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103
my-app/node_modules/websocket-extensions/lib/parser.js
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103
my-app/node_modules/websocket-extensions/lib/parser.js
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'use strict';
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var TOKEN = /([!#\$%&'\*\+\-\.\^_`\|~0-9A-Za-z]+)/,
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NOTOKEN = /([^!#\$%&'\*\+\-\.\^_`\|~0-9A-Za-z])/g,
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QUOTED = /"((?:\\[\x00-\x7f]|[^\x00-\x08\x0a-\x1f\x7f"\\])*)"/,
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PARAM = new RegExp(TOKEN.source + '(?:=(?:' + TOKEN.source + '|' + QUOTED.source + '))?'),
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EXT = new RegExp(TOKEN.source + '(?: *; *' + PARAM.source + ')*', 'g'),
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EXT_LIST = new RegExp('^' + EXT.source + '(?: *, *' + EXT.source + ')*$'),
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NUMBER = /^-?(0|[1-9][0-9]*)(\.[0-9]+)?$/;
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var hasOwnProperty = Object.prototype.hasOwnProperty;
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var Parser = {
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parseHeader: function(header) {
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var offers = new Offers();
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if (header === '' || header === undefined) return offers;
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if (!EXT_LIST.test(header))
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throw new SyntaxError('Invalid Sec-WebSocket-Extensions header: ' + header);
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var values = header.match(EXT);
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values.forEach(function(value) {
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var params = value.match(new RegExp(PARAM.source, 'g')),
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name = params.shift(),
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offer = {};
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params.forEach(function(param) {
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var args = param.match(PARAM), key = args[1], data;
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if (args[2] !== undefined) {
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data = args[2];
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} else if (args[3] !== undefined) {
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data = args[3].replace(/\\/g, '');
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} else {
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data = true;
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}
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if (NUMBER.test(data)) data = parseFloat(data);
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if (hasOwnProperty.call(offer, key)) {
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offer[key] = [].concat(offer[key]);
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offer[key].push(data);
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} else {
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offer[key] = data;
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}
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}, this);
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offers.push(name, offer);
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}, this);
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return offers;
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},
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serializeParams: function(name, params) {
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var values = [];
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var print = function(key, value) {
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if (value instanceof Array) {
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value.forEach(function(v) { print(key, v) });
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} else if (value === true) {
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values.push(key);
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} else if (typeof value === 'number') {
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values.push(key + '=' + value);
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} else if (NOTOKEN.test(value)) {
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values.push(key + '="' + value.replace(/"/g, '\\"') + '"');
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} else {
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values.push(key + '=' + value);
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}
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};
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for (var key in params) print(key, params[key]);
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return [name].concat(values).join('; ');
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}
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};
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var Offers = function() {
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this._byName = {};
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this._inOrder = [];
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};
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Offers.prototype.push = function(name, params) {
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if (!hasOwnProperty.call(this._byName, name))
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this._byName[name] = [];
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this._byName[name].push(params);
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this._inOrder.push({ name: name, params: params });
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};
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Offers.prototype.eachOffer = function(callback, context) {
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var list = this._inOrder;
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for (var i = 0, n = list.length; i < n; i++)
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callback.call(context, list[i].name, list[i].params);
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};
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Offers.prototype.byName = function(name) {
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return this._byName[name] || [];
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};
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Offers.prototype.toArray = function() {
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return this._inOrder.slice();
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};
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module.exports = Parser;
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607
my-app/node_modules/websocket-extensions/lib/pipeline/README.md
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607
my-app/node_modules/websocket-extensions/lib/pipeline/README.md
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# Extension pipelining
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`websocket-extensions` models the extension negotiation and processing pipeline
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of the WebSocket protocol. Between the driver parsing messages from the TCP
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stream and handing those messages off to the application, there may exist a
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stack of extensions that transform the message somehow.
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In the parlance of this framework, a *session* refers to a single instance of an
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extension, acting on a particular socket on either the server or the client
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side. A session may transform messages both incoming to the application and
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outgoing from the application, for example the `permessage-deflate` extension
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compresses outgoing messages and decompresses incoming messages. Message streams
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in either direction are independent; that is, incoming and outgoing messages
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cannot be assumed to 'pair up' as in a request-response protocol.
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Asynchronous processing of messages poses a number of problems that this
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pipeline construction is intended to solve.
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## Overview
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Logically, we have the following:
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+-------------+ out +---+ +---+ +---+ +--------+
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| |------>| |---->| |---->| |------>| |
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| Application | | A | | B | | C | | Driver |
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| |<------| |<----| |<----| |<------| |
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+-------------+ in +---+ +---+ +---+ +--------+
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\ /
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+----------o----------+
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|
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sessions
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For outgoing messages, the driver receives the result of
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C.outgoing(B.outgoing(A.outgoing(message)))
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or, [A, B, C].reduce(((m, ext) => ext.outgoing(m)), message)
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For incoming messages, the application receives the result of
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A.incoming(B.incoming(C.incoming(message)))
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or, [C, B, A].reduce(((m, ext) => ext.incoming(m)), message)
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A session is of the following type, to borrow notation from pseudo-Haskell:
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type Session = {
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incoming :: Message -> Message
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outgoing :: Message -> Message
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close :: () -> ()
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}
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(That `() -> ()` syntax is intended to mean that `close()` is a nullary void
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method; I apologise to any Haskell readers for not using the right monad.)
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|
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The `incoming()` and `outgoing()` methods perform message transformation in the
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respective directions; `close()` is called when a socket closes so the session
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can release any resources it's holding, for example a DEFLATE de/compression
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context.
