NAME

       ratecheck, ppsratecheck — event rate limiting

SYNOPSIS

       #include <sys/time.h>

       int
       ratecheck(struct timeval *lasttime, struct timeval *mininterval);

       int
       ppsratecheck(struct timeval *lasttime, int *curpps, int maxpps);

DESCRIPTION

       The  ratecheck  and  ppsratecheck  functions  facilitate  rate-limiting  of arbitrary events.  The former
       enforces a minimum interval between events while the latter enforces  a  maximum  number  of  events  per
       second.

       The  ratecheck function compares the current time to the value pointed to by lasttime.  If the difference
       is equal to or greater than mininterval, it returns a non-zero value and updates lasttime to the  current
       time.  Otherwise, it returns zero.

       The  ppsratecheck  function  first  compares the current time to lasttime.  If at least a full second has
       passed, the value pointed to by the curpps argument is reset to 1 and lasttime is updated to the  current
       time.   Otherwise,  curpps  is  incremented and lasttime is left untouched.  In either case, ppsratecheck
       returns a non-zero value if and only if the updated curpps is less than or equal to maxpps or  maxpps  is
       negative.

SEE ALSO

       counter(9)

HISTORY

       The ratecheck and ppsratecheck functions first appeared in FreeBSD 5.1.

Debian                                         September 25, 2017                                   RATECHECK(9)