Update mojo sdk to rev f6c8ec07c01deebc13178d516225fd12695c3dc2

mojo/public/dart/src/timer_impl.dart

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// This code is adapted from the Timer implementation in the standalone Dart VM
+// for use in the Mojo embedder.
+
+part of core;
+
+// Timer heap implemented as a array-based binary heap[0].
+// This allows for O(1) `first`, O(log(n)) `remove`/`removeFirst` and O(log(n))
+// `add`.
+//
+// To ensure the timers are ordered by insertion time, the _Timer class has a
+// `_id` field set when added to the heap.
+//
+// [0] http://en.wikipedia.org/wiki/Binary_heap
+class _TimerHeap {
+  List<_Timer> _list;
+  int _used = 0;
+
+  _TimerHeap([int initSize = 7])
+      : _list = new List<_Timer>(initSize);
+
+  bool get isEmpty => _used == 0;
+  bool get isNotEmpty => _used > 0;
+
+  _Timer get first => _list[0];
+
+  bool isFirst(_Timer timer) => timer._indexOrNext == 0;
+
+  void add(_Timer timer) {
+    if (_used == _list.length) {
+      _resize();
+    }
+    timer._indexOrNext = _used++;
+    _list[timer._indexOrNext] = timer;
+    _bubbleUp(timer);
+  }
+
+  _Timer removeFirst() {
+    var f = first;
+    remove(f);
+    return f;
+  }
+
+  void remove(_Timer timer) {
+    _used--;
+    timer._id = -1;
+    if (isEmpty) {
+      _list[0] = null;
+      timer._indexOrNext = null;
+      return;
+    }
+    var last = _list[_used];
+    if (!identical(last, timer)) {
+      last._indexOrNext = timer._indexOrNext;
+      _list[last._indexOrNext] = last;
+      if (last._compareTo(timer) < 0) {
+        _bubbleUp(last);
+      } else {
+        _bubbleDown(last);
+      }
+    }
+    _list[_used] = null;
+    timer._indexOrNext = null;
+  }
+
+  void _resize() {
+    var newList = new List(_list.length * 2 + 1);
+    newList.setRange(0, _used, _list);
+    _list = newList;
+  }
+
+  void _bubbleUp(_Timer timer) {
+    while (!isFirst(timer)) {
+      Timer parent = _parent(timer);
+      if (timer._compareTo(parent) < 0) {
+        _swap(timer, parent);
+      } else {
+        break;
+      }
+    }
+  }
+
+  void _bubbleDown(_Timer timer) {
+    while (true) {
+      int leftIndex = _leftChildIndex(timer._indexOrNext);
+      int rightIndex = _rightChildIndex(timer._indexOrNext);
+      _Timer newest = timer;
+      if (leftIndex < _used && _list[leftIndex]._compareTo(newest) < 0) {
+        newest = _list[leftIndex];
+      }
+      if (rightIndex < _used && _list[rightIndex]._compareTo(newest) < 0) {
+        newest = _list[rightIndex];
+      }
+      if (identical(newest, timer)) {
+        // We are where we should be, break.
+        break;
+      }
+      _swap(newest, timer);
+    }
+  }
+
+  void _swap(_Timer first, _Timer second) {
+    int tmp = first._indexOrNext;
+    first._indexOrNext = second._indexOrNext;
+    second._indexOrNext = tmp;
+    _list[first._indexOrNext] = first;
+    _list[second._indexOrNext] = second;
+  }
+
+  Timer _parent(_Timer timer) => _list[_parentIndex(timer._indexOrNext)];
+  Timer _leftChild(_Timer timer) => _list[_leftChildIndex(timer._indexOrNext)];
+  Timer _rightChild(_Timer timer) =>
+      _list[_rightChildIndex(timer._indexOrNext)];
+
+  static int _parentIndex(int index) => (index - 1) ~/ 2;
+  static int _leftChildIndex(int index) => 2 * index + 1;
+  static int _rightChildIndex(int index) => 2 * index + 2;
+}
+
+class _Timer implements Timer {
+  // Disables the timer.
+  static const int _NO_TIMER = -1;
+
+  // Timers are ordered by wakeup time.
+  static _TimerHeap _heap = new _TimerHeap();
+  static _Timer _firstZeroTimer;
+  static _Timer _lastZeroTimer;
+  static int _idCount = 0;
+
+  static RawReceivePort _receivePort;
+  static SendPort _sendPort;
+  static bool _handlingCallbacks = false;
+
+  Function _callback;
+  int _milliSeconds;
+  int _wakeupTime = 0;
+  var _indexOrNext;
+  int _id = -1;
+
+  static Timer _createTimer(void callback(Timer timer),
+                            int milliSeconds,
+                            bool repeating) {
+    _Timer timer = new _Timer._internal();
+    timer._callback = callback;
+    if (milliSeconds > 0) {
+      // Add one because DateTime.now() is assumed to round down
+      // to nearest millisecond, not up, so that time + duration is before
+      // duration milliseconds from now. Using micosecond timers like
+      // Stopwatch allows detecting that the timer fires early.
+      timer._wakeupTime =
+          new DateTime.now().millisecondsSinceEpoch + 1 + milliSeconds;
+    }
+    timer._milliSeconds = repeating ? milliSeconds : -1;
+    if (timer._addTimerToHeap()) {
+      // The new timer is the first in queue. Update event handler.