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However because this is JavaScript, the `incoming()` and `outgoing()` methods
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may be asynchronous (indeed, `permessage-deflate` is based on `zlib`, whose API
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is stream-based). So their interface is strictly:
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type Session = {
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incoming :: Message -> Callback -> ()
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outgoing :: Message -> Callback -> ()
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close :: () -> ()
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}
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type Callback = Either Error Message -> ()
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This means a message *m2* can be pushed into a session while it's still
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processing the preceding message *m1*. The messages can be processed
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concurrently but they *must* be given to the next session in line (or to the
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application) in the same order they came in. Applications will expect to receive
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messages in the order they arrived over the wire, and sessions require this too.
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So ordering of messages must be preserved throughout the pipeline.
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Consider the following highly simplified extension that deflates messages on the
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wire. `message` is a value conforming the type:
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type Message = {
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rsv1 :: Boolean
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rsv2 :: Boolean
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rsv3 :: Boolean
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opcode :: Number
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data :: Buffer
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||||
}
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Here's the extension:
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||||
|
||||
```js
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var zlib = require('zlib');
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var deflate = {
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outgoing: function(message, callback) {
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zlib.deflateRaw(message.data, function(error, result) {
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message.rsv1 = true;
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message.data = result;
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callback(error, message);
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});
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},
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incoming: function(message, callback) {
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// decompress inbound messages (elided)
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},
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close: function() {
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// no state to clean up
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||||
}
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||||
};
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||||
```
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We can call it with a large message followed by a small one, and the small one
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||||
will be returned first:
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||||
|
||||
```js
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var crypto = require('crypto'),
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large = crypto.randomBytes(1 << 14),
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small = new Buffer('hi');
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||||
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deflate.outgoing({ data: large }, function() {
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console.log(1, 'large');
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||||
});
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||||
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deflate.outgoing({ data: small }, function() {
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||||
console.log(2, 'small');
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});
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||||
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||||
/* prints: 2 'small'
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1 'large' */
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||||
```
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||||
|
||||
So a session that processes messages asynchronously may fail to preserve message
|
||||
ordering.
|
||||
|
||||
Now, this extension is stateless, so it can process messages in any order and
|
||||
still produce the same output. But some extensions are stateful and require
|
||||
message order to be preserved.
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||||
|
||||
For example, when using `permessage-deflate` without `no_context_takeover` set,
|
||||
the session retains a DEFLATE de/compression context between messages, which
|
||||
accumulates state as it consumes data (later messages can refer to sections of
|
||||
previous ones to improve compression). Reordering parts of the DEFLATE stream
|
||||
will result in a failed decompression. Messages must be decompressed in the same
|
||||
order they were compressed by the peer in order for the DEFLATE protocol to
|
||||
work.
|
||||
|
||||
Finally, there is the problem of closing a socket. When a WebSocket is closed by
|
||||
the application, or receives a closing request from the other peer, there may be
|
||||
messages outgoing from the application and incoming from the peer in the
|
||||
pipeline. If we close the socket and pipeline immediately, two problems arise:
|
||||
|
||||
* We may send our own closing frame to the peer before all prior messages we
|
||||
sent have been written to the socket, and before we have finished processing
|
||||
all prior messages from the peer
|
||||
* The session may be instructed to close its resources (e.g. its de/compression
|
||||
context) while it's in the middle of processing a message, or before it has
|
||||
received messages that are upstream of it in the pipeline
|
||||
|
||||
Essentially, we must defer closing the sessions and sending a closing frame
|
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until after all prior messages have exited the pipeline.
|
||||
|
||||
|
||||
## Design goals
|
||||
|
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* Message order must be preserved between the protocol driver, the extension
|
||||
sessions, and the application
|
||||
* Messages should be handed off to sessions and endpoints as soon as possible,
|
||||
to maximise throughput of stateless sessions
|
||||
* The closing procedure should block any further messages from entering the
|
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pipeline, and should allow all existing messages to drain
|
||||
* Sessions should be closed as soon as possible to prevent them holding memory
|
||||
and other resources when they have no more messages to handle
|
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* The closing API should allow the caller to detect when the pipeline is empty
|
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and it is safe to continue the WebSocket closing procedure
|
||||
* Individual extensions should remain as simple as possible to facilitate
|
||||
modularity and independent authorship
|
||||
|
||||
The final point about modularity is an important one: this framework is designed
|
||||
to facilitate extensions existing as plugins, by decoupling the protocol driver,
|
||||
extensions, and application. In an ideal world, plugins should only need to
|
||||
contain code for their specific functionality, and not solve these problems that
|
||||
apply to all sessions. Also, solving some of these problems requires
|
||||
consideration of all active sessions collectively, which an individual session
|
||||
is incapable of doing.
|
||||
|
||||
For example, it is entirely possible to take the simple `deflate` extension
|
||||
above and wrap its `incoming()` and `outgoing()` methods in two `Transform`
|
||||
streams, producing this type:
|
||||
|
||||
type Session = {
|
||||
incoming :: TransformStream
|
||||
outtoing :: TransformStream
|
||||
close :: () -> ()
|
||||
}
|
||||
|
||||
The `Transform` class makes it easy to wrap an async function such that message
|
||||
order is preserved:
|
||||
|
||||
```js
|
||||
var stream = require('stream'),
|
||||
session = new stream.Transform({ objectMode: true });
|
||||
|
||||
session._transform = function(message, _, callback) {
|
||||
var self = this;
|
||||
deflate.outgoing(message, function(error, result) {
|
||||
self.push(result);
|
||||
callback();
|
||||
});
|
||||
};
|
||||
```
|
||||
|
||||
However, this has a negative impact on throughput: it works by deferring
|
||||
`callback()` until the async function has 'returned', which blocks `Transform`
|
||||
from passing further input into the `_transform()` method until the current
|
||||
message is dealt with completely. This would prevent sessions from processing
|
||||
messages concurrently, and would unnecessarily reduce the throughput of
|
||||
stateless extensions.
