import fs from "node:fs";import path from "node:path"; export interface RotatingFileSinkOptions { readonly filePath: string; readonly maxBytes: number; readonly maxFiles: number; readonly throwOnError?: boolean;} export class RotatingFileSink { private readonly filePath: string; private readonly maxBytes: number; private readonly maxFiles: number; private readonly throwOnError: boolean; private currentSize = 0; constructor(options: RotatingFileSinkOptions) { if (options.maxBytes < 1) { throw new Error(`maxBytes must be >= 1 (received ${options.maxBytes})`); } if (options.maxFiles < 1) { throw new Error(`maxFiles must be >= 1 (received ${options.maxFiles})`); } this.filePath = options.filePath; this.maxBytes = options.maxBytes; this.maxFiles = options.maxFiles; this.throwOnError = options.throwOnError ?? false; fs.mkdirSync(path.dirname(this.filePath), { recursive: true }); this.pruneOverflowBackups(); this.currentSize = this.readCurrentSize(); } write(chunk: string | Buffer): void { const buffer = typeof chunk === "string" ? Buffer.from(chunk) : chunk; if (buffer.length === 0) return; try { if (this.currentSize > 0 && this.currentSize + buffer.length > this.maxBytes) { this.rotate(); } fs.appendFileSync(this.filePath, buffer); this.currentSize += buffer.length; if (this.currentSize > this.maxBytes) { this.rotate(); } } catch { this.currentSize = this.readCurrentSize(); if (this.throwOnError) { throw new Error(`Failed to write log chunk to ${this.filePath}`); } } } private rotate(): void { try { const oldest = this.withSuffix(this.maxFiles); if (fs.existsSync(oldest)) { fs.rmSync(oldest, { force: true }); } for (let index = this.maxFiles - 1; index >= 1; index -= 1) { const source = this.withSuffix(index); const target = this.withSuffix(index + 1); if (fs.existsSync(source)) { fs.renameSync(source, target); } } if (fs.existsSync(this.filePath)) { fs.renameSync(this.filePath, this.withSuffix(1)); } this.currentSize = 0; } catch { this.currentSize = this.readCurrentSize(); if (this.throwOnError) { throw new Error(`Failed to rotate log file ${this.filePath}`); } } } private pruneOverflowBackups(): void { try { const dir = path.dirname(this.filePath); const baseName = path.basename(this.filePath); for (const entry of fs.readdirSync(dir)) { if (!entry.startsWith(`${baseName}.`)) continue; const suffix = Number(entry.slice(baseName.length + 1)); if (!Number.isInteger(suffix) || suffix <= this.maxFiles) continue; fs.rmSync(path.join(dir, entry), { force: true }); } } catch { if (this.throwOnError) { throw new Error(`Failed to prune log backups for ${this.filePath}`); } } } private readCurrentSize(): number { try { return fs.statSync(this.filePath).size; } catch { return 0; } } private withSuffix(index: number): string { return `${this.filePath}.${index}`; }}
import fs from "node:fs";
import path from "node:path";
export interface RotatingFileSinkOptions {
readonly filePath: string;
readonly maxBytes: number;
readonly maxFiles: number;
readonly throwOnError?: boolean;
}
export class RotatingFileSink {
private readonly filePath: string;
private readonly maxBytes: number;
private readonly maxFiles: number;
private readonly throwOnError: boolean;
private currentSize = 0;
constructor(options: RotatingFileSinkOptions) {
if (options.maxBytes < 1) {
throw new Error(`maxBytes must be >= 1 (received ${options.maxBytes})`);
}
if (options.maxFiles < 1) {
throw new Error(`maxFiles must be >= 1 (received ${options.maxFiles})`);
}
this.filePath = options.filePath;
this.maxBytes = options.maxBytes;
this.maxFiles = options.maxFiles;
this.throwOnError = options.throwOnError ?? false;
fs.mkdirSync(path.dirname(this.filePath), { recursive: true });
this.pruneOverflowBackups();
this.currentSize = this.readCurrentSize();
}
write(chunk: string | Buffer): void {
const buffer = typeof chunk === "string" ? Buffer.from(chunk) : chunk;
if (buffer.length === 0) return;
try {
if (this.currentSize > 0 && this.currentSize + buffer.length > this.maxBytes) {
this.rotate();
}
fs.appendFileSync(this.filePath, buffer);
this.currentSize += buffer.length;
if (this.currentSize > this.maxBytes) {
this.rotate();
}
} catch {
this.currentSize = this.readCurrentSize();
if (this.throwOnError) {
throw new Error(`Failed to write log chunk to ${this.filePath}`);
}
}
}
private rotate(): void {
try {
const oldest = this.withSuffix(this.maxFiles);
if (fs.existsSync(oldest)) {
fs.rmSync(oldest, { force: true });
}
for (let index = this.maxFiles - 1; index >= 1; index -= 1) {
const source = this.withSuffix(index);
const target = this.withSuffix(index + 1);
if (fs.existsSync(source)) {
fs.renameSync(source, target);
}
}
if (fs.existsSync(this.filePath)) {
fs.renameSync(this.filePath, this.withSuffix(1));
}
this.currentSize = 0;
} catch {
this.currentSize = this.readCurrentSize();
if (this.throwOnError) {
throw new Error(`Failed to rotate log file ${this.filePath}`);
}
}
}
private pruneOverflowBackups(): void {
try {
const dir = path.dirname(this.filePath);
const baseName = path.basename(this.filePath);
for (const entry of fs.readdirSync(dir)) {
if (!entry.startsWith(`${baseName}.`)) continue;
const suffix = Number(entry.slice(baseName.length + 1));
if (!Number.isInteger(suffix) || suffix <= this.maxFiles) continue;
fs.rmSync(path.join(dir, entry), { force: true });
}
} catch {
if (this.throwOnError) {
throw new Error(`Failed to prune log backups for ${this.filePath}`);
}
}
}
private readCurrentSize(): number {
try {
return fs.statSync(this.filePath).size;
} catch {
return 0;
}
}
private withSuffix(index: number): string {
return `${this.filePath}.${index}`;
}
}