class/WindowsBase/System.Windows.Threading/Dispatcher.cs

   1 // TODO:
   2 //    DispatcherObject returned by BeginInvoke must allow:
   3 //       * Waiting until delegate is invoked.
   4 //       See: BeginInvoke documentation for details
   5 //
   6 //    Implement the "Invoke" methods, they are currently not working.
   7 //
   8 //    Add support for disabling the dispatcher and resuming it.
   9 //    Add support for Waiting for new tasks to be pushed, so that we dont busy loop.
  10 //    Add support for aborting an operation (emit the hook.operationaborted too)
  11 //
  12 // Very confusing information about Shutdown: it states that shutdown is
  13 // not over, until all events are unwinded, and also states that all events
  14 // are aborted at that point.  See 'Dispatcher.InvokeShutdown' docs,
  15 //
  16 // Testing reveals that
  17 //     -> InvokeShutdown() stops processing, even if events are available,
  18 //        there is no "unwinding" of events, even of higher priority events,
  19 //        they are just ignored.
  20 //
  21 // The documentation for the Dispatcher family is poorly written, complete
  22 // sections are cut-and-pasted that add no value and the important pieces
  23 // like (what is a frame) is not on the APIs, but scattered everywhere else
  24 //
  25 // -----------------------------------------------------------------------
  26 // Permission is hereby granted, free of charge, to any person obtaining
  27 // a copy of this software and associated documentation files (the
  28 // "Software"), to deal in the Software without restriction, including
  29 // without limitation the rights to use, copy, modify, merge, publish,
  30 // distribute, sublicense, and/or sell copies of the Software, and to
  31 // permit persons to whom the Software is furnished to do so, subject to
  32 // the following conditions:
  33 //
  34 // The above copyright notice and this permission notice shall be
  35 // included in all copies or substantial portions of the Software.
  36 //
  37 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  38 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  39 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  40 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  41 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  42 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  43 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  44 //
  45 // Copyright (c) 2006 Novell, Inc. (http://www.novell.com)
  46 //
  47 // Authors:
  48 //      Miguel de Icaza (miguel@novell.com)
  49 //
  50 using System;
  51 using System.Collections;
  52 using System.Collections.Generic;
  53 using System.ComponentModel;
  54 using System.Security;
  55 using System.Threading;
  56
  57 namespace System.Windows.Threading {
  58
  59         [Flags]
  60         internal enum Flags {
  61                 ShutdownStarted = 1,
  62                 Shutdown = 2,
  63                 Disabled = 4
  64         }
  65
  66         public sealed class Dispatcher {
  67                 static Dictionary<Thread, Dispatcher> dispatchers = new Dictionary<Thread, Dispatcher> ();
  68                 static object olock = new object ();
  69                 static DispatcherFrame main_execution_frame = new DispatcherFrame ();
  70
  71                 const int TOP_PRIO = (int)DispatcherPriority.Send;
  72                 Thread base_thread;
  73                 PokableQueue [] priority_queues = new PokableQueue [TOP_PRIO+1];
  74
  75                 Flags flags;
  76                 int queue_bits;
  77
  78                 //
  79                 // Used to notify the dispatcher thread that new data is available
  80                 //
  81                 EventWaitHandle wait;
  82
  83                 //
  84                 // The hooks for this Dispatcher
  85                 //
  86                 DispatcherHooks hooks;
  87
  88                 //
  89                 // The current DispatcherFrame active in a given Dispatcher, we use this to
  90                 // keep a linked list of all active frames, so we can "ExitAll" frames when
  91                 // requested
  92                 DispatcherFrame current_frame;
  93
  94                 Dispatcher (Thread t)
  95                 {
  96                         base_thread = t;
  97                         for (int i = 1; i <= (int) DispatcherPriority.Send; i++)
  98                                 priority_queues [i] = new PokableQueue ();
  99                         wait = new EventWaitHandle (false, EventResetMode.AutoReset);
 100                         hooks = new DispatcherHooks (this);
 101                 }
 102
 103                 [EditorBrowsable (EditorBrowsableState.Never)]
 104                 public bool CheckAccess ()
 105                 {
 106                         return Thread.CurrentThread == base_thread;
 107                 }
 108
 109                 [EditorBrowsable (EditorBrowsableState.Never)]
 110                 public void VerifyAccess ()
 111                 {
 112                         if (Thread.CurrentThread != base_thread)
