos []os.FileInfo, writer *io.PipeWriter) {
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for _, fileInfo := range fileInfos {
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file, err := os.Open(fileInfo.Name())
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defer file.Close()
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for err != nil {
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writer.CloseWithError(err)
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return
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}
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_, err = io.Copy(writer, file)
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if err != nil {
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writer.CloseWithError(err)
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return
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}
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}
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writer.Close()
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}
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// Takes a file and splits it into chunks with size chunkSize. The output
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// filename is given with outputPrefix.
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func SplitFileWithPrefix(filename string, chunkSize uint64, outputPrefix string) error {
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// open file
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file, err := os.Open(filename)
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defer file.Close()
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if err != nil {
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return err
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}
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if outputPrefix == "" {
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return errors.New("Invalid argument outputPrefix cannot be empty string")
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}
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// start stream splitting goroutine
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ch := SplitStream(file, chunkSize)
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// used to write each chunk out as a separate file. {{outputPrefix}}.{{i}}
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i := 0
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// write each chunk out to a separate file
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for chunk := range ch {
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if chunk.Err != nil {
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return chunk.Err
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}
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err := ioutil.WriteFile(outputPrefix+"."+strconv.Itoa(i), chunk.Data, 0600)
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if err != nil {
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return err
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}
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i = i + 1
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}
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return nil
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}
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