Refactor code structure

package.json

@@ -2,7 +2,7 @@
   "name": "express-pprof-middleware",
   "version": "0.0.8",
   "description": "Express middleware that exposes pprof endpoints for easy profiling",
-  "main": "index.js",
+  "main": "src/index.js",
   "devDependencies": {
     "chai": "~3.5.0",
     "co-mocha": "1.2.2",

src/constants.js

@@ -0,0 +1,17 @@
+const HEAP_FILE_PATH = '/tmp/heap.pb.gz';
+const WALL_FILE_PATH = '/tmp/wall.pb.gz';
+const HEAP_WEB_PATH = '/debug/pprof/heap';
+const HEAP_STOP_PATH = '/debug/pprof/heap/stop';
+const WALL_WEB_PATH = '/debug/pprof/wall';
+const INTERVAL_BYTES = 512 * 1024;
+const STACK_DEPTH = 64;
+
+module.exports = {
+    HEAP_FILE_PATH,
+    WALL_FILE_PATH,
+    HEAP_WEB_PATH,
+    HEAP_STOP_PATH,
+    WALL_WEB_PATH,
+    INTERVAL_BYTES,
+    STACK_DEPTH
+}

src/heap.js

@@ -0,0 +1,24 @@
+const fs = require('fs');
+const { HEAP_FILE_PATH, INTERVAL_BYTES, STACK_DEPTH } = require('./constants');
+
+/**
+ * @param  {Object} pprof - The pprof instance
+ */
+const heap = async (pprof) => {
+	try {
+		pprof.heap.start(INTERVAL_BYTES, STACK_DEPTH);
+	} catch { }
+	const profile = await pprof.heap.profile();
+	const buf = await pprof.encode(profile);
+	return new Promise((resolve, reject) => {
+		fs.writeFile(HEAP_FILE_PATH, buf, (err) => {
+			if (err) {
+				reject(err);
+			} else {
+				resolve(HEAP_FILE_PATH);
+			}
+		});
+	});
+};
+
+module.exports = heap;

src/index.js

@@ -0,0 +1,55 @@
+const pprof = require('pprof');
+const heap = require('./heap');
+const wall = require('./wall');
+const { 
+  HEAP_WEB_PATH,
+  HEAP_STOP_PATH, 
+  WALL_WEB_PATH, 
+  INTERVAL_BYTES, 
+  STACK_DEPTH 
+} = require('./constants');
+
+// Start Heap Profiler
+pprof.heap.start(INTERVAL_BYTES, STACK_DEPTH);
+
+/**
+ * @param  {Object} req
+ * @param  {Object} res
+ * @param  {Function} next
+ */
+const middleware = async (req, res, next) => {
+  switch (req.path) {
+    case HEAP_WEB_PATH:
+      try {
+        const response = await heap(pprof);
+        return res.sendFile(response);
+      } catch (err) {
+        return res.status(500).send(err.message);
+      }
+    case WALL_WEB_PATH:
+      try {
+        let millis = 5000;
+        if (req.query.seconds) {
+          const secs = parseInt(req.query.seconds, 10);
+          if (!Number.isNaN(secs) && secs > 0) {
+            millis = secs * 1000;
+          }
+        }
+        const response = await wall(millis, pprof);
+        return res.sendFile(response);
+      } catch (err) {
+        return res.status(500).send(err.message);
+      }
+    case HEAP_STOP_PATH:
+      try {
+        pprof.heap.stop();
+        return res.send('');
+      } catch (err) {
+        return res.status(500).send(err.message);
+      }
+    default:
+      return next();
+  }
+};
+
+module.exports = middleware;

src/wall.js

@@ -0,0 +1,24 @@
+const fs = require('fs');
+const { WALL_FILE_PATH } = require('./constants');
+
+/**
+ * @param  {number} durationMillis - sampling duration
+ * @param  {Object} pprof - The pprof instance
+ */
+const wall = async (durationMillis, pprof) => {
+	const profile = await pprof.time.profile({
+		durationMillis,
+	});
+	const buf = await pprof.encode(profile);
+	return new Promise((resolve, reject) => {
+		fs.writeFile(WALL_FILE_PATH, buf, (err) => {
+			if (err) {
+				reject(err);
+			} else {
+				resolve(WALL_FILE_PATH);
+			}
+		});
+	});
+};
+
+module.exports = wall;

test/index.test.js

@@ -2,13 +2,13 @@ const { expect } = require('chai');
 
 describe('module main file - index.js', () => {
   it('should call without error', () => {
-    require('../index');
+    require('../src/index');
   });
 });
 
 describe('heap profile', () => {
   it('should be correctly created and called', async () => {
-    const middleware = require('../index');
+    const middleware = require('../src/index');
     expect(middleware).to.be.instanceof(Function);
 
     let heapFilePath = '';
@@ -22,7 +22,7 @@ describe('heap profile', () => {
 
 describe('wall profile', () => {
   it('should be correctly created and called', async () => {
-    const middleware = require('../index');
+    const middleware = require('../src/index');
     expect(middleware).to.be.instanceof(Function);
 
     let wallFilePath = '';
@@ -36,7 +36,7 @@ describe('wall profile', () => {
 
 describe('heap stop', () => {
   it('should be correctly created and called', async () => {
-    const middleware = require('../index');
+    const middleware = require('../src/index');
     expect(middleware).to.be.instanceof(Function);
 
     let sendResult = '';