From be9a01cc03d6cdddf4d4b27b3f5deebe0c87eb15 Mon Sep 17 00:00:00 2001
From: Todd Gruben <todd@molecula.com>
Date: Sun, 19 Feb 2023 15:25:57 -0600
Subject: [PATCH] multi-reader take 2

---
 ctl/broadcast.go | 56 +++++++++++-------------------------------------
 1 file changed, 12 insertions(+), 44 deletions(-)

diff --git a/ctl/broadcast.go b/ctl/broadcast.go
index 9ef644356..6de80f688 100644
--- a/ctl/broadcast.go
+++ b/ctl/broadcast.go
@@ -2,69 +2,37 @@ package ctl
 
 import (
 	"io"
+	"io/ioutil"
 )
 
 type Broadcaster struct {
 	source  io.Reader
 	Readers []io.Reader
+	Writers []io.Writer
 }
 
 func (b *Broadcaster) Consume() {
-	if len(b.Readers) == 1 {
+	if b.source == nil {
 		return
 	}
-	buf := make([]byte, 65535)
-	for {
-		n, err := b.source.Read(buf)
-		if err == io.EOF {
-			// close and shutdown
-			b.shutdown()
-			return
-		}
-		buf = buf[:n]
-		for _, s := range b.Readers {
-			subscriber := s.(*Subscriber)
-			// possibly a timeout channel here
-			subscriber.src <- buf
-		}
-
+	io.Copy(ioutil.Discard, b.source)
+	for _, cl := range b.Writers {
+		c := cl.(io.WriteCloser)
+		c.Close()
 	}
 }
 
-func (b *Broadcaster) shutdown() {
-	for _, s := range b.Readers {
-		subscriber := s.(*Subscriber)
-		close(subscriber.src)
-	}
-}
-
-type Subscriber struct {
-	src   chan []byte
-	local []byte
-	i     int
-}
-
-func (s *Subscriber) Read(b []byte) (n int, err error) {
-	if len(s.local) == 0 {
-		s.local = <-s.src
-	}
-	if len(s.local) == 0 {
-		return 0, io.EOF
-	}
-	n = copy(b, s.local)
-	s.local = s.local[n:]
-	return n, nil
-}
-
 func NewBroadcaster(reader io.Reader, numSubscribers int) *Broadcaster {
-	b := &Broadcaster{Readers: make([]io.Reader, numSubscribers)}
+	b := &Broadcaster{Readers: make([]io.Reader, numSubscribers), Writers: make([]io.Writer, numSubscribers)}
 	if numSubscribers == 1 {
 		b.Readers[0] = reader
 		return b
 	}
 	for i := 0; i < len(b.Readers); i++ {
-		b.Readers[i] = &Subscriber{src: make(chan []byte)}
+		r, w := io.Pipe()
+		b.Readers[i] = r
+		b.Writers[i] = w
 	}
-	b.source = reader
+	b.source = io.TeeReader(reader, io.MultiWriter(b.Writers...))
 	return b
 }