gnunet-android

gnunet_time_lib.h (22867B)

---

 /*
      This file is part of GNUnet.
      Copyright (C) 2001-2022 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.
 
      You should have received a copy of the GNU Affero General Public License
      along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
      SPDX-License-Identifier: AGPL3.0-or-later
  */
 
 /**
  * @addtogroup libgnunetutil
  * Multi-function utilities library for GNUnet programs
  * @{
  *
  * @author Christian Grothoff
  *
  * @file
  * Functions related to time
  *
  * @defgroup time  Time library
  * Time and time calculations.
  * @{
  */
 
 #ifndef GNUNET_TIME_LIB_H
 #define GNUNET_TIME_LIB_H
 
 #ifdef __cplusplus
 extern "C"
 {
 #if 0                           /* keep Emacsens' auto-indent happy */
 }
 #endif
 #endif
 
 
 #include "gnunet_common.h"
 
 /**
  * Time for absolute times used by GNUnet, in microseconds.
  */
 struct GNUNET_TIME_Absolute
 {
   /**
    * The actual value.
    * UINT64_MAX to represents "never".
    */
   uint64_t abs_value_us;
 };
 
 /**
  * Time for timestamps used by GNUnet, in microseconds rounded to seconds.
  */
 struct GNUNET_TIME_Timestamp
 {
   /**
    * The actual value. Must be a round number of seconds in microseconds,
    * or UINT64_MAX to represent "never".
    */
   struct GNUNET_TIME_Absolute abs_time;
 };
 
 /**
  * Time for relative time used by GNUnet, in microseconds.
  * Always positive, so we can only refer to future time.
  */
 struct GNUNET_TIME_Relative
 {
   /**
    * The actual value.
    * UINT64_MAX represents "forever".
    */
   uint64_t rel_value_us;
 };
 
 GNUNET_NETWORK_STRUCT_BEGIN
 
 /**
  * Time for relative time used by GNUnet, in microseconds and in network byte order.
  */
 struct GNUNET_TIME_RelativeNBO
 {
   /**
    * The actual value (in network byte order).
    * UINT64_MAX represents "forever".
    */
   uint64_t rel_value_us__ GNUNET_PACKED;
 };
 
 
 /**
  * Time for absolute time used by GNUnet, in microseconds and in network byte order.
  */
 struct GNUNET_TIME_AbsoluteNBO
 {
   /**
    * The actual value (in network byte order).
    * UINT64_MAX represents "never".
    */
   uint64_t abs_value_us__ GNUNET_PACKED;
 };
 
 /**
  * Time for timestamps used by GNUnet, in seconds and in network byte order.
  */
 struct GNUNET_TIME_TimestampNBO
 {
   /**
    * The actual value. Must be round number in seconds *or*
    * UINT64_MAX to represent "never".
    */
   struct GNUNET_TIME_AbsoluteNBO abs_time_nbo;
 };
 
 GNUNET_NETWORK_STRUCT_END
 
 /**
  * Relative time zero.
  */
 #define GNUNET_TIME_UNIT_ZERO ((struct GNUNET_TIME_Relative){0})
 
 /**
  * Absolute time zero.
  */
 #define GNUNET_TIME_UNIT_ZERO_ABS ((struct GNUNET_TIME_Absolute){0})
 
 /**
  * Timestamp of zero.
  */
 #define GNUNET_TIME_UNIT_ZERO_TS ((struct GNUNET_TIME_Timestamp){{0}})
 
 /**
  * One microsecond, our basic time unit.
  */
 #define GNUNET_TIME_UNIT_MICROSECONDS GNUNET_TIME_relative_get_unit_ ()
 
 /**
  * One millisecond.
  */
 #define GNUNET_TIME_UNIT_MILLISECONDS GNUNET_TIME_relative_get_millisecond_ ()
 
 /**
  * One second.
  */
 #define GNUNET_TIME_UNIT_SECONDS GNUNET_TIME_relative_get_second_ ()
 
