utils: refactor nexttick module.

lib/utils/nexttick-browser.js

@@ -1,9 +1,255 @@
 /*!
- * nexttick.js - setimmediate for bcoin
- * Copyright (c) 2014-2017, Christopher Jeffrey (MIT License).
+ * nexttick.js - nexttick for bcoin
+ * Copyright (c) 2017, Christopher Jeffrey (MIT License).
  * https://github.com/bcoin-org/bcoin
+ *
+ * Parts of this software are based on setimmediate.
+ *
+ * Copyright (c) 2012 Barnesandnoble.com, llc, Donavon West, and Domenic Denicola
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the 'Software'), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
  */
 
 'use strict';
 
-module.exports = require('../../vendor/setimmediate');
+var global = (function() {
+  if (this)
+    return this;
+
+  if (typeof window !== 'undefined')
+    return window;
+
+  if (typeof self !== 'undefined')
+    return self;
+
+  if (typeof global !== 'undefined')
+    return global;
+
+  throw new Error('No global defined.');
+})();
+
+var document = global.document;
+var nextHandle = 1;
+var taskMap = {};
+var running = false;
+var nextTick;
+
+/*
+ * Task Runner
+ */
+
+function addTask(handler) {
+  if (typeof handler !== 'function')
+    throw new Error('callback must be a function.');
+
+  taskMap[nextHandle] = handler;
+
+  return nextHandle++;
+}
+
+function runTask(handle) {
+  var task;
+
+  if (running) {
+    setTimeout(function() {
+      runTask(handle);
+    }, 1);
+    return;
+  }
+
+  task = taskMap[handle];
+
+  if (task) {
+    running = true;
+    try {
+      task();
+    } finally {
+      delete taskMap[handle];
+      running = false;
+    }
+  }
+}
+
+/*
+ * Set Immediate Implementation
+ */
+
+function hasSetImmediate() {
+  return typeof global.setImmediate === 'function';
+}
+
+function installSetImmediate() {
+  return function nextTick(handler) {
+    setImmediate(handler);
+  };
+}
+
+/*
+ * Next Tick Implementation
+ */
+
+function hasNextTick() {
+  // Don't get fooled by browserify.
+  return ({}).toString.call(global.process) === '[object process]';
+}
+
+function installNextTick() {
+  return process.nextTick;
+}
+
+/*
+ * Post Message Implementation
+ */
+
+function hasPostMessage() {
+  var isAsync = false;
+  var onMessage;
+
+  // Be sure to exclude web workers.
+  if (global.postMessage && !global.importScripts) {
+    isAsync = true;
+    onMessage = global.onmessage;
+    global.onmessage = function() {
+      isAsync = false;
+    };
+    global.postMessage('', '*');
+    global.onmessage = onMessage;
+  }
+
+  return isAsync;
+}
+
+function installPostMessage() {
+  var prefix = 'nextTick' + Math.random();
+  var onMessage;
+
+  onMessage = function(event) {
+    if (event.source === global
+        && typeof event.data === 'string'
+        && event.data.indexOf(prefix) === 0) {
+      runTask(+event.data.slice(prefix.length));
+    }
+  };
+
+  if (global.addEventListener)
+    global.addEventListener('message', onMessage, false);
+  else
+    global.attachEvent('onmessage', onMessage);
+
+  return function nextTick(handler) {
+    var handle = addTask(handler);
+    global.postMessage(prefix + handle, '*');
+  };
+}
+
+/*
+ * Message Channel Implementation
+ */
+
+function hasMessageChannel() {
+  return typeof global.MessageChannel === 'function';
+}
+
+function installMessageChannel() {
+  var channel = new MessageChannel();
+
+  channel.port1.onmessage = function(event) {
+    runTask(event.data);
+  };
+
+  return function nextTick(handler) {
+    var handle = addTask(handler);
+    channel.port2.postMessage(handle);
+  };
+}
+
+/*
+ * Ready State Change Implementation
+ */
+
+function hasReadyState() {
+  return document && ('onreadystatechange' in document.createElement('script'));
+}
+
+function installReadyState() {
+  var html = document.documentElement;
+
+  return function nextTick(handler) {
+    var handle = addTask(handler);
+    var script = document.createElement('script');
+
+    script.onreadystatechange = function() {
+      runTask(handle);
+      script.onreadystatechange = null;
+      html.removeChild(script);
+      script = null;
+    };
+
+    html.appendChild(script);
+  };
+}
+
+/*
+ * Set Timeout Implementation
+ */
+
+function hasSetTimeout() {
+  return typeof global.setTimeout === 'function';
+}
+
+function installSetTimeout() {
+  return function nextTick(handler) {
+    var handle = addTask(handler);
+    setTimeout(function() {
+      runTask(handle);
+    }, 1);
+  };
+}
+
+/*
+ * Install
+ */
+
+if (hasSetImmediate()) {
+  // `setImmediate` is already available.
+  nextTick = installSetImmediate();
+} else if (hasNextTick()) {
+  // For Node.js before 0.9.
+  nextTick = installNextTick();
+} else if (hasPostMessage()) {
+  // For non-IE10 modern browsers.
+  nextTick = installPostMessage();
+} else if (hasMessageChannel()) {
+  // For web workers, where supported.
+  nextTick = installMessageChannel();
+} else if (hasReadyState()) {
+  // For IE 6–8.
+  nextTick = installReadyState();
+} else if (hasSetTimeout()) {
+  // For older browsers.
+  nextTick = installSetTimeout();
+} else {
+  throw new Error('nextTick not supported.');
+}
+
+/*
+ * Expose
+ */
+
+module.exports = nextTick;

lib/utils/nexttick.js

@@ -6,6 +6,6 @@
 
 'use strict';
 
-module.exports = typeof setImmediate !== 'function'
-  ? process.nextTick
-  : setImmediate;
+module.exports = function nextTick(handler) {
+  setImmediate(handler);
+};