Derive all database classes from a new AbstractDatabase class

This will make it possible to implement default methods and move over
common behavior.

README.md

@@ -313,22 +313,18 @@ environment variable `NODE_TLS_REJECT_UNAUTHORIZED = 0` and add the flag
 
 ## How to add support for another database
 
-1. Add your database to `packages.json`, this will happen automatically if you
-   run `npm install %yourdatabase%`
-1. Add some example settings to `test/lib/databases.js` for your database.
-1. Look at `databases/mysql_db.js`, your module have to provide the same
-   functions. Call it `DATABASENAME_db.js` and reimplement the functions for
-   your database. Most of your work here will be copy/paste from other databases
-   so don't be scared.
-1. Add your database Travis setup steps to `.travis.yml`, see the
-   `before_install` section and MySQL example. Note that MySQL has a preloaded
-   script (comes from mysql.sql) which preloads the database with 1M records. If
-   you can, you should do the same.
-1. Run `npm test` and ensure it's working.
-1. Branch from master `git checkout -b my-awesome-database` and submit a pull
-   request including the changes which should include **1 new and 3 modified
-   files**.
-1. Once merged we really need you to be on top of maintaining your code.
+1. Add the database driver to `packages.json`, this will happen automatically if
+   you run `npm install %yourdatabase%`
+1. Create `databases/DATABASENAME_db.js` and have it export a `Database` class
+   that derives from `lib/AbstractDatabase.js`. Implement the required
+   functions.
+1. Add a service for the database to the test job in
+   `.github/workflows/npmpublish.yml`.
+1. Add an entry to `test/lib/databases.js` for your database and configure it to
+   work with the service added to the GitHub workflow.
+1. Install and start the database server and configure it to work with the
+   settings in your `test/lib/databases.js` entry.
+1. Run `npm test` to ensure that it works.
 
 ## License
 

databases/cassandra_db.js

@@ -13,9 +13,10 @@
  * limitations under the License.
  */
 
+const AbstractDatabase = require('../lib/AbstractDatabase');
 const cassandra = require('cassandra-driver');
 
-exports.Database = class {
+exports.Database = class extends AbstractDatabase {
   /**
    * @param {Object} settings The required settings object to initiate the Cassandra database
    * @param {String[]} settings.clientOptions See
@@ -28,6 +29,7 @@ exports.Database = class {
    *     information
    */
   constructor(settings) {
+    super();
     if (!settings.clientOptions) {
       throw new Error('The Cassandra client options should be defined');
     }

databases/couch_db.js

@@ -15,6 +15,7 @@
  * limitations under the License.
  */
 
+const AbstractDatabase = require('../lib/AbstractDatabase');
 const nano = require('nano');
 const async = require('async');
 
@@ -25,8 +26,9 @@ const handleError = (er) => {
   if (er) throw new Error(er);
 };
 
-exports.Database = class {
+exports.Database = class extends AbstractDatabase {
   constructor(settings) {
+    super();
     this.db = null;
     this.client = null;
     this.settings = settings;

databases/dirty_db.js

@@ -22,10 +22,12 @@
 *
 */
 
+const AbstractDatabase = require('../lib/AbstractDatabase');
 const Dirty = require('dirty');
 
-exports.Database = class {
+exports.Database = class extends AbstractDatabase {
   constructor(settings) {
+    super();
     this.db = null;
 
     if (!settings || !settings.filename) {

databases/dirty_git_db.js

@@ -15,10 +15,12 @@
  * limitations under the License.
  */
 
+const AbstractDatabase = require('../lib/AbstractDatabase');
 const Dirty = require('dirty');
 
-exports.Database = class {
+exports.Database = class extends AbstractDatabase {
   constructor(settings) {
+    super();
     this.db = null;
 
     if (!settings || !settings.filename) {

databases/elasticsearch_db.js

@@ -15,6 +15,7 @@
  * limitations under the License.
  */
 
+const AbstractDatabase = require('../lib/AbstractDatabase');
 const es = require('elasticsearch');
 
