update-experimental-branches.js
// @ts-check
/// <reference lib="esnext.asynciterable" />
const { Octokit } = require("@octokit/rest");
const { runSequence } = require("./run-sequence");
// The first is used by bot-based kickoffs, the second by automatic triggers
const triggeredPR = process.env.SOURCE_ISSUE || process.env.SYSTEM_PULLREQUEST_PULLREQUESTNUMBER;
/**
* This program should be invoked as `node ./scripts/update-experimental-branches <GithubAccessToken>`
* TODO: the following is racey - if two experiment-enlisted PRs trigger simultaneously and witness one another in an unupdated state, they'll both produce
* a new experimental branch, but each will be missing a change from the other. There's no _great_ way to fix this beyond setting the maximum concurrency
* of this task to 1 (so only one job is allowed to update experiments at a time).
*/
async function main() {
const gh = new Octokit({
auth: process.argv[2]
});
const prnums = (await gh.issues.listForRepo({
labels: "typescript@experimental",
sort: "created",
state: "open",
owner: "Microsoft",
repo: "TypeScript",
})).data.filter(i => !!i.pull_request).map(i => i.number);
if (triggeredPR && !prnums.some(n => n === +triggeredPR)) {
return; // Only have work to do for enlisted PRs
}
console.log(`Performing experimental branch updating and merging for pull requests ${prnums.join(", ")}`);
const userName = process.env.GH_USERNAME;
const remoteUrl = `https://${process.argv[2]}@github.com/${userName}/TypeScript.git`;
// Forcibly cleanup workspace
runSequence([
["git", ["checkout", "."]],
["git", ["fetch", "-fu", "origin", "main:main"]],
["git", ["checkout", "main"]],
["git", ["remote", "add", "fork", remoteUrl]], // Add the remote fork
]);
for (const numRaw of prnums) {
const num = +numRaw;
if (num) {
// PR number rather than branch name - lookup info
const inputPR = await gh.pulls.get({ owner: "Microsoft", repo: "TypeScript", pull_number: num });
// GH calculates the rebaseable-ness of a PR into its target, so we can just use that here
if (!inputPR.data.rebaseable) {
if (+triggeredPR === num) {
await gh.issues.createComment({
owner: "Microsoft",
repo: "TypeScript",
issue_number: num,
body: `This PR is configured as an experiment, and currently has rebase conflicts with main - please rebase onto main and fix the conflicts.`
});
}
throw new Error(`Rebase conflict detected in PR ${num} with main`); // A PR is currently in conflict, give up
}
runSequence([
["git", ["fetch", "origin", `pull/${num}/head:${num}`]],
["git", ["checkout", `${num}`]],
["git", ["rebase", "main"]],
["git", ["push", "-f", "-u", "fork", `${num}`]], // Keep a rebased copy of this branch in our fork
]);
}
else {
throw new Error(`Invalid PR number: ${numRaw}`);
}
}
// Return to `master` and make a new `experimental` branch
runSequence([
["git", ["checkout", "main"]],
["git", ["checkout", "-b", "experimental"]],
]);
// Merge each branch into `experimental` (which, if there is a conflict, we now know is from inter-experiment conflict)
for (const branchnum of prnums) {
const branch = "" + branchnum;
// Find the merge base
const mergeBase = runSequence([
["git", ["merge-base", branch, "experimental"]],
]);
// Simulate the merge and abort if there are conflicts
const mergeTree = runSequence([
["git", ["merge-tree", mergeBase.trim(), branch, "experimental"]]
]);
if (mergeTree.indexOf(`===${"="}===`) >= 0) { // 7 equals is the center of the merge conflict marker
throw new Error(`Merge conflict detected involving PR ${branch} with other experiment`);
}
// Merge (always producing a merge commit)
runSequence([
["git", ["merge", branch, "--no-ff"]],
]);
}
// Every branch merged OK, force push the replacement `experimental` branch
runSequence([
["git", ["push", "-f", "-u", "fork", "experimental"]],
]);
}
main().catch(e => (console.error(e), process.exitCode = 2));