Initial commit

include/rockstream/latency.hpp

@@ -0,0 +1,45 @@
+#pragma once
+
+#include <cstddef>
+#include <cstdint>
+#include <iosfwd>
+#include <span>
+#include <vector>
+
+namespace rockstream {
+using Nanoseconds = std::int64_t;
+Nanoseconds monotonic_ns();
+
+struct FrameTiming {
+    std::uint64_t id = 0;
+    Nanoseconds scheduled = 0;
+    Nanoseconds submit = 0;
+    Nanoseconds accepted = 0;
+    Nanoseconds first = 0;
+    Nanoseconds final = 0;
+    Nanoseconds reclaimed = 0;
+    std::size_t bytes = 0;
+    std::size_t packets = 0;
+    int intra = -1; // -1 when the SDK did not provide an indicator.
+};
+
+// Frame identity is carried in MPP PTS; completion and reclamation are independent.
+class LatencyLog {
+public:
+    explicit LatencyLog(std::size_t capacity);
+    void submitted(std::uint64_t id, Nanoseconds scheduled, Nanoseconds begin, Nanoseconds end);
+    void packet(std::uint64_t id, Nanoseconds observed, std::size_t bytes, bool eoi, int intra);
+    void reclaimed(std::uint64_t id, Nanoseconds observed);
+    [[nodiscard]] bool complete(std::uint64_t id) const;
+    [[nodiscard]] const FrameTiming& at(std::uint64_t id) const;
+    [[nodiscard]] std::span<const FrameTiming> frames() const { return frames_; }
+private:
+    FrameTiming& checked(std::uint64_t id);
+    std::vector<FrameTiming> frames_;
+};
+
+// Nearest-rank percentile; sorts its own copy and rejects empty/invalid inputs.
+double percentile(std::vector<double> values, double percent);
+void print_latency_report(std::ostream& out, const LatencyLog& log, std::uint32_t warmup);
+void write_latency_csv(std::ostream& out, const LatencyLog& log, std::uint32_t warmup);
+} // namespace rockstream