hakmem/core/box/pool_refill.inc.h

// pool_refill.inc.h — Box: L2 Pool refill and adaptive bundling
#ifndef POOL_REFILL_INC_H
#define POOL_REFILL_INC_H

// Adjust bundle factor per class based on windowed hits/misses
static inline void pool_update_bundle_factor(int class_idx) {
    uint64_t h = g_pool.hits[class_idx];
    uint64_t m = g_pool.misses[class_idx];
    uint64_t dh = h - g_pool.last_hits[class_idx];
    uint64_t dm = m - g_pool.last_misses[class_idx];
    uint64_t dt = dh + dm;
    if (dt < 256) return;  // wait for window to accumulate

    int bf = g_pool.bundle_factor[class_idx];
    if (bf <= 0) bf = 1;
    if (dt > 0) {
        double hit_rate = (double)dh / (double)dt;
        if (hit_rate < 0.60 && dm > (dh + 16)) {
            if (bf < 4) bf++;
        } else if (hit_rate > 0.90 && dh > (dm + 32)) {
            if (bf > 1) bf--;
        }
    }
    g_pool.bundle_factor[class_idx] = bf;
    g_pool.last_hits[class_idx] = h;
    g_pool.last_misses[class_idx] = m;
}

// Refill freelist by allocating a new 64KiB page and splitting to blocks
// Returns: 1 on success, 0 on failure
static inline int refill_freelist(int class_idx, int shard_idx) {
    if (class_idx < 0 || class_idx >= POOL_NUM_CLASSES) return 0;
    if (shard_idx < 0 || shard_idx >= POOL_NUM_SHARDS) return 0;

    size_t user_size = g_class_sizes[class_idx];
    size_t block_size = HEADER_SIZE + user_size;
    int blocks_per_page = POOL_PAGE_SIZE / block_size;
    if (blocks_per_page == 0) return 0;

    void* page = mmap(NULL, POOL_PAGE_SIZE, PROT_READ | PROT_WRITE,
                      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
    if (!page) return 0;

    // Update bundle factor based on windowed stats
    pool_update_bundle_factor(class_idx);
    int bundles = g_pool.bundle_factor[class_idx];
    if (bundles < 1) bundles = 1;
    if (bundles > 4) bundles = 4;

    // Soft CAP guidance from FrozenPolicy
    const FrozenPolicy* pol = hkm_policy_get();
    if (pol) {
        uint16_t cap = 0;
        if (class_idx < 5) cap = pol->mid_cap[class_idx];
        else if (class_idx == 5 && pol->mid_dyn1_bytes != 0) cap = pol->mid_cap_dyn1;
        else if (class_idx == 6 && pol->mid_dyn2_bytes != 0) cap = pol->mid_cap_dyn2;
        if (cap > 0) {
            uint64_t have = g_pool.pages_by_class[class_idx];
            if (have >= cap) {
                bundles = 1;  // over cap: refill minimally
            } else {
                uint64_t deficit = (cap - have);
                if (deficit < (uint64_t)bundles) bundles = (int)deficit;
                if (bundles < 1) bundles = 1;
                if (bundles > 4) bundles = 4;
                if (deficit >= (uint64_t)g_pool_min_bundle && bundles < g_pool_min_bundle) bundles = g_pool_min_bundle;
            }
        }
    }

    int pages_allocated_this_call = 0;
    for (int b = 0; b < bundles; b++) {
        // Split page into blocks and link into freelist
        PoolBlock* freelist_head = NULL;
        for (int i = 0; i < blocks_per_page; i++) {
            void* raw_block = (char*)page + (i * block_size);
            __builtin_prefetch((char*)raw_block + block_size, 1, 1);
            PoolBlock* block = (PoolBlock*)raw_block;
            block->next = freelist_head;
            freelist_head = block;
        }
        if (g_pool.freelist[class_idx][shard_idx]) {
            PoolBlock* tail = freelist_head;
            while (tail->next) tail = tail->next;
            tail->next = g_pool.freelist[class_idx][shard_idx];
        }
        g_pool.freelist[class_idx][shard_idx] = freelist_head;
        // Register this 64KiB page (shared owner)
        mid_desc_register(page, class_idx, 0);

        if (b + 1 < bundles) {
            page = mmap(NULL, POOL_PAGE_SIZE, PROT_READ | PROT_WRITE,
                        MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
            if (!page) break;
        }
        pages_allocated_this_call++;
    }

    set_nonempty_bit(class_idx, shard_idx);
    g_pool.refills[class_idx]++;
    g_pool.total_pages_allocated += pages_allocated_this_call;
    g_pool.pages_by_class[class_idx] += pages_allocated_this_call;
    g_pool.total_bytes_allocated += (uint64_t)pages_allocated_this_call * (uint64_t)POOL_PAGE_SIZE;
    return 1;
}

#endif // POOL_REFILL_INC_H