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lib: remove queue implementation from JSStreamWrap
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The streams implementation generally ensures that only one write()
call is active at a time. `JSStreamWrap` instances still kept
queue of write reqeuests in spite of that; refactor it away.

Also, fold `isAlive()` into a constant function on the native side.

PR-URL: #17918
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Minwoo Jung <minwoo@nodesource.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Tiancheng "Timothy" Gu <timothygu99@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
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@addaleax @evanlucas
addaleax authored and evanlucas committed Jan 22, 2018
1 parent 722fe46 commit 32719fb
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Showing 3 changed files with 71 additions and 97 deletions.
159 changes: 70 additions & 89 deletions lib/internal/wrap_js_stream.js
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,15 @@ const uv = process.binding('uv');
const debug = util.debuglog('stream_wrap');
const errors = require('internal/errors');

const kCurrentWriteRequest = Symbol('kCurrentWriteRequest');
const kCurrentShutdownRequest = Symbol('kCurrentShutdownRequest');

function isClosing() { return this.owner.isClosing(); }
function onreadstart() { return this.owner.readStart(); }
function onreadstop() { return this.owner.readStop(); }
function onshutdown(req) { return this.owner.doShutdown(req); }
function onwrite(req, bufs) { return this.owner.doWrite(req, bufs); }

/* This class serves as a wrapper for when the C++ side of Node wants access
* to a standard JS stream. For example, TLS or HTTP do not operate on network
* resources conceptually, although that is the common case and what we are
Expand All @@ -27,12 +36,13 @@ class JSStreamWrap extends Socket {
debug('close');
this.doClose(cb);
};
handle.isAlive = () => this.isAlive();
handle.isClosing = () => this.isClosing();
handle.onreadstart = () => this.readStart();
handle.onreadstop = () => this.readStop();
handle.onshutdown = (req) => this.doShutdown(req);
handle.onwrite = (req, bufs) => this.doWrite(req, bufs);
// Inside of the following functions, `this` refers to the handle
// and `this.owner` refers to this JSStreamWrap instance.
handle.isClosing = isClosing;
handle.onreadstart = onreadstart;
handle.onreadstop = onreadstop;
handle.onshutdown = onshutdown;
handle.onwrite = onwrite;

stream.pause();
stream.on('error', (err) => this.emit('error', err));
Expand Down Expand Up @@ -60,7 +70,10 @@ class JSStreamWrap extends Socket {

super({ handle, manualStart: true });
this.stream = stream;
this._list = null;
this[kCurrentWriteRequest] = null;
this[kCurrentShutdownRequest] = null;

// Start reading.
this.read(0);
}

Expand All @@ -69,10 +82,6 @@ class JSStreamWrap extends Socket {
return JSStreamWrap;
}

isAlive() {
return true;
}

isClosing() {
return !this.readable || !this.writable;
}
Expand All @@ -88,33 +97,56 @@ class JSStreamWrap extends Socket {
}

doShutdown(req) {
assert.strictEqual(this[kCurrentShutdownRequest], null);
this[kCurrentShutdownRequest] = req;

// TODO(addaleax): It might be nice if we could get into a state where
// DoShutdown() is not called on streams while a write is still pending.
//
// Currently, the only part of the code base where that happens is the
// TLS implementation, which calls both DoWrite() and DoShutdown() on the
// underlying network stream inside of its own DoShutdown() method.
// Working around that on the native side is not quite trivial (yet?),
// so for now that is supported here.

if (this[kCurrentWriteRequest] !== null)
return this.on('drain', () => this.doShutdown(req));
assert.strictEqual(this[kCurrentWriteRequest], null);

const handle = this._handle;
const item = this._enqueue('shutdown', req);

this.stream.end(() => {
// Ensure that write was dispatched
setImmediate(() => {
if (!this._dequeue(item))
return;

handle.finishShutdown(req, 0);
this.finishShutdown(handle, 0);
});
});
return 0;
}

