aono-file-handler/FileHandler.js

Aono handler that write to a log file with support for custom formatters and log rotation.

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.FileHandler = void 0;
const fs = require("fs");
const util_1 = require("util");
const path_1 = require("path");
const Builder_1 = require("./Builder");
const LogstashFormatter_1 = require("./LogstashFormatter");
const open = (0, util_1.promisify)(fs.open);
const write = (0, util_1.promisify)(fs.write);
const close = (0, util_1.promisify)(fs.close);
const exists = (0, util_1.promisify)(fs.exists);
const mkdir = (0, util_1.promisify)(fs.mkdir);
const HUNDRED_MEGS = 100 * 1024 * 1024;
const LOGSTASH_FORMATTER = new LogstashFormatter_1.LogstashFormatter();
/**
 * @author Maciej Chalapuk (maciej@chalapuk.pl)
 */
class FileHandler {
    static builder() {
        return new Builder_1.Builder();
    }
    constructor(prefix, formatter = LOGSTASH_FORMATTER, rotationBytesThreshold = HUNDRED_MEGS) {
        this.prefix = prefix;
        this.formatter = formatter;
        this.rotationBytesThreshold = rotationBytesThreshold;
        this._bytesWritten = 0;
        this._currentFile = null;
        this._currentFileSize = 0;
        this._format = this.formatter.format.bind(this.formatter);
    }
    get currentFile() {
        return this._currentFile;
    }
    get currentFileSize() {
        return this._currentFile ? this._currentFileSize : null;
    }
    get bytesWritten() {
        return this._bytesWritten;
    }
    async write(entries) {
        if (entries.length === 0) {
            return;
        }
        if (this.currentFile === null) {
            for (let i = 0;; i++) {
                this._currentFile = this._createFilePath(entries[0].timestamp, i > 0 ? `.${i}` : "");
                await ensureDirectoryExists(this._currentFile);
                try {
                    this._fd = await open(this._currentFile, 'ax');
                    break;
                }
                catch (e) {
                    if (e.code === 'EEXIST') {
                        continue;
                    }
                    throw e;
                }
            }
        }
        const serializedEntries = entries.map(this._format).join('');
        const result = await write(this._fd, serializedEntries);
        this._bytesWritten += result.bytesWritten;
        this._currentFileSize += result.bytesWritten;
        if (this._currentFileSize >= this.rotationBytesThreshold) {
            // New file will be created when handling next batch of entries.
            this._currentFile = null;
            this._currentFileSize = 0;
            await close(this._fd);
        }
    }
    _createFilePath(timestamp, suffix = "") {
        return `${this.prefix}.${dateSuffix(new Date(timestamp))}${suffix}`;
    }
}
exports.FileHandler = FileHandler;
exports.default = FileHandler;
async function ensureDirectoryExists(filePath) {
    const dir = (0, path_1.dirname)(filePath);
    if (await exists(dir)) {
        return;
    }
    ensureDirectoryExists(dir);
    await mkdir(dir);
}
function dateSuffix(date) {
    const iso = date.toISOString();
    return `${iso.slice(0, 10)}_${iso.slice(11, 23)}`;
}
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