hakmem/core/box/free_dispatch_stats_box.h

#ifndef HAKMEM_FREE_DISPATCH_STATS_BOX_H
#define HAKMEM_FREE_DISPATCH_STATS_BOX_H

#include <stdint.h>
#include <stdbool.h>
#include <stdlib.h>

typedef struct FreeDispatchStats {
    uint64_t total_calls;

    // Domain classification
    uint64_t domain_tiny;
    uint64_t domain_mid;
    uint64_t domain_large;

    // Route classification (tiny domain)
    uint64_t route_ultra;         // C4-C7 ULTRA 直行
    uint64_t route_tiny_legacy;   // Tiny legacy path
    uint64_t route_pool_v1;       // pool v1 経由
    uint64_t route_core_v6;       // core v6 (C6-only)
    uint64_t route_core_v7;       // core v7 stub (Phase v7-1)

    // Performance counters
    uint64_t env_checks;          // ENV 読み回数（概算）
    uint64_t route_for_class_calls; // tiny_route_for_class() 呼び出し回数
} FreeDispatchStats;

// ENV gate
static inline bool free_dispatch_stats_enabled(void) {
    static int g_enabled = -1;
    if (__builtin_expect(g_enabled == -1, 0)) {
        const char* e = getenv("HAKMEM_FREE_DISPATCH_STATS");
        g_enabled = (e && *e && *e != '0') ? 1 : 0;
    }
    return g_enabled;
}

// Global stats instance
extern FreeDispatchStats g_free_dispatch_stats;

// Increment macros (with unlikely guard)
#define FREE_DISPATCH_STAT_INC(field) \
    do { if (__builtin_expect(free_dispatch_stats_enabled(), 0)) { \
        g_free_dispatch_stats.field++; \
    } } while(0)

#endif // HAKMEM_FREE_DISPATCH_STATS_BOX_H