aboutsummaryrefslogtreecommitdiff
path: root/src/include/gnunet_scheduler_lib.h
blob: 5f6f415483919ad4ec35b9768b92e0bcce6c55aa (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
/*
      This file is part of GNUnet
      Copyright (C) 2009-2016 GNUnet e.V.

      GNUnet is free software: you can redistribute it and/or modify it
      under the terms of the GNU Affero General Public License as published
      by the Free Software Foundation, either version 3 of the License,
      or (at your option) any later version.

      GNUnet is distributed in the hope that it will be useful, but
      WITHOUT ANY WARRANTY; without even the implied warranty of
      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      Affero General Public License for more details.
 */

/**
 * @author Christian Grothoff
 *
 * @file
 * API to schedule computations using continuation passing style
 *
 * @defgroup scheduler  Scheduler library
 * Event loop (scheduler)
 *
 * Schedule computations using continuation passing style.
 *
 * @{
 */

#ifndef GNUNET_SCHEDULER_LIB_H
#define GNUNET_SCHEDULER_LIB_H

#ifdef __cplusplus
extern "C"
{
#if 0                           /* keep Emacsens' auto-indent happy */
}
#endif
#endif

/**
 * Opaque reference to a task.
 */
struct GNUNET_SCHEDULER_Task;

/**
 * Reasons why the schedule may have triggered
 * the task now.
 */
enum GNUNET_SCHEDULER_Reason
{
  /**
   * This task is not ready.
   */
  GNUNET_SCHEDULER_REASON_NONE = 0,

  /**
   * This is the very first task run during startup.
   */
  GNUNET_SCHEDULER_REASON_STARTUP = 1,

  /**
   * We are shutting down and are running all shutdown-related tasks.
   */
  GNUNET_SCHEDULER_REASON_SHUTDOWN = 2,

  /**
   * The specified timeout has expired.
   * (also set if the delay given was 0).
   */
  GNUNET_SCHEDULER_REASON_TIMEOUT = 4,

  /**
   * The reading socket is ready.
   */
  GNUNET_SCHEDULER_REASON_READ_READY = 8,

  /**
   * The writing socket is ready.
   */
  GNUNET_SCHEDULER_REASON_WRITE_READY = 16,

  /**
   * The prerequisite task is done.
   */
  GNUNET_SCHEDULER_REASON_PREREQ_DONE = 32
};


#include "gnunet_time_lib.h"
#include "gnunet_network_lib.h"


/**
 * Possible events on FDs, used as a bitmask.
 * Modelled after GPollFD.
 */
enum GNUNET_SCHEDULER_EventType
{

  /**
   * No event (useful for timeout).
   */
  GNUNET_SCHEDULER_ET_NONE = 0,

  /**
   * Data available for reading.
   */
  GNUNET_SCHEDULER_ET_IN = 1,

  /**
   * Buffer available for writing.
   */
  GNUNET_SCHEDULER_ET_OUT = 2,

  /**
   *
   */
  GNUNET_SCHEDULER_ET_HUP = 4,

  /**
   *
   */
  GNUNET_SCHEDULER_ET_ERR = 8,

  /**
   *
   */
  GNUNET_SCHEDULER_ET_PRI = 16,

  /**
   *
   */
  GNUNET_SCHEDULER_ET_NVAL = 32

};


/**
 * Information about an event relating to a file descriptor/socket.
 */
struct GNUNET_SCHEDULER_FdInfo
{

  /**
   * GNUnet network socket the event is about, matches @a sock,
   * NULL if this is about a file handle or if no network
   * handle was given to the scheduler originally.
   */
  const struct GNUNET_NETWORK_Handle *fd;

  /**
   * GNUnet file handle the event is about, matches @a sock,
   * NULL if this is about a network socket or if no network
   * handle was given to the scheduler originally.
   */
  const struct GNUNET_DISK_FileHandle *fh;

