improve test and cost function

Author: sokra

lib/reducePlan.js

@@ -74,7 +74,13 @@ module.exports = (plan, limit) => {
 		for (const node of treeMap.values()) {
 			if (node.entries <= 1 || !node.children) continue;
 			if (node.children.length <= 1) continue;
-			const cost = Math.abs(overLimit - node.entries + 1);
+			// Try to select the node with has just a bit more entries than we need to reduce
+			// When just a bit more is over 30% over the limit,
+			// also consider just a bit less entries then we need to reduce
+			const cost =
+				node.entries - 1 >= overLimit
+					? node.entries - 1 - overLimit
+					: overLimit - node.entries + 1 + limit * 0.3;
 			if (cost < bestCost) {
 				bestNode = node;
 				bestCost = cost;

lib/watchEventSource.js

@@ -298,3 +298,7 @@ exports.batch = fn => {
 		execute();
 	}
 };
+
+exports.getNumberOfWatchers = () => {
+	return watcherCount;
+};

test/ManyWatchers.js

@@ -5,6 +5,7 @@ require("should");
 const path = require("path");
 const TestHelper = require("./helpers/TestHelper");
 const Watchpack = require("../lib/watchpack");
+const watchEventSource = require("../lib/watchEventSource");
 
 const fixtures = path.join(__dirname, "fixtures");
 const testHelper = new TestHelper(fixtures);
@@ -16,9 +17,15 @@ describe("ManyWatchers", function() {
 
 	it("should watch more than 4096 directories", done => {
 		const files = [];
-		for (let i = 0; i < 5000; i++) {
-			const dir = `${Math.floor(i / 100)}/${i % 100}`;
-			if (i % 100 === 0) testHelper.dir(`${Math.floor(i / 100)}`);
+		for (let i = 1; i <= 5000; i++) {
+			let highBit = 1;
+			let j = i;
+			while (j > 1) {
+				highBit <<= 1;
+				j >>= 1;
+			}
+			const dir = `${i & highBit}/${i & ~highBit}`;
+			if (i === highBit) testHelper.dir(`${i}`);
 			testHelper.dir(dir);
 			testHelper.file(`${dir}/file`);
 			files.push(path.join(fixtures, dir, "file"));
@@ -28,7 +35,9 @@ describe("ManyWatchers", function() {
 				aggregateTimeout: 1000
 			});
 			w.on("aggregated", function(changes) {
-				Array.from(changes).should.be.eql([path.join(fixtures, "49/49/file")]);
+				Array.from(changes).should.be.eql([
+					path.join(fixtures, "4096/900/file")
+				]);
 				w.close();
 				done();
 			});
@@ -39,7 +48,7 @@ describe("ManyWatchers", function() {
 			}
 			w.watch({ files });
 			testHelper.tick(10000, () => {
-				testHelper.file("49/49/file");
+				testHelper.file("4096/900/file");
 			});
 		});
 	});

test/helpers/TestHelper.js

@@ -5,6 +5,8 @@ var path = require("path");
 var rimraf = require("rimraf");
 var writeFileAtomic = require("write-file-atomic");
 
+var watchEventSource = require("../../lib/watchEventSource");
+
 require("../../lib/getWatcherManager");
 var watcherManagerModule =
 	require.cache[require.resolve("../../lib/getWatcherManager")];
@@ -20,6 +22,7 @@ const checkAllWatcherClosed = () => {
 	for (const watcherManager of allWatcherManager) {
 		Array.from(watcherManager.directoryWatchers.keys()).should.be.eql([]);
 	}
+	watchEventSource.getNumberOfWatchers().should.be.eql(0);
 };
 
 function TestHelper(testdir) {