feat(*): debounce running checker

Author: Nikita Korotkih

package.json

@@ -34,7 +34,7 @@
     "colors": "^1.1.2",
     "enhanced-resolve": "^0.9.1",
     "loader-utils": "^0.2.6",
-    "lodash": "^3.10.0",
+    "lodash": "^3.10.1",
     "object-assign": "^2.1.1",
     "parse-json": "^2.2.0",
     "strip-bom": "^2.0.0",
@@ -59,8 +59,10 @@
     "load-grunt-tasks": "^0.6.0",
     "mkdirp": "^0.5.1",
     "mocha": "^2.3.4",
+    "ps-node": "0.0.5",
     "rimraf": "^2.5.0",
     "tslint": "^3.2.2-dev.1",
-    "typescript": "^1.8.0-dev.20151202"
+    "typescript": "^1.8.0-dev.20151202",
+    "webpack-dev-server": "^1.14.1"
   }
 }

src/instance.ts

@@ -258,6 +258,15 @@ function setupWatchRun(compiler, instanceName: string) {
     });
 }
 
+let runChecker = (instance, payload) => {
+    instance.checker.send({
+        messageType: 'compile',
+        payload
+    });
+};
+
+runChecker = _.debounce(runChecker, 200);
+
 function setupAfterCompile(compiler, instanceName, forkChecker = false) {
     compiler.plugin('after-compile', function(compilation, callback) {
         let instance: ICompilerInstance = resolveInstance(compilation.compiler, instanceName);
@@ -269,10 +278,7 @@ function setupAfterCompile(compiler, instanceName, forkChecker = false) {
                 resolutionCache: state.host.moduleResolutionHost.resolutionCache
             };
 
-            instance.checker.send({
-                messageType: 'compile',
-                payload
-            });
+            runChecker(instance, payload);
         } else {
             if (!state.program) {
                 // program may be undefined here, if all files

test/checker.js

@@ -0,0 +1,102 @@
+var webpack = require('webpack');
+var Promise = require('bluebird');
+var ps = Promise.promisifyAll(require('ps-node'));
+var fs = Promise.promisifyAll(require('fs'));
+var expect = require('expect');
+
+var path = require('path');
+var loader = path.resolve(__dirname, '../dist.babel');
+var ForkCheckerPlugin = require(loader).ForkCheckerPlugin;
+var globalConfig = {
+    watch: true,
+    module: {
+        loaders: [
+            {
+                test: /\.ts?/,
+                loader: loader + '?doTypeCheck&+forkChecker',
+            },
+        ],
+    },
+    plugins: [
+        new ForkCheckerPlugin(),
+    ],
+};
+
+var outputDir = path.resolve(__dirname, './output/');
+
+describe('checker test', function() {
+    var toCheckFilename = './test/fixtures/to-check.ts';
+
+    this.timeout(5000);
+
+    var outputFile = path.resolve(outputDir, toCheckFilename);
+    var config =  {
+        output: {
+            path: outputDir,
+            filename: toCheckFilename,
+        },
+        entry: toCheckFilename,
+    };
+    var getCheckerRuntimeProcess = () => {
+        return ps.lookupAsync({
+            command: new RegExp('node'),
+            arguments: new RegExp('checker-runtime'),
+            psargs: 'aux'
+        }).then(res => {
+            return res[0];
+        });
+    };
+
+    var utilizeProcess = (p) => {
+        expect(p).toExist();
+
+        return ps.killAsync(p.pid);
+    };
+
+    it('should fork checker in separate process', function(done) {
+        // assert that checker starts on startup
+        new Promise((resolve, reject) => {
+            webpack(Object.assign(globalConfig, config), function(err, stat) {
+                resolve();
+            });
+        })
+        .then(getCheckerRuntimeProcess)
+        .then(p => {
+            expect(p).toExist();
+            return utilizeProcess(p);
+        })
+        .then(() => {
+            done();
+        })
+    });
+
+    it('should fork only one checker after multiple changes', function(done) {
+        // I didn't get how to test it more precise, so it's more like a proof of work
+        var fileContent = fs.readFileSync(toCheckFilename);
+        var updateFile = () => fs.writeFileAsync(toCheckFilename, Date.now());
+        var timeoutAsync = (ms) => {
+            return new Promise((resolve, reject) => {
+                setTimeout(resolve, ms);
+            });
+        };
+
+        new Promise((resolve, reject) => {
+            webpack(Object.assign(globalConfig, config), function(err, stat) {
+                resolve();
+            });
+        })
+        .then(getCheckerRuntimeProcess)
+        .then(p => {
+            expect(p).toExist();
+            var times = [];
+            var i = 10;
+            while(i--) { times.push(i); }
+
+            return Promise.each(times, () => {
+                return updateFile().then(() => timeoutAsync(50));
+            }).then(() => fs.writeFileAsync(toCheckFilename, fileContent));
+        })
+        .then(() => timeoutAsync(2000))
+        .then(() => { done(); });
+    });
+});

test/fixtures/to-check.ts

@@ -0,0 +1 @@
+1453065049802