feat(utilities): heapsnapshot

utilities/server.js

@@ -1,14 +1,15 @@
-var sourcemapsReaderServer = require('./servers/sourcemaps-server');
-var {peerRouter, peerConnection, peerDisconnect, peerError} = require('./servers/peerjs-server');
-var express = require('express');
+const dumps = require('./utils/dump');
+const sourcemapsReaderServer = require('./servers/sourcemaps-server');
+const {peerRouter, peerConnection, peerDisconnect, peerError} = require('./servers/peerjs-server');
+const express = require('express');
 const {ExpressPeerServer} = require('peer');
 const socket = require("./servers/websocket");
 
 const HOST = '0.0.0.0';
 const PORT = 9000;
 
-var app = express();
-var wsapp = express();
+const app = express();
+const wsapp = express();
 let debug = process.env.debug === "1" || false;
 const request_logger = (identity) => {
     return (req, res, next) => {
@@ -29,6 +30,13 @@ app.use('/sourcemaps', sourcemapsReaderServer);
 app.use('/assist', peerRouter);
 wsapp.use('/assist', socket.wsRouter);
 
+app.get('/heapdump', dumps.sendHeapSnapshot);
+app.get('/heapdump/save', dumps.saveHeapSnapshot);
+wsapp.get('/heapdump', dumps.sendHeapSnapshot);
+wsapp.get('/heapdump/save', dumps.saveHeapSnapshot);
+
+console.log(`Heapdump enabled. Send a request to "/heapdump" to download a heapdump,\nor "/heapdump/save" to only generate a heapdump.`);
+
 const server = app.listen(PORT, HOST, () => {
     console.log(`App listening on http://${HOST}:${PORT}`);
     console.log('Press Ctrl+C to quit.');

utilities/utils/dump.js

@@ -0,0 +1,50 @@
+const fs = require('fs');
+const v8 = require('v8');
+
+const location = '/tmp/';
+
+async function createHeapSnapshot() {
+    const fileName = `${Date.now()}.heapsnapshot`;
+    await fs.promises.writeFile(
+        location + fileName,
+        v8.getHeapSnapshot()
+    );
+    return fileName;
+}
+
+
+async function sendHeapSnapshot(req, res) {
+    const fileName = await createHeapSnapshot();
+    const file = fs.readFileSync(location + fileName, 'binary');
+    const stat = fs.statSync(location + fileName);
+
+    res.setHeader('Content-Length', stat.size);
+    res.setHeader('Content-Type', 'audio/mpeg');
+    res.setHeader('Content-Disposition', 'attachment; filename=' + fileName);
+    res.write(file, 'binary');
+    res.end();
+    try {
+        fs.unlinkSync(location + fileName)
+    } catch (err) {
+        console.error("error while deleting heapsnapshot file");
+        console.error(err);
+    }
+}
+
+process.on('USR2', () => {
+    console.info('USR2 signal received.');
+});
+
+async function saveHeapSnapshot(req, res) {
+    const fileName = await createHeapSnapshot();
+    const path = location + fileName;
+    console.log(`Heapdump saved to ${path}`)
+    res.statusCode = 200;
+    res.setHeader('Content-Type', 'application/json');
+    res.end(JSON.stringify({path}));
+}
+
+process.on('USR2', () => {
+    console.info('USR2 signal received.');
+});
+module.exports = {sendHeapSnapshot, saveHeapSnapshot}