 /**
  * One minute.
  */
 #define GNUNET_TIME_UNIT_MINUTES GNUNET_TIME_relative_get_minute_ ()
 
 /**
  * One hour.
  */
 #define GNUNET_TIME_UNIT_HOURS   GNUNET_TIME_relative_get_hour_ ()
 
 /**
  * One day.
  */
 #define GNUNET_TIME_UNIT_DAYS    GNUNET_TIME_relative_multiply ( \
           GNUNET_TIME_UNIT_HOURS, 24)
 
 /**
  * One week.
  */
 #define GNUNET_TIME_UNIT_WEEKS   GNUNET_TIME_relative_multiply ( \
           GNUNET_TIME_UNIT_DAYS, 7)
 
 /**
  * One month (30 days).
  */
 #define GNUNET_TIME_UNIT_MONTHS  GNUNET_TIME_relative_multiply ( \
           GNUNET_TIME_UNIT_DAYS, 30)
 
 /**
  * One year (365 days).
  */
 #define GNUNET_TIME_UNIT_YEARS   GNUNET_TIME_relative_multiply ( \
           GNUNET_TIME_UNIT_DAYS, 365)
 
 /**
  * Constant used to specify "forever".  This constant
  * will be treated specially in all time operations.
  */
 #define GNUNET_TIME_UNIT_FOREVER_REL \
         ((struct GNUNET_TIME_Relative){UINT64_MAX})
 
 /**
  * Constant used to specify "forever".  This constant
  * will be treated specially in all time operations.
  */
 #define GNUNET_TIME_UNIT_FOREVER_ABS \
         ((struct GNUNET_TIME_Absolute){UINT64_MAX})
 #define GNUNET_TIME_UNIT_NEVER_ABS \
         ((struct GNUNET_TIME_Absolute){UINT64_MAX})
 
 /**
  * Constant used to specify "forever".  This constant
  * will be treated specially in all time operations.
  */
 #define GNUNET_TIME_UNIT_FOREVER_TS \
         ((struct GNUNET_TIME_Timestamp){{UINT64_MAX}})
 
 
 /**
  * Threshold after which exponential backoff should not increase (15 m).
  */
 #define GNUNET_TIME_STD_EXPONENTIAL_BACKOFF_THRESHOLD \
         GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MINUTES, 15)
 
 
 /**
  * Perform our standard exponential back-off calculation, starting at 1 ms
  * and then going by a factor of 2 up unto a maximum of 15 m.
  *
  * @param r current backoff time, initially zero
  */
 #define GNUNET_TIME_STD_BACKOFF(r) GNUNET_TIME_relative_min ( \
           GNUNET_TIME_STD_EXPONENTIAL_BACKOFF_THRESHOLD, \
           GNUNET_TIME_relative_multiply ( \
             GNUNET_TIME_relative_max (GNUNET_TIME_UNIT_MILLISECONDS, (r)), 2))
 
 
 /**
  * Convert @a ts to human-readable timestamp.
  * Note that the returned value will be overwritten if this function
  * is called again.
  *
  * @param ts the timestamp to convert
  * @return statically allocated string, will change on the next call
  */
 const char *
 GNUNET_TIME_timestamp2s (struct GNUNET_TIME_Timestamp ts);
 
 
 /**
  * @ingroup time
  * Like `asctime`, except for GNUnet time.  Converts a GNUnet internal
  * absolute time (which is in UTC) to a string in local time.
  * Note that the returned value will be overwritten if this function
  * is called again.
  *
  * @param ts the absolute time to convert
  * @return timestamp in human-readable form in local time
  */
 const char *
 GNUNET_TIME_absolute2s (struct GNUNET_TIME_Absolute ts);
 
 
 /**
  * @ingroup time
  * Give relative time in human-readable fancy format.
  * This is one of the very few calls in the entire API that is
  * NOT reentrant!
  *
  * @param delta time in milli seconds
  * @param do_round are we allowed to round a bit?
  * @return string in human-readable form
  */
 const char *
 GNUNET_TIME_relative2s (struct GNUNET_TIME_Relative delta,
                         bool do_round);
 