|
||||
|
||||
So, input should be handed off to sessions as soon as possible, and all we need
|
||||
is a mechanism to reorder the output so that message order is preserved for the
|
||||
next session in line.
|
||||
|
||||
|
||||
## Solution
|
||||
|
||||
We now describe the model implemented here and how it meets the above design
|
||||
goals. The above diagram where a stack of extensions sit between the driver and
|
||||
application describes the data flow, but not the object graph. That looks like
|
||||
this:
|
||||
|
||||
|
||||
+--------+
|
||||
| Driver |
|
||||
+---o----+
|
||||
|
|
||||
V
|
||||
+------------+ +----------+
|
||||
| Extensions o----->| Pipeline |
|
||||
+------------+ +-----o----+
|
||||
|
|
||||
+---------------+---------------+
|
||||
| | |
|
||||
+-----o----+ +-----o----+ +-----o----+
|
||||
| Cell [A] | | Cell [B] | | Cell [C] |
|
||||
+----------+ +----------+ +----------+
|
||||
|
||||
|
||||
A driver using this framework holds an instance of the `Extensions` class, which
|
||||
it uses to register extension plugins, negotiate headers and transform messages.
|
||||
The `Extensions` instance itself holds a `Pipeline`, which contains an array of
|
||||
`Cell` objects, each of which wraps one of the sessions.
|
||||
|
||||
|
||||
### Message processing
|
||||
|
||||
Both the `Pipeline` and `Cell` classes have `incoming()` and `outgoing()`
|
||||
methods; the `Pipeline` interface pushes messages into the pipe, delegates the
|
||||
message to each `Cell` in turn, then returns it back to the driver. Outgoing
|
||||
messages pass through `A` then `B` then `C`, and incoming messages in the
|
||||
reverse order.
|
||||
|
||||
Internally, a `Cell` contains two `Functor` objects. A `Functor` wraps an async
|
||||
function and makes sure its output messages maintain the order of its input
|
||||
messages. This name is due to [@fronx](https://github.com/fronx), on the basis
|
||||
that, by preserving message order, the abstraction preserves the *mapping*
|
||||
between input and output messages. To use our simple `deflate` extension from
|
||||
above:
|
||||
|
||||
```js
|
||||
var functor = new Functor(deflate, 'outgoing');
|
||||
|
||||
functor.call({ data: large }, function() {
|
||||
console.log(1, 'large');
|
||||
});
|
||||
|
||||
functor.call({ data: small }, function() {
|
||||
console.log(2, 'small');
|
||||
});
|
||||
|
||||
/* -> 1 'large'
|
||||
2 'small' */
|
||||
```
|
||||
|
||||
A `Cell` contains two of these, one for each direction:
|
||||
|
||||
|
||||
+-----------------------+
|
||||
+---->| Functor [A, incoming] |
|
||||
+----------+ | +-----------------------+
|
||||
| Cell [A] o------+
|
||||
+----------+ | +-----------------------+
|
||||
+---->| Functor [A, outgoing] |
|
||||
+-----------------------+
|
||||
|
||||
|
||||
This satisfies the message transformation requirements: the `Pipeline` simply
|
||||
loops over the cells in the appropriate direction to transform each message.
|
||||
Because each `Cell` will preserve message order, we can pass a message to the
|
||||
next `Cell` in line as soon as the current `Cell` returns it. This gives each
|
||||
`Cell` all the messages in order while maximising throughput.
|
||||
|
||||
|
||||
### Session closing
|
||||
|
||||
We want to close each session as soon as possible, after all existing messages
|
||||
have drained. To do this, each `Cell` begins with a pending message counter in
|
||||
each direction, labelled `in` and `out` below.
|
||||
|
||||
|
||||
+----------+
|
||||
| Pipeline |
|
||||
+-----o----+
|
||||
|
|
||||
+---------------+---------------+
|
||||
| | |
|
||||
+-----o----+ +-----o----+ +-----o----+
|
||||
| Cell [A] | | Cell [B] | | Cell [C] |
|
||||
+----------+ +----------+ +----------+
|
||||
in: 0 in: 0 in: 0
|
||||
out: 0 out: 0 out: 0
|
||||
|
||||
|
||||
When a message *m1* enters the pipeline, say in the `outgoing` direction, we
|
||||
increment the `pending.out` counter on all cells immediately.
|
||||
|
||||
|
||||
+----------+
|
||||
m1 => | Pipeline |
|
||||
+-----o----+
|
||||
|
|
||||
+---------------+---------------+
|
||||
| | |
|
||||
+-----o----+ +-----o----+ +-----o----+
|
||||
| Cell [A] | | Cell [B] | | Cell [C] |
|
||||
+----------+ +----------+ +----------+
|
||||
in: 0 in: 0 in: 0
|
||||
out: 1 out: 1 out: 1
|
||||
|
||||
|
||||
*m1* is handed off to `A`, meanwhile a second message `m2` arrives in the same
|
||||
direction. All `pending.out` counters are again incremented.
|
||||
|
||||
|
||||
+----------+
|
||||
m2 => | Pipeline |
|
||||
+-----o----+
|
||||
|
|
||||
+---------------+---------------+
|
||||
m1 | | |
|
||||
+-----o----+ +-----o----+ +-----o----+
|
||||
| Cell [A] | | Cell [B] | | Cell [C] |
|
||||
+----------+ +----------+ +----------+
|
||||
in: 0 in: 0 in: 0
|
||||
out: 2 out: 2 out: 2
|
||||
|
||||
|
||||
When the first cell's `A.outgoing` functor finishes processing *m1*, the first
|
||||
`pending.out` counter is decremented and *m1* is handed off to cell `B`.
