Allocate completed futures on dedicated thread pools. (#932)

Author: toinehartman

rascal-lsp/src/main/java/org/rascalmpl/vscode/lsp/parametric/model/ParametricFileFacts.java

@@ -480,7 +480,7 @@ public void clearDiagnostics() {
 
         @Override
         public <T> CompletableFuture<List<T>> lookupInSummaries(SummaryLookup<T> lookup, Versioned<ITree> tree, Position cursor) {
-            return CompletableFuture.completedFuture(List.of());
+            return CompletableFutureUtils.completedFuture(List.of(), exec);
         }
     }
 }

rascal-lsp/src/main/java/org/rascalmpl/vscode/lsp/rascal/RascalTextDocumentService.java

@@ -490,7 +490,7 @@ private MessageParams setMessageParams(IConstructor message) {
                 .thenApply(n -> new Hover(new MarkupContent("plaintext", n))), () -> null);
         }
         else {
-            return CompletableFuture.completedFuture(null);
+            return CompletableFutureUtils.completedFuture(null, exec);
         }
     }
 
@@ -706,7 +706,7 @@ public CompletableFuture<List<Either<Command, CodeAction>>> codeAction(CodeActio
     private CompletableFuture<IList> computeCodeActions(final int startLine, final int startColumn, ITree tree, PathConfig pcfg) {
         return CompletableFuture.supplyAsync(() -> TreeSearch.computeFocusList(tree, startLine, startColumn), exec)
             .thenCompose(focus -> focus.isEmpty()
-                ? CompletableFuture.completedFuture(focus /* an empty list */)
+                ? CompletableFutureUtils.completedFuture(focus /* an empty list */, exec)
                 : availableRascalServices().codeActions(focus, pcfg).get());
     }
 

rascal-lsp/src/main/java/org/rascalmpl/vscode/lsp/rascal/model/FileFacts.java

@@ -45,6 +45,7 @@
 import org.rascalmpl.vscode.lsp.rascal.RascalLanguageServices;
 import org.rascalmpl.vscode.lsp.util.Diagnostics;
 import org.rascalmpl.vscode.lsp.util.Lists;
+import org.rascalmpl.vscode.lsp.util.concurrent.CompletableFutureUtils;
 import org.rascalmpl.vscode.lsp.util.concurrent.InterruptibleFuture;
 import org.rascalmpl.vscode.lsp.util.concurrent.LazyUpdateableReference;
 import org.rascalmpl.vscode.lsp.util.concurrent.ReplaceableFuture;
@@ -205,7 +206,7 @@ public void close() {
         public void clearDiagnostics() {
             summary.invalidate();
             typeCheckerMessages.clear();
-            typeCheckResults.replace(CompletableFuture.completedFuture(Map.of()));
+            typeCheckResults.replace(CompletableFutureUtils.completedFuture(Map.of(), exec));
             client.publishDiagnostics(new PublishDiagnosticsParams(Locations.toUri(file).toString(), List.of()));
         }
     }
@@ -223,7 +224,7 @@ public void reportTypeCheckerErrors(List<Diagnostic> msgs) {
 
         @Override
         public CompletableFuture<@Nullable SummaryBridge> getSummary() {
-            return CompletableFuture.completedFuture(null);
+            return CompletableFutureUtils.completedFuture(null, exec);
         }
 
         @Override