improvements

Author: brendan-kellam

packages/backend/src/git.ts

@@ -126,15 +126,14 @@ export const fetchRepository = async (
 
         // Update HEAD to match the remote's default branch. This handles the case where the remote's
         // default branch changes.
-        const remoteHead = await git.raw(['ls-remote', '--symref', cloneUrl, 'HEAD']);
-        const match = remoteHead.match(/^ref: refs\/heads\/(\S+)\s+HEAD/m);
-        if (match) {
-            const defaultBranch = match[1];
-            await git.raw(['symbolic-ref', 'HEAD', `refs/heads/${defaultBranch}`]);
-            return defaultBranch;
-        }
+        const remoteDefaultBranch = await getRemoteDefaultBranch({
+            path,
+            cloneUrl,
+        });
 
-        return undefined;
+        if (remoteDefaultBranch) {
+            await git.raw(['symbolic-ref', 'HEAD', `refs/heads/${remoteDefaultBranch}`]);
+        }
     } catch (error: unknown) {
         const baseLog = `Failed to fetch repository: ${path}`;
         if (env.SOURCEBOT_LOG_LEVEL !== "debug") {
@@ -310,3 +309,63 @@ export const getCommitHashForRefName = async ({
         return undefined;
     }
 }
+
+/**
+ * Gets the default branch name from the remote repository by querying what
+ * the remote's HEAD symbolic ref points to.
+ *
+ * This is useful for detecting when a remote repository's default branch has
+ * changed (e.g., from "master" to "main").
+ *
+ * @returns The branch name (e.g., "main", "master") or undefined if it cannot be determined
+ */
+export const getRemoteDefaultBranch = async ({
+    path,
+    cloneUrl,
+}: {
+    path: string,
+    cloneUrl: string,
+}) => {
+    const git = createGitClientForPath(path);
+    try {
+        const remoteHead = await git.raw(['ls-remote', '--symref', cloneUrl, 'HEAD']);
+        const match = remoteHead.match(/^ref: refs\/heads\/(\S+)\s+HEAD/m);
+        if (match) {
+            return match[1];
+        }
+    } catch (error: unknown) {
+        // Avoid printing error here since cloneUrl may contain credentials.
+        console.error(`Failed to get remote default branch for repository: ${path}`);
+        return undefined;
+    }
+}
+
+/**
+ * Gets the branch name that the local HEAD symbolic ref points to.
+ *
+ * In a git repository, HEAD is typically a symbolic reference that points to
+ * a branch (e.g., refs/heads/main). This function resolves that symbolic ref
+ * and returns just the branch name.
+ *
+ * @returns The branch name (e.g., "main", "master") or undefined if HEAD is not a symbolic ref
+ */
+export const getLocalDefaultBranch = async ({
+    path,
+}: {
+    path: string,
+}) => {
+    const git = createGitClientForPath(path);
+
+    try {
+        const ref = await git.raw(['symbolic-ref', 'HEAD']);
+        // Returns something like "refs/heads/main\n", so trim and remove prefix
+        const trimmed = ref.trim();
+        const match = trimmed.match(/^refs\/heads\/(.+)$/);
+        if (match) {
+            return match[1];
+        }
+    } catch (error: unknown) {
+        console.error(`Failed to get local default branch for repository: ${path}`);
+        return undefined;
+    }
+}

packages/backend/src/repoIndexManager.ts

@@ -8,7 +8,7 @@ import { Job, Queue, ReservedJob, Worker } from "groupmq";
 import { Redis } from 'ioredis';
 import micromatch from 'micromatch';
 import { GROUPMQ_WORKER_STOP_GRACEFUL_TIMEOUT_MS, INDEX_CACHE_DIR } from './constants.js';
-import { cloneRepository, fetchRepository, getBranches, getCommitHashForRefName, getTags, isPathAValidGitRepoRoot, unsetGitConfig, upsertGitConfig } from './git.js';
+import { cloneRepository, fetchRepository, getBranches, getCommitHashForRefName, getLocalDefaultBranch, getTags, isPathAValidGitRepoRoot, unsetGitConfig, upsertGitConfig } from './git.js';
 import { captureEvent } from './posthog.js';
 import { PromClient } from './promClient.js';
 import { RepoWithConnections, Settings } from "./types.js";
@@ -337,8 +337,6 @@ export class RepoIndexManager {
             }
         }
 
-        let defaultBranch: string | undefined = undefined;
-
         if (existsSync(repoPath) && !isReadOnly) {
             // @NOTE: in #483, we changed the cloning method s.t., we _no longer_
             // write the clone URL (which could contain a auth token) to the
@@ -353,7 +351,7 @@ export class RepoIndexManager {
             });
 
             logger.info(`Fetching ${repo.name} (id: ${repo.id})...`);
-            const { durationMs, data: remoteDefaultBranch } = await measure(() => fetchRepository({
+            const { durationMs } = await measure(() => fetchRepository({
                 cloneUrl: cloneUrlMaybeWithToken,
                 authHeader,
                 path: repoPath,
@@ -366,8 +364,6 @@ export class RepoIndexManager {
 
             process.stdout.write('\n');
             logger.info(`Fetched ${repo.name} (id: ${repo.id}) in ${fetchDuration_s}s`);
-
-            defaultBranch = remoteDefaultBranch;
         } else if (!isReadOnly) {
             logger.info(`Cloning ${repo.name} (id: ${repo.id})...`);
 
@@ -397,6 +393,10 @@ export class RepoIndexManager {
             });
         }
 
+        const defaultBranch = await getLocalDefaultBranch({
+            path: repoPath,
+        });
+
         let revisions = defaultBranch ? [defaultBranch] : ['HEAD'];
 
         if (metadata.branches) {