ztrace

Trace what your program does, inspired by strace(1).

Install: [sudo] npm install -g ztrace

Usage:

test.js:

const fs = require('fs');

fs.statSync('/');

Look at the fs.stat call in action:

$ ztrace -e fs.stat* -s unlimited ./test.js
fs.statSync('/')
 @fs.stat('/') = { dev: 2049, mode: 16877, nlink: 25, uid: 0, gid: 0, rdev: 0, blksize: 4096, ino: 2, size: 4096, blocks: 8, atime: 2016-10-31T08:45:52.988Z, mtime: 2016-10-23T16:04:32.775Z, ctime: 2016-10-23T16:04:32.775Z, birthtime: 2016-10-23T16:04:32.775Z }
-> { dev: 2049, mode: 16877, nlink: 25, uid: 0, gid: 0, rdev: 0, blksize: 4096, ino: 2, size: 4096, blocks: 8, atime: 2016-10-31T08:45:52.988Z, mtime: 2016-10-23T16:04:32.775Z, ctime: 2016-10-23T16:04:32.775Z, birthtime: 2016-10-23T16:04:32.775Z }

(@fs.stat is the call to the C++ layer itself.)

If you want to trace everything, you can do that using just ztrace ./test.js – but be warned: This is still very slow.

There are shortcuts for programatically tracing interactions single objects to stderr:

const ztrace = require('ztrace');

// Displays results of this call to stderr.
ztrace(fs).statSync('.');

// Output:
// ~.statSync('.') = { dev: 44, mode: 16893, nlink:....377Z }

License

Copyright (C) 2016 Anna Henningsen

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.