  /**
   * Type of the event that was generated related to @e sock.
   */
  enum GNUNET_SCHEDULER_EventType et;

  /**
   * Underlying OS handle the event was about.
   */
  int sock;

};


/**
 * Context information passed to each scheduler task.
 */
struct GNUNET_SCHEDULER_TaskContext
{
  /**
   * Reason why the task is run now
   */
  enum GNUNET_SCHEDULER_Reason reason;

  /**
   * Length of the following array.
   */
  unsigned int fds_len;

  /**
   * Array of length @e fds_len with information about ready FDs.
   * Note that we use the same format regardless of the internal
   * event loop that was used.  The given array should only contain
   * information about file descriptors relevant to the current task.
   */
  const struct GNUNET_SCHEDULER_FdInfo *fds;

  /**
   * Set of file descriptors ready for reading; note that additional
   * bits may be set that were not in the original request.
   * @deprecated
   */
  const struct GNUNET_NETWORK_FDSet *read_ready;

  /**
   * Set of file descriptors ready for writing; note that additional
   * bits may be set that were not in the original request.
   * @deprecated
   */
  const struct GNUNET_NETWORK_FDSet *write_ready;

};


/**
 * Function used by event-loop implementations to signal the scheduler
 * that a particular @a task is ready due to an event specified in the
 * et field of @a fdi.
 *
 * This function will then queue the task to notify the application
 * that the task is ready (with the respective priority).
 *
 * @param task the task that is ready
 * @param fdi information about the related FD
 */
void
GNUNET_SCHEDULER_task_ready (struct GNUNET_SCHEDULER_Task *task,
			     struct GNUNET_SCHEDULER_FdInfo *fdi);


/**
 * Handle to the scheduler's state to be used by the driver.
 */
struct GNUNET_SCHEDULER_Handle;


/**
 * Function called by external event loop implementations to tell the
 * scheduler to run some of the tasks that are ready. Must be called
 * only after #GNUNET_SCHEDULER_driver_init has been called and before 
 * #GNUNET_SCHEDULER_driver_done is called.
 * This function may return even though there are tasks left to run
 * just to give other tasks a chance as well.  If we return #GNUNET_YES,
 * the event loop implementation should call this function again as
 * soon as possible, while if we return #GNUNET_NO it must block until
 * either the operating system has more work (the scheduler has no more
 * work to do right now) or the timeout set by the scheduler (using the
 * set_wakeup callback) is reached.
 *
 * @param sh scheduler handle that was returned by
 *        #GNUNET_SCHEDULER_driver_init
 * @return #GNUNET_YES if there are more tasks that are ready,
 *         and thus we would like to run more (yield to avoid
 *         blocking other activities for too long) #GNUNET_NO
 *         if we are done running tasks (yield to block)
 */
int
GNUNET_SCHEDULER_do_work (struct GNUNET_SCHEDULER_Handle *sh);


/**
 * API an external event loop has to implement for
 * #GNUNET_SCHEDULER_driver_init.
 */
struct GNUNET_SCHEDULER_Driver
{

  /**
   * Closure to pass to the functions in this struct.
   */
  void *cls;

  /**
   * Add a @a task to be run if the conditions specified in the 
   * et field of the given @a fdi are satisfied. The et field will
   * be cleared after this call and the driver is expected to set
   * the type of the actual event before passing @a fdi to
   * #GNUNET_SCHEDULER_task_ready.
   *
   * @param cls closure
   * @param task task to add
   * @param fdi conditions to watch for
   * @return #GNUNET_OK on success, #GNUNET_SYSERR on failure
   *   (i.e. @a fdi too high or invalid)
   */
  int
  (*add)(void *cls,
	 struct GNUNET_SCHEDULER_Task *task,
         struct GNUNET_SCHEDULER_FdInfo *fdi);

