Martino FerrariandClaude Sonnet 4.6
41ab151a2f
Adds TimeBase.h/cpp with ClockOffset (latched wall-clock offset with one-sided recalibration on positive drift only, so early-arriving packets do not wobble the trace) and HrtRateFit (sliding-window OLS that recovers an unknown hrt tick rate from receive timestamps). Also adds TimeSignalScale() which maps UDPS type codes to seconds-per-count. 9 new tests, all 28 pass. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
100 lines
3.2 KiB
C++
100 lines
3.2 KiB
C++
#include "TimeBase.h"
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#include <gtest/gtest.h>
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using namespace udpscope;
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TEST(ClockOffset, MapsTheFirstReadingOntoWallClockExactly) {
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ClockOffset off;
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EXPECT_FALSE(off.valid());
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const double wall = 1756291200.5;
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EXPECT_DOUBLE_EQ(off.map(10.0, wall), wall);
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EXPECT_TRUE(off.valid());
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}
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// Network delay jitters the arrival time. If the offset chased every packet
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// the whole trace would wobble, so it is latched and only corrected on real
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// drift.
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TEST(ClockOffset, HoldsTheOffsetThroughSmallArrivalJitter) {
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ClockOffset off;
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off.map(10.0, 1000.0); // offset = 990
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EXPECT_DOUBLE_EQ(off.map(11.0, 1001.02), 1001.0);
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EXPECT_DOUBLE_EQ(off.map(12.0, 1000.97), 1002.0);
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}
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TEST(ClockOffset, RecalibratesWhenDriftExceedsTheThreshold) {
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ClockOffset off;
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off.map(10.0, 1000.0); // offset = 990
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/* Producer clock jumped (restart, re-phase): 5 s of error is not jitter. */
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const double mapped = off.map(11.0, 1006.0);
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EXPECT_DOUBLE_EQ(mapped, 1006.0);
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}
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TEST(ClockOffset, ResetForgetsTheCalibration) {
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ClockOffset off;
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off.map(10.0, 1000.0);
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off.reset();
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EXPECT_FALSE(off.valid());
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EXPECT_DOUBLE_EQ(off.map(50.0, 2000.0), 2000.0);
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}
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// The tick rate of the producer's high-resolution timer is not carried by the
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// protocol, and StreamHub's trick of using the local MARTe timer frequency only
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// works on the producer's own host. Recover it from the data instead.
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TEST(HrtRateFit, RecoversAKnownTickRate) {
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HrtRateFit fit;
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const double ticksPerSec = 2.5e9;
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EXPECT_FALSE(fit.ready());
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for (int i = 0; i < 64; i++) {
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const double wall = 1000.0 + i * 0.01;
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fit.add(static_cast<uint64_t>(wall * ticksPerSec), wall);
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}
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ASSERT_TRUE(fit.ready());
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EXPECT_NEAR(fit.ticksPerSecond(), ticksPerSec, ticksPerSec * 1e-6);
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}
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TEST(HrtRateFit, IsNotReadyBeforeTheMinimumSampleCount) {
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HrtRateFit fit;
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for (size_t i = 0; i < HrtRateFit::kMinSamples - 1; i++) {
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fit.add(static_cast<uint64_t>(i) * 1000000u, 1000.0 + i * 0.001);
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}
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EXPECT_FALSE(fit.ready());
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fit.add(static_cast<uint64_t>(HrtRateFit::kMinSamples) * 1000000u,
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1000.0 + HrtRateFit::kMinSamples * 0.001);
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EXPECT_TRUE(fit.ready());
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}
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TEST(HrtRateFit, ToSecondsUsesTheFittedRate) {
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HrtRateFit fit;
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const double ticksPerSec = 1.0e9;
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for (int i = 0; i < 64; i++) {
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const double wall = 500.0 + i * 0.005;
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fit.add(static_cast<uint64_t>(wall * ticksPerSec), wall);
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}
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ASSERT_TRUE(fit.ready());
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EXPECT_NEAR(fit.toSeconds(2000000000ull), 2.0, 1e-4);
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}
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TEST(HrtRateFit, SurvivesAStalledClock) {
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HrtRateFit fit;
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for (int i = 0; i < 64; i++) {
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fit.add(12345u, 1000.0 + i * 0.01); /* hrt never advances */
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}
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/* A degenerate fit must not produce a rate that would divide by zero. */
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if (fit.ready()) {
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EXPECT_GT(fit.ticksPerSecond(), 0.0);
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}
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}
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TEST(TimeSignalScale, UsesNanosecondsForUint64AndMicrosecondsOtherwise) {
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EXPECT_DOUBLE_EQ(TimeSignalScale(6 /* UDPS_T_UINT64 */), 1.0e-9);
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EXPECT_DOUBLE_EQ(TimeSignalScale(9 /* UDPS_T_FLOAT64 */), 1.0e-6);
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EXPECT_DOUBLE_EQ(TimeSignalScale(4 /* UDPS_T_UINT32 */), 1.0e-6);
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}
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