 
 /**
  * Randomized exponential back-off, starting at 1 ms
  * and going up by a factor of 2+r, where 0 <= r <= 0.5, up
  * to a maximum of the given threshold.
  *
  * @param rt current backoff time, initially zero
  * @param threshold maximum value for backoff
  * @return the next backoff time
  */
 struct GNUNET_TIME_Relative
 GNUNET_TIME_randomized_backoff (struct GNUNET_TIME_Relative rt,
                                 struct GNUNET_TIME_Relative threshold);
 
 
 /**
  * Return a random time value between 0.5*r and 1.5*r.
  *
  * @param r input time for scaling
  * @return randomized time
  */
 struct GNUNET_TIME_Relative
 GNUNET_TIME_randomize (struct GNUNET_TIME_Relative r);
 
 
 /**
  * Return relative time of 0ms.
  */
 struct GNUNET_TIME_Relative
 GNUNET_TIME_relative_get_zero_ (void);
 
 
 /**
  * Return absolute time of 0ms.
  */
 struct GNUNET_TIME_Absolute
 GNUNET_TIME_absolute_get_zero_ (void);
 
 
 /**
  * Return relative time of 1 microsecond.
  */
 struct GNUNET_TIME_Relative
 GNUNET_TIME_relative_get_unit_ (void);
 
 
 /**
  * Return relative time of 1ms.
  */
 struct GNUNET_TIME_Relative
 GNUNET_TIME_relative_get_millisecond_ (void);
 
 
 /**
  * Return relative time of 1s.
  */
 struct GNUNET_TIME_Relative
 GNUNET_TIME_relative_get_second_ (void);
 
 
 /**
  * Return relative time of 1 minute.
  */
 struct GNUNET_TIME_Relative
 GNUNET_TIME_relative_get_minute_ (void);
 
 
 /**
  * Return relative time of 1 hour.
  */
 struct GNUNET_TIME_Relative
 GNUNET_TIME_relative_get_hour_ (void);
 
 
 /**
  * Return "forever".
  */
 struct GNUNET_TIME_Relative
 GNUNET_TIME_relative_get_forever_ (void);
 
 
 /**
  * Return "forever".
  */
 struct GNUNET_TIME_Absolute
 GNUNET_TIME_absolute_get_forever_ (void);
 
 
 /**
  * Get the current time.
  *
  * @return the current time
  */
 struct GNUNET_TIME_Absolute
 GNUNET_TIME_absolute_get (void);
 
 
 /**
  * Convert relative time to an absolute time in the
  * future.
  *
  * @param rel relative time to convert
  * @return timestamp that is "rel" in the future, or FOREVER if rel==FOREVER (or if we would overflow)
  */
 struct GNUNET_TIME_Absolute
 GNUNET_TIME_relative_to_absolute (struct GNUNET_TIME_Relative rel);
 
 
 /**
  * Convert relative time to a timestamp in the
  * future.
  *
  * @param rel relative time to convert
  * @return timestamp that is "rel" in the future, or FOREVER if rel==FOREVER (or if we would overflow)
  */
 struct GNUNET_TIME_Timestamp
 GNUNET_TIME_relative_to_timestamp (struct GNUNET_TIME_Relative rel);
 
 
 /**
  * Round an absolute time to a timestamp.
  *
  * @param at time to round
  * @return the result
  */
 struct GNUNET_TIME_Timestamp
 GNUNET_TIME_absolute_to_timestamp (struct GNUNET_TIME_Absolute at);
 
 
 /**
  * Get timestamp representing the current time.
  *
  * @return current time, rounded down to seconds
  */
 struct GNUNET_TIME_Timestamp
 GNUNET_TIME_timestamp_get (void);
 
