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3 Copyright (C) 2001-2013 GNUnet e.V.
5 GNUnet is free software: you can redistribute it and/or modify it
6 under the terms of the GNU Affero General Public License as published
7 by the Free Software Foundation, either version 3 of the License,
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11 WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Affero General Public License for more details.
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16 along with this program. If not, see <http://www.gnu.org/licenses/>.
18 SPDX-License-Identifier: AGPL3.0-or-later
22 * @author Christian Grothoff
25 * Functions related to time
27 * @defgroup time Time library
28 * Time and time calculations.
32 #ifndef GNUNET_TIME_LIB_H
33 #define GNUNET_TIME_LIB_H
38 #if 0 /* keep Emacsens' auto-indent happy */
43 #include "gnunet_common.h"
46 * Time for absolute times used by GNUnet, in microseconds.
48 struct GNUNET_TIME_Absolute
53 uint64_t abs_value_us;
57 * Time for relative time used by GNUnet, in microseconds.
58 * Always positive, so we can only refer to future time.
60 struct GNUNET_TIME_Relative
65 uint64_t rel_value_us;
68 GNUNET_NETWORK_STRUCT_BEGIN
71 * Time for relative time used by GNUnet, in microseconds and in network byte order.
73 struct GNUNET_TIME_RelativeNBO
76 * The actual value (in network byte order).
78 uint64_t rel_value_us__ GNUNET_PACKED;
83 * Time for absolute time used by GNUnet, in microseconds and in network byte order.
85 struct GNUNET_TIME_AbsoluteNBO
88 * The actual value (in network byte order).
90 uint64_t abs_value_us__ GNUNET_PACKED;
92 GNUNET_NETWORK_STRUCT_END
97 #define GNUNET_TIME_UNIT_ZERO GNUNET_TIME_relative_get_zero_ ()
100 * Absolute time zero.
102 #define GNUNET_TIME_UNIT_ZERO_ABS GNUNET_TIME_absolute_get_zero_ ()
105 * One microsecond, our basic time unit.
107 #define GNUNET_TIME_UNIT_MICROSECONDS GNUNET_TIME_relative_get_unit_ ()
112 #define GNUNET_TIME_UNIT_MILLISECONDS GNUNET_TIME_relative_get_millisecond_ ()
117 #define GNUNET_TIME_UNIT_SECONDS GNUNET_TIME_relative_get_second_ ()
122 #define GNUNET_TIME_UNIT_MINUTES GNUNET_TIME_relative_get_minute_ ()
127 #define GNUNET_TIME_UNIT_HOURS GNUNET_TIME_relative_get_hour_ ()
132 #define GNUNET_TIME_UNIT_DAYS GNUNET_TIME_relative_multiply ( \
133 GNUNET_TIME_UNIT_HOURS, 24)
138 #define GNUNET_TIME_UNIT_WEEKS GNUNET_TIME_relative_multiply ( \
139 GNUNET_TIME_UNIT_DAYS, 7)
142 * One month (30 days).
144 #define GNUNET_TIME_UNIT_MONTHS GNUNET_TIME_relative_multiply ( \
145 GNUNET_TIME_UNIT_DAYS, 30)
148 * One year (365 days).
150 #define GNUNET_TIME_UNIT_YEARS GNUNET_TIME_relative_multiply ( \
151 GNUNET_TIME_UNIT_DAYS, 365)
154 * Constant used to specify "forever". This constant
155 * will be treated specially in all time operations.
157 #define GNUNET_TIME_UNIT_FOREVER_REL GNUNET_TIME_relative_get_forever_ ()
160 * Constant used to specify "forever". This constant
161 * will be treated specially in all time operations.
163 #define GNUNET_TIME_UNIT_FOREVER_ABS GNUNET_TIME_absolute_get_forever_ ()
168 * Threshold after which exponential backoff should not increase (15 m).
170 #define GNUNET_TIME_STD_EXPONENTIAL_BACKOFF_THRESHOLD \
171 GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MINUTES, 15)
175 * Perform our standard exponential back-off calculation, starting at 1 ms
176 * and then going by a factor of 2 up unto a maximum of 15 m.
