Setting up a simple runners cluster to parallelize calculations

package.json

@@ -24,6 +24,7 @@
     "chai": "^3.5.0",
     "chalk": "^1.1.3",
     "co": "^4.6.0",
+    "co-mocha": "^1.1.3",
     "mocha": "^3.1.2"
   }
 }

src/cluster.js

@@ -0,0 +1,60 @@
+const cluster = require('cluster');
+const { length: numCPUs } = require('os').cpus();
+const { fork } = require('child_process');
+const Runner = require('./runner');
+const Layout = require('./layout');
+
+const workers = [];
+if (!process.env.CHILD_WORKER) {
+  while (workers.length < numCPUs) {
+    workers.push(fork(__dirname + '/cluster.js', { env: { CHILD_WORKER: 'yup' } }));
+  }
+} else {
+  let runner;
+  process.on('message', msg => {
+    if (msg.cmd === 'reset') {
+      runner = new Runner(msg.text, msg.options);
+    } else if (msg.cmd === 'run') {
+      const result = runner.typeWith(new Layout(msg.name, msg.config));
+      process.send(Object.assign({}, msg, { cmd: 'result', result }));
+    }
+  });
+}
+
+module.exports = class Cluster {
+  constructor(text, options={}) {
+    workers.forEach(worker => {
+      worker.send({ cmd: 'reset', text, options });
+      worker.on('message', msg => this.receivedMessage(msg));
+    });
+
+    this.waiters = {};
+  }
+
+  *runCollection(layouts) {
+    const promises = layouts.map((layout, index) => {
+      const worker = workers[index % workers.length];
+      return this.scheduleRunWith(layout, worker);
+    });
+
+    return yield Promise.all(promises);
+  }
+
+  scheduleRunWith(layout, worker) {
+    return new Promise(resolve => {
+      const uuid = Date.now() / 10000 + Math.random();
+      this.waiters[uuid] = { resolve, worker };
+      worker.send(Object.assign({ cmd: 'run', uuid }, layout));
+    });
+  }
+
+  receivedMessage(msg) {
+    const { cmd, uuid, result, name, config } = msg;
+    if (cmd === 'result') {
+      const layout = new Layout(name, config);
+      const { worker, resolve } = this.waiters[uuid];
+      delete(this.waiters[uuid]);
+      resolve && resolve({ result, layout });
+    }
+  }
+};

test/cluster_test.js

@@ -0,0 +1,28 @@
+const Cluster = require('../src/cluster');
+const { QWERTY, Dvorak, Colemak, Workman } = require('../src/presets');
+
+const text = global.TEXT_FIXTUE;
+const layouts = [ QWERTY, Dvorak, Colemak, Workman, QWERTY, Dvorak, Colemak, Workman ];
+
+describe('Cluster', () => {
+  const cluster = new Cluster(text, {
+    effortLimit: 2000,
+    sameHandPenalty: 0.5,
+    sameFingerPenalty: 5
+  });
+
+  it('allows to run a bunch of layouts', function * () {
+    const results = yield cluster.runCollection(layouts);
+    const data = results.map(result => `${result.layout.name} - ${result.result.position}`);
+    expect(data.sort()).to.eql([
+      "Colemak - 744",
+      "Colemak - 744",
+      "Dvorak - 586",
+      "Dvorak - 586",
+      "QWERTY - 407",
+      "QWERTY - 407",
+      "Workman - 833",
+      "Workman - 833"
+    ]);
+  });
+});

test/helper.js

@@ -1,2 +1,19 @@
+const mocha = require('mocha');
+const coMocha = require('co-mocha');
 const { expect } = require('chai');
+
 global.expect = expect;
+coMocha(mocha);
+
+global.TEXT_FIXTUE = `
+A long time ago in a galaxy far, far away
+
+It is a period of civil war. Rebel spaceships, striking from a
+hidden base, have won their first victory against the evil Galactic Empire.
+During the battle, Rebel spies managed to steal secret plans to the
+Empire's ultimate weapon, the Death Star, an armored space station
+with enough power to destroy an entire planet.
+Pursued by the Empire's sinister agents, Princess Leia races home
+aboard her starship, custodian of the stolen plans that can save her
+people and restore freedom to the galaxy...
+`;

test/runner_test.js

@@ -1,17 +1,6 @@
 const Runner = require('../src/runner');
 const { QWERTY, Dvorak, Colemak, Workman } = require('../src/presets');
-const text = `
-A long time ago in a galaxy far, far away
-
-It is a period of civil war. Rebel spaceships, striking from a
-hidden base, have won their first victory against the evil Galactic Empire.
-During the battle, Rebel spies managed to steal secret plans to the
-Empire's ultimate weapon, the Death Star, an armored space station
-with enough power to destroy an entire planet.
-Pursued by the Empire's sinister agents, Princess Leia races home
-aboard her starship, custodian of the stolen plans that can save her
-people and restore freedom to the galaxy...
-`;
+const text = global.TEXT_FIXTUE;
 
 describe('Runner', () => {
   const runner = new Runner(text, {

yarn.lock

@@ -148,7 +148,14 @@ cli-table@^0.3.1:
   dependencies:
     colors "1.0.3"
 
-co@^4.6.0:
+co-mocha:
+  version "1.1.3"
+  resolved "https://registry.yarnpkg.com/co-mocha/-/co-mocha-1.1.3.tgz#49bb9c85bcd17e3250f8b84b875dc76668bc41dc"
+  dependencies:
+    co "^4.0.0"
+    is-generator "^1.0.1"
+
+co@^4.0.0, co@^4.6.0:
   version "4.6.0"
   resolved "https://registry.yarnpkg.com/co/-/co-4.6.0.tgz#6ea6bdf3d853ae54ccb8e47bfa0bf3f9031fb184"
 
@@ -360,6 +367,10 @@ inherits@~2.0.1, inherits@2:
   version "2.0.3"
   resolved "https://registry.yarnpkg.com/inherits/-/inherits-2.0.3.tgz#633c2c83e3da42a502f52466022480f4208261de"
 
+is-generator@^1.0.1:
+  version "1.0.3"
+  resolved "https://registry.yarnpkg.com/is-generator/-/is-generator-1.0.3.tgz#c14c21057ed36e328db80347966c693f886389f3"
+
 is-my-json-valid@^2.12.4:
   version "2.15.0"
   resolved "https://registry.yarnpkg.com/is-my-json-valid/-/is-my-json-valid-2.15.0.tgz#936edda3ca3c211fd98f3b2d3e08da43f7b2915b"