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258 lines
5.3 KiB
258 lines
5.3 KiB
/*
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* mjpeg-proxy -- Republish a MJPEG HTTP image stream using a server in Go
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*
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* Copyright (C) 2015-2020, Valentin Vidic
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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package main
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import (
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"errors"
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"fmt"
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"io"
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"io/ioutil"
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"mime/multipart"
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"net/http"
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"net/url"
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"strings"
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"time"
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)
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/* Sample source stream starts like this:
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HTTP/1.1 200 OK
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Content-Type: multipart/x-mixed-replace;boundary=myboundary
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Cache-Control: no-cache
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Pragma: no-cache
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--myboundary
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Content-Type: image/jpeg
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Content-Length: 36291
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JPEG data...
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*/
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type Chunker struct {
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id string
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source string
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username string
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password string
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resp *http.Response
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boundary string
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stop chan struct{}
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rate float64
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}
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func NewChunker(id, source, username, password string, rate float64) (*Chunker, error) {
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chunker := new(Chunker)
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sourceUrl, err := url.Parse(source)
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if err != nil {
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return nil, err
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}
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if !sourceUrl.IsAbs() {
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return nil, fmt.Errorf("uri is not absolute: %s", source)
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}
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chunker.id = id
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chunker.source = source
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chunker.username = username
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chunker.password = password
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chunker.rate = rate
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return chunker, nil
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}
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func (chunker *Chunker) Connect() error {
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fmt.Printf("chunker[%s]: connecting to %s\n", chunker.id, chunker.source)
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req, err := http.NewRequest("GET", chunker.source, nil)
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if err != nil {
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return err
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}
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if chunker.username != "" && chunker.password != "" {
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req.SetBasicAuth(chunker.username, chunker.password)
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}
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client := &http.Client{}
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resp, err := client.Do(req)
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if err != nil {
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return err
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}
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if resp.StatusCode != http.StatusOK {
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chunker.closeResponse(resp)
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return fmt.Errorf("request failed: %s", resp.Status)
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}
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boundary, err := getBoundary(resp)
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if err != nil {
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chunker.closeResponse(resp)
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return err
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}
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chunker.resp = resp
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chunker.boundary = boundary
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chunker.stop = make(chan struct{})
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return nil
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}
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func (chunker *Chunker) closeResponse(resp *http.Response) {
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err := resp.Body.Close()
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if err != nil {
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fmt.Printf("chunker[%s]: body close failed: %s\n", chunker.id, err)
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}
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}
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func parseMediaType(contentType string) (string, map[string]string) {
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mediaType := ""
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params := make(map[string]string)
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for i, s := range strings.Split(contentType, ";") {
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part := strings.TrimSpace(s)
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if i == 0 {
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mediaType = part
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continue
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}
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kv := strings.SplitN(part, "=", 2)
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k := kv[0]
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v := ""
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if len(kv) > 1 {
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v = kv[1]
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}
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if len(v) > 1 && v[0] == '"' && v[len(v)-1] == '"' {
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v = v[1 : len(v)-1]
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}
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params[k] = v
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}
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return mediaType, params
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}
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func getBoundary(resp *http.Response) (string, error) {
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contentType := resp.Header.Get("Content-Type")
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mediaType, params := parseMediaType(contentType)
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if !strings.HasPrefix(mediaType, "multipart/") {
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return "", fmt.Errorf("unexpected media type: %s", contentType)
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}
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boundary := params["boundary"]
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if boundary == "" {
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return "", fmt.Errorf("boundary not found: %s", contentType)
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}
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return boundary, nil
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}
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func (chunker *Chunker) GetHeader() http.Header {
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return chunker.resp.Header
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}
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func (chunker *Chunker) Start(pubChan chan []byte) {
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fmt.Printf("chunker[%s]: started\n", chunker.id)
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body := chunker.resp.Body
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defer func() {
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err := body.Close()
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if err != nil {
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fmt.Printf("chunker[%s]: body close failed: %s\n", chunker.id, err)
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}
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}()
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defer close(pubChan)
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var failure error
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mr := multipart.NewReader(body, chunker.boundary)
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var ticker *time.Ticker
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firstFrame := true
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if chunker.rate > 0 {
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interval := float64(time.Second) / chunker.rate
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ticker = time.NewTicker(time.Duration(interval))
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}
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ChunkLoop:
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for {
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part, err := mr.NextPart()
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if err == io.EOF {
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break ChunkLoop
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}
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if err != nil {
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failure = err
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break ChunkLoop
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}
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data, err := ioutil.ReadAll(part)
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if err != nil {
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failure = err
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break ChunkLoop
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}
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err = part.Close()
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if err != nil {
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failure = err
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break ChunkLoop
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}
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if len(data) == 0 {
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failure = errors.New("received final chunk of size 0")
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break ChunkLoop
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}
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select { // check for stop
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case <-chunker.stop:
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break ChunkLoop
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default:
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}
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if !firstFrame && ticker != nil {
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select {
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case <-ticker.C: // use frame
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default: // skip frame
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continue ChunkLoop
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}
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}
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firstFrame = false
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pubChan <- data
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}
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if ticker != nil {
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ticker.Stop()
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}
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if failure != nil {
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fmt.Printf("chunker[%s]: failed: %s\n", chunker.id, failure)
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} else {
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fmt.Printf("chunker[%s]: stopped\n", chunker.id)
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}
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}
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func (chunker *Chunker) Stop() {
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fmt.Printf("chunker[%s]: stopping\n", chunker.id)
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close(chunker.stop)
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}
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func (chunker *Chunker) Started() bool {
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if chunker.stop == nil { // Never started
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return false
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}
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select {
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case <-chunker.stop: // Already stopped
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return false
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default:
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return true // Still running
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}
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}
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