  /**
   * Delete a @a task from the set of tasks to be run. A task may
   * comprise multiple FdInfo entries previously added with the add
   * function. The driver is expected to delete them all.
   *
   * @param cls closure
   * @param task task to delete
   * @return #GNUNET_OK on success, #GNUNET_SYSERR on failure
   *   (i.e. @a task does not match prior @e add call)
   */
  int
  (*del)(void *cls,
	 struct GNUNET_SCHEDULER_Task *task);

  /**
   * Set time at which we definitively want to get a wakeup call.
   *
   * @param cls closure
   * @param dt time when we want to wake up next
   */
  void
  (*set_wakeup)(void *cls,
		struct GNUNET_TIME_Absolute dt);

};


/**
 * Signature of the main function of a task.
 *
 * @param cls closure
 */
typedef void
(*GNUNET_SCHEDULER_TaskCallback) (void *cls);


/**
 * Function called by external event loop implementations to initialize
 * the scheduler. An external implementation has to provide @a driver
 * which contains callbacks for the scheduler (see definition of struct
 * #GNUNET_SCHEDULER_Driver). The callbacks are used to instruct the 
 * external implementation to watch for events. If it detects any of
 * those events it is expected to call #GNUNET_SCHEDULER_do_work to let
 * the scheduler handle it. If an event is related to a specific task
 * (e.g. the scheduler gave instructions to watch a file descriptor),
 * the external implementation is expected to mark that task ready
 * before by calling #GNUNET_SCHEDULER_task_ready.
 *
 * This function has to be called before any tasks are scheduled and
 * before GNUNET_SCHEDULER_do_work is called for the first time. It 
 * allocates resources that have to be freed again by calling
 * #GNUNET_SCHEDULER_driver_done.
 *
 * This function installs the same signal handlers as 
 * #GNUNET_SCHEDULER_run. This means SIGTERM (and other similar signals)
 * will induce a call to #GNUNET_SCHEDULER_shutdown during the next
 * call to #GNUNET_SCHEDULER_do_work. As a result, SIGTERM causes all
 * active tasks to be scheduled with reason
 * #GNUNET_SCHEDULER_REASON_SHUTDOWN. (However, tasks added afterwards
 * will execute normally!). Note that any particular signal will only
 * shut down one scheduler; applications should always only create a
 * single scheduler.
 *
 * @param driver to use for the event loop
 * @return handle to be passed to #GNUNET_SCHEDULER_do_work and
 *         #GNUNET_SCHEDULER_driver_done
 */
struct GNUNET_SCHEDULER_Handle *
GNUNET_SCHEDULER_driver_init (const struct GNUNET_SCHEDULER_Driver *driver);


/**
 * Counter-part of #GNUNET_SCHEDULER_driver_init. Has to be called
 * by external event loop implementations after the scheduler has
 * shut down. This is the case if both of the following conditions
 * are met:
 * 
 * - all tasks the scheduler has added through the driver's add
 *   callback have been removed again through the driver's del
 *   callback
 * - the timeout the scheduler has set through the driver's
 *   add_wakeup callback is FOREVER
 *
 * @param sh the handle returned by #GNUNET_SCHEDULER_driver_init
 */
void
GNUNET_SCHEDULER_driver_done (struct GNUNET_SCHEDULER_Handle *sh);


/**
 * Obtain the driver for using select() as the event loop.
 *
 * @return NULL on error
 */
struct GNUNET_SCHEDULER_Driver *
GNUNET_SCHEDULER_driver_select (void);


/**
 * Signature of the select function used by the scheduler.
 * #GNUNET_NETWORK_socket_select matches it.
 *
 * @param cls closure
 * @param rfds set of sockets to be checked for readability
 * @param wfds set of sockets to be checked for writability
 * @param efds set of sockets to be checked for exceptions
 * @param timeout relative value when to return
 * @return number of selected sockets, #GNUNET_SYSERR on error
 */
typedef int
(*GNUNET_SCHEDULER_select) (void *cls,
                            struct GNUNET_NETWORK_FDSet *rfds,
                            struct GNUNET_NETWORK_FDSet *wfds,
                            struct GNUNET_NETWORK_FDSet *efds,
                            struct GNUNET_TIME_Relative timeout);


