Merge pull request #3700 from 1c-syntax/copilot/support-cancellation-notification

Add LSP cancellation support in BSLTextDocumentService

Author: nixel2007

src/main/java/com/github/_1c_syntax/bsl/languageserver/BSLTextDocumentService.java

@@ -104,6 +104,7 @@
 import org.eclipse.lsp4j.TextDocumentContentChangeEvent;
 import org.eclipse.lsp4j.TextEdit;
 import org.eclipse.lsp4j.WorkspaceEdit;
+import org.eclipse.lsp4j.jsonrpc.CompletableFutures;
 import org.eclipse.lsp4j.jsonrpc.messages.Either;
 import org.eclipse.lsp4j.jsonrpc.messages.Either3;
 import org.eclipse.lsp4j.services.TextDocumentService;
@@ -755,9 +756,14 @@ private void processDocumentChange(
       waitFuture = CompletableFuture.completedFuture(null);
     }
 
-    return waitFuture.thenApplyAsync(
-      ignored -> supplier.get(),
-      executorService
+    return waitFuture.thenCompose(ignored ->
+      CompletableFutures.computeAsync(
+        executorService,
+        cancelChecker -> {
+          cancelChecker.checkCanceled();
+          return supplier.get();
+        }
+      )
     );
   }
 }

src/test/java/com/github/_1c_syntax/bsl/languageserver/BSLTextDocumentServiceTest.java

@@ -289,6 +289,32 @@ void testRenamePrepare() {
     assertThat(result).isNotNull();
   }
 
+  @Test
+  void testCancellationSupport() throws IOException {
+    // given
+    var textDocumentItem = getTextDocumentItem();
+    var didOpenParams = new DidOpenTextDocumentParams(textDocumentItem);
+    textDocumentService.didOpen(didOpenParams);
+
+    // when - create a future that supports cancellation
+    var params = new DocumentDiagnosticParams(getTextDocumentIdentifier());
+    var future = textDocumentService.diagnostic(params);
+
+    // then - verify that the future supports cancellation (can be cancelled)
+    // The CompletableFutures.computeAsync returns a future that can be cancelled
+    var wasCancelled = future.cancel(true);
+
+    // If the future completed before cancel was called, it returns false
+    // If cancelled successfully, it returns true
+    // Either way, we verify the future is in a terminal state
+    assertThat(future.isDone()).isTrue();
+
+    // If cancellation was successful, verify the cancelled state
+    if (wasCancelled) {
+      assertThat(future.isCancelled()).isTrue();
+    }
+  }
+  
   @Test
   void testImplementation() throws ExecutionException, InterruptedException {
     var params = new ImplementationParams();