mirror of
https://github.com/idanoo/GoScrobble.git
synced 2024-11-25 09:55:15 +00:00
54 lines
1.4 KiB
Markdown
54 lines
1.4 KiB
Markdown
# parallel-transform
|
|
|
|
[Transform stream](http://nodejs.org/api/stream.html#stream_class_stream_transform_1) for Node.js that allows you to run your transforms
|
|
in parallel without changing the order of the output.
|
|
|
|
npm install parallel-transform
|
|
|
|
It is easy to use
|
|
|
|
``` js
|
|
var transform = require('parallel-transform');
|
|
|
|
var stream = transform(10, function(data, callback) { // 10 is the parallism level
|
|
setTimeout(function() {
|
|
callback(null, data);
|
|
}, Math.random() * 1000);
|
|
});
|
|
|
|
for (var i = 0; i < 10; i++) {
|
|
stream.write(''+i);
|
|
}
|
|
stream.end();
|
|
|
|
stream.on('data', function(data) {
|
|
console.log(data); // prints 0,1,2,...
|
|
});
|
|
stream.on('end', function() {
|
|
console.log('stream has ended');
|
|
});
|
|
```
|
|
|
|
If you run the above example you'll notice that it runs in parallel
|
|
(does not take ~1 second between each print) and that the order is preserved
|
|
|
|
## Stream options
|
|
|
|
All transforms are Node 0.10 streams. Per default they are created with the options `{objectMode:true}`.
|
|
If you want to use your own stream options pass them as the second parameter
|
|
|
|
``` js
|
|
var stream = transform(10, {objectMode:false}, function(data, callback) {
|
|
// data is now a buffer
|
|
callback(null, data);
|
|
});
|
|
|
|
fs.createReadStream('filename').pipe(stream).pipe(process.stdout);
|
|
```
|
|
|
|
### Unordered
|
|
Passing the option `{ordered:false}` will output the data as soon as it's processed by a transform, without waiting to respect the order.
|
|
|
|
## License
|
|
|
|
MIT |