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3 (C) 2009, 2011 Christian Grothoff (and other contributing authors)
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22 * @file include/gnunet_scheduler_lib.h
23 * @brief API to schedule computations using continuation passing style
24 * @author Christian Grothoff
27 #ifndef GNUNET_SCHEDULER_LIB_H
28 #define GNUNET_SCHEDULER_LIB_H
33 #if 0 /* keep Emacsens' auto-indent happy */
39 * Opaque reference to a task.
41 typedef unsigned long long GNUNET_SCHEDULER_TaskIdentifier;
45 * Constant used to indicate that the scheduled
46 * task has no others as prerequisites.
48 #define GNUNET_SCHEDULER_NO_TASK ((GNUNET_SCHEDULER_TaskIdentifier) 0)
51 * Reasons why the schedule may have triggered
54 enum GNUNET_SCHEDULER_Reason
57 * This is the very first task run during startup.
59 GNUNET_SCHEDULER_REASON_STARTUP = 0,
62 * We are shutting down and are running all shutdown-related tasks
63 * (regardless of timeout, etc.).
65 GNUNET_SCHEDULER_REASON_SHUTDOWN = 1,
68 * The specified timeout has expired.
69 * (also set if the delay given was 0).
71 GNUNET_SCHEDULER_REASON_TIMEOUT = 2,
74 * The reading socket is ready.
76 GNUNET_SCHEDULER_REASON_READ_READY = 4,
79 * The writing socket is ready.
81 GNUNET_SCHEDULER_REASON_WRITE_READY = 8,
84 * The prerequisite task is done.
86 GNUNET_SCHEDULER_REASON_PREREQ_DONE = 16
91 * Valid task priorities. Use these, do not
92 * pass random integers!
94 enum GNUNET_SCHEDULER_Priority
97 * Run with the same priority as the current job.
99 GNUNET_SCHEDULER_PRIORITY_KEEP = 0,
102 * Run when otherwise idle.
104 GNUNET_SCHEDULER_PRIORITY_IDLE = 1,
107 * Run as background job (higher than idle,
108 * lower than default).
110 GNUNET_SCHEDULER_PRIORITY_BACKGROUND = 2,
113 * Run with the default priority (normal
114 * P2P operations). Higher than BACKGROUND.
116 GNUNET_SCHEDULER_PRIORITY_DEFAULT = 3,
119 * Run with high priority (important requests).
120 * Higher than DEFAULT.
122 GNUNET_SCHEDULER_PRIORITY_HIGH = 4,
125 * Run with priority for interactive tasks.
126 * Higher than "HIGH".
128 GNUNET_SCHEDULER_PRIORITY_UI = 5,
131 * Run with priority for urgent tasks. Use
132 * for things like aborts and shutdowns that
133 * need to preempt "UI"-level tasks.
136 GNUNET_SCHEDULER_PRIORITY_URGENT = 6,
139 * This is an internal priority level that is only used for tasks
140 * that are being triggered due to shutdown (they have automatically
141 * highest priority). User code must not use this priority level
142 * directly. Tasks run with this priority level that internally
143 * schedule other tasks will see their original priority level
144 * be inherited (unless otherwise specified).
146 GNUNET_SCHEDULER_PRIORITY_SHUTDOWN = 7,
149 * Number of priorities (must be the last priority).
150 * This priority must not be used by clients.
152 GNUNET_SCHEDULER_PRIORITY_COUNT = 8
155 #include "gnunet_time_lib.h"
156 #include "gnunet_network_lib.h"
160 * Context information passed to each scheduler task.
162 struct GNUNET_SCHEDULER_TaskContext
165 * Reason why the task is run now
167 enum GNUNET_SCHEDULER_Reason reason;
170 * Set of file descriptors ready for reading;
171 * note that additional bits may be set
172 * that were not in the original request
174 const struct GNUNET_NETWORK_FDSet *read_ready;
177 * Set of file descriptors ready for writing;
178 * note that additional bits may be set
179 * that were not in the original request.
