ncache.js

const isBrowser = (typeof windows !== 'undefined');

class Cache {
	constructor(params = {}) {
		if (!isBrowser) {
			this.crypto = require('crypto');
		}

		this.cache = {};
		this.cacheTime = {};

		this._settings = Object.assign({
			cacheDefaultTime: 5 * 60 * 1000,
			cacheClearProb: 0.01
		}, params);
	}

	settings(key, value) {
		if (typeof key === 'object') {
			Object.assign(this._settings, key);
			return true;
		}

		if (!value) {
			return this._settings[key];
		}

		this._settings[key] = value;
		return true;
	}

	md5(str) {
		if (isBrowser) {
			throw new Error('Not implemented');
		}
		return this.crypto.createHash('md5').update(str).digest("hex");
	}

	hash(_str) {
		let hash = 0;
		const str = _str.toString();

		if (str.length === 0) {
			return hash;
		}

		for (let i = 0; i < str.length; i++) {
			const chr = str.charCodeAt(i);
			hash = ((hash << 5) - hash) + chr;
			hash |= 0;
		}

		return hash;
	}

	check(key) {
		return this.cacheTime[key] &&
			this.cacheTime[key] >= new Date().valueOf() &&
			this.cache[key];
	}

	get(key) {
		if (this.check(key)) {
			return this.cache[key];
		} else {
			this._clearCheck();
			return null;
		}
	}

	set(key, value, livetime) {
		const cacheDefaultTime = this._settings.cacheDefaultTime;
		const data = [];

		if (typeof key === 'object') {
			data.push(key);
		} else {
			data.push({ key, value, livetime });
		}

		data.forEach((d) => {
			this.cache[d.key] = d.value;
			this.cacheTime[d.key] = new Date().valueOf() + (d.livetime >> 0 || cacheDefaultTime);
		});
	}

	remove(key) {
		if (key.endsWith('*')) {
			const start = key.replace(/\*$/, '');

			Object.keys(this.cacheTime)
				.filter(key => key.startsWith(start))
				.forEach(key => this.remove(key));

			this.gc();
		} else {
			delete(this.cacheTime[key]);
			delete(this.cache[key]);
		}
	}

	_clearCheck() {
		if (Math.random() < this._settings.cacheClearProb) {
			this.clean();
		}
	}

	clean() {
		Object.keys(this.cacheTime).forEach((key) => {
			if (this.cacheTime[key] < new Date().valueOf()) {
				this.remove(key);
			}
		});

		this.gc();
	}

	clear() {
		Object.keys(this.cacheTime).forEach((key) => {
			this.remove(key);
		});

		this.gc();
	}

	gc() {
		if (typeof global !== 'undefined' && typeof global.gc === 'function') {
			// perform GC if we can
			global.gc();
		}
	}
}

module.exports = new Cache();