src/rx/rx_clock.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 /* Elapsed time package */
  11 /* See rx_clock.h for calling conventions */
  12
  13 #include <afsconfig.h>
  14 #include <afs/param.h>
  15
  16 #ifdef AFS_SUN59_ENV
  17 #include <sys/time_impl.h>
  18 #endif
  19
  20 #ifdef KERNEL
  21 # ifndef UKERNEL
  22 #  include "h/types.h"
  23 #  include "h/time.h"
  24 # else /* !UKERNEL */
  25 #  include "afs/sysincludes.h"
  26 #  include "afsincludes.h"
  27 # endif /* !UKERNEL */
  28 #else /* KERNEL */
  29 # include <roken.h>
  30 #endif
  31
  32 #ifndef AFS_PTHREAD_ENV
  33
  34 #include "rx.h"
  35 #include "rx_clock.h"
  36
  37 #if !defined(AFS_USE_GETTIMEOFDAY)
  38 /*use this package only if gettimeofday is much much costlier than getitime */
  39
  40 #ifndef KERNEL
  41
  42 #define STARTVALUE 3600
  43 static struct clock startvalue;
  44 static struct clock relclock_epoch;   /* The elapsed time of the last itimer reset */
  45
  46 struct clock clock_now;         /* The last elapsed time ready by clock_GetTimer */
  47
  48 /* This is set to 1 whenever the time is read, and reset to 0 whenever clock_NewTime is called.  This is to allow the caller to control the frequency with which the actual time is re-evaluated (an expensive operation) */
  49 int clock_haveCurrentTime;
  50
  51 int clock_nUpdates;             /* The actual number of clock updates */
  52 static int clockInitialized = 0;
  53
  54 static void
  55 clock_Sync(void)
  56 {
  57     struct itimerval itimer, otimer;
  58     itimer.it_value.tv_sec = STARTVALUE;
  59     itimer.it_value.tv_usec = 0;
  60     itimer.it_interval.tv_sec = 0;
  61     itimer.it_interval.tv_usec = 0;
  62
  63     signal(SIGALRM, SIG_IGN);
  64     if (setitimer(ITIMER_REAL, &itimer, &otimer) != 0) {
  65         osi_Panic("clock:  could not set interval timer; aborted(errno=%d)\n",
  66                   errno);
  67     }
  68     if (relclock_epoch.usec + startvalue.usec >= otimer.it_value.tv_usec) {
  69         relclock_epoch.sec = relclock_epoch.sec +
  70             startvalue.sec - otimer.it_value.tv_sec;
  71         relclock_epoch.usec = relclock_epoch.usec +
  72             startvalue.usec - otimer.it_value.tv_usec;
  73     } else {
  74         relclock_epoch.sec = relclock_epoch.sec +
  75             startvalue.sec - 1 - otimer.it_value.tv_sec;
  76         relclock_epoch.usec = relclock_epoch.usec +
  77             startvalue.usec + 1000000 - otimer.it_value.tv_usec;
  78     }
  79     if (relclock_epoch.usec >= 1000000)
  80         relclock_epoch.usec -= 1000000, relclock_epoch.sec++;
  81     /* the initial value of the interval timer may not be exactly the same
  82      * as the arg passed to setitimer. POSIX allows the implementation to
  83      * round it up slightly, and some nonconformant implementations truncate
  84      * it */
  85     getitimer(ITIMER_REAL, &itimer);
  86     startvalue.sec = itimer.it_value.tv_sec;
  87     startvalue.usec = itimer.it_value.tv_usec;
  88 }
  89
  90 /* Initialize the clock */
  91 void
  92 clock_Init(void)
  93 {
  94     if (!clockInitialized) {
  95         relclock_epoch.sec = relclock_epoch.usec = 0;
  96         startvalue.sec = startvalue.usec = 0;
  97         clock_Sync();
  98         clockInitialized = 1;
  99     }
 100
 101     clock_UpdateTime();
 102 }
 103
 104 /* Make clock uninitialized. */
 105 int
 106 clock_UnInit(void)
 107 {
 108     clockInitialized = 0;
 109     return 0;
 110 }
 111
 112 /* Compute the current time.  The timer gets the current total elapsed time since startup, expressed in seconds and microseconds.  This call is almost 200 usec on an APC RT */
 113 void
 114 clock_UpdateTime(void)
 115 {
 116     struct itimerval itimer;
 117     struct clock offset;
 118     struct clock new;
 119
 120     getitimer(ITIMER_REAL, &itimer);
 121
 122     if (startvalue.usec >= itimer.it_value.tv_usec) {
 123         offset.sec = startvalue.sec - itimer.it_value.tv_sec;
 124         offset.usec = startvalue.usec - itimer.it_value.tv_usec;
 125     } else {
 126         /* The "-1" makes up for adding 1000000 usec, on the next line */
 127         offset.sec = startvalue.sec - 1 - itimer.it_value.tv_sec;
 128         offset.usec = startvalue.usec + 1000000 - itimer.it_value.tv_usec;
 129     }
 130     new.sec = relclock_epoch.sec + offset.sec;
 131     new.usec = relclock_epoch.usec + offset.usec;
 132     if (new.usec >= 1000000)
 133         new.usec -= 1000000, new.sec++;
 134     clock_now.sec = new.sec;
 135     clock_now.usec = new.usec;
 136     if (itimer.it_value.tv_sec < startvalue.sec / 2)
 137         clock_Sync();
 138     clock_haveCurrentTime = 1;
 139     clock_nUpdates++;
 140 }
 141 #else /* KERNEL */
 142 #endif /* KERNEL */
 143
 144 #endif /* AFS_USE_GETTIMEOFDAY */
 145 #endif /* !AFS_PTHREAD_ENV */