.travis.yml

@@ -1,5 +1,6 @@
 language: node_js
 node_js:
+  - '13'
   - '12'
   - '10'
   - '8'

appveyor.yml

@@ -1,5 +1,6 @@
 environment:
   matrix:
+    - nodejs_version: '13'
     - nodejs_version: '12'
     - nodejs_version: '10'
     - nodejs_version: '8'

lib/limiter.js

@@ -0,0 +1,54 @@
+'use strict';
+
+const kDone = Symbol('kDone');
+const kRun = Symbol('kRun');
+
+/**
+ * A very simple job queue with adjustable concurrency. Adapted from
+ * https://github.com/STRML/async-limiter
+ */
+class Limiter {
+  /**
+   * Creates a new `Limiter`.
+   *
+   * @param {Number} concurrency The maximum number of jobs allowed to run
+   *     concurrently
+   */
+  constructor(concurrency) {
+    this[kDone] = () => {
+      this.pending--;
+      this[kRun]();
+    };
+    this.concurrency = concurrency || Infinity;
+    this.jobs = [];
+    this.pending = 0;
+  }
+
+  /**
+   * Adds a job to the queue.
+   *
+   * @public
+   */
+  add(job) {
+    this.jobs.push(job);
+    this[kRun]();
+  }
+
+  /**
+   * Removes a job from the queue and runs it if possible.
+   *
+   * @private
+   */
+  [kRun]() {
+    if (this.pending === this.concurrency) return;
+
+    if (this.jobs.length) {
+      const job = this.jobs.shift();
+
+      this.pending++;
+      job(this[kDone]);
+    }
+  }
+}
+
+module.exports = Limiter;

lib/permessage-deflate.js

@@ -1,14 +1,12 @@
 'use strict';
 
-const Limiter = require('async-limiter');
 const zlib = require('zlib');
 
 const bufferUtil = require('./buffer-util');
+const Limiter = require('./limiter');
 const { kStatusCode, NOOP } = require('./constants');
 
 const TRAILER = Buffer.from([0x00, 0x00, 0xff, 0xff]);
-const EMPTY_BLOCK = Buffer.from([0x00]);
-
 const kPerMessageDeflate = Symbol('permessage-deflate');
 const kTotalLength = Symbol('total-length');
 const kCallback = Symbol('callback');
@@ -66,7 +64,7 @@ class PerMessageDeflate {
         this._options.concurrencyLimit !== undefined
           ? this._options.concurrencyLimit
           : 10;
-      zlibLimiter = new Limiter({ concurrency });
+      zlibLimiter = new Limiter(concurrency);
     }
   }
 
@@ -288,15 +286,15 @@ class PerMessageDeflate {
   }
 
   /**
-   * Decompress data. Concurrency limited by async-limiter.
+   * Decompress data. Concurrency limited.
    *
    * @param {Buffer} data Compressed data
    * @param {Boolean} fin Specifies whether or not this is the last fragment
    * @param {Function} callback Callback
    * @public
    */
   decompress(data, fin, callback) {
-    zlibLimiter.push((done) => {
+    zlibLimiter.add((done) => {
       this._decompress(data, fin, (err, result) => {
         done();
         callback(err, result);
@@ -305,15 +303,15 @@ class PerMessageDeflate {
   }
 
   /**
-   * Compress data. Concurrency limited by async-limiter.
+   * Compress data. Concurrency limited.
    *
    * @param {Buffer} data Data to compress
    * @param {Boolean} fin Specifies whether or not this is the last fragment
    * @param {Function} callback Callback
    * @public
    */
   compress(data, fin, callback) {
-    zlibLimiter.push((done) => {
+    zlibLimiter.add((done) => {
       this._compress(data, fin, (err, result) => {
         done();
         if (err || result) {
@@ -393,11 +391,6 @@ class PerMessageDeflate {
    * @private
    */
   _compress(data, fin, callback) {
-    if (!data || data.length === 0) {
-      process.nextTick(callback, null, EMPTY_BLOCK);
-      return;
-    }
-
     const endpoint = this._isServer ? 'server' : 'client';
 
     if (!this._deflate) {

package.json

@@ -1,6 +1,6 @@
 {
   "name": "ws",
-  "version": "7.2.0",
+  "version": "7.2.1",
   "description": "Simple to use, blazing fast and thoroughly tested websocket client and server for Node.js",
   "keywords": [
     "HyBi",
@@ -17,6 +17,9 @@
   "license": "MIT",
   "main": "index.js",
   "browser": "browser.js",
+  "engines": {
+    "node": ">=8.3.0"
+  },
   "files": [
     "browser.js",
     "index.js",
@@ -27,8 +30,17 @@
     "integration": "npm run lint && mocha --throw-deprecation test/*.integration.js",
     "lint": "eslint --ignore-path .gitignore . && prettier --check --ignore-path .gitignore \"**/*.{json,md,yaml,yml}\""
   },
-  "dependencies": {
-    "async-limiter": "^1.0.0"
+  "peerDependencies": {
+    "bufferutil": "^4.0.1",
+    "utf-8-validate": "^5.0.2"
+  },
+  "peerDependenciesMeta": {
+    "bufferutil": {
+      "optional": true
+    },
+    "utf-8-validate": {
+      "optional": true
+    }
   },
   "devDependencies": {
     "benchmark": "^2.1.4",

test/limiter.test.js

@@ -0,0 +1,41 @@
+'use strict';
+
+const assert = require('assert');
+
+const Limiter = require('../lib/limiter');
+
+describe('Limiter', () => {
+  describe('#ctor', () => {
+    it('takes a `concurrency` argument', () => {
+      const limiter = new Limiter(0);
+
+      assert.strictEqual(limiter.concurrency, Infinity);
+    });
+  });
+
+  describe('#kRun', () => {
+    it('limits the number of jobs allowed to run concurrently', (done) => {
+      const limiter = new Limiter(1);
+
+      limiter.add((callback) => {
+        setImmediate(() => {
+          callback();
+
+          assert.strictEqual(limiter.jobs.length, 0);
+          assert.strictEqual(limiter.pending, 1);
+        });
+      });
+
+      limiter.add((callback) => {
+        setImmediate(() => {
+          callback();
+
+          assert.strictEqual(limiter.pending, 0);
+          done();
+        });
+      });
+
+      assert.strictEqual(limiter.jobs.length, 1);
+    });
+  });
+});

test/sender.test.js

@@ -154,7 +154,7 @@ describe('Sender', () => {
 
           assert.strictEqual(chunks[0].length, 2);
           assert.strictEqual(chunks[0][0] & 0x40, 0x40);
-          assert.strictEqual(chunks[1].length, 1);
+          assert.strictEqual(chunks[1].length, 5);
 
           assert.strictEqual(chunks[2].length, 2);
           assert.strictEqual(chunks[2][0] & 0x40, 0x00);