core/websock.js

   1 /*
   2  * Websock: high-performance binary WebSockets
   3  * Copyright (C) 2012 Joel Martin
   4  * Licensed under MPL 2.0 (see LICENSE.txt)
   5  *
   6  * Websock is similar to the standard WebSocket object but with extra
   7  * buffer handling.
   8  *
   9  * Websock has built-in receive queue buffering; the message event
  10  * does not contain actual data but is simply a notification that
  11  * there is new data available. Several rQ* methods are available to
  12  * read binary data off of the receive queue.
  13  */
  14
  15 import * as Log from './util/logging.js';
  16
  17 // this has performance issues in some versions Chromium, and
  18 // doesn't gain a tremendous amount of performance increase in Firefox
  19 // at the moment.  It may be valuable to turn it on in the future.
  20 const ENABLE_COPYWITHIN = false;
  21 const MAX_RQ_GROW_SIZE = 40 * 1024 * 1024;  // 40 MiB
  22
  23 export default class Websock {
  24     constructor() {
  25         this._websocket = null;  // WebSocket object
  26
  27         this._rQi = 0;           // Receive queue index
  28         this._rQlen = 0;         // Next write position in the receive queue
  29         this._rQbufferSize = 1024 * 1024 * 4; // Receive queue buffer size (4 MiB)
  30         this._rQmax = this._rQbufferSize / 8;
  31         // called in init: this._rQ = new Uint8Array(this._rQbufferSize);
  32         this._rQ = null; // Receive queue
  33
  34         this._sQbufferSize = 1024 * 10;  // 10 KiB
  35         // called in init: this._sQ = new Uint8Array(this._sQbufferSize);
  36         this._sQlen = 0;
  37         this._sQ = null;  // Send queue
  38
  39         this._eventHandlers = {
  40             message: () => {},
  41             open: () => {},
  42             close: () => {},
  43             error: () => {}
  44         };
  45     }
  46
  47     // Getters and Setters
  48     get_sQ() {
  49         return this._sQ;
  50     }
  51
  52     get_rQ() {
  53         return this._rQ;
  54     }
  55
  56     get_rQi() {
  57         return this._rQi;
  58     }
  59
  60     set_rQi(val) {
  61         this._rQi = val;
  62     }
  63
  64     // Receive Queue
  65     rQlen() {
  66         return this._rQlen - this._rQi;
  67     }
  68
  69     rQpeek8() {
  70         return this._rQ[this._rQi];
  71     }
  72
  73     rQshift8() {
  74         return this._rQ[this._rQi++];
  75     }
  76
  77     rQskip8() {
  78         this._rQi++;
  79     }
  80
  81     rQskipBytes(num) {
  82         this._rQi += num;
  83     }
  84
  85     // TODO(directxman12): test performance with these vs a DataView
  86     rQshift16() {
  87         return (this._rQ[this._rQi++] << 8) +
  88                this._rQ[this._rQi++];
  89     }
  90
  91     rQshift32() {
  92         return (this._rQ[this._rQi++] << 24) +
  93                (this._rQ[this._rQi++] << 16) +
  94                (this._rQ[this._rQi++] << 8) +
  95                this._rQ[this._rQi++];
  96     }
  97
  98     rQshiftStr(len) {
  99         if (typeof(len) === 'undefined') { len = this.rQlen(); }
 100         let str = "";
 101         // Handle large arrays in steps to avoid long strings on the stack
 102         for (let i = 0; i < len; i += 4096) {
 103             let part = this.rQshiftBytes(Math.min(4096, len - i));
 104             str += String.fromCharCode.apply(null, part);
 105         }
 106         return str;
 107     }
 108
 109     rQshiftBytes(len) {
 110         if (typeof(len) === 'undefined') { len = this.rQlen(); }
 111         this._rQi += len;
 112         return new Uint8Array(this._rQ.buffer, this._rQi - len, len);
 113     }
 114
 115     rQshiftTo(target, len) {
 116         if (len === undefined) { len = this.rQlen(); }
 117         // TODO: make this just use set with views when using a ArrayBuffer to store the rQ
 118         target.set(new Uint8Array(this._rQ.buffer, this._rQi, len));
 119         this._rQi += len;
 120     }
 121
 122     rQwhole() {
 123         return new Uint8Array(this._rQ.buffer, 0, this._rQlen);
 124     }
 125
 126     rQslice(start, end) {
 127         if (end) {
 128             return new Uint8Array(this._rQ.buffer, this._rQi + start, end - start);
 129         } else {
 130             return new Uint8Array(this._rQ.buffer, this._rQi + start, this._rQlen - this._rQi - start);
 131         }
 132     }
 133
 134     // Check to see if we must wait for 'num' bytes (default to FBU.bytes)
 135     // to be available in the receive queue. Return true if we need to
 136     // wait (and possibly print a debug message), otherwise false.
