facebook#18 Using the bundle url resolve origin source in jsc profiler middleware

Reviewed By: bestander

Differential Revision: D3620292

fbshipit-source-id: e3c54fb30bc65ff1ddd650340a2905a9f0e16231

Author: lukaspiatkowski

local-cli/server/middleware/jscProfilerMiddleware.js

@@ -8,29 +8,133 @@
  */
 'use strict';
 
+const SourceMapConsumer = require('../../../node_modules/source-map').SourceMapConsumer;
 const fs = require('fs');
+const http = require('http');
+const urlLib = require('url');
+
+class TreeTransformator {
+  constructor() {
+    this.urlResults = {};
+  }
+
+  transform(tree, callback) {
+    this.afterUrlsCacheBuild(tree, () => {
+      callback(this.transformNode(tree));
+    });
+  }
+
+  // private
+  transformNode(tree) {
+    if (tree.url in this.urlResults) {
+      const original = this.urlResults[tree.url].originalPositionFor({
+        line: tree.lineNumber,
+        column: tree.columnNumber,
+      });
+      tree.scriptId = tree.id;
+      tree.url = 'file://' + original.source;
+      tree.lineNumber = original.line;
+      tree.columnNumber = original.column;
+    }
+    tree.children = tree.children.map((t) => this.transformNode(t));
+    return tree;
+  }
+
+  // private
+  afterUrlsCacheBuild(tree, callback) {
+    let urls = new Set();
+    this.gatherUrls(tree, urls);
+
+    let size = urls.size;
+    if (size === 0) {
+      callback();
+    } else {
+      urls.forEach((url) => {
+        this.callUrlCached(url, () => {
+          --size;
+          if (size === 0) {
+            callback();
+          }
+        });
+      });
+    }
+  }
+
+  // private
+  gatherUrls(tree, urls) {
+    urls.add(tree.url);
+    tree.children.map((t) => this.gatherUrls(t, urls));
+  }
+
+  // private
+  callUrlCached(url, callback) {
+    if (url === '' || url === null || url in this.urlResults) {
+      callback();
+      return;
+    }
+
+    const parsedUrl = urlLib.parse(url);
+    const options = {
+      host: parsedUrl.hostname,
+      port: parsedUrl.port,
+      path: parsedUrl.pathname.replace(/\.bundle$/, '.map') + parsedUrl.search,
+    };
+
+    http.get(options, (res) => {
+      res.setEncoding('utf8');
+      let sawEnd = false;
+      let resBody = '';
+      res.on('data', (chunk) => {
+        resBody += chunk;
+      }).on('end', () => {
+        sawEnd = true;
+        const map = JSON.parse(resBody.replace(/^\)\]\}'/, ''));
+        this.urlResults[url] = new SourceMapConsumer(map);
+        callback();
+      }).on('close', (err) => {
+        if (!sawEnd) {
+          console.error('Connection terminated prematurely because of: '
+                        + err.code + ' for url: ' + url);
+          this.urlResults[url] = null;
+          callback();
+        }
+      });
+    }).on('error', (err) => {
+      console.error('Could not get response from: ' + url);
+      this.urlResults[url] = null;
+      callback();
+    });
+  }
+}
 
 module.exports = function(req, res, next) {
   if (req.url !== '/jsc-profile') {
     next();
     return;
   }
 
-  console.log('Dumping JSC profile information...');
-  const dumpName = '/tmp/jsc-profile_' + Date.now() + '.cpuprofile';
-  fs.writeFile(dumpName, req.rawBody, (err) => {
-    var response = '';
-    if (err) {
-      response =
-        'An error occured when trying to save the profile at ' + dumpName;
-      console.error(response, err);
-    } else {
-      response =
-        'Your profile was generated at\n\n' + dumpName + '\n\n' +
-        'Open `Chrome Dev Tools > Profiles > Load` '
-        + 'and select the profile to visualize it.';
-      console.log(response);
-    }
-    res.end(response);
+  console.log('Received request from JSC profiler, post processing it...');
+  let profile = JSON.parse(req.rawBody);
+  (new TreeTransformator()).transform(profile.head, (newHead) => {
+    profile.head = newHead;
+
+    console.log('Dumping JSC profile information...');
+    const dumpName = '/tmp/jsc-profile_' + Date.now() + '.cpuprofile';
+
+    fs.writeFile(dumpName, JSON.stringify(profile), (err) => {
+      let response = '';
+      if (err) {
+        response =
+          'An error occured when trying to save the profile at ' + dumpName;
+        console.error(response, err);
+      } else {
+        response =
+          'Your profile was generated at\n\n' + dumpName + '\n\n' +
+          'Open `Chrome/Atom Dev Tools > Profiles > Load` '
+          + 'and select the profile to visualize it.';
+        console.log(response);
+      }
+      res.end(response);
+    });
   });
 };