From 6c88f7c6b9d8cc6bbf615791dac973e89ae2ba9b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Timoth=C3=A9=20Larivi=C3=A8re?=
 <timothe.lariviere@kanoyatech.com>
Date: Mon, 12 Feb 2024 16:39:09 +0100
Subject: [PATCH] Improve handling of messages after Runner gets disposed

---
 src/Fabulous/MvuComponent.fs | 10 ++++++++--
 src/Fabulous/Runner.fs       | 10 +++++++---
 2 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/src/Fabulous/MvuComponent.fs b/src/Fabulous/MvuComponent.fs
index 379e89e5f..a93978a72 100644
--- a/src/Fabulous/MvuComponent.fs
+++ b/src/Fabulous/MvuComponent.fs
@@ -28,8 +28,14 @@ module MvuComponent =
 
                         let ctx = new ComponentContext(1)
 
-                        let runner =
-                            new Runner<obj, obj, obj>((fun () -> ctx.TryGetValue(0).Value), (fun v -> ctx.SetValue(0, v)), data.Program)
+                        let getModel () =
+                            match ctx.TryGetValue(0) with
+                            | ValueNone -> failwith("Model not found in ComponentContext " + ctx.Id.ToString())
+                            | ValueSome model -> model
+
+                        let setModel v = ctx.SetValue(0, v)
+
+                        let runner = new Runner<obj, obj, obj>(getModel, setModel, data.Program)
 
                         ctx.LinkDisposable(runner)
 
diff --git a/src/Fabulous/Runner.fs b/src/Fabulous/Runner.fs
index 910f230a8..ba24bd339 100644
--- a/src/Fabulous/Runner.fs
+++ b/src/Fabulous/Runner.fs
@@ -10,6 +10,7 @@ open System.Collections.Concurrent
 type Runner<'arg, 'model, 'msg>(getState: unit -> 'model, setState: 'model -> unit, program: Program<'arg, 'model, 'msg>) =
     let mutable _activeSubs = Sub.Internal.empty
     let mutable _reentering = false
+    let mutable _stopped = false
     let queue = ConcurrentQueue<'msg>()
 
     let onError (message, exn) =
@@ -21,7 +22,7 @@ type Runner<'arg, 'model, 'msg>(getState: unit -> 'model, setState: 'model -> un
     let processMsgs dispatch msg =
         let mutable lastMsg = ValueSome msg
 
-        while lastMsg.IsSome do
+        while not _stopped && lastMsg.IsSome do
             let model = getState()
             let newModel, cmd = program.Update(lastMsg.Value, model)
             let subs = program.Subscribe(newModel)
@@ -39,7 +40,9 @@ type Runner<'arg, 'model, 'msg>(getState: unit -> 'model, setState: 'model -> un
 
     let rec dispatch msg =
         try
-            if _reentering then
+            if _stopped then
+                () // Message arrived after Runner got disposed, simply discard it
+            else if _reentering then
                 queue.Enqueue(msg)
             else
                 _reentering <- true
@@ -74,7 +77,8 @@ type Runner<'arg, 'model, 'msg>(getState: unit -> 'model, setState: 'model -> un
 
     let stop () =
         try
-            _reentering <- true
+            _stopped <- true
+            queue.Clear()
             Sub.Internal.Fx.stop onError _activeSubs
             _activeSubs <- Sub.Internal.empty
         with ex ->