chore: set up v8 autoroll script

.github/workflows/update-v8.yml

@@ -0,0 +1,21 @@
+name: Update V8
+
+on:
+  schedule:
+    - cron:  '0 10 * * *'
+  workflow_dispatch:
+
+jobs:
+  update:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Clone repository
+        uses: actions/checkout@v1
+        with:
+          fetch-depth: 10
+          submodules: recursive
+      - uses: denoland/setup-deno@main
+        with:
+          deno-version: v1.x
+      - run: deno run -A ./tools/auto_update_v8.ts
+

tools/auto_update_v8.ts

@@ -0,0 +1,85 @@
+const V8_TRACKING_BRANCH = "9.1-lkgr";
+const AUTOROLL_BRANCH = "autoroll";
+
+function extractVersion() {
+  const MAJOR_PREFIX = "#define V8_MAJOR_VERSION ";
+  const MINOR_PREFIX = "#define V8_MINOR_VERSION ";
+  const BUILD_PREFIX = "#define V8_BUILD_NUMBER ";
+  const PATCH_PREFIX = "#define V8_PATCH_LEVEL ";
+
+  const versionDotH = Deno.readTextFileSync("./v8/include/v8-version.h");
+  const lines = versionDotH.split("\n");
+  const major = parseInt(lines.find((s) => s.startsWith(MAJOR_PREFIX))!
+    .substring(MAJOR_PREFIX.length));
+  const minor = parseInt(lines.find((s) => s.startsWith(MINOR_PREFIX))!
+    .substring(MINOR_PREFIX.length));
+  const build = parseInt(lines.find((s) => s.startsWith(BUILD_PREFIX))!
+    .substring(BUILD_PREFIX.length));
+  const patch = parseInt(lines.find((s) => s.startsWith(PATCH_PREFIX))!
+    .substring(PATCH_PREFIX.length));
+
+  return `${major}.${minor}.${build}.${patch}`;
+}
+
+await run(["git", "branch", "-f", AUTOROLL_BRANCH, "origin/main"]);
+await run(["git", "checkout", AUTOROLL_BRANCH]);
+await run(["git", "reset", "origin/main", "--hard"]);
+
+const currentVersion = extractVersion();
+console.log(`Starting auto update. Currently on ${currentVersion}`);
+
+async function run(cmd: string[], cwd?: string) {
+  const proc = Deno.run({ cmd, cwd });
+  const status = await proc.status();
+  if (!status.success) {
+    console.error(`Failed to run ${cmd.join(" ")}`);
+    Deno.exit(1);
+  }
+}
+
+// Update v8 submodule
+await run(["git", "checkout", `origin/${V8_TRACKING_BRANCH}`], "./v8");
+
+const newVersion = extractVersion();
+if (currentVersion == newVersion) {
+  console.log(`No new version available. Staying on ${newVersion}`);
+  Deno.exit(0);
+}
+
+console.log(`Updated to version ${newVersion}`);
+
+// Update version in readme
+let readme = Deno.readTextFileSync("README.md");
+readme = readme.replace(
+  `V8 Version: ${currentVersion}`,
+  `V8 Version: ${newVersion}`,
+);
+Deno.writeTextFileSync("README.md", readme);
+
+// Stage the changes
+await run(["git", "add", "v8", "README.md"]);
+
+// Commit the changes
+await run(["git", "commit", "-m", `Rolling to V8 ${newVersion}`]);
+
+// Push to the `denoland/rusty_v8#autoroll`
+await run(["git", "push", "--force", "origin", `HEAD:${AUTOROLL_BRANCH}`]);
+
+const proc = Deno.run({
+  cmd: ["gh", "pr", "view", AUTOROLL_BRANCH],
+});
+const status = await proc.status();
+if (status.code == 1) {
+  console.log("No PR open. Creating a new PR.");
+  await run([
+    "gh",
+    "pr",
+    "create",
+    "--fill",
+    "--head",
+    AUTOROLL_BRANCH,
+  ]);
+} else {
+  console.log("Already open PR. Not creating a new PR.");
+  // TODO(lucacasonato): update the title of the open PR here
+}