From 6e9439f4e3344dbdea9aa4e215700774bb217ed1 Mon Sep 17 00:00:00 2001
From: James Shubin <james@shubin.ca>
Date: Thu, 14 Jan 2016 23:58:49 -0500
Subject: [PATCH] Avoid panic's when referencing non-existing objects

No idea why wrapping the cmd in a function avoids a panic. Probably
something about the gc...
---
 examples/graph8d.yaml | 15 +++++++++++++++
 exec.go               |  8 ++++++--
 types.go              | 12 ++++++++----
 3 files changed, 29 insertions(+), 6 deletions(-)
 create mode 100644 examples/graph8d.yaml

diff --git a/examples/graph8d.yaml b/examples/graph8d.yaml
new file mode 100644
index 00000000..4433ea59
--- /dev/null
+++ b/examples/graph8d.yaml
@@ -0,0 +1,15 @@
+---
+graph: mygraph
+types:
+  exec:
+  - name: exec1
+    cmd: echo hello from exec1
+    shell: ''
+    timeout: 0
+    watchcmd: sleep 5s
+    watchshell: ''
+    ifcmd: ''
+    ifshell: ''
+    pollint: 0
+    state: present
+edges: []
diff --git a/exec.go b/exec.go
index bc5eab89..d84683e6 100644
--- a/exec.go
+++ b/exec.go
@@ -132,8 +132,12 @@ func (obj *ExecType) Watch() {
 		}
 		scanner := bufio.NewScanner(cmdReader)
 
-		defer cmd.Wait()         // XXX: is this necessary?
-		defer cmd.Process.Kill() // TODO: is this necessary?
+		defer cmd.Wait() // XXX: is this necessary?
+		defer func() {
+			// FIXME: without wrapping this in this func it panic's
+			// when running examples/graph8d.yaml
+			cmd.Process.Kill() // TODO: is this necessary?
+		}()
 		if err := cmd.Start(); err != nil {
 			log.Printf("%v[%v]: Error starting Cmd: %v", obj.GetType(), obj.GetName(), err)
 			log.Fatal(err) // XXX: how should we handle errors?
diff --git a/types.go b/types.go
index 25174f09..0aeaf9dd 100644
--- a/types.go
+++ b/types.go
@@ -52,7 +52,7 @@ type Type interface {
 	SetVertex(*Vertex)
 	SetConvegedCallback(ctimeout int, converged chan bool)
 	Compare(Type) bool
-	SendEvent(eventName, bool, bool)
+	SendEvent(eventName, bool, bool) bool
 	IsWatching() bool
 	SetWatching(bool)
 	GetConvergedState() typeConvergedState
@@ -234,10 +234,14 @@ func (obj *BaseType) BackPoke() {
 }
 
 // push an event into the message queue for a particular type vertex
-func (obj *BaseType) SendEvent(event eventName, sync bool, activity bool) {
+func (obj *BaseType) SendEvent(event eventName, sync bool, activity bool) bool {
+	// TODO: isn't this race-y ?
+	if !obj.IsWatching() { // element has already exited
+		return false // if we don't return, we'll block on the send
+	}
 	if !sync {
 		obj.events <- Event{event, nil, "", activity}
-		return
+		return true
 	}
 
 	resp := make(chan bool)
@@ -246,7 +250,7 @@ func (obj *BaseType) SendEvent(event eventName, sync bool, activity bool) {
 		value := <-resp
 		// wait until true value
 		if value {
-			return
+			return true
 		}
 	}
 }