 113                                 throw new InvalidOperationException ("Invoked from a different thread");
 114                 }
 115
 116                 public static void ValidatePriority (DispatcherPriority priority, string parameterName)
 117                 {
 118                         if (priority < DispatcherPriority.Inactive || priority > DispatcherPriority.Send)
 119                                 throw new InvalidEnumArgumentException (parameterName);
 120                 }
 121
 122                 public DispatcherOperation BeginInvoke (Delegate method, object[] args)
 123                 {
 124                         throw new NotImplementedException ();
 125                 }
 126
 127                 public DispatcherOperation BeginInvoke (Delegate method, DispatcherPriority priority, object[] args)
 128                 {
 129                         throw new NotImplementedException ();
 130                 }
 131
 132                 [Browsable (false)]
 133                 [EditorBrowsable (EditorBrowsableState.Never)]
 134                 public DispatcherOperation BeginInvoke (DispatcherPriority priority, Delegate method)
 135                 {
 136                         if (priority < 0 || priority > DispatcherPriority.Send)
 137                                 throw new InvalidEnumArgumentException ("priority");
 138                         if (priority == DispatcherPriority.Inactive)
 139                                 throw new ArgumentException ("priority can not be inactive", "priority");
 140                         if (method == null)
 141                                 throw new ArgumentNullException ("method");
 142
 143                         DispatcherOperation op = new DispatcherOperation (this, priority, method);
 144                         Queue (priority, op);
 145
 146                         return op;
 147                 }
 148
 149                 [Browsable (false)]
 150                 [EditorBrowsable (EditorBrowsableState.Never)]
 151                 public DispatcherOperation BeginInvoke (DispatcherPriority priority, Delegate method, object arg)
 152                 {
 153                         if (priority < 0 || priority > DispatcherPriority.Send)
 154                                 throw new InvalidEnumArgumentException ("priority");
 155                         if (priority == DispatcherPriority.Inactive)
 156                                 throw new ArgumentException ("priority can not be inactive", "priority");
 157                         if (method == null)
 158                                 throw new ArgumentNullException ("method");
 159
 160                         DispatcherOperation op = new DispatcherOperation (this, priority, method, arg);
 161
 162                         Queue (priority, op);
 163
 164                         return op;
 165                 }
 166
 167                 [Browsable (false)]
 168                 [EditorBrowsable (EditorBrowsableState.Never)]
 169                 public DispatcherOperation BeginInvoke (DispatcherPriority priority, Delegate method, object arg, params object [] args)
 170                 {
 171                         if (priority < 0 || priority > DispatcherPriority.Send)
 172                                 throw new InvalidEnumArgumentException ("priority");
 173                         if (priority == DispatcherPriority.Inactive)
 174                                 throw new ArgumentException ("priority can not be inactive", "priority");
 175                         if (method == null)
 176                                 throw new ArgumentNullException ("method");
 177
 178                         DispatcherOperation op = new DispatcherOperation (this, priority, method, arg, args);
 179                         Queue (priority, op);
 180
 181                         return op;
 182                 }
 183
 184                 public object Invoke (Delegate method, object[] args)
 185                 {
 186                         throw new NotImplementedException ();
 187                 }
 188
 189                 public object Invoke (Delegate method, TimeSpan timeout, object[] args)
 190                 {
 191                         throw new NotImplementedException ();
 192                 }
 193
 194                 public object Invoke (Delegate method, TimeSpan timeout, DispatcherPriority priority, object[] args)
 195                 {
 196                         throw new NotImplementedException ();
 197                 }
 198
 199                 public object Invoke (Delegate method, DispatcherPriority priority, object[] args)
 200                 {
 201                         throw new NotImplementedException ();
 202                 }
 203
 204                 [Browsable (false)]
 205                 [EditorBrowsable (EditorBrowsableState.Never)]
 206                 public object Invoke (DispatcherPriority priority, Delegate method)
 207                 {
 208                         if (priority < 0 || priority > DispatcherPriority.Send)
 209                                 throw new InvalidEnumArgumentException ("priority");
 210                         if (priority == DispatcherPriority.Inactive)