181 const struct GNUNET_NETWORK_FDSet *write_ready;
187 * Signature of the main function of a task.
190 * @param tc context information (why was this task triggered now)
192 typedef void (*GNUNET_SCHEDULER_Task) (void *cls,
193 const struct GNUNET_SCHEDULER_TaskContext
198 * Signature of the select function used by the scheduler.
199 * GNUNET_NETWORK_socket_select matches it.
202 * @param rfds set of sockets to be checked for readability
203 * @param wfds set of sockets to be checked for writability
204 * @param efds set of sockets to be checked for exceptions
205 * @param timeout relative value when to return
206 * @return number of selected sockets, GNUNET_SYSERR on error
208 typedef int (*GNUNET_SCHEDULER_select) (void *cls,
209 struct GNUNET_NETWORK_FDSet * rfds,
210 struct GNUNET_NETWORK_FDSet * wfds,
211 struct GNUNET_NETWORK_FDSet * efds,
212 struct GNUNET_TIME_Relative timeout);
214 * Initialize and run scheduler. This function will return when all
215 * tasks have completed. On systems with signals, receiving a SIGTERM
216 * (and other similar signals) will cause "GNUNET_SCHEDULER_shutdown"
217 * to be run after the active task is complete. As a result, SIGTERM
218 * causes all active tasks to be scheduled with reason
219 * "GNUNET_SCHEDULER_REASON_SHUTDOWN". (However, tasks added
220 * afterwards will execute normally!). Note that any particular
221 * signal will only shut down one scheduler; applications should
222 * always only create a single scheduler.
224 * @param task task to run first (and immediately)
225 * @param task_cls closure of task
227 void GNUNET_SCHEDULER_run (GNUNET_SCHEDULER_Task task, void *task_cls);
231 * Request the shutdown of a scheduler. Marks all currently
232 * pending tasks as ready because of shutdown. This will
233 * cause all tasks to run (as soon as possible, respecting
234 * priorities and prerequisite tasks). Note that tasks
235 * scheduled AFTER this call may still be delayed arbitrarily.
237 void GNUNET_SCHEDULER_shutdown ();
241 * Get information about the current load of this scheduler. Use this
242 * function to determine if an elective task should be added or simply
243 * dropped (if the decision should be made based on the number of
244 * tasks ready to run).
246 * * @param p priority-level to query, use KEEP to query the level
247 * of the current task, use COUNT to get the sum over
248 * all priority levels
249 * @return number of tasks pending right now
251 unsigned int GNUNET_SCHEDULER_get_load (enum GNUNET_SCHEDULER_Priority p);
255 * Obtain the reason code for why the current task was
256 * started. Will return the same value as
257 * the GNUNET_SCHEDULER_TaskContext's reason field.
259 * * @return reason(s) why the current task is run
261 enum GNUNET_SCHEDULER_Reason GNUNET_SCHEDULER_get_reason ();
265 * Cancel the task with the specified identifier.
266 * The task must not yet have run.
268 * * @param task id of the task to cancel
269 * @return the closure of the callback of the cancelled task
271 void *GNUNET_SCHEDULER_cancel (GNUNET_SCHEDULER_TaskIdentifier task);
275 * Continue the current execution with the given function. This is
276 * similar to the other "add" functions except that there is no delay
277 * and the reason code can be specified.
279 * * @param task main function of the task
280 * @param task_cls closure of task
281 * @param reason reason for task invocation
283 void GNUNET_SCHEDULER_add_continuation (GNUNET_SCHEDULER_Task task,
285 enum GNUNET_SCHEDULER_Reason reason);
289 * Schedule a new task to be run after the specified prerequisite task
290 * has completed. It will be run with the priority of the calling
293 * * @param prerequisite_task run this task after the task with the given
294 * task identifier completes (and any of our other
295 * conditions, such as delay, read or write-readiness
296 * are satisfied). Use GNUNET_SCHEDULER_NO_TASK to not have any dependency
297 * on completion of other tasks (this will cause the task to run as
299 * @param task main function of the task
300 * @param task_cls closure of task
301 * @return unique task identifier for the job
302 * only valid until "task" is started!