|
||||
|
||||
|
||||
+----------+
|
||||
| Pipeline |
|
||||
+-----o----+
|
||||
|
|
||||
+---------------+---------------+
|
||||
m2 | m1 | |
|
||||
+-----o----+ +-----o----+ +-----o----+
|
||||
| Cell [A] | | Cell [B] | | Cell [C] |
|
||||
+----------+ +----------+ +----------+
|
||||
in: 0 in: 0 in: 0
|
||||
out: 1 out: 2 out: 2
|
||||
|
||||
|
||||
|
||||
As `B` finishes with *m1*, and as `A` finishes with *m2*, the `pending.out`
|
||||
counters continue to decrement.
|
||||
|
||||
|
||||
+----------+
|
||||
| Pipeline |
|
||||
+-----o----+
|
||||
|
|
||||
+---------------+---------------+
|
||||
| m2 | m1 |
|
||||
+-----o----+ +-----o----+ +-----o----+
|
||||
| Cell [A] | | Cell [B] | | Cell [C] |
|
||||
+----------+ +----------+ +----------+
|
||||
in: 0 in: 0 in: 0
|
||||
out: 0 out: 1 out: 2
|
||||
|
||||
|
||||
|
||||
Say `C` is a little slow, and begins processing *m2* while still processing
|
||||
*m1*. That's fine, the `Functor` mechanism will keep *m1* ahead of *m2* in the
|
||||
output.
|
||||
|
||||
|
||||
+----------+
|
||||
| Pipeline |
|
||||
+-----o----+
|
||||
|
|
||||
+---------------+---------------+
|
||||
| | m2 | m1
|
||||
+-----o----+ +-----o----+ +-----o----+
|
||||
| Cell [A] | | Cell [B] | | Cell [C] |
|
||||
+----------+ +----------+ +----------+
|
||||
in: 0 in: 0 in: 0
|
||||
out: 0 out: 0 out: 2
|
||||
|
||||
|
||||
Once all messages are dealt with, the counters return to `0`.
|
||||
|
||||
|
||||
+----------+
|
||||
| Pipeline |
|
||||
+-----o----+
|
||||
|
|
||||
+---------------+---------------+
|
||||
| | |
|
||||
+-----o----+ +-----o----+ +-----o----+
|
||||
| Cell [A] | | Cell [B] | | Cell [C] |
|
||||
+----------+ +----------+ +----------+
|
||||
in: 0 in: 0 in: 0
|
||||
out: 0 out: 0 out: 0
|
||||
|
||||
|
||||
The same process applies in the `incoming` direction, the only difference being
|
||||
that messages are passed to `C` first.
|
||||
|
||||
This makes closing the sessions quite simple. When the driver wants to close the
|
||||
socket, it calls `Pipeline.close()`. This *immediately* calls `close()` on all
|
||||
the cells. If a cell has `in == out == 0`, then it immediately calls
|
||||
`session.close()`. Otherwise, it stores the closing call and defers it until
|
||||
`in` and `out` have both ticked down to zero. The pipeline will not accept new
|
||||
messages after `close()` has been called, so we know the pending counts will not
|
||||
increase after this point.
|
||||
|
||||
This means each session is closed as soon as possible: `A` can close while the
|
||||
slow `C` session is still working, because it knows there are no more messages
|
||||
on the way. Similarly, `C` will defer closing if `close()` is called while *m1*
|
||||
is still in `B`, and *m2* in `A`, because its pending count means it knows it
|
||||
has work yet to do, even if it's not received those messages yet. This concern
|
||||
cannot be addressed by extensions acting only on their own local state, unless
|
||||
we pollute individual extensions by making them all implement this same
|
||||
mechanism.
|
||||
|
||||
The actual closing API at each level is slightly different:
|
||||
|
||||
type Session = {
|
||||
close :: () -> ()
|
||||
}
|
||||
|
||||
type Cell = {
|
||||
close :: () -> Promise ()
|
||||
}
|
||||
|
||||
type Pipeline = {
|
||||
close :: Callback -> ()
|
||||
}
|
||||
|
||||
This might appear inconsistent so it's worth explaining. Remember that a
|
||||
`Pipeline` holds a list of `Cell` objects, each wrapping a `Session`. The driver
|
||||
talks (via the `Extensions` API) to the `Pipeline` interface, and it wants
|
||||
`Pipeline.close()` to do two things: close all the sessions, and tell me when
|
||||
it's safe to start the closing procedure (i.e. when all messages have drained
|
||||
from the pipe and been handed off to the application or socket). A callback API
|
||||
works well for that.
|
||||
|
||||
At the other end of the stack, `Session.close()` is a nullary void method with
|
||||
no callback or promise API because we don't care what it does, and whatever it
|
||||
does do will not block the WebSocket protocol; we're not going to hold off
|
||||
processing messages while a session closes its de/compression context. We just
|
||||
tell it to close itself, and don't want to wait while it does that.
|
||||
|
||||
In the middle, `Cell.close()` returns a promise rather than using a callback.
|
||||
This is for two reasons. First, `Cell.close()` might not do anything
|
||||
immediately, it might have to defer its effect while messages drain. So, if
|
||||
given a callback, it would have to store it in a queue for later execution.
|
||||
Callbacks work fine if your method does something and can then invoke the
|
||||
callback itself, but if you need to store callbacks somewhere so another method
|
||||
can execute them, a promise is a better fit. Second, it better serves the
|
||||
purposes of `Pipeline.close()`: it wants to call `close()` on each of a list of
|
||||
cells, and wait for all of them to finish. This is simple and idiomatic using
|
||||
promises:
|
||||
|
||||
```js
|
||||
var closed = cells.map((cell) => cell.close());
|
||||
Promise.all(closed).then(callback);
|
||||
```
|
||||
|
||||
(We don't actually use a full *Promises/A+* compatible promise here, we use a
|
||||
much simplified construction that acts as a callback aggregater and resolves
|
||||
synchronously and does not support chaining, but the principle is the same.)
