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ntp: refactor timestamp selection and interval calculation

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Prepare the code for a third option in the timestamp selection and clean
it up a bit.
This commit is contained in:
Miroslav Lichvar 2017-07-21 10:17:42 +02:00
parent 43cd119d6d
commit 2e0870ee0c
1 changed files with 46 additions and 44 deletions
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80
ntp_core.c
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@ -178,6 +178,9 @@ struct NCR_Instance_Record {
NTP_int64 local_ntp_tx;
NTP_Local_Timestamp local_tx;
/* Previous local transmit timestamp for the interleaved mode */
NTP_Local_Timestamp prev_local_tx;
/* The instance record in the main source management module. This
performs the statistical analysis on the samples we generate */
@ -643,6 +646,7 @@ NCR_ResetInstance(NCR_Instance instance)
UTI_ZeroNtp64(&instance->local_ntp_rx);
UTI_ZeroNtp64(&instance->local_ntp_tx);
zero_local_timestamp(&instance->local_rx);
zero_local_timestamp(&instance->prev_local_tx);
}
/* ================================================== */
@ -1349,9 +1353,9 @@ receive_packet(NCR_Instance inst, NTP_Local_Address *local_addr,
measurement in seconds */
double error_in_estimate;
double remote_interval, local_interval, server_interval;
NTP_Local_Timestamp local_receive, local_transmit;
double remote_interval, local_interval, response_time;
double delay_time, precision;
NTP_Timestamp_Source sample_rx_tss;
/* ==================== */
@ -1421,38 +1425,33 @@ receive_packet(NCR_Instance inst, NTP_Local_Address *local_addr,
if (synced_packet && (!interleaved_packet || inst->valid_timestamps)) {
/* These are the timespec equivalents of the remote and local epochs */
struct timespec remote_receive, remote_transmit, prev_remote_receive;
struct timespec remote_receive, remote_transmit, remote_request_receive;
struct timespec local_average, remote_average;
double rx_ts_err;
precision = LCL_GetSysPrecisionAsQuantum() +
UTI_Log2ToDouble(message->precision);
SST_GetFrequencyRange(stats, &source_freq_lo, &source_freq_hi);
/* Select remote and local timestamps for the new sample */
if (interleaved_packet) {
UTI_Ntp64ToTimespec(&message->receive_ts, &remote_receive);
UTI_Ntp64ToTimespec(&message->transmit_ts, &remote_transmit);
UTI_Ntp64ToTimespec(&inst->remote_ntp_rx, &remote_request_receive);
local_receive = inst->local_rx;
local_transmit = inst->local_tx;
} else {
UTI_Ntp64ToTimespec(&message->receive_ts, &remote_receive);
UTI_Ntp64ToTimespec(&message->transmit_ts, &remote_transmit);
remote_request_receive = remote_receive;
local_receive = *rx_ts;
local_transmit = inst->local_tx;
}
/* Calculate intervals between remote and local timestamps */
if (interleaved_packet) {
UTI_Ntp64ToTimespec(&inst->remote_ntp_rx, &prev_remote_receive);
UTI_AverageDiffTimespecs(&remote_transmit, &remote_receive,
&remote_average, &remote_interval);
UTI_AverageDiffTimespecs(&inst->local_rx.ts, &inst->local_tx.ts,
&local_average, &local_interval);
server_interval = UTI_DiffTimespecsToDouble(&remote_transmit,
&prev_remote_receive);
rx_ts_err = inst->local_rx.err;
sample_rx_tss = inst->local_rx.source;
} else {
UTI_AverageDiffTimespecs(&remote_receive, &remote_transmit,
&remote_average, &remote_interval);
UTI_AverageDiffTimespecs(&inst->local_tx.ts, &rx_ts->ts,
UTI_AverageDiffTimespecs(&local_transmit.ts, &local_receive.ts,
&local_average, &local_interval);
server_interval = remote_interval;
rx_ts_err = rx_ts->err;
sample_rx_tss = rx_ts->source;
}
response_time = fabs(UTI_DiffTimespecsToDouble(&remote_transmit,
&remote_request_receive));
precision = LCL_GetSysPrecisionAsQuantum() + UTI_Log2ToDouble(message->precision);
/* Calculate delay */
delay = fabs(local_interval - remote_interval);
@ -1473,11 +1472,13 @@ receive_packet(NCR_Instance inst, NTP_Local_Address *local_addr,
sample pair. */
sample_time = local_average;
SST_GetFrequencyRange(stats, &source_freq_lo, &source_freq_hi);
/* Calculate skew */
