metro/systraceProfileMiddleware.js

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/**
* Copyright (c) 2015-present, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under the BSD-style license found in the
* LICENSE file in the root directory of this source tree. An additional grant
* of patent rights can be found in the PATENTS file in the same directory.
*/
'use strict';
const exec = require('child_process').exec;
const fs = require('fs');
const path = require('path');
module.exports = function(req, res, next) {
if (req.url !== '/systrace') {
next();
return;
}
console.log('Dumping profile information...');
var dumpName = '/tmp/dump_' + Date.now() + '.json';
var prefix = process.env.TRACE_VIEWER_PATH || '';
var cmd = path.join(prefix, 'trace2html') + ' ' + dumpName;
fs.writeFileSync(dumpName, req.rawBody);
exec(cmd, function(error) {
if (error) {
if (error.code === 127) {
var response = '\n** Failed executing `' + cmd + '` **\n\n' +
'Google trace-viewer is required to visualize the data, ' +
'You can install it with `brew install trace2html`\n\n' +
'NOTE: Your profile data was kept at:\n' + dumpName;
console.log(response);
res.end(response);
} else {
console.error(error);
res.end('Unknown error: ' + error.message);
}
return;
} else {
exec('rm ' + dumpName);
exec('open ' + dumpName.replace(/json$/, 'html'), function(err) {
if (err) {
console.error(err);
res.end(err.message);
} else {
res.end();
}
});
}
});
};