rtt.lc

unix network ,unix network unix network

/* include rtt1 */
#include    "unprtt.h"##  1 ##src/lib/rtt.c##

int     rtt_d_flag = 0;         /* debug flag; can be set nonzero by caller */##  2 ##src/lib/rtt.c##

/*##  3 ##src/lib/rtt.c##
 * Calculate the RTO value based on current estimators:##  4 ##src/lib/rtt.c##
 *      smoothed RTT plus four times the deviation.##  5 ##src/lib/rtt.c##
 */##  6 ##src/lib/rtt.c##
#define RTT_RTOCALC(ptr) ((ptr)->rtt_srtt + (4.0 * (ptr)->rtt_rttvar))##  7 ##src/lib/rtt.c##

static float##  8 ##src/lib/rtt.c##
rtt_minmax(float rto)##  9 ##src/lib/rtt.c##
{## 10 ##src/lib/rtt.c##
    if (rto < RTT_RXTMIN)## 11 ##src/lib/rtt.c##
        rto = RTT_RXTMIN;## 12 ##src/lib/rtt.c##
    else if (rto > RTT_RXTMAX)## 13 ##src/lib/rtt.c##
        rto = RTT_RXTMAX;## 14 ##src/lib/rtt.c##
    return (rto);## 15 ##src/lib/rtt.c##
}## 16 ##src/lib/rtt.c##

void## 17 ##src/lib/rtt.c##
rtt_init(struct rtt_info *ptr)## 18 ##src/lib/rtt.c##
{## 19 ##src/lib/rtt.c##
    struct timeval tv;## 20 ##src/lib/rtt.c##

    Gettimeofday(&tv, NULL);## 21 ##src/lib/rtt.c##
    ptr->rtt_base = tv.tv_sec;  /* #sec since 1/1/1970 at start */## 22 ##src/lib/rtt.c##

    ptr->rtt_rtt = 0;## 23 ##src/lib/rtt.c##
    ptr->rtt_srtt = 0;## 24 ##src/lib/rtt.c##
    ptr->rtt_rttvar = 0.75;## 25 ##src/lib/rtt.c##
    ptr->rtt_rto = rtt_minmax(RTT_RTOCALC(ptr));## 26 ##src/lib/rtt.c##
    /* first RTO at (srtt + (4 * rttvar)) = 3 seconds */## 27 ##src/lib/rtt.c##
}## 28 ##src/lib/rtt.c##
/* end rtt1 */

/*## 29 ##src/lib/rtt.c##
 * Return the current timestamp.## 30 ##src/lib/rtt.c##
 * Our timestamps are 32-bit integers that count milliseconds since## 31 ##src/lib/rtt.c##
 * rtt_init() was called.## 32 ##src/lib/rtt.c##
 */## 33 ##src/lib/rtt.c##

/* include rtt_ts */
uint32_t## 34 ##src/lib/rtt.c##
rtt_ts(struct rtt_info *ptr)## 35 ##src/lib/rtt.c##
{## 36 ##src/lib/rtt.c##
    uint32_t ts;## 37 ##src/lib/rtt.c##
    struct timeval tv;## 38 ##src/lib/rtt.c##

    Gettimeofday(&tv, NULL);## 39 ##src/lib/rtt.c##
    ts = ((tv.tv_sec - ptr->rtt_base) * 1000) + (tv.tv_usec / 1000);## 40 ##src/lib/rtt.c##
    return (ts);## 41 ##src/lib/rtt.c##
}## 42 ##src/lib/rtt.c##

void## 43 ##src/lib/rtt.c##
rtt_newpack(struct rtt_info *ptr)## 44 ##src/lib/rtt.c##
{## 45 ##src/lib/rtt.c##
    ptr->rtt_nrexmt = 0;## 46 ##src/lib/rtt.c##
}## 47 ##src/lib/rtt.c##

int## 48 ##src/lib/rtt.c##
rtt_start(struct rtt_info *ptr)## 49 ##src/lib/rtt.c##
{## 50 ##src/lib/rtt.c##
    return ((int) (ptr->rtt_rto + 0.5));    /* round float to int */## 51 ##src/lib/rtt.c##
    /* 4return value can be used as: alarm(rtt_start(&foo)) */## 52 ##src/lib/rtt.c##
}## 53 ##src/lib/rtt.c##
/* end rtt_ts */

