svc: support closing via context (#13)

svc/svc.go

@@ -1,6 +1,9 @@
 package svc
 
-import "os/signal"
+import (
+	"context"
+	"os/signal"
+)
 
 // Create variable signal.Notify function so we can mock it in tests
 var signalNotify = signal.Notify
@@ -27,6 +30,13 @@ type Service interface {
 	Stop() error
 }
 
+// Context interface contains an optional Context function which a Service can implement.
+// When implemented the context.Done() channel will be used in addition to signal handling
+// to exit a process.
+type Context interface {
+	Context() context.Context
+}
+
 // Environment contains information about the environment
 // your application is running in.
 type Environment interface {

svc/svc_other.go

@@ -9,7 +9,7 @@ import (
 
 // Run runs your Service.
 //
-// Run will block until one of the signals specified in sig is received.
+// Run will block until one of the signals specified in sig is received or a provided context is done.
 // If sig is empty syscall.SIGINT and syscall.SIGTERM are used by default.
 func Run(service Service, sig ...os.Signal) error {
 	env := environment{}
@@ -27,7 +27,16 @@ func Run(service Service, sig ...os.Signal) error {
 
 	signalChan := make(chan os.Signal, 1)
 	signalNotify(signalChan, sig...)
-	<-signalChan
+
+	var doneChan <-chan struct{}
+	if s, ok := service.(Context); ok {
+		doneChan = s.Context().Done()
+	}
+
+	select {
+	case <-signalChan:
+	case <-doneChan:
+	}
 
 	return service.Stop()
 }