From 46ebd66376a1affdab37eaf2f16bbaa026666cbb Mon Sep 17 00:00:00 2001
From: Pepijn Van Eeckhoudt <pepijn.vaneeckhoudt@datadobi.com>
Date: Thu, 12 May 2022 15:53:34 +0200
Subject: [PATCH] Adapt forceMessageHandling

---
 .../client/communication/MessageHandler.java  | 22 +++++++------
 .../client/communication/MessageSender.java   | 31 ++++++++++++++++---
 2 files changed, 39 insertions(+), 14 deletions(-)

diff --git a/flow-client/src/main/java/com/vaadin/client/communication/MessageHandler.java b/flow-client/src/main/java/com/vaadin/client/communication/MessageHandler.java
index b888a8fa536..09ab36df996 100644
--- a/flow-client/src/main/java/com/vaadin/client/communication/MessageHandler.java
+++ b/flow-client/src/main/java/com/vaadin/client/communication/MessageHandler.java
@@ -227,8 +227,7 @@ protected void handleJSON(final ValueMap valueMap) {
             return;
         }
 
-        registry.getMessageSender()
-                .setResynchronizationState(ResynchronizationState.NOT_ACTIVE);
+        registry.getMessageSender().clearResynchronizationState();
 
         if (hasResynchronize && !isNextExpectedMessage(serverId)) {
             // Resynchronize request. We must remove any old pending
@@ -579,13 +578,6 @@ private int getExpectedServerId() {
     }
 
     private void forceMessageHandling() {
-        // Clear previous request if it exists. Otherwise resyncrhonize can
-        // trigger
-        // "Trying to start a new request while another is active" exception and
-        // fail.
-        if (registry.getRequestResponseTracker().hasActiveRequest()) {
-            registry.getRequestResponseTracker().endRequest();
-        }
         if (!responseHandlingLocks.isEmpty()) {
             // Lock which was never release -> bug in locker or things just
             // too slow
@@ -606,6 +598,18 @@ private void forceMessageHandling() {
             // has been lost
             // Drop pending messages and resynchronize
             pendingUIDLMessages.clear();
+
+            // Inform the message sender that resynchronize is desired already
+            // since endRequest may already send out a next request
+            registry.getMessageSender().requestResynchronize();
+
+            // Clear previous request if it exists.
+            if (registry.getRequestResponseTracker().hasActiveRequest()) {
+                registry.getRequestResponseTracker().endRequest();
+            }
+
+            // Call resynchronize to make sure a resynchronize request is sent in
+            // case endRequest did not already do this.
             registry.getMessageSender().resynchronize();
         }
     }
diff --git a/flow-client/src/main/java/com/vaadin/client/communication/MessageSender.java b/flow-client/src/main/java/com/vaadin/client/communication/MessageSender.java
index e05667541c0..4e89be4e6c0 100644
--- a/flow-client/src/main/java/com/vaadin/client/communication/MessageSender.java
+++ b/flow-client/src/main/java/com/vaadin/client/communication/MessageSender.java
@@ -231,9 +231,9 @@ public String getCommunicationMethodName() {
      * state from the server
      */
     public void resynchronize() {
-        Console.log("Resynchronize from server requested");
-        resynchronizationState = ResynchronizationState.SEND_TO_SERVER;
-        sendInvocationsToServer();
+        if (requestResynchronize()) {
+            sendInvocationsToServer();
+        }
     }
 
     /**
@@ -276,8 +276,29 @@ public void setClientToServerMessageId(int nextExpectedId, boolean force) {
         }
     }
 
-    void setResynchronizationState(ResynchronizationState state) {
-        resynchronizationState = state;
+    /**
+     * Modifies the resynchronize state to indicate that resynchronization is desired
+     *
+     * @return true if the resynchronize request still needs to be sent; false otherwise
+     */
+    boolean requestResynchronize() {
+        switch (resynchronizationState) {
+            case NOT_ACTIVE:
+                Console.log("Resynchronize from server requested");
+                resynchronizationState = ResynchronizationState.SEND_TO_SERVER;
+                return true;
+            case SEND_TO_SERVER:
+                // Resynchronize has already been requested, but hasn't been sent yet
+                return true;
+            case WAITING_FOR_RESPONSE:
+            default:
+                // Resynchronize has already been requested, but response hasn't been received yet
+                return false;
+        }
+    }
+
+    void clearResynchronizationState() {
+        resynchronizationState = ResynchronizationState.NOT_ACTIVE;
     }
 
     ResynchronizationState getResynchronizationState() {