perf: try to avoid buffer allocations

lib/sender.js

@@ -46,7 +46,7 @@ class Sender {
   /**
    * Frames a piece of data according to the HyBi WebSocket protocol.
    *
-   * @param {Buffer} data The data to frame
+   * @param {Buffer|String} data The data to frame
    * @param {Object} options Options object
    * @param {Boolean} [options.fin=false] Specifies whether or not to set the
    *     FIN bit
@@ -58,7 +58,7 @@ class Sender {
    *     key
    * @param {Number} options.opcode The opcode
    * @param {Boolean} [options.readOnly=false] Specifies whether `data` can be
-   *     modified
+   *     modified. Only relevant if data is a `Buffer`.
    * @param {Boolean} [options.rsv1=false] Specifies whether or not to set the
    *     RSV1 bit
    * @return {Buffer[]} The framed data as a list of `Buffer` instances
@@ -80,12 +80,31 @@ class Sender {
       }
 
       skipMasking = (mask[0] | mask[1] | mask[2] | mask[3]) === 0;
-      if (options.readOnly && !skipMasking) merge = true;
 
       offset = 6;
     }
 
-    let payloadLength = data.length;
+    let dataLength = options.payloadLength;
+
+    if (typeof data === 'string') {
+      if (!options.mask || skipMasking) {
+        if (dataLength == null) {
+          dataLength = Buffer.byteLength(data);
+        }
+      } else {
+        data = toBuffer(data);
+        dataLength = data.length;
+      }
+    } else if (Buffer.isBuffer(data)) {
+      dataLength = data.length;
+      merge = options.mask && options.readOnly && !skipMasking;
+    } else {
+      data = toBuffer(data);
+      dataLength = data.length;
+      merge = options.mask && toBuffer.readOnly && !skipMasking;
+    }
+
+    let payloadLength = dataLength;
 
     if (data.length >= 65536) {
       offset += 8;
@@ -95,18 +114,18 @@ class Sender {
       payloadLength = 126;
     }
 
-    const target = Buffer.allocUnsafe(merge ? data.length + offset : offset);
+    const target = Buffer.allocUnsafe(merge ? dataLength + offset : offset);
 
     target[0] = options.fin ? options.opcode | 0x80 : options.opcode;
     if (options.rsv1) target[0] |= 0x40;
 
     target[1] = payloadLength;
 
     if (payloadLength === 126) {
-      target.writeUInt16BE(data.length, 2);
+      target.writeUInt16BE(dataLength, 2);
     } else if (payloadLength === 127) {
       target[2] = target[3] = 0;
-      target.writeUIntBE(data.length, 4, 6);
+      target.writeUIntBE(dataLength, 4, 6);
     }
 
     if (!options.mask) return [target, data];
@@ -188,7 +207,7 @@ class Sender {
         mask,
         maskBuffer: this._maskBuffer,
         generateMask: this._generateMask,
-        readOnly: false
+        readOnly: true
       }),
       cb
     );
@@ -203,16 +222,16 @@ class Sender {
    * @public
    */
   ping(data, mask, cb) {
-    const buf = toBuffer(data);
+    const payloadLength = Buffer.byteLength(data);
 
-    if (buf.length > 125) {
+    if (payloadLength > 125) {
       throw new RangeError('The data size must not be greater than 125 bytes');
     }
 
     if (this._deflating) {
-      this.enqueue([this.doPing, buf, mask, toBuffer.readOnly, cb]);
+      this.enqueue([this.doPing, data, mask, payloadLength, cb]);
     } else {
-      this.doPing(buf, mask, toBuffer.readOnly, cb);
+      this.doPing(data, mask, payloadLength, cb);
     }
   }
 
@@ -221,11 +240,10 @@ class Sender {
    *
    * @param {Buffer} data The message to send
    * @param {Boolean} [mask=false] Specifies whether or not to mask `data`
-   * @param {Boolean} [readOnly=false] Specifies whether `data` can be modified
    * @param {Function} [cb] Callback
    * @private
    */
-  doPing(data, mask, readOnly, cb) {
+  doPing(data, mask, payloadLength, cb) {
     this.sendFrame(
       Sender.frame(data, {
         fin: true,
@@ -234,7 +252,8 @@ class Sender {
         mask,
         maskBuffer: this._maskBuffer,
         generateMask: this._generateMask,
-        readOnly
+        payloadLength,
+        readOnly: true
       }),
       cb
     );
@@ -249,16 +268,16 @@ class Sender {
    * @public
    */
   pong(data, mask, cb) {
-    const buf = toBuffer(data);
+    const payloadLength = Buffer.byteLength(data);
 
-    if (buf.length > 125) {
+    if (payloadLength > 125) {
       throw new RangeError('The data size must not be greater than 125 bytes');
     }
 
     if (this._deflating) {
-      this.enqueue([this.doPong, buf, mask, toBuffer.readOnly, cb]);
+      this.enqueue([this.doPong, data, mask, payloadLength, cb]);
     } else {
-      this.doPong(buf, mask, toBuffer.readOnly, cb);
+      this.doPong(data, mask, payloadLength, cb);
     }
   }
 
@@ -267,11 +286,10 @@ class Sender {
    *
    * @param {Buffer} data The message to send
    * @param {Boolean} [mask=false] Specifies whether or not to mask `data`
-   * @param {Boolean} [readOnly=false] Specifies whether `data` can be modified
    * @param {Function} [cb] Callback
    * @private
    */
-  doPong(data, mask, readOnly, cb) {
+  doPong(data, mask, payloadLength, cb) {
     this.sendFrame(
       Sender.frame(data, {
         fin: true,
@@ -280,7 +298,8 @@ class Sender {
         mask,
         maskBuffer: this._maskBuffer,
         generateMask: this._generateMask,
-        readOnly
+        payloadLength,
+        readOnly: true
       }),
       cb
     );
@@ -303,11 +322,12 @@ class Sender {
    * @public
    */
   send(data, options, cb) {
-    const buf = toBuffer(data);
     const perMessageDeflate = this._extensions[PerMessageDeflate.extensionName];
     let opcode = options.binary ? 2 : 1;
     let rsv1 = options.compress;
 
+    let payloadLength = options.payloadLength;
+
     if (this._firstFragment) {
       this._firstFragment = false;
       if (
@@ -319,7 +339,10 @@ class Sender {
             : 'client_no_context_takeover'
         ]
       ) {
-        rsv1 = buf.length >= perMessageDeflate._threshold;
+        if (payloadLength == null) {
+          payloadLength = Buffer.byteLength(data);
+        }
+        rsv1 = payloadLength >= perMessageDeflate._threshold;
       }
       this._compress = rsv1;
     } else {
@@ -337,24 +360,26 @@ class Sender {
         mask: options.mask,
         maskBuffer: this._maskBuffer,
         generateMask: this._generateMask,
-        readOnly: toBuffer.readOnly
+        payloadLength,
+        readOnly: true
       };
 
       if (this._deflating) {
-        this.enqueue([this.dispatch, buf, this._compress, opts, cb]);
+        this.enqueue([this.dispatch, data, this._compress, opts, cb]);
       } else {
-        this.dispatch(buf, this._compress, opts, cb);
+        this.dispatch(data, this._compress, opts, cb);
       }
     } else {
       this.sendFrame(
-        Sender.frame(buf, {
+        Sender.frame(data, {
           fin: options.fin,
           rsv1: false,
           opcode,
           mask: options.mask,
           maskBuffer: this._maskBuffer,
           generateMask: this._generateMask,
-          readOnly: toBuffer.readOnly
+          payloadLength,
+          readOnly: true
         }),
         cb
       );