|
||||
|
||||
|
||||
### Error handling
|
||||
|
||||
We've not mentioned error handling so far but it bears some explanation. The
|
||||
above counter system still applies, but behaves slightly differently in the
|
||||
presence of errors.
|
||||
|
||||
Say we push three messages into the pipe in the outgoing direction:
|
||||
|
||||
|
||||
+----------+
|
||||
m3, m2, m1 => | Pipeline |
|
||||
+-----o----+
|
||||
|
|
||||
+---------------+---------------+
|
||||
| | |
|
||||
+-----o----+ +-----o----+ +-----o----+
|
||||
| Cell [A] | | Cell [B] | | Cell [C] |
|
||||
+----------+ +----------+ +----------+
|
||||
in: 0 in: 0 in: 0
|
||||
out: 3 out: 3 out: 3
|
||||
|
||||
|
||||
They pass through the cells successfully up to this point:
|
||||
|
||||
|
||||
+----------+
|
||||
| Pipeline |
|
||||
+-----o----+
|
||||
|
|
||||
+---------------+---------------+
|
||||
m3 | m2 | m1 |
|
||||
+-----o----+ +-----o----+ +-----o----+
|
||||
| Cell [A] | | Cell [B] | | Cell [C] |
|
||||
+----------+ +----------+ +----------+
|
||||
in: 0 in: 0 in: 0
|
||||
out: 1 out: 2 out: 3
|
||||
|
||||
|
||||
At this point, session `B` produces an error while processing *m2*, that is *m2*
|
||||
becomes *e2*. *m1* is still in the pipeline, and *m3* is queued behind *m2*.
|
||||
What ought to happen is that *m1* is handed off to the socket, then *m2* is
|
||||
released to the driver, which will detect the error and begin closing the
|
||||
socket. No further processing should be done on *m3* and it should not be
|
||||
released to the driver after the error is emitted.
|
||||
|
||||
To handle this, we allow errors to pass down the pipeline just like messages do,
|
||||
to maintain ordering. But, once a cell sees its session produce an error, or it
|
||||
receives an error from upstream, it should refuse to accept any further
|
||||
messages. Session `B` might have begun processing *m3* by the time it produces
|
||||
the error *e2*, but `C` will have been given *e2* before it receives *m3*, and
|
||||
can simply drop *m3*.
|
||||
|
||||
Now, say *e2* reaches the slow session `C` while *m1* is still present,
|
||||
meanwhile *m3* has been dropped. `C` will never receive *m3* since it will have
|
||||
been dropped upstream. Under the present model, its `out` counter will be `3`
|
||||
but it is only going to emit two more values: *m1* and *e2*. In order for
|
||||
closing to work, we need to decrement `out` to reflect this. The situation
|
||||
should look like this:
|
||||
|
||||
|
||||
+----------+
|
||||
| Pipeline |
|
||||
+-----o----+
|
||||
|
|
||||
+---------------+---------------+
|
||||
| | e2 | m1
|
||||
+-----o----+ +-----o----+ +-----o----+
|
||||
| Cell [A] | | Cell [B] | | Cell [C] |
|
||||
+----------+ +----------+ +----------+
|
||||
in: 0 in: 0 in: 0
|
||||
out: 0 out: 0 out: 2
|
||||
|
||||
|
||||
When a cell sees its session emit an error, or when it receives an error from
|
||||
upstream, it sets its pending count in the appropriate direction to equal the
|
||||
number of messages it is *currently* processing. It will not accept any messages
|
||||
after it sees the error, so this will allow the counter to reach zero.
|
||||
|
||||
Note that while *e2* is in the pipeline, `Pipeline` should drop any further
|
||||
messages in the outgoing direction, but should continue to accept incoming
|
||||
messages. Until *e2* makes it out of the pipe to the driver, behind previous
|
||||
successful messages, the driver does not know an error has happened, and a
|
||||
message may arrive over the socket and make it all the way through the incoming
|
||||
pipe in the meantime. We only halt processing in the affected direction to avoid
|
||||
doing unnecessary work since messages arriving after an error should not be
|
||||
processed.
|
||||
|
||||
Some unnecessary work may happen, for example any messages already in the
|
||||
pipeline following *m2* will be processed by `A`, since it's upstream of the
|
||||
error. Those messages will be dropped by `B`.
|
||||
|
||||
|
||||
## Alternative ideas
|
||||
|
||||
I am considering implementing `Functor` as an object-mode transform stream
|
||||
rather than what is essentially an async function. Being object-mode, a stream
|
||||
would preserve message boundaries and would also possibly help address
|
||||
back-pressure. I'm not sure whether this would require external API changes so
|
||||
that such streams could be connected to the downstream driver's streams.
|
||||
|
||||
|
||||
## Acknowledgements
|
||||
|
||||
Credit is due to [@mnowster](https://github.com/mnowster) for helping with the
|
||||
design and to [@fronx](https://github.com/fronx) for helping name things.