304 GNUNET_SCHEDULER_TaskIdentifier
305 GNUNET_SCHEDULER_add_after (GNUNET_SCHEDULER_TaskIdentifier prerequisite_task,
306 GNUNET_SCHEDULER_Task task, void *task_cls);
310 * Schedule a new task to be run with a specified priority.
312 * * @param prio how important is the new task?
313 * @param task main function of the task
314 * @param task_cls closure of task
315 * @return unique task identifier for the job
316 * only valid until "task" is started!
318 GNUNET_SCHEDULER_TaskIdentifier GNUNET_SCHEDULER_add_with_priority (enum
319 GNUNET_SCHEDULER_Priority
321 GNUNET_SCHEDULER_Task
328 * Schedule a new task to be run as soon as possible. The task
329 * will be run with the priority of the calling task.
331 * * @param task main function of the task
332 * @param task_cls closure of task
333 * @return unique task identifier for the job
334 * only valid until "task" is started!
336 GNUNET_SCHEDULER_TaskIdentifier GNUNET_SCHEDULER_add_now (GNUNET_SCHEDULER_Task
337 task, void *task_cls);
341 * Schedule a new task to be run as soon as possible with the
342 * (transitive) ignore-shutdown flag either explicitly set or
343 * explicitly enabled. This task (and all tasks created from it,
344 * other than by another call to this function) will either count or
345 * not count for the 'lifeness' of the process. This API is only
346 * useful in a few special cases.
348 * @param lifeness GNUNET_YES if the task counts for lifeness, GNUNET_NO if not.
349 * @param task main function of the task
350 * @param task_cls closure of task
351 * @return unique task identifier for the job
352 * only valid until "task" is started!
354 GNUNET_SCHEDULER_TaskIdentifier GNUNET_SCHEDULER_add_now_with_lifeness (int
356 GNUNET_SCHEDULER_Task
363 * Schedule a new task to be run with a specified delay. The task
364 * will be scheduled for execution once the delay has expired. It
365 * will be run with the priority of the calling task.
367 * * @param delay when should this operation time out? Use
368 * GNUNET_TIME_UNIT_FOREVER_REL for "on shutdown"
369 * @param task main function of the task
370 * @param task_cls closure of task
371 * @return unique task identifier for the job
372 * only valid until "task" is started!
374 GNUNET_SCHEDULER_TaskIdentifier GNUNET_SCHEDULER_add_delayed (struct
377 GNUNET_SCHEDULER_Task
383 * Schedule a new task to be run with a specified delay or when the
384 * specified file descriptor is ready for reading. The delay can be
385 * used as a timeout on the socket being ready. The task will be
386 * scheduled for execution once either the delay has expired or the
387 * socket operation is ready. It will be run with the priority of
390 * * @param delay when should this operation time out? Use
391 * GNUNET_TIME_UNIT_FOREVER_REL for "on shutdown"
392 * @param rfd read file-descriptor
393 * @param task main function of the task
394 * @param task_cls closure of task
395 * @return unique task identifier for the job
396 * only valid until "task" is started!
398 GNUNET_SCHEDULER_TaskIdentifier GNUNET_SCHEDULER_add_read_net (struct
402 GNUNET_NETWORK_Handle
404 GNUNET_SCHEDULER_Task
410 * Schedule a new task to be run with a specified delay or when the
411 * specified file descriptor is ready for writing. The delay can be
412 * used as a timeout on the socket being ready. The task will be
413 * scheduled for execution once either the delay has expired or the
414 * socket operation is ready. It will be run with the priority of
417 * * @param delay when should this operation time out? Use
418 * GNUNET_TIME_UNIT_FOREVER_REL for "on shutdown"
419 * @param wfd write file-descriptor
420 * @param task main function of the task
421 * @param task_cls closure of task
422 * @return unique task identifier for the job
423 * only valid until "task" is started!