/**
 * Initialize and run scheduler.  This function will return when all
 * tasks have completed.  On systems with signals, receiving a SIGTERM
 * (and other similar signals) will cause #GNUNET_SCHEDULER_shutdown
 * to be run after the active task is complete.  As a result, SIGTERM
 * causes all shutdown tasks to be scheduled with reason
 * #GNUNET_SCHEDULER_REASON_SHUTDOWN.  (However, tasks added
 * afterwards will execute normally!).  Note that any particular
 * signal will only shut down one scheduler; applications should
 * always only create a single scheduler.
 *
 * @param task task to run first (and immediately)
 * @param task_cls closure of @a task
 */
void
GNUNET_SCHEDULER_run (GNUNET_SCHEDULER_TaskCallback task,
                      void *task_cls);

/**
 * Initialize and run scheduler.  This function will return when all
 * tasks have completed.  When @ install_signals is GNUNET_YES, then
 * this function behaves in the same was as GNUNET_SCHEDULER_run does.
 * If @ install_signals is GNUNET_NO then no signal handlers are
 * installed.
 *
 * @param install_signals whether to install signals (GNUNET_YES/NO)
 * @param task task to run first (and immediately)
 * @param task_cls closure of @a task
 */
void
GNUNET_SCHEDULER_run_with_optional_signals (int install_signals,
                                            GNUNET_SCHEDULER_TaskCallback task,
                                            void *task_cls);


/**
 * Request the shutdown of a scheduler.  Marks all tasks
 * awaiting shutdown as ready. Note that tasks
 * scheduled with #GNUNET_SCHEDULER_add_shutdown() AFTER this call
 * will be delayed until the next shutdown signal.
 */
void
GNUNET_SCHEDULER_shutdown (void);


/**
 * Get information about the current load of this scheduler.  Use this
 * function to determine if an elective task should be added or simply
 * dropped (if the decision should be made based on the number of
 * tasks ready to run).
 *
 * @param p priority-level to query, use KEEP to query the level
 *          of the current task, use COUNT to get the sum over
 *          all priority levels
 * @return number of tasks pending right now
 */
unsigned int
GNUNET_SCHEDULER_get_load (enum GNUNET_SCHEDULER_Priority p);


/**
 * Obtain the reasoning why the current task was
 * started.
 *
 * @return task context with information why the current task is run
 */
const struct GNUNET_SCHEDULER_TaskContext *
GNUNET_SCHEDULER_get_task_context (void);


/**
 * Cancel the task with the specified identifier.
 * The task must not yet have run. Only allowed to be called as long as the
 * scheduler is running, that is one of the following conditions is met:
 *
 * - #GNUNET_SCHEDULER_run has been called and has not returned yet
 * - #GNUNET_SCHEDULER_driver_init has been run and
 *   #GNUNET_SCHEDULER_driver_done has not been called yet
 *
 * @param task id of the task to cancel
 * @return original closure of the task
 */
void *
GNUNET_SCHEDULER_cancel (struct GNUNET_SCHEDULER_Task *task);


/**
 * Continue the current execution with the given function.  This is
 * similar to the other "add" functions except that there is no delay
 * and the reason code can be specified.
 *
 * @param task main function of the task
 * @param task_cls closure for @a task
 * @param reason reason for task invocation
 * @param priority priority to use for the task
 */
void
GNUNET_SCHEDULER_add_with_reason_and_priority (GNUNET_SCHEDULER_TaskCallback task,
                                               void *task_cls,
                                               enum GNUNET_SCHEDULER_Reason reason,
                                               enum GNUNET_SCHEDULER_Priority priority);


