Debounce LSP processing

newt-vscode-lsp/src/lsp.ts

@@ -21,17 +21,51 @@ import { TextDocument } from "vscode-languageserver-textdocument";
 const connection = createConnection(ProposedFeatures.all);
 const documents = new TextDocuments(TextDocument);
 
+// the last is the most important to the user, but we run FIFO
+// to ensure dependencies are seen in causal order
+let changes: TextDocument[] = []
+let running: NodeJS.Timeout | undefined
+function addChange(doc: TextDocument) {
+  console.log('enqueue', doc.uri)
+  // drop stale pending changes
+  let before = changes.length
+  changes = changes.filter(ch => ch.uri != doc.uri)
+  console.log('DROP', changes.length - before);
+  changes.push(doc)
+  if (!running) running = setTimeout(runChange, 1)
+}
+
+function runChange() {
+  let doc = changes.shift()
+  if (!doc) {
+    running = undefined
+    return
+  }
+  const uri = doc.uri
+  const diagnostics = LSP_checkFile(doc.uri)
+  connection.sendDiagnostics({uri,diagnostics})
+  console.log('SENT', doc.uri);
+  running = undefined
+  // give more a chance to file in.
+  running = setTimeout(runChange,1)
+}
+
 documents.onDidChangeContent(async (change) => {
   console.log('DIDCHANGE', change.document.uri)
   const uri = change.document.uri;
   const text = change.document.getText();
   LSP_updateFile(uri, text);
-  const diagnostics = LSP_checkFile(uri);
-  console.log(`Got ${JSON.stringify(diagnostics, null, '  ')}`)
-  connection.sendDiagnostics({ uri, diagnostics })
+  // we defer the check to let all of the changes file in.
+  addChange(change.document);
+  // const diagnostics = LSP_checkFile(uri);
+  // console.log(`Got ${JSON.stringify(diagnostics, null, '  ')}`)
+  // connection.sendDiagnostics({ uri, diagnostics })
 });
 
 connection.onHover((params): Hover | null => {
+  // wait until quiesced (REVIEW after query-based)
+  if (running) return null
+
   const uri = params.textDocument.uri;
   const pos = params.position;
   console.log('HOVER', uri, pos)