Implemented Snapshot.export

[3y3]

For @thlorenz review.

[thlorenz]

Looks nice after quick review and should solve the problem I was trying to tackle in #55.
I'll review this in more detail and give you better feedback by Monday.

[3y3]

@thlorenz , Ok, thanks.
@bajtos , any thoughts?

[bajtos]

I'd say the solution is overcomplicated, it should be enough to support the flavour export().pipe(). Everything else can be achieved by stream composition, there is no need to repeat it in v8-profiler.

[3y3]

@bajtos , are you propose to return Writable stream if there are no arguments passed to function, or you also propose to completely remove callback strategy for this method?

[bajtos]

are you propose to return Writable stream if there are no arguments passed to function, or you also propose to completely remove callback strategy for this method?

Yes and yes.

See concat-stream for an example of converting a stream-based interface to a callback-based one.

[bajtos]

Code sample:

var callback = function(err, data) { /*...*/ };
var concatStream = require('concat-stream')(function(data) { callback(null, data); });
profiler.takeSnapshot().export()
  .on('error', callback)
  .pipe(concatStream)
  .on('error', callback);

[bajtos]

Also toStream() may be a better method name than export.

[3y3]

Also toStream() may be a better method name than export.

I take export name, because I want to implement also import.snapshot method.
Completed API will look like:

var fs = require('fs') ;

profiler.gc().takeSnapshot().export() // We don't need to keep snapshot in memory
  .pipe(fs.createWriteStream('snapshot1'))
  .on('finish', profiler.gc)
  .on('finish', function test() {
    // Do something here.
    //...
    compareHeapState();
  });

function compareHeapState() {
  var currentHeap = profiler.takeSnapshot(),
    startHeap = profiler.import.snapshot('snapshot1');

  return currentHeap.compare(startHeap);
}

Of course we don't have gc method now =)

[eljefedelrodeodeljefe]

@3y3 are you moving forwards with this?

[3y3]

Landed.
I prefer to keep callback api, because not a good idea to install external dependencie only to have ability to save snapshot.