 
 /**
  * Compare two absolute times.
  *
  * @param t1 first time
  * @param op compare operator
  * @param t2 second time
  * @return true if @a t1 @a op @a t2
  */
 #define GNUNET_TIME_absolute_cmp(t1,op,t2) \
         ((void) (1 op 2), (t1).abs_value_us op (t2).abs_value_us)
 
 
 /**
  * Compare two timestamps
  *
  * @param t1 first timestamp
  * @param op compare operator
  * @param t2 second timestamp
  * @return true if @a t1 @a op @a t2
  */
 #define GNUNET_TIME_timestamp_cmp(t1,op,t2) \
         GNUNET_TIME_absolute_cmp ((t1).abs_time,op,(t2).abs_time)
 
 
 /**
  * Compare two relative times.
  *
  * @param t1 first time
  * @param op compare operator
  * @param t2 second time
  * @return true if @a t1 @a op @a t2
  */
 #define GNUNET_TIME_relative_cmp(t1,op,t2) \
         ((void) (1 op 2), (t1).rel_value_us op (t2).rel_value_us)
 
 
 /**
  * Return the minimum of two relative time values.
  *
  * @param t1 first timestamp
  * @param t2 other timestamp
  * @return timestamp that is smaller
  */
 struct GNUNET_TIME_Relative
 GNUNET_TIME_relative_min (struct GNUNET_TIME_Relative t1,
                           struct GNUNET_TIME_Relative t2);
 
 
 /**
  * Return the maximum of two relative time values.
  *
  * @param t1 first timestamp
  * @param t2 other timestamp
  * @return timestamp that is larger
  */
 struct GNUNET_TIME_Relative
 GNUNET_TIME_relative_max (struct GNUNET_TIME_Relative t1,
                           struct GNUNET_TIME_Relative t2);
 
 
 /**
  * Return the minimum of two absolute time values.
  *
  * @param t1 first timestamp
  * @param t2 other timestamp
  * @return timestamp that is smaller
  */
 struct GNUNET_TIME_Absolute
 GNUNET_TIME_absolute_min (struct GNUNET_TIME_Absolute t1,
                           struct GNUNET_TIME_Absolute t2);
 
 
 /**
  * Return the maximum of two absolute time values.
  *
  * @param t1 first timestamp
  * @param t2 other timestamp
  * @return timestamp that is smaller
  */
 struct GNUNET_TIME_Absolute
 GNUNET_TIME_absolute_max (struct GNUNET_TIME_Absolute t1,
                           struct GNUNET_TIME_Absolute t2);
 
 
 /**
  * Round down absolute time @a at to multiple of @a rt.
  *
  * @param at absolute time to round
  * @param rt multiple to round to (non-zero)
  * @return rounded time
  */
 struct GNUNET_TIME_Absolute
 GNUNET_TIME_absolute_round_down (struct GNUNET_TIME_Absolute at,
                                  struct GNUNET_TIME_Relative rt);
 
 
 /**
  * Return the maximum of two timestamps.
  *
  * @param t1 first timestamp
  * @param t2 other timestamp
  * @return timestamp that is smaller
  */
 struct GNUNET_TIME_Timestamp
 GNUNET_TIME_timestamp_max (struct GNUNET_TIME_Timestamp t1,
                            struct GNUNET_TIME_Timestamp t2);
 
 
 /**
  * Return the minimum of two timestamps.
  *
  * @param t1 first timestamp
  * @param t2 other timestamp
  * @return timestamp that is smaller
  */
 struct GNUNET_TIME_Timestamp
 GNUNET_TIME_timestamp_min (struct GNUNET_TIME_Timestamp t1,
                            struct GNUNET_TIME_Timestamp t2);
 
 
 /**
  * Given a timestamp in the future, how much time
  * remains until then?
  *
  * @param future some absolute time, typically in the future
  * @return future - now, or 0 if now >= future, or FOREVER if future==FOREVER.
  */
 struct GNUNET_TIME_Relative
 GNUNET_TIME_absolute_get_remaining (struct GNUNET_TIME_Absolute future);
 
