feat: Disable push diagnostic when pull is supported by the client

CHANGELOG.md

@@ -3,6 +3,10 @@ All notable changes to this project will be documented in this file.
 
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
+## [Unrelease]
+* Implement pull diagnostics for better performance;
+  - https://github.com/razzmatazz/csharp-language-server/pull/174
+
 ## [0.14.0] - 2024-06-23 / Palanga
 * Speed up completion by not showing name suggestions or items from unimported namespaces
   - https://github.com/razzmatazz/csharp-language-server/pull/168

src/CSharpLanguageServer/State/ServerState.fs

@@ -313,12 +313,16 @@ let processServerEvent (logger: ILog) state postSelf msg : Async<ServerState> =
                 | [] -> (None, [])
                 | uri :: remainder -> (Some uri, remainder)
 
-            match nextDocUri with
-            | None ->
-                // backlog is empty, nothing to do
-                return state
-
-            | Some docUri ->
+            // push diagnostic is enabled only if pull diagnostics is
+            // not reported to be supported by the client
+            let diagnosticPullSupported =
+                state.ClientCapabilities.TextDocument
+                |> Option.map _.Diagnostic
+                |> Option.map (fun _ -> true)
+                |> Option.defaultValue false
+
+            match diagnosticPullSupported, nextDocUri with
+            | false, Some docUri ->
                 let newState = { state with PushDiagnosticsDocumentBacklog = newBacklog }
 
                 let docAndTypeMaybe = docUri |> getDocumentForUriOfType state ServerDocumentType.AnyDocument
@@ -356,6 +360,10 @@ let processServerEvent (logger: ILog) state postSelf msg : Async<ServerState> =
 
                     return newState
 
+            | _, _->
+                // backlog is empty or pull diagnostics is enabled instead,--nothing to do
+                return state
+
     | PushDiagnosticsDocumentDiagnosticsResolution result ->
         // enqueue processing for the next doc on the queue (if any)
         postSelf PushDiagnosticsProcessPendingDocuments