 137     rQwait(msg, num, goback) {
 138         const rQlen = this._rQlen - this._rQi; // Skip rQlen() function call
 139         if (rQlen < num) {
 140             if (goback) {
 141                 if (this._rQi < goback) {
 142                     throw new Error("rQwait cannot backup " + goback + " bytes");
 143                 }
 144                 this._rQi -= goback;
 145             }
 146             return true; // true means need more data
 147         }
 148         return false;
 149     }
 150
 151     // Send Queue
 152
 153     flush() {
 154         if (this._sQlen > 0 && this._websocket.readyState === WebSocket.OPEN) {
 155             this._websocket.send(this._encode_message());
 156             this._sQlen = 0;
 157         }
 158     }
 159
 160     send(arr) {
 161         this._sQ.set(arr, this._sQlen);
 162         this._sQlen += arr.length;
 163         this.flush();
 164     }
 165
 166     send_string(str) {
 167         this.send(str.split('').map(chr => chr.charCodeAt(0)));
 168     }
 169
 170     // Event Handlers
 171     off(evt) {
 172         this._eventHandlers[evt] = () => {};
 173     }
 174
 175     on(evt, handler) {
 176         this._eventHandlers[evt] = handler;
 177     }
 178
 179     _allocate_buffers() {
 180         this._rQ = new Uint8Array(this._rQbufferSize);
 181         this._sQ = new Uint8Array(this._sQbufferSize);
 182     }
 183
 184     init() {
 185         this._allocate_buffers();
 186         this._rQi = 0;
 187         this._websocket = null;
 188     }
 189
 190     open(uri, protocols) {
 191         this.init();
 192
 193         this._websocket = new WebSocket(uri, protocols);
 194         this._websocket.binaryType = 'arraybuffer';
 195
 196         this._websocket.onmessage = this._recv_message.bind(this);
 197         this._websocket.onopen = () => {
 198             Log.Debug('>> WebSock.onopen');
 199             if (this._websocket.protocol) {
 200                 Log.Info("Server choose sub-protocol: " + this._websocket.protocol);
 201             }
 202
 203             this._eventHandlers.open();
 204             Log.Debug("<< WebSock.onopen");
 205         };
 206         this._websocket.onclose = (e) => {
 207             Log.Debug(">> WebSock.onclose");
 208             this._eventHandlers.close(e);
 209             Log.Debug("<< WebSock.onclose");
 210         };
 211         this._websocket.onerror = (e) => {
 212             Log.Debug(">> WebSock.onerror: " + e);
 213             this._eventHandlers.error(e);
 214             Log.Debug("<< WebSock.onerror: " + e);
 215         };
 216     }
 217
 218     close() {
 219         if (this._websocket) {
 220             if ((this._websocket.readyState === WebSocket.OPEN) ||
 221                     (this._websocket.readyState === WebSocket.CONNECTING)) {
 222                 Log.Info("Closing WebSocket connection");
 223                 this._websocket.close();
 224             }
 225
 226             this._websocket.onmessage = () => {};
 227         }
 228     }
 229
 230     // private methods
 231     _encode_message() {
 232         // Put in a binary arraybuffer
 233         // according to the spec, you can send ArrayBufferViews with the send method
 234         return new Uint8Array(this._sQ.buffer, 0, this._sQlen);
 235     }
 236
 237     _expand_compact_rQ(min_fit) {
 238         const resizeNeeded = min_fit || this._rQlen - this._rQi > this._rQbufferSize / 2;
 239         if (resizeNeeded) {
 240             if (!min_fit) {
 241                 // just double the size if we need to do compaction
 242                 this._rQbufferSize *= 2;
 243             } else {
 244                 // otherwise, make sure we satisy rQlen - rQi + min_fit < rQbufferSize / 8
 245                 this._rQbufferSize = (this._rQlen - this._rQi + min_fit) * 8;
 246             }
 247         }
 248
 249         // we don't want to grow unboundedly
 250         if (this._rQbufferSize > MAX_RQ_GROW_SIZE) {
 251             this._rQbufferSize = MAX_RQ_GROW_SIZE;
 252             if (this._rQbufferSize - this._rQlen - this._rQi < min_fit) {
 253                 throw new Error("Receive Queue buffer exceeded " + MAX_RQ_GROW_SIZE + " bytes, and the new message could not fit");
 254             }
 255         }
 256
 257         if (resizeNeeded) {
 258             const old_rQbuffer = this._rQ.buffer;
 259             this._rQmax = this._rQbufferSize / 8;
 260             this._rQ = new Uint8Array(this._rQbufferSize);
 261             this._rQ.set(new Uint8Array(old_rQbuffer, this._rQi));
 262         } else {
 263             if (ENABLE_COPYWITHIN) {
 264                 this._rQ.copyWithin(0, this._rQi);
 265             } else {
 266                 this._rQ.set(new Uint8Array(this._rQ.buffer, this._rQi));
 267             }
 268         }
 269
 270         this._rQlen = this._rQlen - this._rQi;
 271         this._rQi = 0;
 272     }
 273
 274     _decode_message(data) {
 275         // push arraybuffer values onto the end
 276         const u8 = new Uint8Array(data);
 277         if (u8.length > this._rQbufferSize - this._rQlen) {
 278             this._expand_compact_rQ(u8.length);
 279         }
 280         this._rQ.set(u8, this._rQlen);
 281         this._rQlen += u8.length;
 282     }
 283
 284     _recv_message(e) {
 285         this._decode_message(e.data);
 286         if (this.rQlen() > 0) {
 287             this._eventHandlers.message();
 288             // Compact the receive queue
 289             if (this._rQlen == this._rQi) {
 290                 this._rQlen = 0;
 291                 this._rQi = 0;
 292             } else if (this._rQlen > this._rQmax) {
 293                 this._expand_compact_rQ();
 294             }
 295         } else {
 296             Log.Debug("Ignoring empty message");
 297         }
 298     }
 299 }