From b1537d3f2717a7a72182e7e194526a0230b2d7cc Mon Sep 17 00:00:00 2001
From: David Anthoff <anthoff@berkeley.edu>
Date: Mon, 6 Sep 2021 11:29:48 -0700
Subject: [PATCH] Use tokens for timeout in dynamic completions

---
 src/canceltokenutils.ts        | 17 ++++++++++++
 src/interactive/completions.ts | 49 +++++++++++++++-------------------
 2 files changed, 38 insertions(+), 28 deletions(-)
 create mode 100644 src/canceltokenutils.ts

diff --git a/src/canceltokenutils.ts b/src/canceltokenutils.ts
new file mode 100644
index 000000000..1a7a6bfbe
--- /dev/null
+++ b/src/canceltokenutils.ts
@@ -0,0 +1,17 @@
+import { CancellationToken, CancellationTokenSource } from 'vscode-jsonrpc'
+
+export function createTimeoutCancellation(millis: number): CancellationToken {
+    const source = new CancellationTokenSource()
+    setTimeout(() => source.cancel(), millis)
+    return source.token
+}
+
+export function combineCancellationTokens(a: CancellationToken, b: CancellationToken): CancellationToken {
+    if (a.isCancellationRequested || b.isCancellationRequested) {
+        return CancellationToken.Cancelled
+    }
+    const source = new CancellationTokenSource()
+    a.onCancellationRequested(() => source.cancel())
+    b.onCancellationRequested(() => source.cancel())
+    return source.token
+}
diff --git a/src/interactive/completions.ts b/src/interactive/completions.ts
index b4b179d82..898cec98c 100644
--- a/src/interactive/completions.ts
+++ b/src/interactive/completions.ts
@@ -3,6 +3,7 @@
 import * as vscode from 'vscode'
 import * as rpc from 'vscode-jsonrpc'
 import { Disposable, MessageConnection } from 'vscode-jsonrpc'
+import { combineCancellationTokens, createTimeoutCancellation } from '../canceltokenutils'
 import { getModuleForEditor } from './modules'
 import { onExit, onInit } from './repl'
 
@@ -36,42 +37,34 @@ const requestTypeGetCompletionItems = new rpc.RequestType<
     void
     >('repl/getcompletions')
 
+
 function completionItemProvider(conn: MessageConnection): vscode.CompletionItemProvider {
     return {
         provideCompletionItems: async (document, position, token, context) => {
             if (!vscode.workspace.getConfiguration('julia.runtimeCompletions')) {
                 return
             }
-            const completionPromise = (async () => {
-                const startPosition = new vscode.Position(position.line, 0)
-                const lineRange = new vscode.Range(startPosition, position)
-                const line = document.getText(lineRange)
-                const mod: string = await getModuleForEditor(document, position)
-                return {
-                    items: await conn.sendRequest(requestTypeGetCompletionItems, { line, mod }),
-                    isIncomplete: true
-                }
-            })()
 
-            const cancelPromise: Promise<vscode.CompletionList> = new Promise(resolve => {
-                token.onCancellationRequested(() => resolve({
-                    items: [],
-                    isIncomplete: true
-                }))
-                setTimeout(() => {
-                    if (!token.isCancellationRequested) {
-                        resolve({
-                            items: [],
-                            isIncomplete: true
-                        })
-                    }
-                }, 500)
-            })
+            const newToken = combineCancellationTokens(
+                token,
+                createTimeoutCancellation(500)
+            )
+
+            const startPosition = new vscode.Position(position.line, 0)
+            const lineRange = new vscode.Range(startPosition, position)
+            const line = document.getText(lineRange)
+            const mod: string = await getModuleForEditor(document, position) // TODO pass newToken once we support tokens in JSONRPC.jl
+
+            if (newToken.isCancellationRequested) { return }
 
-            return Promise.race([
-                completionPromise,
-                cancelPromise
-            ])
+            const items = await conn.sendRequest(requestTypeGetCompletionItems, { line, mod }) // TODO pass newToken once we support tokens in JSONRPC.jl
+
+            if (newToken.isCancellationRequested) { return }
+
+            return {
+                items: items,
+                isIncomplete: true
+            }
         }
     }
 }