 211                                 throw new ArgumentException ("priority can not be inactive", "priority");
 212                         if (method == null)
 213                                 throw new ArgumentNullException ("method");
 214
 215                         DispatcherOperation op = new DispatcherOperation (this, priority, method);
 216                         Queue (priority, op);
 217                         PushFrame (new DispatcherFrame ());
 218
 219                         throw new NotImplementedException ();
 220                 }
 221
 222                 [Browsable (false)]
 223                 [EditorBrowsable (EditorBrowsableState.Never)]
 224                 public object Invoke (DispatcherPriority priority, Delegate method, object arg)
 225                 {
 226                         if (priority < 0 || priority > DispatcherPriority.Send)
 227                                 throw new InvalidEnumArgumentException ("priority");
 228                         if (priority == DispatcherPriority.Inactive)
 229                                 throw new ArgumentException ("priority can not be inactive", "priority");
 230                         if (method == null)
 231                                 throw new ArgumentNullException ("method");
 232
 233                         Queue (priority, new DispatcherOperation (this, priority, method, arg));
 234                         throw new NotImplementedException ();
 235                 }
 236
 237                 [Browsable (false)]
 238                 [EditorBrowsable (EditorBrowsableState.Never)]
 239                 public object Invoke (DispatcherPriority priority, Delegate method, object arg, params object [] args)
 240                 {
 241                         if (priority < 0 || priority > DispatcherPriority.Send)
 242                                 throw new InvalidEnumArgumentException ("priority");
 243                         if (priority == DispatcherPriority.Inactive)
 244                                 throw new ArgumentException ("priority can not be inactive", "priority");
 245                         if (method == null)
 246                                 throw new ArgumentNullException ("method");
 247
 248                         Queue (priority, new DispatcherOperation (this, priority, method, arg, args));
 249
 250                         throw new NotImplementedException ();
 251                 }
 252
 253                 [Browsable (false)]
 254                 [EditorBrowsable (EditorBrowsableState.Never)]
 255                 public object Invoke (DispatcherPriority priority, TimeSpan timeout, Delegate method)
 256                 {
 257                         throw new NotImplementedException ();
 258                 }
 259
 260                 [Browsable (false)]
 261                 [EditorBrowsable (EditorBrowsableState.Never)]
 262                 public object Invoke (DispatcherPriority priority, TimeSpan timeout, Delegate method, object arg)
 263                 {
 264                         throw new NotImplementedException ();
 265                 }
 266
 267                 [Browsable (false)]
 268                 [EditorBrowsable (EditorBrowsableState.Never)]
 269                 public object Invoke (DispatcherPriority priority, TimeSpan timeout, Delegate method, object arg, params object [] args)
 270                 {
 271                         throw new NotImplementedException ();
 272                 }
 273
 274                 void Queue (DispatcherPriority priority, DispatcherOperation x)
 275                 {
 276                         int p = ((int) priority);
 277                         PokableQueue q = priority_queues [p];
 278
 279                         lock (q){
 280                                 int flag = 1 << p;
 281                                 q.Enqueue (x);
 282                                 queue_bits |= flag;
 283                         }
 284                         hooks.EmitOperationPosted (x);
 285
 286                         if (Thread.CurrentThread != base_thread)
 287                                 wait.Set ();
 288                 }
 289
 290                 internal void Reprioritize (DispatcherOperation op, DispatcherPriority oldpriority)
 291                 {
 292                         int oldp = (int) oldpriority;
 293                         PokableQueue q = priority_queues [oldp];
 294
 295                         lock (q){
 296                                 q.Remove (op);
 297                         }
 298                         Queue (op.Priority, op);
 299                         hooks.EmitOperationPriorityChanged (op);
 300                 }
 301
 302                 public static Dispatcher CurrentDispatcher {
 303                         get {
 304                                 lock (olock){
 305                                         Thread t = Thread.CurrentThread;
 306                                         Dispatcher dis = FromThread (t);
 307
 308                                         if (dis != null)
 309                                                 return dis;
 310
