From f76a0dec6d0ed95f30f63811da0d0adadb587313 Mon Sep 17 00:00:00 2001
From: Christian Schwarz <me@cschwarz.com>
Date: Tue, 27 Feb 2018 00:20:32 +0100
Subject: [PATCH] util.Semaphore: initial commit

---
 util/semaphore.go | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)
 create mode 100644 util/semaphore.go

diff --git a/util/semaphore.go b/util/semaphore.go
new file mode 100644
index 0000000..2a0d509
--- /dev/null
+++ b/util/semaphore.go
@@ -0,0 +1,17 @@
+package util
+
+type Semaphore struct {
+	c chan struct{}
+}
+
+func NewSemaphore(cap int) Semaphore {
+	return Semaphore{make(chan struct{}, cap)}
+}
+
+func (s Semaphore) Down() {
+	s.c <- struct{}{}
+}
+
+func (s Semaphore) Up() {
+	<-s.c
+}