Multi-threading

README.md

@@ -3,6 +3,10 @@ Gotube is a YouTube downloader using go language.
 go language is a new light-weight language developed by Google, 
 it provides not only many powerful libraries, but also a simple multi-threading syntax.
 
+This tool is an easy way to download any non-age-restricted videos in YouTube. 
+You can also perform batch downloading by keywords via search function.
+Gotube will generate a number of go-routines (no more than the number of your CPU cores) to download multiple videos simultaneously. 
+
 ##Installation
 - Install go from [https://golang.org/](https://golang.org/)
 - Set up go environment as in [https://golang.org/doc/install](https://golang.org/doc/install)

script.go

@@ -5,6 +5,8 @@ import (
  "fmt"
  . "github.com/KeluDiao/gotube/api"
  "log"
+ "runtime"
+ "sync"
 )
 
 func main() {
@@ -77,25 +79,42 @@ func main() {
  if *isRetList {
  fmt.Printf("The top %v results for key words \"%v\" are:\n\n", *k, *search)
  }
+ //Waiting group is used to prevent main thread ending before child threads end
+ wg := new(sync.WaitGroup)
+ wg.Add(len(ids))
+ //Channel is used to control the maximum threads
+ end := make(chan bool, MaxParallelism())
  for _, vid := range ids {
  vl, err = GetVideoListFromId(vid)
  if err != nil {
  log.Fatal(err)
  }
- Exec(vl, *isDownload, *isRetList, *rep, *quality, *extension)
+ go Exec(vl, *isDownload, *isRetList, *rep, *quality, *extension, wg, end)
+ end <- true
  }
+ wg.Wait()
  return
  }
  if err != nil {
  log.Fatal(err)
  }
- Exec(vl, *isDownload, *isRetList, *rep, *quality, *extension)
+ //dummy variables
+ wg := new(sync.WaitGroup)
+ wg.Add(1)
+ var end chan bool
+ Exec(vl, *isDownload, *isRetList, *rep, *quality, *extension, wg, end)
 }
 
 /*
 * Choose either downloading or retrieving video list
 */
-func Exec(vl VideoList, isDownload, isRetList bool, rep, quality, extension string) {
+func Exec(vl VideoList, isDownload, isRetList bool, rep, quality, extension string, wg *sync.WaitGroup, end chan bool) {
+ //Set up synchronization function
+ defer func() {
+ <- end
+ wg.Done()
+ }
+
  if isDownload {
  fmt.Printf("Downloading %v...\n", vl.Title)
  err := vl.Download(rep, quality, extension)
@@ -110,4 +129,16 @@ func Exec(vl VideoList, isDownload, isRetList bool, rep, quality, extension stri
  }
  fmt.Println(vl)
  }
+}
+
+/*
+* Find out the maximum go routines allowed
+*/
+func MaxParallelism() int {
+ maxProcs := runtime.GOMAXPROCS(0)
+ numCPU := runtime.NumCPU()
+ if maxProcs < numCPU {
+ return maxProcs
+ }
+ return numCPU
 }