 
 /**
  * Test if @a a1 and @a a2 are equal within a margin of
  * error of @a t.
  *
  * @param a1 time to compare
  * @param a2 time to compare
  * @param t tolerance to apply
  * @return true if "|a1-a2|<=t" holds.
  */
 bool
 GNUNET_TIME_absolute_approx_eq (struct GNUNET_TIME_Absolute a1,
                                 struct GNUNET_TIME_Absolute a2,
                                 struct GNUNET_TIME_Relative t);
 
 
 /**
  * Calculate the estimate time of arrival/completion
  * for an operation.
  *
  * @param start when did the operation start?
  * @param finished how much has been done?
  * @param total how much must be done overall (same unit as for "finished")
  * @return remaining duration for the operation,
  *        assuming it continues at the same speed
  */
 struct GNUNET_TIME_Relative
 GNUNET_TIME_calculate_eta (struct GNUNET_TIME_Absolute start,
                            uint64_t finished,
                            uint64_t total);
 
 
 /**
  * Compute the time difference between the given start and end times.
  * Use this function instead of actual subtraction to ensure that
  * "FOREVER" and overflows are handled correctly.
  *
  * @param start some absolute time
  * @param end some absolute time (typically larger or equal to start)
  * @return 0 if start >= end; FOREVER if end==FOREVER; otherwise end - start
  */
 struct GNUNET_TIME_Relative
 GNUNET_TIME_absolute_get_difference (struct GNUNET_TIME_Absolute start,
                                      struct GNUNET_TIME_Absolute end);
 
 
 /**
  * Get the duration of an operation as the
  * difference of the current time and the given start time "hence".
  *
  * @param whence some absolute time, typically in the past
  * @return 0 if hence > now, otherwise now-hence.
  */
 struct GNUNET_TIME_Relative
 GNUNET_TIME_absolute_get_duration (struct GNUNET_TIME_Absolute whence);
 
 
 /**
  * Add a given relative duration to the
  * given start time.
  *
  * @param start some absolute time
  * @param duration some relative time to add
  * @return FOREVER if either argument is FOREVER or on overflow; start+duration otherwise
  */
 struct GNUNET_TIME_Absolute
 GNUNET_TIME_absolute_add (struct GNUNET_TIME_Absolute start,
                           struct GNUNET_TIME_Relative duration);
 
 
 /**
  * Subtract a given relative duration from the
  * given start time.
  *
  * @param start some absolute time
  * @param duration some relative time to subtract
  * @return ZERO if start <= duration, or FOREVER if start time is FOREVER; start-duration otherwise
  */
 struct GNUNET_TIME_Absolute
 GNUNET_TIME_absolute_subtract (struct GNUNET_TIME_Absolute start,
                                struct GNUNET_TIME_Relative duration);
 
 
 /**
  * Multiply relative time by a given factor.
  *
  * @param rel some duration
  * @param factor double to multiply with
  * @return FOREVER if rel=FOREVER or on overflow; otherwise rel*factor
  */
 struct GNUNET_TIME_Relative
 GNUNET_TIME_relative_multiply_double (struct GNUNET_TIME_Relative rel,
                                       double factor);
 
 /**
  * Multiply relative time by a given factor.
  *
  * @param rel some duration
  * @param factor integer to multiply with
  * @return FOREVER if rel=FOREVER or on overflow; otherwise rel*factor
  */
 struct GNUNET_TIME_Relative
 GNUNET_TIME_relative_multiply (struct GNUNET_TIME_Relative rel,
                                unsigned long long factor);
 
 
 /**
  * Saturating multiply relative time by a given factor.
  *
  * @param rel some duration
  * @param factor integer to multiply with
  * @return FOREVER if rel=FOREVER or on overflow; otherwise rel*factor
  */
 struct GNUNET_TIME_Relative
 GNUNET_TIME_relative_saturating_multiply (struct GNUNET_TIME_Relative rel,
                                           unsigned long long factor);
 