/*## 54 ##src/lib/rtt.c##
 * A response was received.## 55 ##src/lib/rtt.c##
 * Stop the timer and update the appropriate values in the structure## 56 ##src/lib/rtt.c##
 * based on this packet's RTT.  We calculate the RTT, then update the## 57 ##src/lib/rtt.c##
 * estimators of the RTT and its mean deviation.## 58 ##src/lib/rtt.c##
 * This function should be called right after turning off the## 59 ##src/lib/rtt.c##
 * timer with alarm(0), or right after a timeout occurs.## 60 ##src/lib/rtt.c##
 */## 61 ##src/lib/rtt.c##

/* include rtt_stop */
void## 62 ##src/lib/rtt.c##
rtt_stop(struct rtt_info *ptr, uint32_t ms)## 63 ##src/lib/rtt.c##
{## 64 ##src/lib/rtt.c##
    double  delta;## 65 ##src/lib/rtt.c##

    ptr->rtt_rtt = ms / 1000.0; /* measured RTT in seconds */## 66 ##src/lib/rtt.c##

    /* ## 67 ##src/lib/rtt.c##
     * Update our estimators of RTT and mean deviation of RTT.## 68 ##src/lib/rtt.c##
     * See Jacobson's SIGCOMM '88 paper, Appendix A, for the details.## 69 ##src/lib/rtt.c##
     * We use floating point here for simplicity.## 70 ##src/lib/rtt.c##
     */## 71 ##src/lib/rtt.c##

    delta = ptr->rtt_rtt - ptr->rtt_srtt;## 72 ##src/lib/rtt.c##
    ptr->rtt_srtt += delta / 8; /* g = 1/8 */## 73 ##src/lib/rtt.c##

    if (delta < 0.0)## 74 ##src/lib/rtt.c##
        delta = -delta;         /* |delta| */## 75 ##src/lib/rtt.c##

    ptr->rtt_rttvar += (delta - ptr->rtt_rttvar) / 4;   /* h = 1/4 */## 76 ##src/lib/rtt.c##

    ptr->rtt_rto = rtt_minmax(RTT_RTOCALC(ptr));## 77 ##src/lib/rtt.c##
}## 78 ##src/lib/rtt.c##
/* end rtt_stop */

/*## 79 ##src/lib/rtt.c##
 * A timeout has occurred.## 80 ##src/lib/rtt.c##
 * Return -1 if it's time to give up, else return 0.## 81 ##src/lib/rtt.c##
 */## 82 ##src/lib/rtt.c##

/* include rtt_timeout */
int## 83 ##src/lib/rtt.c##
rtt_timeout(struct rtt_info *ptr)## 84 ##src/lib/rtt.c##
{## 85 ##src/lib/rtt.c##
    ptr->rtt_rto *= 2;          /* next RTO */## 86 ##src/lib/rtt.c##

    if (++ptr->rtt_nrexmt > RTT_MAXNREXMT)## 87 ##src/lib/rtt.c##
        return (-1);            /* time to give up for this packet */## 88 ##src/lib/rtt.c##
    return (0);## 89 ##src/lib/rtt.c##
}## 90 ##src/lib/rtt.c##
/* end rtt_timeout */

/*## 91 ##src/lib/rtt.c##
 * Print debugging information on stderr, if the "rtt_d_flag" is nonzero.## 92 ##src/lib/rtt.c##
 */## 93 ##src/lib/rtt.c##

void## 94 ##src/lib/rtt.c##
rtt_debug(struct rtt_info *ptr)## 95 ##src/lib/rtt.c##
{## 96 ##src/lib/rtt.c##
    if (rtt_d_flag == 0)## 97 ##src/lib/rtt.c##
        return;## 98 ##src/lib/rtt.c##

    fprintf(stderr, "rtt = %.3f, srtt = %.3f, rttvar = %.3f, rto = %.3f\n",## 99 ##src/lib/rtt.c##
            ptr->rtt_rtt, ptr->rtt_srtt, ptr->rtt_rttvar, ptr->rtt_rto);##100 ##src/lib/rtt.c##
    fflush(stderr);##101 ##src/lib/rtt.c##
}##102 ##src/lib/rtt.c##