dev: measure request transfer amount

src/backend/src/middleware/measure.js

@@ -0,0 +1,48 @@
+const express = require('express');
+const { PassThrough } = require('stream');
+const { pausing_tee } = require('../util/streamutil');
+
+function measure () {
+    return async (req, res, next) => {
+        if ( ! req.readable ) {
+            return next();
+        }
+
+        let sz_incoming = 0;
+        // let sz_outgoing = 0; // future
+
+        try {
+            const [req_monitor, req_pass] = pausing_tee(req, 2);
+
+            req_monitor.on('data', (chunk) => {
+                sz_incoming += chunk.length;
+            });
+
+            const replaces = ['readable', 'pipe', 'on', 'once', 'removeListener'];
+            for ( const replace of replaces ) {
+                const replacement = req_pass[replace]
+                Object.defineProperty(req, replace, {
+                    get () {
+                        if ( typeof replacement === 'function' ) {
+                            return replacement.bind(req_pass);
+                        }
+                        return replacement;
+                    }
+                });
+            }
+        } catch (e) {
+            console.error(e);
+            return next();
+        }
+
+        // Wait for the request to finish processing
+        res.on('finish', () => {
+            console.log(`Incoming Data: ${sz_incoming} bytes`);
+            // console.log(`Outgoing Data: ${sz_outgoing} bytes`); // future
+        });
+
+        next();
+    };
+}
+
+module.exports = measure;

src/backend/src/modules/web/WebServerService.js

@@ -26,6 +26,7 @@ const config = require('../../config.js');
 var http = require('http');
 const fs = require('fs');
 const auth = require('../../middleware/auth.js');
+const measure = require('../../middleware/measure.js');
 const { surrounding_box, es_import_promise } = require('../../fun/dev-console-ui-utils.js');
 
 const relative_require = require;
@@ -330,6 +331,9 @@ class WebServerService extends BaseService {
             next();
         });
 
+        // Measure data transfer amounts
+        app.use(measure());
+
         // Instrument logging to use our log service
         {
             const morgan = require('morgan');