|
53
my-app/node_modules/websocket-extensions/lib/pipeline/cell.js
generated
vendored
Executable file
53
my-app/node_modules/websocket-extensions/lib/pipeline/cell.js
generated
vendored
Executable file
|
@ -0,0 +1,53 @@
|
|||
'use strict';
|
||||
|
||||
var Functor = require('./functor'),
|
||||
Pledge = require('./pledge');
|
||||
|
||||
var Cell = function(tuple) {
|
||||
this._ext = tuple[0];
|
||||
this._session = tuple[1];
|
||||
|
||||
this._functors = {
|
||||
incoming: new Functor(this._session, 'processIncomingMessage'),
|
||||
outgoing: new Functor(this._session, 'processOutgoingMessage')
|
||||
};
|
||||
};
|
||||
|
||||
Cell.prototype.pending = function(direction) {
|
||||
var functor = this._functors[direction];
|
||||
if (!functor._stopped) functor.pending += 1;
|
||||
};
|
||||
|
||||
Cell.prototype.incoming = function(error, message, callback, context) {
|
||||
this._exec('incoming', error, message, callback, context);
|
||||
};
|
||||
|
||||
Cell.prototype.outgoing = function(error, message, callback, context) {
|
||||
this._exec('outgoing', error, message, callback, context);
|
||||
};
|
||||
|
||||
Cell.prototype.close = function() {
|
||||
this._closed = this._closed || new Pledge();
|
||||
this._doClose();
|
||||
return this._closed;
|
||||
};
|
||||
|
||||
Cell.prototype._exec = function(direction, error, message, callback, context) {
|
||||
this._functors[direction].call(error, message, function(err, msg) {
|
||||
if (err) err.message = this._ext.name + ': ' + err.message;
|
||||
callback.call(context, err, msg);
|
||||
this._doClose();
|
||||
}, this);
|
||||
};
|
||||
|
||||
Cell.prototype._doClose = function() {
|
||||
var fin = this._functors.incoming,
|
||||
fout = this._functors.outgoing;
|
||||
|
||||
if (!this._closed || fin.pending + fout.pending !== 0) return;
|
||||
if (this._session) this._session.close();
|
||||
this._session = null;
|
||||
this._closed.done();
|
||||
};
|
||||
|
||||
module.exports = Cell;
|
72
my-app/node_modules/websocket-extensions/lib/pipeline/functor.js
generated
vendored
Executable file
72
my-app/node_modules/websocket-extensions/lib/pipeline/functor.js
generated
vendored
Executable file
|
@ -0,0 +1,72 @@
|
|||
'use strict';
|
||||
|
||||
var RingBuffer = require('./ring_buffer');
|
||||
|
||||
var Functor = function(session, method) {
|
||||
this._session = session;
|
||||
this._method = method;
|
||||
this._queue = new RingBuffer(Functor.QUEUE_SIZE);
|
||||
this._stopped = false;
|
||||
this.pending = 0;
|
||||
};
|
||||
|
||||
Functor.QUEUE_SIZE = 8;
|
||||
|
||||
Functor.prototype.call = function(error, message, callback, context) {
|
||||
if (this._stopped) return;
|
||||
|
||||
var record = { error: error, message: message, callback: callback, context: context, done: false },
|
||||
called = false,
|
||||
self = this;
|
||||
|
||||
this._queue.push(record);
|
||||
|
||||
if (record.error) {
|
||||
record.done = true;
|
||||
this._stop();
|
||||
return this._flushQueue();
|
||||
}
|
||||
|
||||
var handler = function(err, msg) {
|
||||
if (!(called ^ (called = true))) return;
|
||||
|
||||
if (err) {
|
||||
self._stop();
|
||||
record.error = err;
|
||||
record.message = null;
|
||||
} else {
|
||||
record.message = msg;
|
||||
}
|
||||
|
||||
record.done = true;
|
||||
self._flushQueue();
|
||||
};
|
||||
|
||||
try {
|
||||
this._session[this._method](message, handler);
|
||||
} catch (err) {
|
||||
handler(err);
|
||||
}
|
||||
};
|
||||
|
||||
Functor.prototype._stop = function() {
|
||||
this.pending = this._queue.length;
|
||||
this._stopped = true;
|
||||
};
|
||||
|
||||
Functor.prototype._flushQueue = function() {
|
||||
var queue = this._queue, record;
|
||||
|
||||
while (queue.length > 0 && queue.peek().done) {
|
||||
record = queue.shift();
|
||||
if (record.error) {
|
||||
this.pending = 0;
|
||||
queue.clear();
|
||||
} else {
|
||||
this.pending -= 1;
|
||||
}
|
||||
record.callback.call(record.context, record.error, record.message);
|
||||
}
|
||||
};
|
||||
|
||||
module.exports = Functor;
|
47
my-app/node_modules/websocket-extensions/lib/pipeline/index.js
generated
vendored
Executable file
47
my-app/node_modules/websocket-extensions/lib/pipeline/index.js
generated
vendored
Executable file
|
@ -0,0 +1,47 @@
|
|||
'use strict';
|
||||
|
||||
var Cell = require('./cell'),
|
||||
Pledge = require('./pledge');
|
||||
|
||||
var Pipeline = function(sessions) {
|
||||
this._cells = sessions.map(function(session) { return new Cell(session) });
|
||||
this._stopped = { incoming: false, outgoing: false };
|
||||
};
|
||||
|
||||
Pipeline.prototype.processIncomingMessage = function(message, callback, context) {
|
||||
if (this._stopped.incoming) return;
|
||||
this._loop('incoming', this._cells.length - 1, -1, -1, message, callback, context);
|
||||
};
|
||||
|
||||
Pipeline.prototype.processOutgoingMessage = function(message, callback, context) {
|
||||
if (this._stopped.outgoing) return;
|
||||
this._loop('outgoing', 0, this._cells.length, 1, message, callback, context);
