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socket: don't emit premature 'close' #20745

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socket: don't emit premature 'close' #20745

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5 changes: 1 addition & 4 deletions doc/api/net.md
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Original file line number Diff line number Diff line change
Expand Up @@ -407,10 +407,7 @@ endpoint, depending on what it [`connect()`][`socket.connect()`] to.
added: v0.1.90
-->

* `hadError` {boolean} `true` if the socket had a transmission error.

Emitted once the socket is fully closed. The argument `hadError` is a boolean
which says if the socket was closed due to a transmission error.
Emitted once the socket is fully closed.

### Event: 'connect'
<!-- YAML
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36 changes: 17 additions & 19 deletions lib/net.js
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Expand Up @@ -249,8 +249,6 @@ function Socket(options) {

// Prevent the "no-half-open enforcer" from being inherited from `Duplex`.
options.allowHalfOpen = true;
// For backwards compat do not emit close on destroy.
options.emitClose = false;
stream.Duplex.call(this, options);

// Default to *not* allowing half open sockets.
Expand Down Expand Up @@ -583,33 +581,33 @@ Socket.prototype._destroy = function(exception, cb) {
clearTimeout(s[kTimeout]);
}

debug('close');
const onClosed = () => {
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I didn't test but I think this still does not prevent the 'error' event from being emitted multiple times. Assume that socket.destroy(err) is called twice.

First call will wait for this callback to be called and emit 'error' and 'close' when that happens.
Second call will find _readableState.destroyed set to true but _writableState.errorEmitted is not set to true yet as that will happen when this callback if invoked, so another 'error' event will be emitted.

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But isn't that true for any stream? If you call destroy twice with error it will emit error twice... I would say the problem is in the destroy impl then?

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No, it's emitted only once

const { Writable } = require('stream');

const w = new Writable();

w.on('error', console.log);
w.destroy(new Error('Oops'));
w.destroy(new Error('Oops'));

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@ronag ronag May 20, 2018 •
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Twice like this...

const { Writable } = require('stream');

const w = new Writable({
    destroy (err, cb) {
        process.nextTick(() => cb(err))
    }
});

w.on('error', console.log);
w.destroy(new Error('Oops'));
w.destroy(new Error('Oops'));

it's only once if you call cb synchronously. Which doesn't seem like the usual case or we wouldn't have a callback?

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The callback on destroy is not a public api. It is used only internally.

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@ronag ronag May 20, 2018 •
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I'm confused... https://nodejs.org/dist/latest-v10.x/docs/api/stream.html#stream_constructor_new_stream_writable_options and https://nodejs.org/dist/latest-v10.x/docs/api/stream.html#stream_writable_destroy_err_callback

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You are right, sorry, I was referring to https://nodejs.org/api/stream.html#stream_writable_destroy_error.

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(We should fix that error being emitted more than once in streams imo.)

cb(exception);

if (this._server) {
COUNTER_NET_SERVER_CONNECTION_CLOSE(this);
debug('has server');
this._server._connections--;
if (this._server._emitCloseIfDrained) {
this._server._emitCloseIfDrained();
}
}
};

if (this._handle) {
debug('close');
if (this !== process.stderr)
debug('close handle');
var isException = exception ? true : false;
// `bytesRead` and `kBytesWritten` should be accessible after `.destroy()`
this[kBytesRead] = this._handle.bytesRead;
this[kBytesWritten] = this._handle.bytesWritten;

this._handle.close(() => {
debug('emit close');
this.emit('close', isException);
});
this._handle.close(onClosed);
this._handle.onread = noop;
this._handle = null;
this._sockname = null;
}

cb(exception);

if (this._server) {
COUNTER_NET_SERVER_CONNECTION_CLOSE(this);
debug('has server');
this._server._connections--;
if (this._server._emitCloseIfDrained) {
this._server._emitCloseIfDrained();
}
} else {
onClosed();
}
};

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