 311                                         dis = new Dispatcher (t);
 312                                         dispatchers [t] = dis;
 313                                         return dis;
 314                                 }
 315                         }
 316                 }
 317
 318                 public static Dispatcher FromThread (Thread thread)
 319                 {
 320                         Dispatcher dis;
 321
 322                         if (dispatchers.TryGetValue (thread, out dis))
 323                                 return dis;
 324
 325                         return null;
 326                 }
 327
 328                 public Thread Thread {
 329                         get {
 330                                 return base_thread;
 331                         }
 332                 }
 333
 334                 [SecurityCritical]
 335                 public static void Run ()
 336                 {
 337                         PushFrame (main_execution_frame);
 338                 }
 339
 340                 [SecurityCritical]
 341                 public static void PushFrame (DispatcherFrame frame)
 342                 {
 343                         if (frame == null)
 344                                 throw new ArgumentNullException ("frame");
 345
 346                         Dispatcher dis = CurrentDispatcher;
 347
 348                         if (dis.HasShutdownFinished)
 349                                 throw new InvalidOperationException ("The Dispatcher has shut down");
 350                         if (frame.dispatcher != null)
 351                                 throw new InvalidOperationException ("Frame is already running on a different dispatcher");
 352                         if ((dis.flags & Flags.Disabled) != 0)
 353                                 throw new InvalidOperationException ("Dispatcher processing has been disabled");
 354
 355                         frame.ParentFrame = dis.current_frame;
 356                         dis.current_frame = frame;
 357
 358                         frame.dispatcher = dis;
 359
 360                         dis.RunFrame (frame);
 361                 }
 362
 363                 void PerformShutdown ()
 364                 {
 365                         EventHandler h;
 366
 367                         h = ShutdownStarted;
 368                         if (h != null)
 369                                 h (this, new EventArgs ());
 370
 371                         flags |= Flags.Shutdown;
 372
 373                         h = ShutdownFinished;
 374                         if (h != null)
 375                                 h (this, new EventArgs ());
 376
 377                         priority_queues = null;
 378                         wait = null;
 379                 }
 380
 381                 void RunFrame (DispatcherFrame frame)
 382                 {
 383                         do {
 384                                 while (queue_bits != 0){
 385                                         for (int i = TOP_PRIO; i > 0 && queue_bits != 0; i--){
 386                                                 int current_bit = queue_bits & (1 << i);
 387                                                 if (current_bit != 0){
 388                                                         PokableQueue q = priority_queues [i];
 389
 390                                                         do {
 391                                                                 DispatcherOperation task;
 392
 393                                                                 lock (q){
 394                                                                         task = (DispatcherOperation) q.Dequeue ();
 395                                                                 }
 396
 397                                                                 task.Invoke ();
 398
 399                                                                 //
 400                                                                 // call hooks.
 401                                                                 //
 402                                                                 if (task.Status == DispatcherOperationStatus.Aborted)
 403                                                                         hooks.EmitOperationAborted (task);
 404                                                                 else
 405                                                                         hooks.EmitOperationCompleted (task);
 406
 407                                                                 if (!frame.Continue)
 408                                                                         return;
 409
 410                                                                 if (HasShutdownStarted){
 411                                                                         PerformShutdown ();
 412                                                                         return;
 413                                                                 }
 414
 415                                                                 // if we are done with this queue, leave.