178 * @param r current backoff time, initially zero
180 #define GNUNET_TIME_STD_BACKOFF(r) GNUNET_TIME_relative_min ( \
181 GNUNET_TIME_STD_EXPONENTIAL_BACKOFF_THRESHOLD, \
182 GNUNET_TIME_relative_multiply ( \
183 GNUNET_TIME_relative_max (GNUNET_TIME_UNIT_MILLISECONDS, (r)), 2));
187 * Randomized exponential back-off, starting at 1 ms
188 * and going up by a factor of 2+r, where 0 <= r <= 0.5, up
189 * to a maximum of the given threshold.
191 * @param rt current backoff time, initially zero
192 * @param threshold maximum value for backoff
193 * @return the next backoff time
195 struct GNUNET_TIME_Relative
196 GNUNET_TIME_randomized_backoff (struct GNUNET_TIME_Relative rt, struct
197 GNUNET_TIME_Relative threshold);
201 * Return a random time value between 0.5*r and 1.5*r.
203 * @param r input time for scaling
204 * @return randomized time
206 struct GNUNET_TIME_Relative
207 GNUNET_TIME_randomize (struct GNUNET_TIME_Relative r);
211 * Return relative time of 0ms.
213 struct GNUNET_TIME_Relative
214 GNUNET_TIME_relative_get_zero_ (void);
218 * Return absolute time of 0ms.
220 struct GNUNET_TIME_Absolute
221 GNUNET_TIME_absolute_get_zero_ (void);
225 * Return relative time of 1 microsecond.
227 struct GNUNET_TIME_Relative
228 GNUNET_TIME_relative_get_unit_ (void);
232 * Return relative time of 1ms.
234 struct GNUNET_TIME_Relative
235 GNUNET_TIME_relative_get_millisecond_ (void);
239 * Return relative time of 1s.
241 struct GNUNET_TIME_Relative
242 GNUNET_TIME_relative_get_second_ (void);
246 * Return relative time of 1 minute.
248 struct GNUNET_TIME_Relative
249 GNUNET_TIME_relative_get_minute_ (void);
253 * Return relative time of 1 hour.
255 struct GNUNET_TIME_Relative
256 GNUNET_TIME_relative_get_hour_ (void);
262 struct GNUNET_TIME_Relative
263 GNUNET_TIME_relative_get_forever_ (void);
269 struct GNUNET_TIME_Absolute
270 GNUNET_TIME_absolute_get_forever_ (void);
274 * Get the current time.
276 * @return the current time
278 struct GNUNET_TIME_Absolute
279 GNUNET_TIME_absolute_get (void);
283 * Convert relative time to an absolute time in the
286 * @param rel relative time to convert
287 * @return timestamp that is "rel" in the future, or FOREVER if rel==FOREVER (or if we would overflow)
289 struct GNUNET_TIME_Absolute
290 GNUNET_TIME_relative_to_absolute (struct GNUNET_TIME_Relative rel);
294 * Round a time value so that it is suitable for transmission
295 * via JSON encodings.
297 * @param at time to round
298 * @return #GNUNET_OK if time was already rounded, #GNUNET_NO if
299 * it was just now rounded
302 GNUNET_TIME_round_abs (struct GNUNET_TIME_Absolute *at);
306 * Round a time value so that it is suitable for transmission
307 * via JSON encodings.
309 * @param rt time to round
310 * @return #GNUNET_OK if time was already rounded, #GNUNET_NO if
311 * it was just now rounded
314 GNUNET_TIME_round_rel (struct GNUNET_TIME_Relative *rt);
318 * Return the minimum of two relative time values.
320 * @param t1 first timestamp
321 * @param t2 other timestamp
322 * @return timestamp that is smaller
324 struct GNUNET_TIME_Relative
325 GNUNET_TIME_relative_min (struct GNUNET_TIME_Relative t1,
326 struct GNUNET_TIME_Relative t2);
331 * Return the maximum of two relative time values.
333 * @param t1 first timestamp
334 * @param t2 other timestamp
335 * @return timestamp that is larger
337 struct GNUNET_TIME_Relative
338 GNUNET_TIME_relative_max (struct GNUNET_TIME_Relative t1,
339 struct GNUNET_TIME_Relative t2);
343 * Return the minimum of two absolute time values.