425 GNUNET_SCHEDULER_TaskIdentifier GNUNET_SCHEDULER_add_write_net (struct
429 GNUNET_NETWORK_Handle
431 GNUNET_SCHEDULER_Task
437 * Schedule a new task to be run with a specified delay or when the
438 * specified file descriptor is ready for reading. The delay can be
439 * used as a timeout on the socket being ready. The task will be
440 * scheduled for execution once either the delay has expired or the
441 * socket operation is ready. It will be run with the priority of
444 * * @param delay when should this operation time out? Use
445 * GNUNET_TIME_UNIT_FOREVER_REL for "on shutdown"
446 * @param rfd read file-descriptor
447 * @param task main function of the task
448 * @param task_cls closure of task
449 * @return unique task identifier for the job
450 * only valid until "task" is started!
452 GNUNET_SCHEDULER_TaskIdentifier GNUNET_SCHEDULER_add_read_file (struct
456 GNUNET_DISK_FileHandle
458 GNUNET_SCHEDULER_Task
464 * Schedule a new task to be run with a specified delay or when the
465 * specified file descriptor is ready for writing. The delay can be
466 * used as a timeout on the socket being ready. The task will be
467 * scheduled for execution once either the delay has expired or the
468 * socket operation is ready. It will be run with the priority of
471 * * @param delay when should this operation time out? Use
472 * GNUNET_TIME_UNIT_FOREVER_REL for "on shutdown"
473 * @param wfd write file-descriptor
474 * @param task main function of the task
475 * @param task_cls closure of task
476 * @return unique task identifier for the job
477 * only valid until "task" is started!
479 GNUNET_SCHEDULER_TaskIdentifier GNUNET_SCHEDULER_add_write_file (struct
483 GNUNET_DISK_FileHandle
485 GNUNET_SCHEDULER_Task
492 * Schedule a new task to be run with a specified delay or when any of
493 * the specified file descriptor sets is ready. The delay can be used
494 * as a timeout on the socket(s) being ready. The task will be
495 * scheduled for execution once either the delay has expired or any of
496 * the socket operations is ready. This is the most general
497 * function of the "add" family. Note that the "prerequisite_task"
498 * must be satisfied in addition to any of the other conditions. In
499 * other words, the task will be started when
505 * || shutdown-active)
508 * * @param prio how important is this task?
509 * @param prerequisite_task run this task after the task with the given
510 * task identifier completes (and any of our other
511 * conditions, such as delay, read or write-readiness
512 * are satisfied). Use GNUNET_SCHEDULER_NO_TASK to not have any dependency
513 * on completion of other tasks.
514 * @param delay how long should we wait? Use GNUNET_TIME_UNIT_FOREVER_REL for "forever",
515 * which means that the task will only be run after we receive SIGTERM
516 * @param rs set of file descriptors we want to read (can be NULL)
517 * @param ws set of file descriptors we want to write (can be NULL)
518 * @param task main function of the task
519 * @param task_cls closure of task
520 * @return unique task identifier for the job
521 * only valid until "task" is started!
523 GNUNET_SCHEDULER_TaskIdentifier GNUNET_SCHEDULER_add_select (enum
524 GNUNET_SCHEDULER_Priority
526 GNUNET_SCHEDULER_TaskIdentifier
537 GNUNET_SCHEDULER_Task
542 * Sets the select function to use in the scheduler (scheduler_select).
544 * @param new_select new select function to use (NULL to reset to default)
545 * @param new_select_cls closure for 'new_select'
547 void GNUNET_SCHEDULER_set_select (GNUNET_SCHEDULER_select new_select,
548 void *new_select_cls);
551 #if 0 /* keep Emacsens' auto-indent happy */