src/lwp/fasttime.c

   1 /*
   2  * Copyright 2000, International Business Machines Corporation and others.
   3  * All Rights Reserved.
   4  *
   5  * This software has been released under the terms of the IBM Public
   6  * License.  For details, see the LICENSE file in the top-level source
   7  * directory or online at http://www.openafs.org/dl/license10.html
   8  */
   9
  10 /*
  11  *      fasttime.c -- Get the time of day quickly by mapping the kernel's
  12  *                    time of day variable.
  13  *
  14  *      6 January 1986
  15  *
  16  *      Modification History
  17  *      3/21/86:  Added FT_ApproxTime which returns the last time
  18  *                in seconds returned by RT_FastTime.  The intent is to give
  19  *                routines which aren't too concerned about the exact time
  20  *                fast access to the time, even on kernels without mmap.
  21  *      4/2/86:   Fixed my previous mod and fixed FT_Init so it doesn't initialize
  22  *                a second time if explicitly called after being implicitly called.
  23  *                This saves a (precious) file descriptor.
  24  */
  25
  26 #include <afsconfig.h>
  27 #include <afs/param.h>
  28
  29 #include <roken.h>
  30
  31 int ft_debug;
  32
  33 #define TRUE    1
  34 #define FALSE   0
  35
  36 static enum InitState { notTried, tried, done } initState = notTried;
  37
  38 struct timeval FT_LastTime;     /* last time returned by RT_FastTime.  Used to implement
  39                                  * FT_ApproxTime */
  40
  41
  42 /* Call this to get the memory mapped.  It will return -1 if anything went
  43    wrong.  In that case, calls to FT_GetTimeOfDay will call gettimeofday
  44    instead.  If printErrors is true, errors in initialization will cause
  45    error messages to be printed on stderr.  If notReally is true, then
  46    things are set up so that all calls to FT_GetTimeOfDay call gettimeofday.
  47    You might want this if your program won't run too long and the nlist
  48    call is too expensive.  Yeah, it's pretty horrible.
  49 */
  50 int
  51 FT_Init(int printErrors, int notReally)
  52 {
  53     if (initState != notTried && !notReally)
  54         return (initState == done ? 0 : -1);    /* This is in case explicit initialization
  55                                                  * occurs after automatic initialization */
  56     initState = tried;
  57     if (notReally)
  58         return 0;               /* fake success, but leave initState
  59                                  * wrong. */
  60     if (printErrors)
  61         fprintf(stderr, "FT_Init: mmap  not implemented on this kernel\n");
  62     return (-1);
  63 }
  64
  65 /* Call this to get the time of day.  It will automatically initialize the
  66    first time you call it.  If you want error messages when you initialize,
  67    call FT_Init yourself.  If the initialization failed, this will just
  68    call gettimeofday.  If you ask for the timezone info, this routine will
  69    punt to gettimeofday. */
  70 int
  71 FT_GetTimeOfDay(struct timeval *tv, struct timezone *tz)
  72 {
  73     int ret;
  74     ret = gettimeofday(tv, tz);
  75     if (!ret) {
  76         /* need to bounds check 'cause Unix can fail these checks, (esp on Suns)
  77          * and time package can generate invalid (to select syscall) values
  78          * for the time until the next interesting event if it encounters
  79          * out of range microsecond fields */
  80         if (tv->tv_usec < 0)
  81             tv->tv_usec = 0;
  82         if (tv->tv_usec > 999999)
  83             tv->tv_usec = 999999;
  84         FT_LastTime.tv_sec = tv->tv_sec;
  85         FT_LastTime.tv_usec = tv->tv_usec;
  86     }
  87     return ret;
  88 }
  89
  90
  91 /* For compatibility.  Should go away. */
  92 int
  93 TM_GetTimeOfDay(struct timeval *tv, struct timezone *tz)
  94 {
  95     return FT_GetTimeOfDay(tv, tz);
  96 }
  97
  98 int
  99 FT_AGetTimeOfDay(struct timeval *tv, struct timezone *tz)
 100 {
 101     if (FT_LastTime.tv_sec) {
 102         tv->tv_sec = FT_LastTime.tv_sec;
 103         tv->tv_usec = FT_LastTime.tv_usec;
 104         return 0;
 105     }
 106     return FT_GetTimeOfDay(tv, tz);
 107 }
 108
 109 #ifdef AFS_PTHREAD_ENV
 110 unsigned int FT_ApproxTime(void)
 111 {
 112     return time(0);
 113 }
 114 #else
 115 unsigned int
 116 FT_ApproxTime(void)
 117 {
 118     if (!FT_LastTime.tv_sec) {
 119         FT_GetTimeOfDay(&FT_LastTime, 0);
 120     }
 121     return FT_LastTime.tv_sec;
 122 }
 123 #endif