345 * @param t1 first timestamp
346 * @param t2 other timestamp
347 * @return timestamp that is smaller
349 struct GNUNET_TIME_Absolute
350 GNUNET_TIME_absolute_min (struct GNUNET_TIME_Absolute t1,
351 struct GNUNET_TIME_Absolute t2);
355 * Return the maximum of two absolute time values.
357 * @param t1 first timestamp
358 * @param t2 other timestamp
359 * @return timestamp that is smaller
361 struct GNUNET_TIME_Absolute
362 GNUNET_TIME_absolute_max (struct GNUNET_TIME_Absolute t1,
363 struct GNUNET_TIME_Absolute t2);
367 * Given a timestamp in the future, how much time
368 * remains until then?
370 * @param future some absolute time, typically in the future
371 * @return future - now, or 0 if now >= future, or FOREVER if future==FOREVER.
373 struct GNUNET_TIME_Relative
374 GNUNET_TIME_absolute_get_remaining (struct GNUNET_TIME_Absolute future);
378 * Calculate the estimate time of arrival/completion
381 * @param start when did the operation start?
382 * @param finished how much has been done?
383 * @param total how much must be done overall (same unit as for "finished")
384 * @return remaining duration for the operation,
385 * assuming it continues at the same speed
387 struct GNUNET_TIME_Relative
388 GNUNET_TIME_calculate_eta (struct GNUNET_TIME_Absolute start,
394 * Compute the time difference between the given start and end times.
395 * Use this function instead of actual subtraction to ensure that
396 * "FOREVER" and overflows are handeled correctly.
398 * @param start some absolute time
399 * @param end some absolute time (typically larger or equal to start)
400 * @return 0 if start >= end; FOREVER if end==FOREVER; otherwise end - start
402 struct GNUNET_TIME_Relative
403 GNUNET_TIME_absolute_get_difference (struct GNUNET_TIME_Absolute start,
404 struct GNUNET_TIME_Absolute end);
408 * Get the duration of an operation as the
409 * difference of the current time and the given start time "hence".
411 * @param whence some absolute time, typically in the past
412 * @return 0 if hence > now, otherwise now-hence.
414 struct GNUNET_TIME_Relative
415 GNUNET_TIME_absolute_get_duration (struct GNUNET_TIME_Absolute whence);
419 * Add a given relative duration to the
422 * @param start some absolute time
423 * @param duration some relative time to add
424 * @return FOREVER if either argument is FOREVER or on overflow; start+duration otherwise
426 struct GNUNET_TIME_Absolute
427 GNUNET_TIME_absolute_add (struct GNUNET_TIME_Absolute start,
428 struct GNUNET_TIME_Relative duration);
432 * Subtract a given relative duration from the
435 * @param start some absolute time
436 * @param duration some relative time to subtract
437 * @return ZERO if start <= duration, or FOREVER if start time is FOREVER; start-duration otherwise
439 struct GNUNET_TIME_Absolute
440 GNUNET_TIME_absolute_subtract (struct GNUNET_TIME_Absolute start,
441 struct GNUNET_TIME_Relative duration);
445 * Multiply relative time by a given factor.
447 * @param rel some duration
448 * @param factor integer to multiply with
449 * @return FOREVER if rel=FOREVER or on overflow; otherwise rel*factor
451 struct GNUNET_TIME_Relative
452 GNUNET_TIME_relative_multiply (struct GNUNET_TIME_Relative rel,
453 unsigned long long factor);
457 * Saturating multiply relative time by a given factor.
459 * @param rel some duration
460 * @param factor integer to multiply with
461 * @return FOREVER if rel=FOREVER or on overflow; otherwise rel*factor
463 struct GNUNET_TIME_Relative
464 GNUNET_TIME_relative_saturating_multiply (struct GNUNET_TIME_Relative rel,
465 unsigned long long factor);
469 * Divide relative time by a given factor.
