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streams: introduce StreamWrap and JSStream #926

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streams: introduce StreamWrap and JSStream #926

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streams: introduce StreamWrap and JSStream
indutny Feb 23, 2015
d9711b1
fix
indutny Feb 23, 2015
866e957
fixes
indutny Feb 23, 2015
3310b48
fixes
indutny Feb 24, 2015
b9c004b
fix
indutny Feb 24, 2015
cef4c46
fix
indutny Feb 24, 2015
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95 changes: 95 additions & 0 deletions lib/_stream_wrap.js
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Original file line number Diff line number Diff line change
@@ -0,0 +1,95 @@
const util = require('util');
const Socket = require('net').Socket;
const JSStream = process.binding('js_stream').JSStream;

function StreamWrap(stream) {
var handle = new JSStream();

this.stream = stream;

var self = this;
handle.close = function(cb) {
cb();
};
handle.isAlive = function() {
return self.isAlive();
};
handle.isClosing = function() {
return self.isClosing();
};
handle.onreadstart = function() {
return self.readStart();
};
handle.onreadstop = function() {
return self.readStop();
};
handle.onshutdown = function(req) {
return self.shutdown(req);
};
handle.onwrite = function(req, bufs) {
return self.write(req, bufs);
};

this.stream.pause();
this.stream.on('data', function(chunk) {
self._handle.readBuffer(chunk);
});
this.stream.once('end', function() {
self._handle.emitEOF();
});

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What happens when the underlying stream emits an error? Per this diagram I don't think the stream will emit "end" or "finish". Is there a way to recover from an error in this state?

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I guess this should be handled by the code that created this stream... it could be propagated to the StreamWrap object, though, and handled in _tls_wrap.js. Does this sound plausible?

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I think that sound plausible – my expectation would be that a StreamWrap'd stream would expose the inner stream's errors on the outer stream.

I guess this should be handled by the code that created this stream...

This could be a situation where a user gets a stream from package X, instantiates it and passes it to TLSSocket Y; I think the user assumes responsibility for adding error handlers to TLSSocket Y, while TLSSocket Y would be responsible for shutting down / closing / cleaning up once an error on stream X happens.

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But this is not the way it works for piping the streams right now, right?

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An error downstream will unpipe and clean up listeners on the upstream stream, but will not shut down or destroy the source stream. This has caused a bit of confusion for stream users.

In addition, the act of nesting streams is distinct from piping streams, though piping can be involved in nesting. We don't nest streams often in core (TLS and arguably http are the only places we do something like this.) In userland usually the wrapping stream assumes responsibility for shutting itself down on inner stream error and exposing those errors to userland. Illustrated:

// user assumes responsibility for streams a, b, and c
a = stream()
b = stream()
c = stream()
a.pipe(b).pipe(c).pipe(b).pipe(a)

// user assumes responsibility for streams a and b, but not stream c
a = stream()
c = stream()
b = stream(c)
a.pipe(b).pipe(a).

Socket.call(this, {
handle: handle
});
}
util.inherits(StreamWrap, Socket);
exports.StreamWrap = StreamWrap;
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Tiny nit: may as well module.exports = here.

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Yeah, good idea.


StreamWrap.prototype.isAlive = function isAlive() {
return this.readable && this.writable;
};

StreamWrap.prototype.isClosing = function isClosing() {
return !this.isAlive();
};

StreamWrap.prototype.readStart = function readStart() {
this.stream.resume();
return 0;
};

StreamWrap.prototype.readStop = function readStop() {
this.stream.pause();
return 0;
};

StreamWrap.prototype.shutdown = function shutdown(req) {
var self = this;

this.stream.end(function() {
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I think we can get an error here, too.

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No, we can't :(

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I am mistaken!

// Ensure that write was dispatched
setImmediate(function() {
self._handle.finishShutdown(req, 0);
});
});
};

StreamWrap.prototype.write = function write(req, bufs) {
var pending = bufs.length;
var self = this;

bufs.forEach(function(buf) {
self.stream.write(buf, done);
});
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Might be useful to sniff for self.stream._writev, and if present, surround the forEach with cork() / uncork()?

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Good suggestion.

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I think it should be enough to just use .cork()/.uncork() and hope for the best.

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Fixed.


function done() {
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We may want to take error here.

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Actually, ignore that – if we're listening on error on the inner stream we should be okay.

if (--pending !== 0)
return;
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Does this mean that if there's an error we'll never execute the rest of the function?

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My mistake, will fix it in a bit.

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Fixed.


