From a719cd25a1a9f48f48f2e6a86541b624b5bfe45d Mon Sep 17 00:00:00 2001
From: Reya C <reya.gitea@reya.zone>
Date: Sat, 3 Apr 2021 01:58:25 -0400
Subject: [PATCH] Add concurrency limiting semaphore

---
 drive-demuxer.go | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drive-demuxer.go b/drive-demuxer.go
index 87fe422..bac12d3 100644
--- a/drive-demuxer.go
+++ b/drive-demuxer.go
@@ -16,6 +16,7 @@ type TopLevel struct {
 	LeftOutput     string
 	CombinedOutput string
 	RightOutput    string
+	OpenHandles    chan int
 }
 
 type Step struct {
@@ -181,7 +182,7 @@ func (s *Step) ListChildren() []string {
 		results[file.Name()] = true
 	}
 	out := make([]string, 0, len(results))
-	for file, _ := range results {
+	for file := range results {
 		out = append(out, file)
 	}
 	return out
@@ -298,7 +299,11 @@ func (s *Step) Walk() {
 				}
 				wg.Add(1)
 				go func() {
-					defer func() { wg.Done() }()
+					defer func() {
+						<-s.OpenHandles
+						wg.Done()
+					}()
+					s.OpenHandles <- 1
 					substep.Walk()
 					s.RemoveInputDirs(child)
 				}()
@@ -314,7 +319,9 @@ func (s *Step) Walk() {
 }
 
 func main() {
-	settings := TopLevel{}
+	settings := TopLevel{
+		OpenHandles: make(chan int, 300),
+	}
 	flag.StringVar(&settings.LeftInput,
 		"left-input", "./input/left", "The name of the left side of the input.")
 	flag.StringVar(&settings.RightInput,