Graceful renames, better errors in updater

ts/updater/util.ts

@@ -2,10 +2,15 @@
 // SPDX-License-Identifier: AGPL-3.0-only
 
 import { createReadStream } from 'fs';
+import { rename } from 'fs/promises';
 import { pipeline } from 'stream/promises';
 import { createHash } from 'crypto';
 
 import * as Errors from '../types/errors';
+import type { LoggerType } from '../types/Logging';
+import * as durations from '../util/durations';
+import { isOlderThan } from '../util/timestamp';
+import { sleep } from '../util/sleep';
 
 export type CheckIntegrityResultType = Readonly<
   | {
@@ -42,3 +47,76 @@ export async function checkIntegrity(
     };
   }
 }
+
+async function doGracefulRename({
+  logger,
+  fromPath,
+  toPath,
+  startedAt,
+  retryCount,
+  retryAfter = 5 * durations.SECOND,
+  timeout = 5 * durations.MINUTE,
+}: {
+  logger: LoggerType;
+  fromPath: string;
+  toPath: string;
+  startedAt: number;
+  retryCount: number;
+  retryAfter?: number;
+  timeout?: number;
+}): Promise<void> {
+  try {
+    await rename(fromPath, toPath);
+
+    if (retryCount !== 0) {
+      logger.info(
+        `gracefulRename: succeeded after ${retryCount} retries, renamed ` +
+          `${fromPath} to ${toPath}`
+      );
+    }
+  } catch (error) {
+    if (error.code !== 'EACCESS' && error.code !== 'EPERM') {
+      throw error;
+    }
+
+    if (isOlderThan(startedAt, timeout)) {
+      logger.warn(
+        'gracefulRename: timed out while retrying renaming ' +
+          `${fromPath} to ${toPath}`
+      );
+      throw error;
+    }
+
+    logger.warn(
+      `gracefulRename: got ${error.code} when renaming ` +
+        `${fromPath} to ${toPath}, retrying in one second. ` +
+        `(retryCount=${retryCount})`
+    );
+
+    await sleep(retryAfter);
+
+    return doGracefulRename({
+      logger,
+      fromPath,
+      toPath,
+      startedAt,
+      retryCount: retryCount + 1,
+      retryAfter,
+      timeout,
+    });
+  }
+}
+
+export async function gracefulRename(
+  logger: LoggerType,
+  fromPath: string,
+  toPath: string
+): Promise<void> {
+  return doGracefulRename({
+    logger,
+    fromPath,
+    toPath,
+    startedAt: Date.now(),
+    retryCount: 0,
+  });
+}