/**
 * Schedule a new task to be run with a specified priority.
 *
 * @param prio how important is the new task?
 * @param task main function of the task
 * @param task_cls closure of @a task
 * @return unique task identifier for the job
 *         only valid until @a task is started!
 */
struct GNUNET_SCHEDULER_Task *
GNUNET_SCHEDULER_add_with_priority (enum GNUNET_SCHEDULER_Priority prio,
                                    GNUNET_SCHEDULER_TaskCallback task,
                                    void *task_cls);


/**
 * Schedule a new task to be run as soon as possible. Note that this
 * does not guarantee that this will be the next task that is being
 * run, as other tasks with higher priority (or that are already ready
 * to run) might get to run first.  Just as with delays, clients must
 * not rely on any particular order of execution between tasks
 * scheduled concurrently.
 *
 * The task will be run with the DEFAULT priority.
 *
 * @param task main function of the task
 * @param task_cls closure of @a task
 * @return unique task identifier for the job
 *         only valid until @a task is started!
 */
struct GNUNET_SCHEDULER_Task *
GNUNET_SCHEDULER_add_now (GNUNET_SCHEDULER_TaskCallback task,
                          void *task_cls);


/**
 * Schedule a new task to be run on shutdown, that is when a CTRL-C
 * signal is received, or when #GNUNET_SCHEDULER_shutdown() is being
 * invoked.
 *
 * @param task main function of the task
 * @param task_cls closure of @a task
 * @return unique task identifier for the job
 *         only valid until @a task is started!
 */
struct GNUNET_SCHEDULER_Task *
GNUNET_SCHEDULER_add_shutdown (GNUNET_SCHEDULER_TaskCallback task,
			       void *task_cls);


/**
 * Schedule a new task to be run as soon as possible with the
 * (transitive) ignore-shutdown flag either explicitly set or
 * explicitly enabled.  This task (and all tasks created from it,
 * other than by another call to this function) will either count or
 * not count for the 'lifeness' of the process.  This API is only
 * useful in a few special cases.
 *
 * @param lifeness #GNUNET_YES if the task counts for lifeness, #GNUNET_NO if not.
 * @param task main function of the task
 * @param task_cls closure of @a task
 * @return unique task identifier for the job
 *         only valid until @a task is started!
 */
struct GNUNET_SCHEDULER_Task *
GNUNET_SCHEDULER_add_now_with_lifeness (int lifeness,
                                        GNUNET_SCHEDULER_TaskCallback task,
                                        void *task_cls);


/**
 * Schedule a new task to be run with a specified delay.  The task
 * will be scheduled for execution once the delay has expired. It
 * will be run with the DEFAULT priority.
 *
 * @param delay with which the operation should be run
 * @param task main function of the task
 * @param task_cls closure of @a task
 * @return unique task identifier for the job
 *         only valid until @a task is started!
 */
struct GNUNET_SCHEDULER_Task *
GNUNET_SCHEDULER_add_delayed (struct GNUNET_TIME_Relative delay,
                              GNUNET_SCHEDULER_TaskCallback task,
                              void *task_cls);


/**
 * Schedule a new task to be run at the specified time.  The task
 * will be scheduled for execution once specified time has been
 * reached. It will be run with the DEFAULT priority.
 *
 * @param at time at which this operation should run
 * @param task main function of the task
 * @param task_cls closure of @a task
 * @return unique task identifier for the job
 *         only valid until @a task is started!
 */
struct GNUNET_SCHEDULER_Task *
GNUNET_SCHEDULER_add_at (struct GNUNET_TIME_Absolute at,
                         GNUNET_SCHEDULER_TaskCallback task,
                         void *task_cls);