|
||||
};
|
||||
|
||||
Pipeline.prototype.close = function(callback, context) {
|
||||
this._stopped = { incoming: true, outgoing: true };
|
||||
|
||||
var closed = this._cells.map(function(a) { return a.close() });
|
||||
if (callback)
|
||||
Pledge.all(closed).then(function() { callback.call(context) });
|
||||
};
|
||||
|
||||
Pipeline.prototype._loop = function(direction, start, end, step, message, callback, context) {
|
||||
var cells = this._cells,
|
||||
n = cells.length,
|
||||
self = this;
|
||||
|
||||
while (n--) cells[n].pending(direction);
|
||||
|
||||
var pipe = function(index, error, msg) {
|
||||
if (index === end) return callback.call(context, error, msg);
|
||||
|
||||
cells[index][direction](error, msg, function(err, m) {
|
||||
if (err) self._stopped[direction] = true;
|
||||
pipe(index + step, err, m);
|
||||
});
|
||||
};
|
||||
pipe(start, null, message);
|
||||
};
|
||||
|
||||
module.exports = Pipeline;
|
37
my-app/node_modules/websocket-extensions/lib/pipeline/pledge.js
generated
vendored
Executable file
37
my-app/node_modules/websocket-extensions/lib/pipeline/pledge.js
generated
vendored
Executable file
|
@ -0,0 +1,37 @@
|
|||
'use strict';
|
||||
|
||||
var RingBuffer = require('./ring_buffer');
|
||||
|
||||
var Pledge = function() {
|
||||
this._complete = false;
|
||||
this._callbacks = new RingBuffer(Pledge.QUEUE_SIZE);
|
||||
};
|
||||
|
||||
Pledge.QUEUE_SIZE = 4;
|
||||
|
||||
Pledge.all = function(list) {
|
||||
var pledge = new Pledge(),
|
||||
pending = list.length,
|
||||
n = pending;
|
||||
|
||||
if (pending === 0) pledge.done();
|
||||
|
||||
while (n--) list[n].then(function() {
|
||||
pending -= 1;
|
||||
if (pending === 0) pledge.done();
|
||||
});
|
||||
return pledge;
|
||||
};
|
||||
|
||||
Pledge.prototype.then = function(callback) {
|
||||
if (this._complete) callback();
|
||||
else this._callbacks.push(callback);
|
||||
};
|
||||
|
||||
Pledge.prototype.done = function() {
|
||||
this._complete = true;
|
||||
var callbacks = this._callbacks, callback;
|
||||
while (callback = callbacks.shift()) callback();
|
||||
};
|
||||
|
||||
module.exports = Pledge;
|
66
my-app/node_modules/websocket-extensions/lib/pipeline/ring_buffer.js
generated
vendored
Executable file
66
my-app/node_modules/websocket-extensions/lib/pipeline/ring_buffer.js
generated
vendored
Executable file
|
@ -0,0 +1,66 @@
|
|||
'use strict';
|
||||
|
||||
var RingBuffer = function(bufferSize) {
|
||||
this._bufferSize = bufferSize;
|
||||
this.clear();
|
||||
};
|
||||
|
||||
RingBuffer.prototype.clear = function() {
|
||||
this._buffer = new Array(this._bufferSize);
|
||||
this._ringOffset = 0;
|
||||
this._ringSize = this._bufferSize;
|
||||
this._head = 0;
|
||||
this._tail = 0;
|
||||
this.length = 0;
|
||||
};
|
||||
|
||||
RingBuffer.prototype.push = function(value) {
|
||||
var expandBuffer = false,
|
||||
expandRing = false;
|
||||
|
||||
if (this._ringSize < this._bufferSize) {
|
||||
expandBuffer = (this._tail === 0);
|
||||
} else if (this._ringOffset === this._ringSize) {
|
||||
expandBuffer = true;
|
||||
expandRing = (this._tail === 0);
|
||||
}
|
||||
|
||||
if (expandBuffer) {
|
||||
this._tail = this._bufferSize;
|
||||
this._buffer = this._buffer.concat(new Array(this._bufferSize));
|
||||
this._bufferSize = this._buffer.length;
|
||||
|
||||
if (expandRing)
|
||||
this._ringSize = this._bufferSize;
|
||||
}
|
||||
|
||||
this._buffer[this._tail] = value;
|
||||
this.length += 1;
|
||||
if (this._tail < this._ringSize) this._ringOffset += 1;
|
||||
this._tail = (this._tail + 1) % this._bufferSize;
|
||||
};
|
||||
|
||||
RingBuffer.prototype.peek = function() {
|
||||
if (this.length === 0) return void 0;
|
||||
return this._buffer[this._head];
|
||||
};
|
||||
|
||||
RingBuffer.prototype.shift = function() {
|
||||
if (this.length === 0) return void 0;
|
||||
|
||||
var value = this._buffer[this._head];
|
||||
this._buffer[this._head] = void 0;
|
||||
this.length -= 1;
|
||||
this._ringOffset -= 1;
|
||||
|
||||
if (this._ringOffset === 0 && this.length > 0) {
|
||||
this._head = this._ringSize;
|
||||
this._ringOffset = this.length;
|
||||
this._ringSize = this._bufferSize;
|
||||
} else {
|
||||
this._head = (this._head + 1) % this._ringSize;
|
||||
}
|
||||
return value;
|
||||
};
|
||||
|
||||
module.exports = RingBuffer;
|
162
my-app/node_modules/websocket-extensions/lib/websocket_extensions.js
generated
vendored
Executable file
162
my-app/node_modules/websocket-extensions/lib/websocket_extensions.js
generated
vendored
Executable file
|
@ -0,0 +1,162 @@
|
|||
'use strict';
|
||||
|
||||
var Parser = require('./parser'),
|
||||
Pipeline = require('./pipeline');
|
||||
|
||||
var Extensions = function() {
|
||||
this._rsv1 = this._rsv2 = this._rsv3 = null;
|
||||
|
||||
this._byName = {};
|
||||
this._inOrder = [];
|
||||
this._sessions = [];
|
||||
this._index = {};
|
||||
};
|
||||
|
||||
Extensions.MESSAGE_OPCODES = [1, 2];
|
||||
|