 416                                                                 lock (q){
 417                                                                         if (q.Count == 0){
 418                                                                                 queue_bits &= ~(1 << i);
 419                                                                                 break;
 420                                                                         }
 421                                                                 }
 422
 423                                                                 //
 424                                                                 // If a higher-priority task comes in, go do that
 425                                                                 //
 426                                                                 if (current_bit < (queue_bits & ~current_bit))
 427                                                                         break;
 428                                                         } while (true);
 429                                                 }
 430                                         }
 431                                 }
 432                                 hooks.EmitInactive ();
 433
 434                                 wait.WaitOne ();
 435                                 wait.Reset ();
 436                         } while (frame.Continue);
 437                 }
 438
 439                 [EditorBrowsable (EditorBrowsableState.Advanced)]
 440                 public DispatcherHooks Hooks {
 441                         [SecurityCritical]
 442                         get { throw new NotImplementedException (); }
 443                 }
 444
 445                 public bool HasShutdownStarted {
 446                         get {
 447                                 return (flags & Flags.ShutdownStarted) != 0;
 448                         }
 449                 }
 450
 451                 public bool HasShutdownFinished {
 452                         get {
 453                                 return (flags & Flags.Shutdown) != 0;
 454                         }
 455                 }
 456
 457                 //
 458                 // Do no work here, so that any events are thrown on the owning thread
 459                 //
 460                 [SecurityCritical]
 461                 public void InvokeShutdown ()
 462                 {
 463                         flags |= Flags.ShutdownStarted;
 464                 }
 465
 466                 [SecurityCritical]
 467                 public void BeginInvokeShutdown (DispatcherPriority priority)
 468                 {
 469                         throw new NotImplementedException ();
 470                 }
 471
 472                 [SecurityCritical]
 473                 public static void ExitAllFrames ()
 474                 {
 475                         Dispatcher dis = CurrentDispatcher;
 476
 477                         for (DispatcherFrame frame = dis.current_frame; frame != null; frame = frame.ParentFrame){
 478                                 if (frame.exit_on_request)
 479                                         frame.Continue = false;
 480                                 else {
 481                                         //
 482                                         // Stop unwinding the frames at the first frame that is
 483                                         // long running
 484                                         break;
 485                                 }
 486                         }
 487                 }
 488
 489                 public DispatcherProcessingDisabled DisableProcessing ()
 490                 {
 491                         throw new NotImplementedException ();
 492                 }
 493
 494                 public event EventHandler ShutdownStarted;
 495                 public event EventHandler ShutdownFinished;
 496                 public event DispatcherUnhandledExceptionEventHandler UnhandledException;
 497                 public event DispatcherUnhandledExceptionFilterEventHandler UnhandledExceptionFilter;
 498         }
 499
 500         internal class PokableQueue {
 501                 const int initial_capacity = 32;
 502
 503                 int size, head, tail;
 504                 object [] array;
 505
 506                 internal PokableQueue (int capacity)
 507                 {
 508                         array = new object [capacity];
 509                 }
 510
 511                 internal PokableQueue () : this (initial_capacity)
 512                 {
 513                 }
 514
 515                 public void Enqueue (object obj)
 516                 {
 517                         if (size == array.Length)
 518                                 Grow ();
 519                         array[tail] = obj;
 520                         tail = (tail+1) % array.Length;
 521                         size++;
 522                 }
 523
 524                 public object Dequeue ()
 525                 {
 526                         if (size < 1)
 527                                 throw new InvalidOperationException ();
 528                         object result = array[head];
 529                         array [head] = null;
 530                         head = (head + 1) % array.Length;
 531                         size--;
 532                         return result;
 533                 }
 534
 535                 void Grow () {
 536                         int newc = array.Length * 2;
 537                         object[] new_contents = new object[newc];
 538                         array.CopyTo (new_contents, 0);
 539                         array = new_contents;
 540                         head = 0;
 541                         tail = head + size;
 542                 }
 543
 544                 public int Count {
 545                         get {
 546                                 return size;
 547                         }
 548                 }
 549
 550                 public void Remove (object obj)
 551                 {
 552                         for (int i = 0; i < size; i++){
 553                                 if (array [(head+i) % array.Length] == obj){
 554                                         for (int j = i; j < size-i; j++)
 555                                                 array [(head +j) % array.Length] = array [(head+j+1) % array.Length];
 556                                         size--;
 557                                         if (size < 0)
 558                                                 size = array.Length-1;
 559                                         tail--;
 560                                 }
 561                         }
 562                 }
 563         }
 564 }