471 * @param rel some duration
472 * @param factor integer to divide by
473 * @return FOREVER if rel=FOREVER or factor==0; otherwise rel/factor
475 struct GNUNET_TIME_Relative
476 GNUNET_TIME_relative_divide (struct GNUNET_TIME_Relative rel,
477 unsigned long long factor);
481 * Add relative times together.
483 * @param a1 some relative time
484 * @param a2 some other relative time
485 * @return FOREVER if either argument is FOREVER or on overflow; a1+a2 otherwise
487 struct GNUNET_TIME_Relative
488 GNUNET_TIME_relative_add (struct GNUNET_TIME_Relative a1,
489 struct GNUNET_TIME_Relative a2);
493 * Subtract relative timestamp from the other.
495 * @param a1 first timestamp
496 * @param a2 second timestamp
497 * @return ZERO if a2>=a1 (including both FOREVER), FOREVER if a1 is FOREVER, a1-a2 otherwise
499 struct GNUNET_TIME_Relative
500 GNUNET_TIME_relative_subtract (struct GNUNET_TIME_Relative a1,
501 struct GNUNET_TIME_Relative a2);
505 * Convert relative time to network byte order.
507 * @param a time to convert
508 * @return converted time value
510 struct GNUNET_TIME_RelativeNBO
511 GNUNET_TIME_relative_hton (struct GNUNET_TIME_Relative a);
515 * Convert relative time from network byte order.
517 * @param a time to convert
518 * @return converted time value
520 struct GNUNET_TIME_Relative
521 GNUNET_TIME_relative_ntoh (struct GNUNET_TIME_RelativeNBO a);
525 * Convert absolute time to network byte order.
527 * @param a time to convert
528 * @return converted time value
530 struct GNUNET_TIME_AbsoluteNBO
531 GNUNET_TIME_absolute_hton (struct GNUNET_TIME_Absolute a);
535 * Convert absolute time from network byte order.
537 * @param a time to convert
538 * @return converted time value
540 struct GNUNET_TIME_Absolute
541 GNUNET_TIME_absolute_ntoh (struct GNUNET_TIME_AbsoluteNBO a);
545 * Set the timestamp offset for this instance.
547 * @param offset the offset to skew the locale time by
550 GNUNET_TIME_set_offset (long long offset);
554 * Get the timestamp offset for this instance.
556 * @return the offset we currently skew the locale time by
559 GNUNET_TIME_get_offset (void);
563 * Return the current year (i.e. '2011').
566 GNUNET_TIME_get_current_year (void);
570 * Convert a year to an expiration time of January 1st of that year.
572 * @param year a year (after 1970, please ;-)).
573 * @return absolute time for January 1st of that year.
575 struct GNUNET_TIME_Absolute
576 GNUNET_TIME_year_to_time (unsigned int year);
580 * Convert an expiration time to the respective year (rounds)
582 * @param at absolute time
583 * @return year a year (after 1970), 0 on error
586 GNUNET_TIME_time_to_year (struct GNUNET_TIME_Absolute at);
590 * A configuration object.
592 struct GNUNET_CONFIGURATION_Handle;
596 * Obtain the current time and make sure it is monotonically
597 * increasing. Guards against systems without an RTC or
598 * clocks running backwards and other nasty surprises. Does
599 * not guarantee that the returned time is near the current
600 * time returned by #GNUNET_TIME_absolute_get(). Two
601 * subsequent calls (within a short time period) may return the
602 * same value. Persists the last returned time on disk to
603 * ensure that time never goes backwards. As a result, the
604 * resulting value can be used to check if a message is the
605 * "most recent" value and replays of older messages (from
606 * the same origin) would be discarded.
608 * @param cfg configuration, used to determine where to
609 * store the time; user can also insist RTC is working
610 * nicely and disable the feature
611 * @return monotonically increasing time
613 struct GNUNET_TIME_Absolute
614 GNUNET_TIME_absolute_get_monotonic (const struct
615 GNUNET_CONFIGURATION_Handle *cfg);
618 #if 0 /* keep Emacsens' auto-indent happy */
625 /* ifndef GNUNET_TIME_LIB_H */
628 /** @} */ /* end of group time */
630 /* end of gnunet_time_lib.h */