// handle === this._handle except when called from doClose().
finishShutdown(handle, errCode) {
// The shutdown request might already have been cancelled.
if (this[kCurrentShutdownRequest] === null)
return;
const req = this[kCurrentShutdownRequest];
this[kCurrentShutdownRequest] = null;
handle.finishShutdown(req, errCode);
}

doWrite(req, bufs) {
const self = this;
const handle = this._handle;
assert.strictEqual(this[kCurrentWriteRequest], null);
assert.strictEqual(this[kCurrentShutdownRequest], null);
this[kCurrentWriteRequest] = req;

var pending = bufs.length;
const handle = this._handle;
const self = this;

// Queue the request to be able to cancel it
const item = this._enqueue('write', req);
let pending = bufs.length;

this.stream.cork();
for (var n = 0; n < bufs.length; n++)
this.stream.write(bufs[n], done);
for (var i = 0; i < bufs.length; ++i)
this.stream.write(bufs[i], done);
this.stream.uncork();

function done(err) {
Expand All @@ -126,93 +158,42 @@ class JSStreamWrap extends Socket {

let errCode = 0;
if (err) {
const code = uv[`UV_${err.code}`];
errCode = (err.code && code) ? code : uv.UV_EPIPE;
errCode = uv[`UV_${err.code}`] || uv.UV_EPIPE;
}

// Ensure that write was dispatched
setImmediate(function() {
// Do not invoke callback twice
if (!self._dequeue(item))
return;

handle.finishWrite(req, errCode);
setImmediate(() => {
self.finishWrite(handle, errCode);
});
}

return 0;
}

_enqueue(type, req) {
const item = new QueueItem(type, req);
if (this._list === null) {
this._list = item;
return item;
}

item.next = this._list.next;
item.prev = this._list;
item.next.prev = item;
item.prev.next = item;

return item;
}

_dequeue(item) {
assert(item instanceof QueueItem);

var next = item.next;
var prev = item.prev;

if (next === null && prev === null)
return false;

item.next = null;
item.prev = null;

if (next === item) {
prev = null;
next = null;
} else {
prev.next = next;
next.prev = prev;
}

if (this._list === item)
this._list = next;
// handle === this._handle except when called from doClose().
finishWrite(handle, errCode) {
// The write request might already have been cancelled.
if (this[kCurrentWriteRequest] === null)
return;
const req = this[kCurrentWriteRequest];
this[kCurrentWriteRequest] = null;

return true;
handle.finishWrite(req, errCode);
}

doClose(cb) {
const handle = this._handle;

setImmediate(() => {
while (this._list !== null) {
const item = this._list;
const req = item.req;
this._dequeue(item);

const errCode = uv.UV_ECANCELED;
if (item.type === 'write') {
handle.finishWrite(req, errCode);
} else if (item.type === 'shutdown') {
handle.finishShutdown(req, errCode);
}
}

// Should be already set by net.js
assert.strictEqual(this._handle, null);

this.finishWrite(handle, uv.UV_ECANCELED);
this.finishShutdown(handle, uv.UV_ECANCELED);

cb();
});
}
}

function QueueItem(type, req) {
this.type = type;
this.req = req;
this.prev = this;
this.next = this;
}

module.exports = JSStreamWrap;
1 change: 0 additions & 1 deletion src/env.h
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Original file line number Diff line number Diff line change
Expand Up @@ -165,7 +165,6 @@ class ModuleWrap;
V(internal_string, "internal") \
V(ipv4_string, "IPv4") \
V(ipv6_string, "IPv6") \
V(isalive_string, "isAlive") \
V(isclosing_string, "isClosing") \
V(issuer_string, "issuer") \
V(issuercert_string, "issuerCertificate") \
Expand Down
8 changes: 1 addition & 7 deletions src/js_stream.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -80,13 +80,7 @@ AsyncWrap* JSStream::GetAsyncWrap() {


bool JSStream::IsAlive() {
HandleScope scope(env()->isolate());
Context::Scope context_scope(env()->context());
v8::Local<v8::Value> fn = object()->Get(env()->isalive_string());
if (!fn->IsFunction())
return false;
return MakeCallback(fn.As<v8::Function>(), 0, nullptr)
.ToLocalChecked()->IsTrue();
return true;
}


Expand Down

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