60 lines
1.7 KiB
TypeScript
60 lines
1.7 KiB
TypeScript
import { randomUUID } from 'crypto';
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import * as fs from 'fs';
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import * as path from 'path';
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const EPERM_MAX_RETRIES = 3;
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const EPERM_RETRY_DELAY_MS = 50;
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function sleep(ms: number): Promise<void> {
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return new Promise((resolve) => setTimeout(resolve, ms));
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}
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async function renameWithRetry(src: string, dest: string): Promise<void> {
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for (let attempt = 0; attempt <= EPERM_MAX_RETRIES; attempt++) {
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try {
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await fs.promises.rename(src, dest);
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return;
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} catch (error) {
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const code = (error as NodeJS.ErrnoException).code;
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if (code === 'EXDEV') {
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await fs.promises.copyFile(src, dest);
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await fs.promises.unlink(src).catch(() => undefined);
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return;
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}
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if (code === 'EPERM' && attempt < EPERM_MAX_RETRIES) {
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await sleep(EPERM_RETRY_DELAY_MS * (attempt + 1));
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continue;
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}
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throw error;
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}
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}
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}
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/**
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* Async atomic write: write tmp file then rename over target.
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* Uses best-effort fsync and EXDEV/EPERM fallback for safety.
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*/
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export async function atomicWriteAsync(targetPath: string, data: string | Buffer): Promise<void> {
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const dir = path.dirname(targetPath);
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const tmpPath = path.join(dir, `.tmp.${randomUUID()}`);
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try {
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await fs.promises.mkdir(dir, { recursive: true });
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await fs.promises.writeFile(tmpPath, data, typeof data === 'string' ? 'utf8' : undefined);
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let fd: fs.promises.FileHandle | null = null;
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try {
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fd = await fs.promises.open(tmpPath, 'r+');
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await fd.sync();
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} catch {
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// fsync is best-effort.
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} finally {
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await fd?.close();
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}
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await renameWithRetry(tmpPath, targetPath);
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} catch (error) {
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await fs.promises.unlink(tmpPath).catch(() => undefined);
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throw error;
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}
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}
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