 
 /**
  * Divide relative time by a given factor.
  *
  * @param rel some duration
  * @param factor integer to divide by
  * @return FOREVER if rel=FOREVER or factor==0; otherwise rel/factor
  */
 struct GNUNET_TIME_Relative
 GNUNET_TIME_relative_divide (struct GNUNET_TIME_Relative rel,
                              unsigned long long factor);
 
 
 /**
  * Add relative times together.
  *
  * @param a1 some relative time
  * @param a2 some other relative time
  * @return FOREVER if either argument is FOREVER or on overflow; a1+a2 otherwise
  */
 struct GNUNET_TIME_Relative
 GNUNET_TIME_relative_add (struct GNUNET_TIME_Relative a1,
                           struct GNUNET_TIME_Relative a2);
 
 
 /**
  * Subtract relative timestamp from the other.
  *
  * @param a1 first timestamp
  * @param a2 second timestamp
  * @return ZERO if a2>=a1 (including both FOREVER), FOREVER if a1 is FOREVER, a1-a2 otherwise
  */
 struct GNUNET_TIME_Relative
 GNUNET_TIME_relative_subtract (struct GNUNET_TIME_Relative a1,
                                struct GNUNET_TIME_Relative a2);
 
 
 /**
  * Convert relative time to network byte order.
  *
  * @param a time to convert
  * @return converted time value
  */
 struct GNUNET_TIME_RelativeNBO
 GNUNET_TIME_relative_hton (struct GNUNET_TIME_Relative a);
 
 
 /**
  * Convert relative time from network byte order.
  *
  * @param a time to convert
  * @return converted time value
  */
 struct GNUNET_TIME_Relative
 GNUNET_TIME_relative_ntoh (struct GNUNET_TIME_RelativeNBO a);
 
 
 /**
  * Convert absolute time to network byte order.
  *
  * @param a time to convert
  * @return converted time value
  */
 struct GNUNET_TIME_AbsoluteNBO
 GNUNET_TIME_absolute_hton (struct GNUNET_TIME_Absolute a);
 
 
 /**
  * Convert timestamp to network byte order.
  *
  * @param t time to convert
  * @return converted time value
  */
 struct GNUNET_TIME_TimestampNBO
 GNUNET_TIME_timestamp_hton (struct GNUNET_TIME_Timestamp t);
 
 
 /**
  * Convert milliseconds after the UNIX epoch to absolute time.
  *
  * @param ms_after_epoch millisecond timestamp to convert
  * @return converted time value
  */
 struct GNUNET_TIME_Absolute
 GNUNET_TIME_absolute_from_ms (uint64_t ms_after_epoch);
 
 
 /**
  * Test if @a abs is never.
  *
  * @return true if it is.
  */
 bool
 GNUNET_TIME_absolute_is_never (struct GNUNET_TIME_Absolute abs);
 
 
 /**
  * Test if @a abs is truly in the past (excluding now).
  *
  * @return true if it is.
  */
 bool
 GNUNET_TIME_absolute_is_past (struct GNUNET_TIME_Absolute abs);
 
 
 /**
  * Test if @a abs is truly zero.
  *
  * @return true if it is.
  */
 bool
 GNUNET_TIME_absolute_is_zero (struct GNUNET_TIME_Absolute abs);
 
 
 /**
  * Test if @a abs is truly in the future (excluding now).
  *
  * @return true if it is.
  */
 bool
 GNUNET_TIME_absolute_is_future (struct GNUNET_TIME_Absolute abs);
 
 
 /**
  * Test if @a rel is forever.
  *
  * @return true if it is.
  */
 bool
 GNUNET_TIME_relative_is_forever (struct GNUNET_TIME_Relative rel);
 
 
 /**
  * Test if @a rel is zero.
  *
  * @return true if it is.
  */
 bool
 GNUNET_TIME_relative_is_zero (struct GNUNET_TIME_Relative rel);
 
