http: emit abort event from ClientRequest

[evanlucas]

ClientRequest will now emit an abort event to detect when abort is
called.

Ref: nodejs/node-v0.x-archive#9278

[cjihrig]

@evanlucas this is what I had in mind, and this LGTM. However, would you be opposed to the following code as the test:

var assert = require('assert');
var http = require('http');
var common = require('../common');
var server = http.createServer(function(req, res) {
  res.end();
});

server.listen(common.PORT, function() {
  var req = http.request({
    port: common.PORT
  }, function() {
    assert(false, 'should not receive data');
  });

  req.on('abort', function() {
    server.close();
  });

  req.end();
  req.abort();
});

[brendanashworth]

+1

[kanongil]

So from now on I will have to listen to end, error, and abort to know when a request is "done"? Why not just fix the missing error emit regression?

[mscdex]

@kanongil IIRC isn't close always emitted after end and error (for sockets anyway)? I'm assuming close would fire after abort too? I typically just listen for close to know when the socket/request/whatever is "done."

[kanongil]

@mscdex Maybe, but the new abort logic can prevent the request from ever being assigned a socket.

[evanlucas]

@cjihrig works for me. Updated :]

[chrisdickinson]

Should we gate this so that abort can only be emitted once?

[evanlucas]

I think we should. Fixing it now.

[chrisdickinson]

LGTM, other than the gating question.

[evanlucas]

ok, updated so that abort will only be emitted if it hasn't already been emitted

[chrisdickinson]

LGTM.

[cjihrig]

Thanks! Landed in 2ca22aa. I added a note to the docs stating that abort would only be emitted on the first call to abort(). I floated in the current libuv patch locally to run the tests (but did not commit it).