/**
 * Schedule a new task to be run with a specified delay.  The task
 * will be scheduled for execution once the delay has expired.
 *
 * @param delay when should this operation time out?
 * @param priority priority to use for the task
 * @param task main function of the task
 * @param task_cls closure of @a task
 * @return unique task identifier for the job
 *         only valid until @a task is started!
 */
struct GNUNET_SCHEDULER_Task *
GNUNET_SCHEDULER_add_delayed_with_priority (struct GNUNET_TIME_Relative delay,
					    enum GNUNET_SCHEDULER_Priority priority,
					    GNUNET_SCHEDULER_TaskCallback task,
                                            void *task_cls);


/**
 * Schedule a new task to be run at the specified time.  The task
 * will be scheduled for execution at time @a at.
 *
 * @param at time when the operation should run
 * @param priority priority to use for the task
 * @param task main function of the task
 * @param task_cls closure of @a task
 * @return unique task identifier for the job
 *         only valid until @a task is started!
 */
struct GNUNET_SCHEDULER_Task *
GNUNET_SCHEDULER_add_at_with_priority (struct GNUNET_TIME_Absolute at,
                                       enum GNUNET_SCHEDULER_Priority priority,
                                       GNUNET_SCHEDULER_TaskCallback task,
                                       void *task_cls);


/**
 * Schedule a new task to be run with a specified delay or when the
 * specified file descriptor is ready for reading.  The delay can be
 * used as a timeout on the socket being ready.  The task will be
 * scheduled for execution once either the delay has expired or the
 * socket operation is ready.  It will be run with the DEFAULT priority.
 * Only allowed to be called as long as the scheduler is running, that
 * is one of the following conditions is met:
 *
 * - #GNUNET_SCHEDULER_run has been called and has not returned yet
 * - #GNUNET_SCHEDULER_driver_init has been run and
 *   #GNUNET_SCHEDULER_driver_done has not been called yet
 *
 * @param delay when should this operation time out?
 * @param rfd read file-descriptor
 * @param task main function of the task
 * @param task_cls closure of @a task
 * @return unique task identifier for the job
 *         only valid until @a task is started!
 */
struct GNUNET_SCHEDULER_Task *
GNUNET_SCHEDULER_add_read_net (struct GNUNET_TIME_Relative delay,
                               struct GNUNET_NETWORK_Handle *rfd,
                               GNUNET_SCHEDULER_TaskCallback task,
                               void *task_cls);


/**
 * Schedule a new task to be run with a specified priority and to be
 * run after the specified delay or when the specified file descriptor
 * is ready for reading.  The delay can be used as a timeout on the
 * socket being ready.  The task will be scheduled for execution once
 * either the delay has expired or the socket operation is ready.  It
 * will be run with the DEFAULT priority.
 * Only allowed to be called as long as the scheduler is running, that
 * is one of the following conditions is met:
 *
 * - #GNUNET_SCHEDULER_run has been called and has not returned yet
 * - #GNUNET_SCHEDULER_driver_init has been run and
 *   #GNUNET_SCHEDULER_driver_done has not been called yet
 *
 * @param delay when should this operation time out?
 * @param priority priority to use for the task
 * @param rfd read file-descriptor
 * @param task main function of the task
 * @param task_cls closure of @a task
 * @return unique task identifier for the job
 *         only valid until @a task is started!
 */
struct GNUNET_SCHEDULER_Task *
GNUNET_SCHEDULER_add_read_net_with_priority (struct GNUNET_TIME_Relative delay,
					     enum GNUNET_SCHEDULER_Priority priority,
					     struct GNUNET_NETWORK_Handle *rfd,
					     GNUNET_SCHEDULER_TaskCallback task,
                                             void *task_cls);


