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TIMEOUT(9)               BSD Kernel Developer's Manual              TIMEOUT(9)

NAME
     timeout_set, timeout_add, timeout_add_sec, timeout_add_msec,
     timeout_add_nsec, timeout_add_usec, timeout_add_tv, timeout_add_ts,
     timeout_add_bt, timeout_del, timeout_pending, timeout_initialized,
     timeout_triggered, TIMEOUT_INITIALIZER -- execute a function after a
     specified period of time

SYNOPSIS
     #include <&lt;sys/types.h>&gt;
     #include <&lt;sys/timeout.h>&gt;

     void
     timeout_set(struct timeout *to, void (*fn)(void *), void *arg);

     int
     timeout_add(struct timeout *to, int ticks);

     int
     timeout_del(struct timeout *to);

     int
     timeout_pending(struct timeout *to);

     int
     timeout_initialized(struct timeout *to);

     int
     timeout_triggered(struct timeout *to);

     int
     timeout_add_tv(struct timeout *to, struct timeval *);

     int
     timeout_add_ts(struct timeout *to, struct timespec *);

     int
     timeout_add_bt(struct timeout *to, struct bintime *);

     int
     timeout_add_sec(struct timeout *to, int sec);

     int
     timeout_add_msec(struct timeout *to, int msec);

     int
     timeout_add_usec(struct timeout *to, int usec);

     int
     timeout_add_nsec(struct timeout *to, int nsec);

     TIMEOUT_INITIALIZER(void (*fn)(void *), void *arg);

DESCRIPTION
     The timeout API provides a mechanism to execute a function at a given
     time.  The granularity of the time is limited by the granularity of the
     hardclock(9) timer which executes hz(9) times a second.  The function
     will be called at softclock interrupt level.

     It is the responsibility of the caller to provide these functions with
     pre-allocated timeout structures.

     The function timeout_set() prepares the timeout structure to to be used
     in future calls to timeout_add() and timeout_del().  The timeout will be
     prepared to call the function specified by the fn argument with a void *
     argument given in the arg argument.  Once initialized, the to structure
     can be used repeatedly in timeout_add() and timeout_del() and does not
     need to be reinitialized unless the function called and/or its argument
     must change.

     The function timeout_add() schedules the execution of the to timeout in
     at least ticks/hz seconds.  Negative values of ticks are illegal.  If the
     value is '0' it will, in the current implementation, be treated as '1',
     but in the future it might cause an immediate timeout.  The timeout in
     the to argument must be already initialized by timeout_set() and may not
     be used in calls to timeout_set() until it has timed out or been removed
     with timeout_del().  If the timeout in the to argument is already sched-
     uled, the old execution time will be replaced by the new one.

     The function timeout_del() will cancel the timeout in the argument to.
     If the timeout has already executed or has never been added the call will
     have no effect.

     The timeout_pending() macro can be used to check if a timeout is sched-
     uled to run.

     The timeout_initialized() macro can be used to check if a timeout has
     been initialized.

     The timeout_triggered() macro can be used to check if a timeout is run-
     ning or has been run.  The timeout_add() and timeout_del() functions
     clear the triggered state for that timeout.

     When possible, use the timeout_add_tv(), timeout_add_ts(),
     timeout_add_bt(), timeout_add_sec(), timeout_add_msec(),
     timeout_add_usec(), and timeout_add_nsec() functions instead of
     timeout_add().  Those functions add a timeout whilst converting the time
     specified by the respective types.

     A timeout declaration can be initialised with the TIMEOUT_INITIALIZER()
     macro.  The timeout will be prepared to call the function specified by
     the fn argument with the void * argument given in arg.

CONTEXT
     timeout_set() can be called during autoconf, from process context, or
     from interrupt context.

     timeout_add(), timeout_add_sec(), timeout_add_msec(), timeout_add_nsec(),
     timeout_add_usec(), timeout_add_tv(), timeout_add_ts(), timeout_add_bt(),
     timeout_del(), timeout_pending(), timeout_initialized(),
     timeout_triggered() can be called during autoconf, from process context,
     or from any interrupt context at or below IPL_CLOCK.

RETURN VALUES
     timeout_add(), timeout_add_sec(), timeout_add_msec(), timeout_add_nsec(),
     timeout_add_usec(), timeout_add_tv(), timeout_add_ts(), and
     timeout_add_bt() will return 1 if the timeout to was added to the timeout
     schedule or 0 if it was already queued.

     timeout_del() will return 1 if the timeout to was removed from the pend-
     ing timeout schedule or 0 if it was not currently queued.

CODE REFERENCES
     These functions are implemented in the file sys/kern/kern_timeout.c.

SEE ALSO
     hz(9), hzto(9), splclock(9), tsleep(9), tvtohz(9)

BSD                            December 22, 2014                           BSD