||||
var instance = {
|
||||
add: function(ext) {
|
||||
if (typeof ext.name !== 'string') throw new TypeError('extension.name must be a string');
|
||||
if (ext.type !== 'permessage') throw new TypeError('extension.type must be "permessage"');
|
||||
|
||||
if (typeof ext.rsv1 !== 'boolean') throw new TypeError('extension.rsv1 must be true or false');
|
||||
if (typeof ext.rsv2 !== 'boolean') throw new TypeError('extension.rsv2 must be true or false');
|
||||
if (typeof ext.rsv3 !== 'boolean') throw new TypeError('extension.rsv3 must be true or false');
|
||||
|
||||
if (this._byName.hasOwnProperty(ext.name))
|
||||
throw new TypeError('An extension with name "' + ext.name + '" is already registered');
|
||||
|
||||
this._byName[ext.name] = ext;
|
||||
this._inOrder.push(ext);
|
||||
},
|
||||
|
||||
generateOffer: function() {
|
||||
var sessions = [],
|
||||
offer = [],
|
||||
index = {};
|
||||
|
||||
this._inOrder.forEach(function(ext) {
|
||||
var session = ext.createClientSession();
|
||||
if (!session) return;
|
||||
|
||||
var record = [ext, session];
|
||||
sessions.push(record);
|
||||
index[ext.name] = record;
|
||||
|
||||
var offers = session.generateOffer();
|
||||
offers = offers ? [].concat(offers) : [];
|
||||
|
||||
offers.forEach(function(off) {
|
||||
offer.push(Parser.serializeParams(ext.name, off));
|
||||
}, this);
|
||||
}, this);
|
||||
|
||||
this._sessions = sessions;
|
||||
this._index = index;
|
||||
|
||||
return offer.length > 0 ? offer.join(', ') : null;
|
||||
},
|
||||
|
||||
activate: function(header) {
|
||||
var responses = Parser.parseHeader(header),
|
||||
sessions = [];
|
||||
|
||||
responses.eachOffer(function(name, params) {
|
||||
var record = this._index[name];
|
||||
|
||||
if (!record)
|
||||
throw new Error('Server sent an extension response for unknown extension "' + name + '"');
|
||||
|
||||
var ext = record[0],
|
||||
session = record[1],
|
||||
reserved = this._reserved(ext);
|
||||
|
||||
if (reserved)
|
||||
throw new Error('Server sent two extension responses that use the RSV' +
|
||||
reserved[0] + ' bit: "' +
|
||||
reserved[1] + '" and "' + ext.name + '"');
|
||||
|
||||
if (session.activate(params) !== true)
|
||||
throw new Error('Server sent unacceptable extension parameters: ' +
|
||||
Parser.serializeParams(name, params));
|
||||
|
||||
this._reserve(ext);
|
||||
sessions.push(record);
|
||||
}, this);
|
||||
|
||||
this._sessions = sessions;
|
||||
this._pipeline = new Pipeline(sessions);
|
||||
},
|
||||
|
||||
generateResponse: function(header) {
|
||||
var sessions = [],
|
||||
response = [],
|
||||
offers = Parser.parseHeader(header);
|
||||
|
||||
this._inOrder.forEach(function(ext) {
|
||||
var offer = offers.byName(ext.name);
|
||||
if (offer.length === 0 || this._reserved(ext)) return;
|
||||
|
||||
var session = ext.createServerSession(offer);
|
||||
if (!session) return;
|
||||
|
||||
this._reserve(ext);
|
||||
sessions.push([ext, session]);
|
||||
response.push(Parser.serializeParams(ext.name, session.generateResponse()));
|
||||
}, this);
|
||||
|
||||
this._sessions = sessions;
|
||||
this._pipeline = new Pipeline(sessions);
|
||||
|
||||
return response.length > 0 ? response.join(', ') : null;
|
||||
},
|
||||
|
||||
validFrameRsv: function(frame) {
|
||||
var allowed = { rsv1: false, rsv2: false, rsv3: false },
|
||||
ext;
|
||||
|
||||
if (Extensions.MESSAGE_OPCODES.indexOf(frame.opcode) >= 0) {
|
||||
for (var i = 0, n = this._sessions.length; i < n; i++) {
|
||||
ext = this._sessions[i][0];
|
||||
allowed.rsv1 = allowed.rsv1 || ext.rsv1;
|
||||
allowed.rsv2 = allowed.rsv2 || ext.rsv2;
|
||||
allowed.rsv3 = allowed.rsv3 || ext.rsv3;
|
||||
}
|
||||
}
|
||||
|
||||
return (allowed.rsv1 || !frame.rsv1) &&
|
||||
(allowed.rsv2 || !frame.rsv2) &&
|
||||
(allowed.rsv3 || !frame.rsv3);
|
||||
},
|
||||
|
||||
processIncomingMessage: function(message, callback, context) {
|
||||
this._pipeline.processIncomingMessage(message, callback, context);
|
||||
},
|
||||
|
||||
processOutgoingMessage: function(message, callback, context) {
|
||||
this._pipeline.processOutgoingMessage(message, callback, context);
|
||||
},
|
||||
|
||||
close: function(callback, context) {
|
||||
if (!this._pipeline) return callback.call(context);
|
||||
this._pipeline.close(callback, context);
|
||||
},
|
||||
|
||||
_reserve: function(ext) {
|
||||
this._rsv1 = this._rsv1 || (ext.rsv1 && ext.name);
|
||||
this._rsv2 = this._rsv2 || (ext.rsv2 && ext.name);
|
||||
this._rsv3 = this._rsv3 || (ext.rsv3 && ext.name);
|
||||
},
|
||||
|
||||
_reserved: function(ext) {
|
||||
if (this._rsv1 && ext.rsv1) return [1, this._rsv1];
|
||||
if (this._rsv2 && ext.rsv2) return [2, this._rsv2];
|
||||
if (this._rsv3 && ext.rsv3) return [3, this._rsv3];
|
||||
return false;
|
||||
}
|
||||
};
|
||||
|
||||
for (var key in instance)
|
||||
Extensions.prototype[key] = instance[key];
|
||||
|
||||
module.exports = Extensions;
|
Loading…
Add table
Add a link
Reference in a new issue