locked-atomic-ws

A combination of fs-write-stream-atomic and node-proper-lockfile to ensure that no more than one (atomic) write stream can be used at a time for a certain file. Since atomically streaming to a file requires a temporary file (&& fs.rename afterwords), aquiring a lock means preventing work in vain.

Example

1var fs = require('fs');
2var getWriteStream = require('../');
3
4getWriteStream(__dirname + '/out.txt', function(err, isLocked, ws) {
5  if (err) { throw err; }
6
7  if (isLocked) {
8    return console.error('please try again later');
9  }
10
11  // once we get here we are sure that nobody else (using this module)
12  // is trying to write to the same file
13  // also, the write-stream will be atomic (see https://github.com/npm/fs-write-stream-atomic/)
14
15  ws.on('error', die);
16  ws.on('close', function() {
17    console.log('all done');
18  });
19
20  var rs = fs.createReadStream(__filename);
21
22  rs
23    .on('error', die)
24    .pipe(ws)
25});
26
27function die(err) {
28  throw err;
29}

Status

Alpha, read the source code for more info on how this works. Needs tests.

License

MIT