From 9c53bcd6fefd554246da88d55efcc283aff63659 Mon Sep 17 00:00:00 2001
From: Peter Bourgon <peterbourgon@users.noreply.github.com>
Date: Wed, 8 Jan 2020 06:15:07 +0100
Subject: [PATCH] Add SignalHandler helper (#13)

---
 actors.go | 38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)
 create mode 100644 actors.go

diff --git a/actors.go b/actors.go
new file mode 100644
index 0000000..ef93495
--- /dev/null
+++ b/actors.go
@@ -0,0 +1,38 @@
+package run
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"os/signal"
+)
+
+// SignalHandler returns an actor, i.e. an execute and interrupt func, that
+// terminates with SignalError when the process receives one of the provided
+// signals, or the parent context is canceled.
+func SignalHandler(ctx context.Context, signals ...os.Signal) (execute func() error, interrupt func(error)) {
+	ctx, cancel := context.WithCancel(ctx)
+	return func() error {
+			c := make(chan os.Signal, 1)
+			signal.Notify(c, signals...)
+			select {
+			case sig := <-c:
+				return SignalError{Signal: sig}
+			case <-ctx.Done():
+				return ctx.Err()
+			}
+		}, func(error) {
+			cancel()
+		}
+}
+
+// SignalError is returned by the signal handler's execute function
+// when it terminates due to a received signal.
+type SignalError struct {
+	Signal os.Signal
+}
+
+// Error implements the error interface.
+func (e SignalError) Error() string {
+	return fmt.Sprintf("received signal %s", e.Signal)
+}