hakmem/core/tiny_mmap_gate.h

// tiny_mmap_gate.h - Mmap Gate (must-adopt-before-mmap)
#pragma once
#include "hakmem_tiny_superslab.h"
#include "tiny_refill.h"
#include "hakmem_super_registry.h"
#include "tiny_route.h"
// Box: adopt gate (header-only)
#include "box/adopt_gate_box.h"

// Returns adopted SuperSlab* or NULL
static inline SuperSlab* tiny_must_adopt_gate(int class_idx, TinyTLSSlab* tls) {
    // Env: enable gate
    static int en = -1;
    if (__builtin_expect(en == -1, 0)) {
        const char* s = getenv("HAKMEM_TINY_MUST_ADOPT");
        en = (s && atoi(s) != 0) ? 1 : 0;
    }
    if (!en) return NULL;
    // Adaptive: require remote activity and apply cooldown on failures
    extern _Atomic int g_ss_remote_seen;
    if (atomic_load_explicit(&g_ss_remote_seen, memory_order_relaxed) == 0) {
        return NULL;  // No remote traffic observed yet → skip heavy adopt path
    }
    // Cooldown (TLS per-class)
    static __thread int s_cooldown[TINY_NUM_CLASSES] = {0};
    static int s_cd_def = -1;
    if (__builtin_expect(s_cd_def == -1, 0)) {
        const char* cd = getenv("HAKMEM_TINY_SS_ADOPT_COOLDOWN");
        int v = cd ? atoi(cd) : 32;  // default: 32 missesの間は休む
        if (v < 0) v = 0;
        if (v > 1024) v = 1024;
        s_cd_def = v;
    }
    if (s_cooldown[class_idx] > 0) {
        s_cooldown[class_idx]--;
        return NULL;
    }

    // Delegate to Box
    SuperSlab* ss = adopt_gate_try(class_idx, tls);
    if (!ss && s_cd_def > 0) {
        s_cooldown[class_idx] = s_cd_def;  // backoff on miss
    }
    return ss;
}