Return synchronized if seen document version > required document version for resolve action endpoint

src/Razor/src/Microsoft.VisualStudio.LanguageServer.ContainedLanguage/DefaultLSPDocumentSynchronizer.cs

@@ -58,13 +58,15 @@ internal class DefaultLSPDocumentSynchronizer : LSPDocumentSynchronizer
             requiredHostDocumentVersion,
             hostDocumentUri,
             rejectOnNewerParallelRequest: true,
-            cancellationToken);
+            cancellationToken,
+            isResolveCodeActionSync: false);
 
     public override async Task<SynchronizedResult<TVirtualDocumentSnapshot>> TrySynchronizeVirtualDocumentAsync<TVirtualDocumentSnapshot>(
         int requiredHostDocumentVersion,
         Uri hostDocumentUri,
         bool rejectOnNewerParallelRequest,
-        CancellationToken cancellationToken)
+        CancellationToken cancellationToken,
+        bool isResolveCodeActionSync = false)
         where TVirtualDocumentSnapshot : class
     {
         if (hostDocumentUri is null)
@@ -90,7 +92,7 @@ internal class DefaultLSPDocumentSynchronizer : LSPDocumentSynchronizer
             }
 
             // Currently tracked synchronizing context is not sufficient, need to update a new one.
-            onSynchronizedTask = documentContext.GetSynchronizationTaskAsync(requiredHostDocumentVersion, rejectOnNewerParallelRequest, cancellationToken);
+            onSynchronizedTask = documentContext.GetSynchronizationTaskAsync(requiredHostDocumentVersion, rejectOnNewerParallelRequest, cancellationToken, isResolveCodeActionSync);
         }
 
         var onSynchronizedResult = await onSynchronizedTask.ConfigureAwait(false);
@@ -279,7 +281,7 @@ internal class DefaultLSPDocumentSynchronizer : LSPDocumentSynchronizer
             }
         }
 
-        public Task<bool> GetSynchronizationTaskAsync(int requiredHostDocumentVersion, bool rejectOnNewerParallelRequest, CancellationToken cancellationToken)
+        public Task<bool> GetSynchronizationTaskAsync(int requiredHostDocumentVersion, bool rejectOnNewerParallelRequest, CancellationToken cancellationToken, bool isResolveCodeActionSync = false)
         {
             // Cancel any out-of-date existing synchronizing contexts.
 
@@ -295,6 +297,14 @@ internal class DefaultLSPDocumentSynchronizer : LSPDocumentSynchronizer
                 }
             }
 
+            // TODO this is a partial workaround to fix prefix completion by avoiding sync (which times out during resolve endpoint) if we are currently at a higher version value
+            // this does not fix postfix completion and should be superceded by eventual synchronization fix
+
+            if (isResolveCodeActionSync && SeenHostDocumentVersion >= requiredHostDocumentVersion)
+            {
+                return Task.FromResult(true);
+            }
+
             var synchronizingContext = new DocumentSynchronizingContext(requiredHostDocumentVersion, rejectOnNewerParallelRequest, _synchronizingTimeout, cancellationToken);
             _synchronizingContexts.Add(synchronizingContext);
             return synchronizingContext.OnSynchronizedAsync;

src/Razor/src/Microsoft.VisualStudio.LanguageServer.ContainedLanguage/LSPDocumentSynchronizer.cs

@@ -20,7 +20,8 @@ internal abstract class LSPDocumentSynchronizer : LSPDocumentChangeListener
         int requiredHostDocumentVersion,
         Uri hostDocumentUri,
         bool rejectOnNewerParallelRequest,
-        CancellationToken cancellationToken)
+        CancellationToken cancellationToken,
+        bool isResolveCodeActionEndpoint = false)
         where TVirtualDocumentSnapshot : VirtualDocumentSnapshot;
 
     [Obsolete]

src/Razor/src/Microsoft.VisualStudio.LanguageServerClient.Razor/DefaultRazorLanguageServerCustomMessageTarget.cs

@@ -1015,7 +1015,9 @@ internal class DefaultRazorLanguageServerCustomMessageTarget : RazorLanguageServ
             (synchronized, virtualDocumentSnapshot) = await _documentSynchronizer.TrySynchronizeVirtualDocumentAsync<CSharpVirtualDocumentSnapshot>(
                 request.HostDocument.Version,
                 request.HostDocument.Uri,
-                cancellationToken);
+                rejectOnNewerParallelRequest: true,
+                cancellationToken,
+                isResolveCodeActionEndpoint: true);
             languageServerName = RazorLSPConstants.RazorCSharpLanguageServerName;
         }
         else