Migrate dart2js stubs for dart:io

tool/input_sdk/lib/io/http_session.dart

+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of dart.io;
+
+const String _DART_SESSION_ID = "DARTSESSID";
+
+// A _HttpSession is a node in a double-linked list, with _next and _prev being
+// the previous and next pointers.
+class _HttpSession implements HttpSession {
+  // Destroyed marked. Used by the http connection to see if a session is valid.
+  bool _destroyed = false;
+  bool _isNew = true;
+  DateTime _lastSeen;
+  Function _timeoutCallback;
+  _HttpSessionManager _sessionManager;
+  // Pointers in timeout queue.
+  _HttpSession _prev;
+  _HttpSession _next;
+  final String id;
+
+  final Map _data = new HashMap();
+
+  _HttpSession(this._sessionManager, this.id) : _lastSeen = new DateTime.now();
+
+  void destroy() {
+    _destroyed = true;
+    _sessionManager._removeFromTimeoutQueue(this);
+    _sessionManager._sessions.remove(id);
+  }
+
+  // Mark the session as seen. This will reset the timeout and move the node to
+  // the end of the timeout queue.
+  void _markSeen() {
+    _lastSeen = new DateTime.now();
+    _sessionManager._bumpToEnd(this);
+  }
+
+  DateTime get lastSeen => _lastSeen;
+
+  bool get isNew => _isNew;
+
+  void set onTimeout(void callback()) {
+    _timeoutCallback = callback;
+  }
+
+  // Map implementation:
+  bool containsValue(value) => _data.containsValue(value);
+  bool containsKey(key) => _data.containsKey(key);
+  operator [](key) => _data[key];
+  void operator []=(key, value) { _data[key] = value; }
+  putIfAbsent(key, ifAbsent) => _data.putIfAbsent(key, ifAbsent);
+  addAll(Map other) => _data.addAll(other);
+  remove(key) => _data.remove(key);
+  void clear() { _data.clear(); }
+  void forEach(void f(key, value)) { _data.forEach(f); }
+  Iterable get keys => _data.keys;
+  Iterable get values => _data.values;
+  int get length => _data.length;
+  bool get isEmpty => _data.isEmpty;
+  bool get isNotEmpty => _data.isNotEmpty;
+
+  String toString() => 'HttpSession id:$id $_data';
+}
+
+// Private class used to manage all the active sessions. The sessions are stored
+// in two ways:
+//
+//  * In a map, mapping from ID to HttpSession.
+//  * In a linked list, used as a timeout queue.
+class _HttpSessionManager {
+  Map<String, _HttpSession> _sessions;
+  int _sessionTimeout = 20 * 60;  // 20 mins.
+  _HttpSession _head;
+  _HttpSession _tail;
+  Timer _timer;
+
+  _HttpSessionManager() : _sessions = {};
+
+  String createSessionId() {
+    const int _KEY_LENGTH = 16;  // 128 bits.
+    var data = _IOCrypto.getRandomBytes(_KEY_LENGTH);
+    return _CryptoUtils.bytesToHex(data);
+  }
+
+  _HttpSession getSession(String id) => _sessions[id];
+
+  _HttpSession createSession() {
+    var id = createSessionId();
+    // TODO(ajohnsen): Consider adding a limit and throwing an exception.
+    // Should be very unlikely however.
+    while (_sessions.containsKey(id)) {
+      id = createSessionId();
+    }
+    var session = _sessions[id] = new _HttpSession(this, id);
+    _addToTimeoutQueue(session);
+    return session;
+  }
+
+  void set sessionTimeout(int timeout) {
+    _sessionTimeout = timeout;
+    _stopTimer();
+    _startTimer();
+  }
+
+  void close() { _stopTimer(); }
+
+  void _bumpToEnd(_HttpSession session) {
+    _removeFromTimeoutQueue(session);
+    _addToTimeoutQueue(session);
+  }
+
+  void _addToTimeoutQueue(_HttpSession session) {
+    if (_head == null) {
+      assert(_tail == null);
+      _tail = _head = session;
+      _startTimer();
+    } else {
+      assert(_timer != null);
+      assert(_tail != null);
+      // Add to end.
+      _tail._next = session;
+      session._prev = _tail;
+      _tail = session;
+    }
+  }
+
+  void _removeFromTimeoutQueue(_HttpSession session) {
+    if (session._next != null) {
+      session._next._prev = session._prev;
+    }
+    if (session._prev != null) {
+      session._prev._next = session._next;
+    }
+    if (_head == session) {
+      // We removed the head element, start new timer.
+      _head = session._next;
+      _stopTimer();
+      _startTimer();
+    }
+    if (_tail == session) {
+      _tail = session._prev;
+    }
+    session._next = session._prev = null;
+  }
+
+  void _timerTimeout() {
+    _stopTimer();  // Clear timer.
+    assert(_head != null);
+    var session = _head;
+    session.destroy();  // Will remove the session from timeout queue and map.
+    if (session._timeoutCallback != null) {
+      session._timeoutCallback();
+    }
+  }
+
+  void _startTimer() {
+    assert(_timer == null);
+    if (_head != null) {
+      int seconds = new DateTime.now().difference(_head.lastSeen).inSeconds;
+      _timer = new Timer(new Duration(seconds: _sessionTimeout - seconds),
+                         _timerTimeout);
+    }
+  }
+
+  void _stopTimer() {
+    if (_timer != null) {
+      _timer.cancel();
+      _timer = null;
+    }
+  }
+}
+