@metrics/process/lib/collector-max-file-descriptors.js

Module for collecting different process and system metrics and providing them as a metric stream

"use strict";

const Metric = require("@metrics/metric");
const fs = require("fs");

const CollectorMaxFileDescriptors = class CollectorMaxFileDescriptors {
	constructor(prefix = "") {
		Object.defineProperty(this, "prefix", {
			value: prefix,
		});

		Object.defineProperty(this, "collected", {
			writable: true,
			value: false,
		});
	}

	get [Symbol.toStringTag]() {
		return "CollectorMaxFileDescriptors";
	}

	collect(timestamp) {
		if (process.platform !== "linux") {
			return null;
		}

		if (this.collected) {
			return null;
		}

		return new Promise((resolve) => {
			fs.readFile("/proc/self/limits", "utf8", (error, limits) => {
				if (error) {
					resolve(null);
					return;
				}

				const lines = limits.split("\n");

				let result = "";
				lines.find((line) => {
					if (line.startsWith("Max open files")) {
						[, result] = line.split(/  +/);
						return true;
					}
					return false;
				});

				if (result === "") {
					resolve(null);
					return;
				}

				resolve([
					new Metric({
						name: `${this.prefix}process_max_fds`,
						description: "Maximum number of open file descriptors",
						type: 1,
						value: parseInt(result, 10),
						timestamp,
					}),
				]);

				this.collected = true;
			});
		});
	}
};

module.exports = CollectorMaxFileDescriptors;