update

README.md

@@ -1,10 +1,10 @@
-DRAFT
+SQLite3 Cluster
-=====
+===============
 
-This is just hypothetical while I build out the API
+Works with node cluster, or completely and unrelated node processes.
 
-SQLite3 Server
+**Note**: Most people would probably prefer to just use PostgreSQL rather than
-=============
+wrap SQLite as a service... but I am not most people.
 
 Node.js runs on a single core, which isn't very effective.
 
@@ -15,21 +15,126 @@ This module will either run client-server style in environments that benefit fro
 (such as the Raspberry Pi 2 with 4 cores), or in-process for environments that don't
 (such as the Raspberry Pi B and B+).
 
+This also works with **SQLCipher**.
+
 Usage
 =====
 
+The default behavior is to try to connect to a master and, if that fails, to become the master.
+
+However, if you are in fact using the `cluster` rather than spinning up random instances,
+you'll probably prefer to use this pattern:
+
 ```js
-var sqlite = require('sqlite3-server');
+var cluster = require('cluster');
+var sqlite = require('sqlite3-cluster');
+var numCores = require('os').cpus().length;
+
 var opts = {
-  key: '1892d335081d8d346e556c9c3c8ff2c3'
+  filename: '/tmp/mydb.sqlcipher'
-, bits: 128
+, sock: '/tmp/mydb.sqlcipher.sock'
-, filename: path.join('/tmp/authn.sqlcipher')
 , verbose: false
-, port: 3232 // default random
+
-, forceServer: true // default false
+  // a good default to use for instances where you might want
+  // to cluster or to run standalone, but with the same API
+, serve: cluster.isMaster
+, connect: cluster.isWorker
+, standalone: (1 === numCores) // overrides serve and connect
+
+  // if using SQLCipher, you can supply the key and desired bit-length
+  // and the appropriate PRAGMA statements will be issued before the database is returned
+, key: '00000000000000000000000000000000'
+, bits: 128
 };
 
 sqlite.create(opts).then(function (db) {
-  // EXACT same api as db
+  // same api as new sqlite3.Database(options.filename)
+
+  client.run("SELECT 1", [], function (err) {
+    if (err) {
+      console.error('[ERROR]', cluster.isMaster && '0' || cluster.worker.id);
+      console.error(err);
+      return;
+    }
+
+    console.log('[this]', cluster.isMaster && '0' || cluster.worker.id);
+    console.log(this);
+  });
 });
 ```
+
+If you wish to always use clustering, even on a single core system, see `test-cluster.js`.
+
+Likewise, if you wish to use standalone mode in a particular worker process see `test-standalone.js`.
+
+API
+===
+
+The API is exactly the same as `node-sqlite`, with these few exceptions:
+
+1 Database Creation
+-------------------
+
+Instead of this:
+
+```js
+var db = new require('sqlite3').Database(filename);
+```
+
+You must do this:
+
+```js
+require('sqlite3-cluster').create(filename);
+```
+
+2 db.escape
+-----------
+
+This is an additional helper function.
+
+If you need at any time to concatonate strings with user input
+(which you should rarely need to do since `db.run(stmt, arr, fn)`
+is usually sufficient), you can use the escape function.
+
+```js
+var sqlEscape = require('sqlite3-cluster').escape;
+```
+
+also
+
+```js
+require('sqlite3-cluster').create(options).then(function (db) {
+  // obligatory xkcd reference https://xkcd.com/327/
+  var userInput = db.escape("Robert'); DROP TABLE Students;");
+});
+```
+
+3 serialize / parallelize
+-------------------------
+
+`db.serialize(fn)` and `db.parallelize(fn)` are not supported because it would require
+copying a chunk of code from `node-sqlite3` and adapting it.
+
+It wouldn't be a difficult task, just tedious and generally no longer necessary since
+recent versions of node include native `Promise`s.
+
+Standalone / Master Mode is raw sqlite3
+========================
+
+The `master` in the cluster (meaning `opts.serve = true`) will have a direct connection
+to the sqlite3 database using `node-sqlite`, directly.
+
+Likewise, when only one process is being used (`opts.standalone = true`) the listener is
+not started and the connection is direct.
+
+If you take a look at `wrapper.js` you'll see that it simply resolves with an instance of
+`node-sqlite3`.
+
+Security Warning
+================
+
+Note that any application on the system could connect to the socket.
+
+In the future I may add a `secret` field in the options object to be
+used for authentication across processes. This would not be difficult,
+it's just not necessary for my use case at the moment.