// Ensure that write was dispatched
setImmediate(function() {
self._handle.doAfterWrite(req);
self._handle.finishWrite(req, 0);
});
}
};
11 changes: 9 additions & 2 deletions lib/_tls_wrap.js
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,8 @@ const tls = require('tls');
const util = require('util');
const listenerCount = require('events').listenerCount;
const common = require('_tls_common');
const StreamWrap = require('_stream_wrap').StreamWrap;
const Duplex = require('stream').Duplex;
const debug = util.debuglog('tls');
const Timer = process.binding('timer_wrap').Timer;
const tls_wrap = process.binding('tls_wrap');
Expand Down Expand Up @@ -224,6 +226,10 @@ function TLSSocket(socket, options) {
this.authorized = false;
this.authorizationError = null;

// Wrap plain JS Stream into StreamWrap
if (socket instanceof Duplex)
socket = new StreamWrap(socket);

// Just a documented property to make secure sockets
// distinguishable from regular ones.
this.encrypted = true;
Expand Down Expand Up @@ -280,7 +286,8 @@ TLSSocket.prototype._wrapHandle = function(handle) {
// Proxy HandleWrap, PipeWrap and TCPWrap methods
proxiedMethods.forEach(function(name) {
res[name] = function methodProxy() {
return handle[name].apply(handle, arguments);
if (handle[name])
return handle[name].apply(handle, arguments);
};
});

Expand Down Expand Up @@ -373,7 +380,7 @@ TLSSocket.prototype._init = function(socket) {
this.setTimeout(options.handshakeTimeout, this._handleTimeout);

// Socket already has some buffered data - emulate receiving it
if (socket && socket._readableState.length) {
if (socket && socket._readableState && socket._readableState.length) {
var buf;
while ((buf = socket.read()) !== null)
ssl.receive(buf);
Expand Down
3 changes: 3 additions & 0 deletions node.gyp
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Expand Up @@ -56,6 +56,7 @@
'lib/_stream_duplex.js',
'lib/_stream_transform.js',
'lib/_stream_passthrough.js',
'lib/_stream_wrap.js',
'lib/string_decoder.js',
'lib/sys.js',
'lib/timers.js',
Expand Down Expand Up @@ -95,6 +96,7 @@
'src/fs_event_wrap.cc',
'src/cares_wrap.cc',
'src/handle_wrap.cc',
'src/js_stream.cc',
'src/node.cc',
'src/node_buffer.cc',
'src/node_constants.cc',
Expand Down Expand Up @@ -132,6 +134,7 @@
'src/env.h',
'src/env-inl.h',
'src/handle_wrap.h',
'src/js_stream.h',
'src/node.h',
'src/node_buffer.h',
'src/node_constants.h',
Expand Down
1 change: 1 addition & 0 deletions src/async-wrap.h
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Expand Up @@ -17,6 +17,7 @@ namespace node {
V(FSREQWRAP) \
V(GETADDRINFOREQWRAP) \
V(GETNAMEINFOREQWRAP) \
V(JSSTREAM) \
V(PIPEWRAP) \
V(PROCESSWRAP) \
V(QUERYWRAP) \
Expand Down
7 changes: 7 additions & 0 deletions src/env.h
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Expand Up @@ -107,6 +107,8 @@ namespace node {
V(ipv4_string, "IPv4") \
V(ipv6_lc_string, "ipv6") \
V(ipv6_string, "IPv6") \
V(isalive_string, "isAlive") \
V(isclosing_string, "isClosing") \
V(issuer_string, "issuer") \
V(issuercert_string, "issuerCertificate") \
V(kill_signal_string, "killSignal") \
Expand Down Expand Up @@ -141,9 +143,13 @@ namespace node {
V(onnewsessiondone_string, "onnewsessiondone") \
V(onocspresponse_string, "onocspresponse") \
V(onread_string, "onread") \
V(onreadstart_string, "onreadstart") \
V(onreadstop_string, "onreadstop") \
V(onselect_string, "onselect") \
V(onshutdown_string, "onshutdown") \
V(onsignal_string, "onsignal") \
V(onstop_string, "onstop") \
V(onwrite_string, "onwrite") \
V(output_string, "output") \
V(order_string, "order") \
V(owner_string, "owner") \
Expand Down Expand Up @@ -225,6 +231,7 @@ namespace node {
V(context, v8::Context) \
V(domain_array, v8::Array) \
V(fs_stats_constructor_function, v8::Function) \
V(jsstream_constructor_template, v8::FunctionTemplate) \
V(module_load_list_array, v8::Array) \
V(pipe_constructor_template, v8::FunctionTemplate) \
V(process_object, v8::Object) \
Expand Down
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