 // initialize w/ default settings
@@ -30,8 +31,9 @@ const elasticsearchSettings = {
 
 let client;
 
-exports.Database = class {
+exports.Database = class extends AbstractDatabase {
   constructor(settings) {
+    super();
     this.db = null;
 
     this.settings = settings || {};

databases/mongodb_db.js

@@ -15,8 +15,11 @@
  * limitations under the License.
  */
 
-exports.Database = class {
+const AbstractDatabase = require('../lib/AbstractDatabase');
+
+exports.Database = class extends AbstractDatabase {
   constructor(settings) {
+    super();
     this.settings = settings;
 
     if (!this.settings.url) throw new Error('You must specify a mongodb url');

databases/mssql_db.js

@@ -21,11 +21,13 @@
  *
  */
 
+const AbstractDatabase = require('../lib/AbstractDatabase');
 const async = require('async');
 const mssql = require('mssql');
 
-exports.Database = class {
+exports.Database = class extends AbstractDatabase {
   constructor(settings) {
+    super();
     settings = settings || {};
 
     if (settings.json != null) {

databases/mysql_db.js

@@ -15,11 +15,13 @@
  * limitations under the License.
  */
 
+const AbstractDatabase = require('../lib/AbstractDatabase');
 const mysql = require('mysql');
 const util = require('util');
 
-exports.Database = class {
+exports.Database = class extends AbstractDatabase {
   constructor(settings) {
+    super();
     this.logger = console;
     this._mysqlSettings = {
       charset: 'utf8mb4', // temp hack needs a proper fix..

databases/postgres_common.js

@@ -15,9 +15,10 @@
  * limitations under the License.
  */
 
+const AbstractDatabase = require('../lib/AbstractDatabase');
 const async = require('async');
 
-exports.Database = class {
+exports.Database = class extends AbstractDatabase {
   init(callback) {
     const testTableExists = "SELECT 1 as exists FROM pg_tables WHERE tablename = 'store'";
 

databases/redis_db.js

@@ -17,11 +17,13 @@
  * limitations under the License.
  */
 
+const AbstractDatabase = require('../lib/AbstractDatabase');
 const async = require('async');
 const redis = require('redis');
 
-exports.Database = class {
+exports.Database = class extends AbstractDatabase {
   constructor(settings) {
+    super();
     this.client = null;
     this.settings = settings || {};
   }

databases/rethink_db.js

@@ -15,11 +15,13 @@
  * limitations under the License.
  */
 
+const AbstractDatabase = require('../lib/AbstractDatabase');
 const r = require('rethinkdb');
 const async = require('async');
 
-exports.Database = class {
+exports.Database = class extends AbstractDatabase {
   constructor(settings) {
+    super();
     if (!settings) settings = {};
     if (!settings.host) { settings.host = 'localhost'; }
     if (!settings.port) { settings.port = 28015; }

databases/sqlite_db.js

@@ -25,12 +25,14 @@ try {
       '"npm install sqlite3" in your etherpad-lite root folder.');
 }
 
+const AbstractDatabase = require('../lib/AbstractDatabase');
 const util = require('util');
 
 const escape = (val) => `'${val.replace(/'/g, "''")}'`;
 
-exports.Database = class {
+exports.Database = class extends AbstractDatabase {
   constructor(settings) {
+    super();
     this.db = null;
 
     if (!settings || !settings.filename) {

lib/AbstractDatabase.js

@@ -0,0 +1,18 @@
+'use strict';
+
+module.exports = class AbstractDatabase {
+  constructor() {
+    if (new.target === module.exports) {
+      throw new TypeError('cannot instantiate Abstract Database directly');
+    }
+    for (const fn of ['init', 'close', 'get', 'findKeys', 'remove', 'set']) {
+      if (typeof this[fn] !== 'function') throw new TypeError(`method ${fn} not defined`);
+    }
+  }
+
+  doBulk(operations, cb) {
+    throw new Error('the doBulk method must be implemented if write caching is enabled');
+  }
+
+  get isAsync() { return false; }
+};