Files
plotter/tests/test_measure.cpp
T
Martino Ferrari a08b184481 fix(plot,render,gl): live streaming measurements, handed-back GL state
Final whole-branch review fixes.

1 (Important). Plot::measurement() cached on (series pointer, sample count)
only, so a saturated StreamSeries -- whose size() stays pinned while x0()
advances every acquire() -- froze its readout on the first saturated frame
until a cursor moved. The cache key now carries the series' x0() (new
MeasureSlot::last_x0), so a sliding window recomputes and a static series
still does not: asserted with a new macro-gated counter hook
(plot/detail/measure_count.hpp, PLOT_COUNT_MEASURE_RECOMPUTES, wired like the
pyramid and ring counters, absent from the release library). New case
saturated_stream_measurement_tracks_the_sliding_window: saturated ring,
stationary cursors, ramp in absolute x -- zero recomputes for repeated reads
with nothing moving, one per acquire while it slides.

2-3, 9. Spec: 4.3 described a GL_LINE_STRIP path that does not exist (there is
one rasteriser -- instanced anti-aliased quads -- and dense_threshold_spp
selects the gather level, not a primitive); 8 named a PLOT_GL_CHECK() macro
that exists nowhere, and stated no exception policy. The table, the field's
comment and 8 now describe the real gather-level threshold, the real
glGetError() drain plus the stores' drop-to-orphan fallbacks, and the real
policy: library failures return Status/bool, allocating entry points propagate
std::bad_alloc.

4. The frame handed back neither GL_UNPACK_ALIGNMENT (init() sets 1 for the
atlas) nor the clear colour (queried once with a new glGetFloatv entry).
end_frame() restores both and renderer.hpp lists them in the residue
contract.

5. draw() kept a host TextBackend for layout while drawing with its own font.
The renderer now installs its font unconditionally -- strips and labels measure
and draw with one backend -- with a debug-build diagnostic if a different one
was set, and Plot::set_text_backend() is documented as the no-renderer path.
New case renderer_measures_the_labels_it_draws asserts layout, measuring and
the drawn label's ink agree.

6-10. draw()'s style overwrite stated at the call site; the load-sensitive
wall-clock bound in test_measure.cpp replaced by a counter assertion (same
interval, same fold count over a 512x length ratio); dump_frame_ppm drops
noexcept and says why it may allocate; error.txt ignored (not this project's,
not generated here) rather than deleted.

Verified: debug and release build clean (-Wall -Wextra -Wpedantic -Wconversion
-Wshadow), 4/4 ctest entries pass, 130 cases pass (was 127), umbrella and
header self-containment checks pass, and no counter symbol in the release
archive.
2026-09-28 03:42:34 +02:00

65 lines
3.2 KiB
C++

#include "harness.hpp"
#include <plot/plot/measure.hpp>
#include <plot/data/array_series.hpp>
#include <plot/data/detail/cover_count.hpp>
#include <algorithm>
#include <atomic>
#include <cmath>
#include <vector>
PLOT_TEST(measurement_over_interval_matches_direct_computation) {
std::vector<f32> y; for (int i = 0; i < 1000; ++i) y.push_back(f32(std::sin(static_cast<double>(i) * 0.01)));
plot::data::ArraySeries s(std::move(y), 0.0, 1.0);
const auto m = plot::Measure::evaluate(s, 100, 800);
double sum = 0, sumsq = 0, integral = 0; float lo = 1e30f, hi = -1e30f;
for (u64 i = 100; i < 800; ++i) {
const double v = std::sin(static_cast<double>(i) * 0.01);
sum += v; sumsq += v * v; integral += v; // dx == 1
lo = std::min(lo, float(v)); hi = std::max(hi, float(v));
}
const double n = 700;
PLOT_CHECK_NEAR(m.mean, sum / n, 1e-5);
PLOT_CHECK_NEAR(m.rms, std::sqrt(sumsq / n), 1e-5);
PLOT_CHECK_NEAR(m.integral, integral, 1e-3);
PLOT_CHECK_NEAR(m.ymin, lo, 1e-6);
PLOT_CHECK_NEAR(m.ymax, hi, 1e-6);
PLOT_CHECK_NEAR(m.dx, 699.0, 1e-9);
}
PLOT_TEST(measurement_uses_pyramid_not_scan) {
// Guard against a future regression that linear-scans the series, counted rather
// than timed: a query's cost is the pyramid's covering decomposition -- at most
// two entries per level -- so the entry count must depend on the *interval* and
// never on the series length. The wall-clock bound this replaced (1000 evals in
// < 50 ms) failed on a loaded machine and passed vacuously on a fast one, while
// saying nothing about the shape of the work.
std::vector<f32> big(1u << 22, 1.0f); // 4M samples
plot::data::ArraySeries s_big(std::move(big), 0.0, 1.0);
std::vector<f32> small(1u << 13, 1.0f); // 8k samples: 512x shorter
plot::data::ArraySeries s_small(std::move(small), 0.0, 1.0);
auto covers = [](const plot::data::Series& s, u64 begin, u64 end) {
plot::data::detail::cover_entry_count().store(0, std::memory_order_relaxed);
(void)plot::Measure::evaluate(s, begin, end);
return plot::data::detail::cover_entry_count().load(std::memory_order_relaxed);
};
// The same absolute interval over both series walks the same run of level-0
// buckets, so it must fold the same entries: a decomposition that degenerated
// with series length -- one bucket at a time, or a scan -- shows up here.
const u64 big_covers = covers(s_big, 1024, 7000);
PLOT_CHECK(big_covers == covers(s_small, 1024, 7000));
PLOT_CHECK(big_covers > 0u); // the interior came from the pyramid
PLOT_CHECK(big_covers <= 32u); // ~2 entries per level, few levels here
// A 1-sample interval needs no whole bucket at all: its answer is the two partial
// edge buckets a pyramid of complete buckets cannot cover (at most 2 * kBucket raw
// samples through copy_raw), so it folds nothing whatever the series holds.
PLOT_CHECK(covers(s_big, 1'000'000, 1'000'001) == 0u);
}
PLOT_TEST(empty_and_single_sample_intervals_are_valid_false) {
std::vector<f32> y{3.0f};
plot::data::ArraySeries s(std::move(y), 0.0, 1.0);
PLOT_CHECK(!plot::Measure::evaluate(s, 0, 0).valid);
PLOT_CHECK(!plot::Measure::evaluate(s, 1, 1).valid);
}