skew = (source_freq_hi - source_freq_lo) / 2.0;
/* and then calculate peer dispersion */
dispersion = MAX(precision, MAX(inst->local_tx.err, rx_ts_err)) +
dispersion = MAX(precision, MAX(local_transmit.err, local_receive.err)) +
skew * fabs(local_interval);
/* Additional tests required to pass before accumulating the sample */
@ -1488,7 +1489,7 @@ receive_packet(NCR_Instance inst, NTP_Local_Address *local_addr,
the delay is not longer than half of the remote polling interval to
detect missed packets */
testA = delay - dispersion <= inst->max_delay && precision <= inst->max_delay &&
!(inst->mode == MODE_CLIENT && server_interval > MAX_SERVER_INTERVAL) &&
!(inst->mode == MODE_CLIENT && response_time > MAX_SERVER_INTERVAL) &&
!(inst->mode == MODE_ACTIVE && interleaved_packet &&
delay > UTI_Log2ToDouble(message->poll - 1));
@ -1512,10 +1513,11 @@ receive_packet(NCR_Instance inst, NTP_Local_Address *local_addr,
testD = message->stratum <= 1 || REF_GetMode() != REF_ModeNormal ||
pkt_refid != UTI_IPToRefid(&local_addr->ip_addr);
} else {
remote_interval = local_interval = server_interval = 0.0;
remote_interval = local_interval = response_time = 0.0;
offset = delay = dispersion = 0.0;
sample_time = rx_ts->ts;
sample_rx_tss = rx_ts->source;
local_receive = *rx_ts;
local_transmit = inst->local_tx;
testA = testB = testC = testD = 0;
}
@ -1561,8 +1563,8 @@ receive_packet(NCR_Instance inst, NTP_Local_Address *local_addr,
inst->valid_rx = 1;
}
if ((int)sample_rx_tss < 0 || sample_rx_tss >= sizeof (tss_chars) ||
(int)inst->local_tx.source < 0 || inst->local_tx.source >= sizeof (tss_chars))
if ((unsigned int)local_receive.source >= sizeof (tss_chars) ||
(unsigned int)local_transmit.source >= sizeof (tss_chars))
assert(0);
DEBUG_LOG("NTP packet lvm=%o stratum=%d poll=%d prec=%d root_delay=%f root_disp=%f refid=%"PRIx32" [%s]",
@ -1576,9 +1578,9 @@ receive_packet(NCR_Instance inst, NTP_Local_Address *local_addr,
UTI_Ntp64ToString(&message->transmit_ts));
DEBUG_LOG("offset=%.9f delay=%.9f dispersion=%f root_delay=%f root_dispersion=%f",
offset, delay, dispersion, root_delay, root_dispersion);
DEBUG_LOG("remote_interval=%.9f local_interval=%.9f server_interval=%.9f txs=%c rxs=%c",
remote_interval, local_interval, server_interval,
tss_chars[inst->local_tx.source], tss_chars[sample_rx_tss]);
DEBUG_LOG("remote_interval=%.9f local_interval=%.9f response_time=%.9f txs=%c rxs=%c",
remote_interval, local_interval, response_time,
tss_chars[local_transmit.source], tss_chars[local_receive.source]);
DEBUG_LOG("test123=%d%d%d test567=%d%d%d testABCD=%d%d%d%d kod_rate=%d interleaved=%d presend=%d valid=%d good=%d updated=%d",
test1, test2, test3, test5, test6, test7, testA, testB, testC, testD,
kod_rate, interleaved_packet, inst->presend_done, valid_packet, good_packet,
@ -1682,15 +1684,15 @@ receive_packet(NCR_Instance inst, NTP_Local_Address *local_addr,
inst->report.offset = offset;
inst->report.peer_delay = delay;
inst->report.peer_dispersion = dispersion;
inst->report.response_time = server_interval;
inst->report.response_time = response_time;
inst->report.jitter_asymmetry = SST_GetJitterAsymmetry(stats);
inst->report.tests = ((((((((test1 << 1 | test2) << 1 | test3) << 1 |
test5) << 1 | test6) << 1 | test7) << 1 |
testA) << 1 | testB) << 1 | testC) << 1 | testD;
inst->report.interleaved = interleaved_packet;
inst->report.authenticated = inst->auth_mode != AUTH_NONE;
inst->report.tx_tss_char = tss_chars[inst->local_tx.source];
inst->report.rx_tss_char = tss_chars[sample_rx_tss];
inst->report.tx_tss_char = tss_chars[local_transmit.source];
inst->report.rx_tss_char = tss_chars[local_receive.source];
inst->report.total_valid_count++;
}
@ -1708,8 +1710,8 @@ receive_packet(NCR_Instance inst, NTP_Local_Address *local_addr,
offset, delay, dispersion,
pkt_root_delay, pkt_root_dispersion, pkt_refid,
NTP_LVM_TO_MODE(message->lvm), interleaved_packet ? 'I' : 'B',
tss_chars[inst->local_tx.source],
tss_chars[sample_rx_tss]);
tss_chars[local_transmit.source],
tss_chars[local_receive.source]);
}
return good_packet;