/**
 * Schedule a new task to be run with a specified delay or when the
 * specified file descriptor is ready for writing.  The delay can be
 * used as a timeout on the socket being ready.  The task will be
 * scheduled for execution once either the delay has expired or the
 * socket operation is ready.  It will be run with the priority of
 * the calling task.
 * Only allowed to be called as long as the scheduler is running, that
 * is one of the following conditions is met:
 *
 * - #GNUNET_SCHEDULER_run has been called and has not returned yet
 * - #GNUNET_SCHEDULER_driver_init has been run and
 *   #GNUNET_SCHEDULER_driver_done has not been called yet
 *
 * @param delay when should this operation time out?
 * @param wfd write file-descriptor
 * @param task main function of the task
 * @param task_cls closure of @a task
 * @return unique task identifier for the job
 *         only valid until @a task is started!
 */
struct GNUNET_SCHEDULER_Task *
GNUNET_SCHEDULER_add_write_net (struct GNUNET_TIME_Relative delay,
                                struct GNUNET_NETWORK_Handle *wfd,
                                GNUNET_SCHEDULER_TaskCallback task,
                                void *task_cls);


/**
 * Schedule a new task to be run with a specified delay or when the
 * specified file descriptor is ready.  The delay can be
 * used as a timeout on the socket being ready.  The task will be
 * scheduled for execution once either the delay has expired or the
 * socket operation is ready.
 * Only allowed to be called as long as the scheduler is running, that
 * is one of the following conditions is met:
 *
 * - #GNUNET_SCHEDULER_run has been called and has not returned yet
 * - #GNUNET_SCHEDULER_driver_init has been run and
 *   #GNUNET_SCHEDULER_driver_done has not been called yet
 *
 * @param delay when should this operation time out?
 * @param priority priority of the task
 * @param fd file-descriptor
 * @param on_read whether to poll the file-descriptor for readability
 * @param on_write whether to poll the file-descriptor for writability
 * @param task main function of the task
 * @param task_cls closure of task
 * @return unique task identifier for the job
 *         only valid until "task" is started!
 */
struct GNUNET_SCHEDULER_Task *
GNUNET_SCHEDULER_add_net_with_priority  (struct GNUNET_TIME_Relative delay,
                                         enum GNUNET_SCHEDULER_Priority priority,
                                         struct GNUNET_NETWORK_Handle *fd,
                                         int on_read,
                                         int on_write,
                                         GNUNET_SCHEDULER_TaskCallback task,
                                         void *task_cls);


/**
 * Schedule a new task to be run with a specified delay or when the
 * specified file descriptor is ready for reading.  The delay can be
 * used as a timeout on the socket being ready.  The task will be
 * scheduled for execution once either the delay has expired or the
 * socket operation is ready. It will be run with the DEFAULT priority.
 * Only allowed to be called as long as the scheduler is running, that
 * is one of the following conditions is met:
 *
 * - #GNUNET_SCHEDULER_run has been called and has not returned yet
 * - #GNUNET_SCHEDULER_driver_init has been run and
 *   #GNUNET_SCHEDULER_driver_done has not been called yet
 *
 * @param delay when should this operation time out?
 * @param rfd read file-descriptor
 * @param task main function of the task
 * @param task_cls closure of @a task
 * @return unique task identifier for the job
 *         only valid until @a task is started!
 */
struct GNUNET_SCHEDULER_Task *
GNUNET_SCHEDULER_add_read_file (struct GNUNET_TIME_Relative delay,
                                const struct GNUNET_DISK_FileHandle *rfd,
                                GNUNET_SCHEDULER_TaskCallback task,
                                void *task_cls);


/**
 * Schedule a new task to be run with a specified delay or when the
 * specified file descriptor is ready for writing.  The delay can be
 * used as a timeout on the socket being ready.  The task will be
 * scheduled for execution once either the delay has expired or the
 * socket operation is ready. It will be run with the DEFAULT priority.
 * Only allowed to be called as long as the scheduler is running, that
 * is one of the following conditions is met:
 *
 * - #GNUNET_SCHEDULER_run has been called and has not returned yet
 * - #GNUNET_SCHEDULER_driver_init has been run and
 *   #GNUNET_SCHEDULER_driver_done has not been called yet
 *
 * @param delay when should this operation time out?
 * @param wfd write file-descriptor
 * @param task main function of the task
 * @param task_cls closure of @a task
 * @return unique task identifier for the job
 *         only valid until @a task is started!
 */
struct GNUNET_SCHEDULER_Task *
GNUNET_SCHEDULER_add_write_file (struct GNUNET_TIME_Relative delay,
                                 const struct GNUNET_DISK_FileHandle *wfd,
                                 GNUNET_SCHEDULER_TaskCallback task,
                                 void *task_cls);


