From 067b286a2e96b6e3f2d908043fd4b13db4dd6559 Mon Sep 17 00:00:00 2001
From: Louis Thibault <l.thibault@sentimens.com>
Date: Tue, 15 Feb 2022 18:29:38 -0500
Subject: [PATCH] Bugfix:  handle non-string panic values.

Fixes: https://github.com/thejerf/suture/issues/59
---
 v4/events.go     |  5 +++++
 v4/messages.go   |  6 +++---
 v4/supervisor.go | 13 ++++++++++---
 3 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/v4/events.go b/v4/events.go
index 0aa36aa..4d4ed33 100644
--- a/v4/events.go
+++ b/v4/events.go
@@ -19,6 +19,11 @@ type (
 	EventType int
 
 	EventHook func(Event)
+
+	// SprintFunc formats an arbitrary Go value into a string.
+	// It is used by the supervisor to format the value of a call
+	// to recover().
+	SprintFunc func(interface{}) string
 )
 
 const (
diff --git a/v4/messages.go b/v4/messages.go
index 054d392..380fd6e 100644
--- a/v4/messages.go
+++ b/v4/messages.go
@@ -29,13 +29,13 @@ type syncSupervisor struct {
 
 func (ss syncSupervisor) isSupervisorMessage() {}
 
-func (s *Supervisor) fail(id serviceID, panicMsg string, stacktrace []byte) {
-	s.control <- serviceFailed{id, panicMsg, stacktrace}
+func (s *Supervisor) fail(id serviceID, panicVal interface{}, stacktrace []byte) {
+	s.control <- serviceFailed{id, panicVal, stacktrace}
 }
 
 type serviceFailed struct {
 	id         serviceID
-	panicMsg   string
+	panicVal   interface{}
 	stacktrace []byte
 }
 
diff --git a/v4/supervisor.go b/v4/supervisor.go
index 781c347..db2f3b1 100644
--- a/v4/supervisor.go
+++ b/v4/supervisor.go
@@ -358,7 +358,7 @@ func (s *Supervisor) Serve(ctx context.Context) error {
 		case m := <-s.control:
 			switch msg := m.(type) {
 			case serviceFailed:
-				s.handleFailedService(ctx, msg.id, msg.panicMsg, msg.stacktrace, true)
+				s.handleFailedService(ctx, msg.id, msg.panicVal, msg.stacktrace, true)
 			case serviceEnded:
 				_, monitored := s.services[msg.id]
 				if monitored {
@@ -507,7 +507,7 @@ func (s *Supervisor) handleFailedService(ctx context.Context, id serviceID, err
 				CurrentFailures:  s.failures,
 				FailureThreshold: s.spec.FailureThreshold,
 				Restarting:       curState == normal,
-				PanicMsg:         err.(string),
+				PanicMsg:         s.spec.Sprint(err),
 				Stacktrace:       string(stacktrace),
 			})
 		} else {
@@ -543,7 +543,7 @@ func (s *Supervisor) runService(ctx context.Context, service Service, id service
 					buf := make([]byte, 65535)
 					written := runtime.Stack(buf, false)
 					buf = buf[:written]
-					s.fail(id, r.(string), buf)
+					s.fail(id, r, buf)
 				}
 			}()
 		}
@@ -848,6 +848,7 @@ var ErrSupervisorNotStarted = errors.New("supervisor not started yet")
 // supervisor. See the New function for full documentation.
 type Spec struct {
 	EventHook                EventHook
+	Sprint                   SprintFunc
 	FailureDecay             float64
 	FailureThreshold         float64
 	FailureBackoff           time.Duration
@@ -880,4 +881,10 @@ func (s *Spec) configureDefaults(supervisorName string) {
 			log.Print(e)
 		}
 	}
+
+	if s.Sprint == nil {
+		s.Sprint = func(v interface{}) string {
+			return fmt.Sprintf("%v", v)
+		}
+	}
 }