Add WebTorrent module

pkg/core/helpers.go

@@ -1,71 +1,19 @@
 package core
 
 import (
-	"sync"
+	cryptorand "crypto/rand"
 )
 
-// Waiter support:
-// - autotart on first Wait
-// - block new waiters after last Done
-// - safe Done after finish
-type Waiter struct {
-	sync.WaitGroup
-	mu    sync.Mutex
-	state int // state < 0 means finish
-}
+const digits = "0123456789abcdefghijklmnopqrstuvwxyz"
+const maxSize = byte(len(digits))
 
-func (w *Waiter) Add(delta int) {
-	w.mu.Lock()
-	if w.state >= 0 {
-		w.state += delta
-		w.WaitGroup.Add(delta)
+func RandString(size byte) string {
+	b := make([]byte, size)
+	if _, err := cryptorand.Read(b); err != nil {
+		panic(err)
 	}
-	w.mu.Unlock()
-}
-
-func (w *Waiter) Wait() {
-	w.mu.Lock()
-	// first wait auto start waiter
-	if w.state == 0 {
-		w.state++
-		w.WaitGroup.Add(1)
+	for i := byte(0); i < size; i++ {
+		b[i] = digits[b[i]%maxSize]
 	}
-	w.mu.Unlock()
-
-	w.WaitGroup.Wait()
-}
-
-func (w *Waiter) Done() {
-	w.mu.Lock()
-
-	// safe run Done only when have tasks
-	if w.state > 0 {
-		w.state--
-		w.WaitGroup.Done()
-	}
-
-	// block waiter for any operations after last done
-	if w.state == 0 {
-		w.state = -1
-	}
-
-	w.mu.Unlock()
-}
-
-func (w *Waiter) WaitChan() <-chan struct{} {
-	var ch chan struct{}
-
-	w.mu.Lock()
-
-	if w.state >= 0 {
-		ch = make(chan struct{})
-		go func() {
-			w.Wait()
-			ch <- struct{}{}
-		}()
-	}
-
-	w.mu.Unlock()
-
-	return ch
+	return string(b)
 }