+      _notifyEventHandler();
+    }
+    return timer;
+  }
+
+  factory _Timer(int milliSeconds, void callback(Timer timer)) {
+    return _createTimer(callback, milliSeconds, false);
+  }
+
+  factory _Timer.periodic(int milliSeconds, void callback(Timer timer)) {
+    return _createTimer(callback, milliSeconds, true);
+  }
+
+  _Timer._internal() {}
+
+  bool get _isInHeap => _id >= 0;
+
+  void _clear() {
+    _callback = null;
+  }
+
+  int _compareTo(_Timer other) {
+    int c = _wakeupTime - other._wakeupTime;
+    if (c != 0) return c;
+    return _id - other._id;
+  }
+
+  bool get _repeating => _milliSeconds >= 0;
+
+  bool get isActive => _callback != null;
+
+  // Cancels a set timer. The timer is removed from the timer list and if
+  // the given timer is the earliest timer the native timer is reset.
+  void cancel() {
+    _clear();
+    if (!_isInHeap) return;
+    assert(_wakeupTime != 0);
+    bool update = (_firstZeroTimer == null) && _heap.isFirst(this);
+    _heap.remove(this);
+    if (update) {
+      _notifyEventHandler();
+    }
+  }
+
+  void _advanceWakeupTime() {
+    assert(_milliSeconds >= 0);
+    _wakeupTime += _milliSeconds;
+  }
+
+  // Adds a timer to the timer list. Timers with the same wakeup time are
+  // enqueued in order and notified in FIFO order.
+  bool _addTimerToHeap() {
+    if (_wakeupTime == 0) {
+      if (_firstZeroTimer == null) {
+        _lastZeroTimer = this;
+        _firstZeroTimer = this;
+        return true;
+      } else {
+        _lastZeroTimer._indexOrNext = this;
+        _lastZeroTimer = this;
+        return false;
+      }
+    } else {
+      _id = _idCount++;
+      _heap.add(this);
+      return _firstZeroTimer == null && _heap.isFirst(this);
+    }
+  }
+
+
+  static void _notifyEventHandler() {
+    if (_handlingCallbacks) {
+      // While we are already handling callbacks we will not notify the event
+      // handler. _handleTimeout will call _notifyEventHandler once all pending
+      // timers are processed.
+      return;
+    }
+
+    if (_firstZeroTimer == null && _heap.isEmpty) {
+      // No pending timers: Close the receive port and let the event handler
+      // know.
+      if (_receivePort != null) {
+        MojoHandleWatcher.timer(_sendPort, _NO_TIMER);
+        _shutdownTimerHandler();
+      }
+    } else {
+      if (_receivePort == null) {
+        // Create a receive port and register a message handler for the timer
+        // events.
+        _createTimerHandler();
+      }
+      if (_firstZeroTimer != null) {
+        _sendPort.send(null);
+      } else {
+        MojoHandleWatcher.timer(_sendPort, _heap.first._wakeupTime);
+      }
+    }
+  }
+
+  static void _handleTimeout(_) {
+    int currentTime = new DateTime.now().millisecondsSinceEpoch;
+    // Collect all pending timers.
+    var timer = _firstZeroTimer;
+    var nextTimer = _lastZeroTimer;
+    _firstZeroTimer = null;
+    _lastZeroTimer = null;
+    while (_heap.isNotEmpty && _heap.first._wakeupTime <= currentTime) {
+      var next = _heap.removeFirst();
+      if (timer == null) {
+        nextTimer = next;
+        timer = next;
+      } else {
+        nextTimer._indexOrNext = next;
+        nextTimer = next;
+      }
+    }
+
+    // Trigger all of the pending timers. New timers added as part of the
+    // callbacks will be enqueued now and notified in the next spin at the
+    // earliest.
+    _handlingCallbacks = true;
+    try {
+      while (timer != null) {
+        var next = timer._indexOrNext;
+        timer._indexOrNext = null;
+        // One of the timers in the pending_timers list can cancel
+        // one of the later timers which will set the callback to
+        // null.
+        if (timer._callback != null) {
+          var callback = timer._callback;
+          if (!timer._repeating) {
+            // Mark timer as inactive.
+            timer._callback = null;
+          }
+          callback(timer);
+          // Re-insert repeating timer if not canceled.
+          if (timer._repeating && timer._callback != null) {
+            timer._advanceWakeupTime();
+            timer._addTimerToHeap();
+          }
+        }
+        timer = next;
+      }
+    } finally {
+      _handlingCallbacks = false;
+      _notifyEventHandler();
+    }
+  }
+
+  // Creates a receive port and registers the timer handler on that
+  // receive port.
+  static void _createTimerHandler() {
+    if(_receivePort == null) {
+      _receivePort = new RawReceivePort(_handleTimeout);
+      _sendPort = _receivePort.sendPort;
+    }
+  }
+
+  static void _shutdownTimerHandler() {
+    _receivePort.close();
+    _receivePort = null;
+    _sendPort = null;
+  }
+}
+
+// Provide a closure which will allocate a Timer object to be able to hook
+// up the Timer interface in dart:isolate with the implementation here.
+_getTimerFactoryClosure() {
+  return (int milliSeconds, void callback(Timer timer), bool repeating) {
+    if (repeating) {
+      return new _Timer.periodic(milliSeconds, callback);
+    }
+    return new _Timer(milliSeconds, callback);
+  };
+}