 
 /**
  * Convert seconds after the UNIX epoch to absolute time.
  *
  * @param s_after_epoch seconds after epoch to convert
  * @return converted time value
  */
 struct GNUNET_TIME_Absolute
 GNUNET_TIME_absolute_from_s (uint64_t s_after_epoch);
 
 
 /**
  * Convert seconds after the UNIX epoch to timestamp.
  *
  * @param s_after_epoch seconds after epoch to convert
  * @return converted time value
  */
 struct GNUNET_TIME_Timestamp
 GNUNET_TIME_timestamp_from_s (uint64_t s_after_epoch);
 
 
 /**
  * Convert timestamp to number of seconds after the UNIX epoch.
  *
  * @param ts timestamp to convert
  * @return converted time value
  */
 uint64_t
 GNUNET_TIME_timestamp_to_s (struct GNUNET_TIME_Timestamp ts);
 
 
 /**
  * Convert absolute time from network byte order.
  *
  * @param a time to convert
  * @return converted time value
  */
 struct GNUNET_TIME_Absolute
 GNUNET_TIME_absolute_ntoh (struct GNUNET_TIME_AbsoluteNBO a);
 
 
 /**
  * Convert timestamp from network byte order.
  *
  * @param tn time to convert
  * @return converted time value
  */
 struct GNUNET_TIME_Timestamp
 GNUNET_TIME_timestamp_ntoh (struct GNUNET_TIME_TimestampNBO tn);
 
 
 /**
  * Set the timestamp offset for this instance.
  *
  * @param offset the offset to skew the locale time by
  */
 void
 GNUNET_TIME_set_offset (long long offset);
 
 
 /**
  * Get the timestamp offset for this instance.
  *
  * @return the offset we currently skew the locale time by
  */
 long long
 GNUNET_TIME_get_offset (void);
 
 
 /**
  * Return the current year (e.g. '2011').
  */
 unsigned int
 GNUNET_TIME_get_current_year (void);
 
 
 /**
  * Convert a year to an expiration time of January 1st of that year.
  *
  * @param year a year (after 1970, please ;-)).
  * @return absolute time for January 1st of that year.
  */
 struct GNUNET_TIME_Absolute
 GNUNET_TIME_year_to_time (unsigned int year);
 
 
 /**
  * Convert an expiration time to the respective year (rounds)
  *
  * @param at absolute time
  * @return year a year (after 1970), 0 on error
  */
 unsigned int
 GNUNET_TIME_time_to_year (struct GNUNET_TIME_Absolute at);
 
 
 /**
  * A configuration object.
  */
 struct GNUNET_CONFIGURATION_Handle;
 
 
 /**
  * Obtain the current time and make sure it is monotonically
  * increasing.  Guards against systems without an RTC or
  * clocks running backwards and other nasty surprises. Does
  * not guarantee that the returned time is near the current
  * time returned by #GNUNET_TIME_absolute_get().  Two
  * subsequent calls (within a short time period) may return the
  * same value. Persists the last returned time on disk to
  * ensure that time never goes backwards. As a result, the
  * resulting value can be used to check if a message is the
  * "most recent" value and replays of older messages (from
  * the same origin) would be discarded.
  *
  * @param cfg configuration, used to determine where to
  *   store the time; user can also insist RTC is working
  *   nicely and disable the feature
  * @return monotonically increasing time
  */
 struct GNUNET_TIME_Absolute
 GNUNET_TIME_absolute_get_monotonic (
   const struct GNUNET_CONFIGURATION_Handle *cfg);
 
 
 #if 0                           /* keep Emacsens' auto-indent happy */
 {
 #endif
 #ifdef __cplusplus
 }
 #endif
 
 /* ifndef GNUNET_TIME_LIB_H */
 #endif
 
 /** @} */ /* end of group time */
 
 /** @} */ /* end of group addition */
 
 /* end of gnunet_time_lib.h */