/**
 * Schedule a new task to be run with a specified delay or when the
 * specified file descriptor is ready.  The delay can be
 * used as a timeout on the socket being ready.  The task will be
 * scheduled for execution once either the delay has expired or the
 * socket operation is ready.
 * Only allowed to be called as long as the scheduler is running, that
 * is one of the following conditions is met:
 *
 * - #GNUNET_SCHEDULER_run has been called and has not returned yet
 * - #GNUNET_SCHEDULER_driver_init has been run and
 *   #GNUNET_SCHEDULER_driver_done has not been called yet
 *
 * @param delay when should this operation time out?
 * @param priority priority of the task
 * @param fd file-descriptor
 * @param on_read whether to poll the file-descriptor for readability
 * @param on_write whether to poll the file-descriptor for writability
 * @param task main function of the task
 * @param task_cls closure of @a task
 * @return unique task identifier for the job
 *         only valid until @a task is started!
 */
struct GNUNET_SCHEDULER_Task *
GNUNET_SCHEDULER_add_file_with_priority (struct GNUNET_TIME_Relative delay,
                                         enum GNUNET_SCHEDULER_Priority priority,
                                         const struct GNUNET_DISK_FileHandle *fd,
                                         int on_read, int on_write,
                                         GNUNET_SCHEDULER_TaskCallback task,
                                         void *task_cls);


/**
 * Schedule a new task to be run with a specified delay or when any of
 * the specified file descriptor sets is ready.  The delay can be used
 * as a timeout on the socket(s) being ready.  The task will be
 * scheduled for execution once either the delay has expired or any of
 * the socket operations is ready.  This is the most general
 * function of the "add" family.  Note that the "prerequisite_task"
 * must be satisfied in addition to any of the other conditions.  In
 * other words, the task will be started when
 * <code>
 * (prerequisite-run)
 * && (delay-ready
 *     || any-rs-ready
 *     || any-ws-ready) )
 * </code>
 * Only allowed to be called as long as the scheduler is running, that
 * is one of the following conditions is met:
 *
 * - #GNUNET_SCHEDULER_run has been called and has not returned yet
 * - #GNUNET_SCHEDULER_driver_init has been run and
 *   #GNUNET_SCHEDULER_driver_done has not been called yet
 *
 * @param prio how important is this task?
 * @param delay how long should we wait?
 * @param rs set of file descriptors we want to read (can be NULL)
 * @param ws set of file descriptors we want to write (can be NULL)
 * @param task main function of the task
 * @param task_cls closure of @a task
 * @return unique task identifier for the job
 *         only valid until @a task is started!
 */
struct GNUNET_SCHEDULER_Task *
GNUNET_SCHEDULER_add_select (enum GNUNET_SCHEDULER_Priority prio,
                             struct GNUNET_TIME_Relative delay,
                             const struct GNUNET_NETWORK_FDSet *rs,
                             const struct GNUNET_NETWORK_FDSet *ws,
                             GNUNET_SCHEDULER_TaskCallback task,
                             void *task_cls);

/**
 * Sets the select function to use in the scheduler (scheduler_select).
 *
 * @param new_select new select function to use (NULL to reset to default)
 * @param new_select_cls closure for @a new_select
 */
void
GNUNET_SCHEDULER_set_select (GNUNET_SCHEDULER_select new_select,
                             void *new_select_cls);


#if 0                           /* keep Emacsens' auto-indent happy */
{
#endif
#ifdef __cplusplus
}
#endif

#endif

/** @} */ /* end of group scheduler */