Added start signal, and used it to restore gql server if was previously running

gql.go

@@ -1000,18 +1000,35 @@ func (ext *GQLExt) Process(ctx *Context, source NodeID, node *Node, signal Signa
     sig := signal.(StringSignal)
     switch sig.Str {
     case "start_server":
+      if ext.State == "stopped" {
         err := ext.StartGQLServer(ctx, node)
         if err == nil {
+          ext.State = "running"
           ctx.Send(node.ID, source, StringSignal{NewDirectSignal(GQLStateSignalType), "server_started"})
         }
+      }
     case "stop_server":
+      if ext.State == "running" {
         err := ext.StopGQLServer()
         if err == nil {
+          ext.State = "stopped"
           ctx.Send(node.ID, source, StringSignal{NewDirectSignal(GQLStateSignalType), "server_stopped"})
         }
+      }
     default:
       ctx.Log.Logf("gql", "unknown gql state %s", sig.Str)
     }
+  } else if signal.Type() == StartSignalType {
+    switch ext.State {
+    case "running":
+      err := ext.StartGQLServer(ctx, node)
+      if err == nil {
+        ctx.Send(node.ID, source, StringSignal{NewDirectSignal(GQLStateSignalType), "server_started"})
+      }
+    case "stopped":
+    default:
+      ctx.Log.Logf("gql", "unknown state to restore from: %s", ext.State)
+    }
   }
 }
 
@@ -1090,6 +1107,7 @@ func NewGQLExt(ctx *Context, listen string, tls_cert []byte, tls_key []byte, sta
     tls_key = ssl_key_pem
   }
   return &GQLExt{
+    State: state,
     Listen: listen,
     resolver_reads: map[uuid.UUID]uuid.UUID{},
     resolver_chans: map[uuid.UUID]chan *ReadResultSignal{},

gql_test.go

@@ -20,7 +20,7 @@ func TestGQL(t *testing.T) {
   err := ctx.RegisterNodeType(TestNodeType, []ExtType{LockableExtType, ACLExtType})
   fatalErr(t, err)
 
-  gql_ext, err := NewGQLExt(ctx, ":0", nil, nil, "start")
+  gql_ext, err := NewGQLExt(ctx, ":0", nil, nil, "stopped")
   fatalErr(t, err)
   listener_ext := NewListenerExt(10)
   policy := NewAllNodesPolicy(Actions{MakeAction("+")})

node.go

@@ -195,6 +195,10 @@ func nodeLoop(ctx *Context, node *Node) error {
   if started == false {
     return fmt.Errorf("%s is already started, will not start again", node.ID)
   }
+
+  // Queue the signal for extensions to perform startup actions
+  node.QueueSignal(time.Now(), NewDirectSignal(StartSignalType))
+
   for true {
     var signal Signal
     var source NodeID

signal.go

@@ -17,6 +17,7 @@ import (
 type SignalDirection int
 const (
   StopSignalType SignalType = "STOP"
+  StartSignalType           = "START"
   ErrorSignalType           = "ERROR"
   StatusSignalType          = "STATUS"
   LinkSignalType            = "LINK"