test

#include <cmath>

#include <mutex>

// Cached once (mirrors ensureQuicPerfReporterStarted()'s "single getenv()

// call and nothing else" pattern below): callgrind profiling of a bulk

// transfer showed getenv("QUIC_TRACE") re-queried on every single QUIC_DBG

// call -- and there are 61 call sites, several in the per-packet hot path

// (sendPacket, processApplicationPacketsBatch, unprotectPacket) -- becoming

// the single largest cost in the whole program (~18% of instructions) once

// an unrelated per-packet memset elsewhere was fixed. The environment

// variable can't change once the process has started, so checking it any

// more than once is pure waste.

inline bool quicTraceEnabled() {

    static const bool enabled = (getenv("QUIC_TRACE") != nullptr);

    return enabled;

}

#define QUIC_DBG(fmt, ...) do { \

    if (getenv("QUIC_TRACE")) { \

    if (quicTraceEnabled()) { \

        fprintf(stderr, "[%.6f] " fmt "\n", \

                std::chrono::duration<double>(std::chrono::steady_clock::now().time_since_epoch()).count(), ##__VA_ARGS__); \

    } \