index.js

'use strict';

const EventEmitter = require('events').EventEmitter;

function getRandomInt(min, max) {
	return Math.floor(Math.random() * (max - min + 1)) + min;
}

class KnexStore extends EventEmitter {
	constructor(knex, options) {
		super();

		this.knex = knex;

		this.options = Object.assign({
			tableName: 'Sessions',
			sync: true,               // if true, create the table if it doesn’t exist
			syncTimeout: 3000,        // if sync is true, how long to wait for initial sync (ms)
			gcFrequency: 10000,       // do garbage collection approx. every this many requests
			timestamps: false,        // if true, add knex updated_at and created_at columns
			browserSessionLifetime: 86400 * 1000  // how long to remember sessions without a TTL
		}, options || {});

		this.synced = false;

		if (this.options.sync) {
			this.knex.schema.hasTable(this.options.tableName)
			.then((exists) => {
				if (!exists) {
					return this.knex.schema.createTableIfNotExists(this.options.tableName, (table) => {
						table.string('id', 100).primary();
						table.text('data');
						table.bigInteger('expires');
						table.index('expires');
						if(this.options.timestamps) {
							table.timestamps();
						}
					});
				}
			})
				.then(() => {
					this.synced = true;
					this.emit('connect');
				});
		} else {
			this.synced = true;
			this.emit('connect');
		}
	}

	waitForSync() {
		if (this.synced) { return Promise.resolve(); }

		return new Promise((resolve, reject) => {
			const end = Date.now() + this.options.syncTimeout;
			const timerId = setInterval(() => {
				if (this.synced) {
					clearInterval(timerId);
					return resolve();
				}
				if (Date.now() > end) {
					clearInterval(timerId);
					const errMessage = `could not sync() the ${this.options.tableName} table`;
					return reject(new Error(errMessage));
				}
			}, 100);
		});
	}

	get(sid) {
		return this.waitForSync().then(() => {
			if (this.options.gcFrequency > 0) {
				if (getRandomInt(1, this.options.gcFrequency) === 1) { this.gc(); }
			}

			return this.knex(this.options.tableName)
				.where('id', sid)
				.andWhere('expires', '>', Math.floor(Date.now() / 1000))
				.limit(1)
				.then(rows => {
					if (!rows || rows.length === 0) { return null; }
					return JSON.parse(rows[0].data);
				});
		});
	}

	set(sid, sess, ttl) {
		if (!ttl) {
			if (sess.cookie && sess.cookie.maxAge) {
				// standard expiring cookie
				return this.set(sid, sess, sess.cookie.maxAge);
			} else if (this.options.browserSessionLifetime > 0) {
				// browser-session cookie
				return this.set(sid, sess, this.options.browserSessionLifetime);
			}
		}

		return this.waitForSync().then(() => {
			const expires = Math.floor((Date.now() + (Math.max(ttl, 0) || 0)) / 1000);

			return this.knex(this.options.tableName)
				.where('id', sid)
				.then((rows) => {
					if(rows && rows.length > 0) {
						return this.knex(this.options.tableName)
							.where('id', sid)
							.update({
								data: JSON.stringify(sess),
								expires: expires
							});
					}else {
						return this.knex(this.options.tableName)
							.insert({
								id: sid,
								data: JSON.stringify(sess),
								expires: expires
							})
					}
				});

		});
	}

	destroy(sid) {
		return this.waitForSync().then(() => {
			return this.knex(this.options.tableName)
				.where('id', sid)
				.del();
		});
	}

	gc() {
		return this.waitForSync().then(() => {
			return this.knex(this.options.tableName)
				.where('expires', '<=', Math.floor(Date.now() / 1000))
				.del();
		});
	}
}

module.exports = KnexStore;