fix: cancel token-gate waits and detect complete LFS prefixes

src/core/GitHubUtils.ts

@@ -15,6 +15,7 @@ import { getCredential, getCredentialToken } from "./credentials";
 import config from "../config";
 import { createLogger } from "./logger";
 import { measureStage } from "./request-monitoring";
+import { setTimeout as delay } from "timers/promises";
 
 const logger = createLogger("github");
 
@@ -85,7 +86,18 @@ export function getTokenGateResetAt(token: string): number {
   return gate.resetAt;
 }
 
-async function waitForTokenGate(token: string): Promise<void> {
+function abortableGateLookup(lookup: Promise<number>, signal: AbortSignal): Promise<number> {
+  return new Promise((resolve, reject) => {
+    const cancelled = () => { signal.removeEventListener("abort", cancelled); reject(signal.reason); };
+    if (signal.aborted) cancelled();
+    else signal.addEventListener("abort", cancelled, { once: true });
+    lookup.then(value => { signal.removeEventListener("abort", cancelled); resolve(value); },
+      error => { signal.removeEventListener("abort", cancelled); reject(error); });
+  });
+}
+
+async function waitForTokenGate(token: string, signal?: AbortSignal): Promise<void> {
+  signal?.throwIfAborted();
   const key = githubQuotaKey(token);
   const localGate = tokenGates.get(key);
   let waitMs = 0;
@@ -96,7 +108,9 @@ async function waitForTokenGate(token: string): Promise<void> {
     waitMs = resetAt - Date.now();
   }
 
-  const redisResetAt = await getRedisGateResetAt(key);
+  const lookup = getRedisGateResetAt(key);
+  const redisResetAt = await (signal ? abortableGateLookup(lookup, signal) : lookup);
+  signal?.throwIfAborted();
   if (redisResetAt > resetAt) {
     resetAt = redisResetAt;
     waitMs = resetAt - Date.now();
@@ -112,7 +126,7 @@ async function waitForTokenGate(token: string): Promise<void> {
     waitMs,
     resetAt: new Date(resetAt).toISOString(),
   });
-  await new Promise((resolve) => setTimeout(resolve, waitMs));
+  await delay(waitMs, undefined, { signal });
   if (localGate) tokenGates.delete(key);
 }
 

src/core/source/GitHubStream.ts

@@ -149,7 +149,7 @@ export default class GitHubStream extends GitHubBase {
       } catch (error) {
         if (!token || githubTokenContext(token)?.publicRepository ||
             (error as { response?: { statusCode?: number } }).response?.statusCode !== 404) throw error;
-        await waitForTokenGate(token);
+        await waitForTokenGate(token, cancellation.signal);
         const response = await octokit(token).repos.getContent({
           owner: data.organization, repo: data.repoName,
           path: filePath, ref: data.commit || "HEAD", mediaType: { format: "object" },
@@ -186,7 +186,7 @@ export default class GitHubStream extends GitHubBase {
           if (checked) { yield chunk; continue; }
           probe = Buffer.concat([probe, Buffer.from(chunk)]);
           if (probe.length < 150) continue;
-          if (probe.toString("utf8", 0, 39) === "version https://git-lfs.github.com/spec/") {
+          if (probe.toString("utf8").startsWith("version https://git-lfs.github.com/spec/")) {
             throw new AnonymousError("upstream_error", { httpStatus: 502 });
           }
           checked = true; yield probe;
@@ -294,7 +294,7 @@ export default class GitHubStream extends GitHubBase {
         probe = Buffer.concat([probe, bytes]);
         if (probe.length < 150) continue;
         decided = true;
-        if (probe.toString("utf8", 0, 39) === "version https://git-lfs.github.com/spec/") {
+        if (probe.toString("utf8").startsWith("version https://git-lfs.github.com/spec/")) {
           active = downloadRaw();
           for await (const raw of active) yield raw;
           return;