Move systrace helper out of the packager

Summary: @​public

The profiler helper shouldn't live inside the packager itself, move
it to the packager.js file with other middlewares.

Reviewed By: @martinbigio

Differential Revision: D2424878

packager.js

@@ -10,7 +10,7 @@
 
 var fs = require('fs');
 var path = require('path');
-var execFile = require('child_process').execFile;
+var childProcess = require('child_process');
 var http = require('http');
 var isAbsolutePath = require('absolute-path');
 
@@ -198,7 +198,7 @@ function getDevToolsLauncher(options) {
       var debuggerURL = 'http://localhost:' + options.port + '/debugger-ui';
       var script = 'launchChromeDevTools.applescript';
       console.log('Launching Dev Tools...');
-      execFile(path.join(__dirname, script), [debuggerURL], function(err, stdout, stderr) {
+      childProcess.execFile(path.join(__dirname, script), [debuggerURL], function(err, stdout, stderr) {
         if (err) {
           console.log('Failed to run ' + script, err);
         }
@@ -223,6 +223,47 @@ function statusPageMiddleware(req, res, next) {
   }
 }
 
+function systraceProfileMiddleware(req, res, next) {
+  if (req.url !== '/profile') {
+    next();
+    return;
+  }
+
+  console.log('Dumping profile information...');
+  const dumpName = '/tmp/dump_' + Date.now() + '.json';
+  const prefix = process.env.TRACE_VIEWER_PATH || '';
+  const cmd = path.join(prefix, 'trace2html') + ' ' + dumpName;
+  fs.writeFileSync(dumpName, req.rawBody);
+  childProcess.exec(cmd, function(error) {
+    if (error) {
+      if (error.code === 127) {
+        console.error(
+          '\n** Failed executing `' + cmd + '` **\n\n' +
+          'Google trace-viewer is required to visualize the data, do you have it installled?\n\n' +
+          'You can get it at:\n\n' +
+          '  https://github.com/google/trace-viewer\n\n' +
+          'If it\'s not in your path,  you can set a custom path with:\n\n' +
+          '  TRACE_VIEWER_PATH=/path/to/trace-viewer\n\n' +
+          'NOTE: Your profile data was kept at:\n\n' +
+          '  ' + dumpName
+        );
+      } else {
+        console.error('Unknown error', error);
+      }
+      res.end();
+      return;
+    } else {
+      childProcess.exec('rm ' + dumpName);
+      childProcess.exec('open ' + dumpName.replace(/json$/, 'html'), function(err) {
+        if (err) {
+          console.error(err);
+        }
+        res.end();
+      });
+    }
+  });
+}
+
 function getAppMiddleware(options) {
   var transformerPath = options.transformer;
   if (!isAbsolutePath(transformerPath)) {
@@ -255,6 +296,7 @@ function runServer(
     .use(openStackFrameInEditor)
     .use(getDevToolsLauncher(options))
     .use(statusPageMiddleware)
+    .use(systraceProfileMiddleware)
     // Temporarily disable flow check until it's more stable
     //.use(getFlowTypeCheckMiddleware(options))
     .use(getAppMiddleware(options));

react-packager/src/Server/index.js

@@ -16,8 +16,6 @@ const Promise = require('promise');
 
 const _ = require('underscore');
 const declareOpts = require('../lib/declareOpts');
-const exec = require('child_process').exec;
-const fs = require('fs');
 const path = require('path');
 const url = require('url');
 
@@ -290,42 +288,6 @@ class Server {
       ).done(() => Activity.endEvent(assetEvent));
   }
 
-  _processProfile(req, res) {
-    console.log('Dumping profile information...');
-    const dumpName = '/tmp/dump_' + Date.now() + '.json';
-    const prefix = process.env.TRACE_VIEWER_PATH || '';
-    const cmd = path.join(prefix, 'trace2html') + ' ' + dumpName;
-    fs.writeFileSync(dumpName, req.rawBody);
-    exec(cmd, error => {
-      if (error) {
-        if (error.code === 127) {
-          console.error(
-            '\n** Failed executing `' + cmd + '` **\n\n' +
-            'Google trace-viewer is required to visualize the data, do you have it installled?\n\n' +
-            'You can get it at:\n\n' +
-            '  https://github.com/google/trace-viewer\n\n' +
-            'If it\'s not in your path,  you can set a custom path with:\n\n' +
-            '  TRACE_VIEWER_PATH=/path/to/trace-viewer\n\n' +
-            'NOTE: Your profile data was kept at:\n\n' +
-            '  ' + dumpName
-          );
-        } else {
-          console.error('Unknown error', error);
-        }
-        res.end();
-        return;
-      } else {
-        exec('rm ' + dumpName);
-        exec('open ' + dumpName.replace(/json$/, 'html'), err => {
-          if (err) {
-            console.error(err);
-          }
-          res.end();
-        });
-      }
-    });
-  }
-
   processRequest(req, res, next) {
     const urlObj = url.parse(req.url, true);
     var pathname = urlObj.pathname;
@@ -346,9 +308,6 @@ class Server {
     } else if (pathname.match(/^\/assets\//)) {
       this._processAssetsRequest(req, res);
       return;
-    } else if (pathname.match(/^\/profile\/?$/)) {
-      this._processProfile(req, res);
-      return;
     } else {
       next();
       return;