hakmem/core/box/hak_alloc_api.inc.h

// hak_alloc_api.inc.h — Box: hak_alloc_at() implementation
// Phase 2 Update: Lane-based allocation routing (Single Source of Truth)
#ifndef HAK_ALLOC_API_INC_H
#define HAK_ALLOC_API_INC_H

#include "../hakmem_tiny.h"     // For tiny_get_max_size() + hak_lane_classify.inc.h
#include "../hakmem_pool.h"     // Phase 2: For hak_pool_try_alloc() (Pool lane 1025B-52KB)
#include "../hakmem_smallmid.h" // For Small-Mid Front Box (Phase 17-1)

#ifdef HAKMEM_POOL_TLS_PHASE1
#include "../pool_tls.h"
#endif

#include "mid_large_config_box.h"  // Phase 5-Step3: Compile-time config for Mid/Large

// Centralized OS mapping boundary to keep syscalls in one place
static inline void* hak_os_map_boundary(size_t size, uintptr_t site_id) {
#if HAKMEM_DEBUG_TIMING
    HKM_TIME_START(t_mmap);
#endif
    void* p = hak_alloc_mmap_impl(size);
#if HAKMEM_DEBUG_TIMING
    HKM_TIME_END(HKM_CAT_SYSCALL_MMAP, t_mmap);
#endif
    (void)site_id; // reserved for future accounting/learning
    return p;
}

__attribute__((always_inline))
inline void* hak_alloc_at(size_t size, hak_callsite_t site) {

#if HAKMEM_DEBUG_TIMING
    HKM_TIME_START(t0);
#endif
    static _Atomic int g_hak_alloc_at_trace = 0;
    if (atomic_fetch_add_explicit(&g_hak_alloc_at_trace, 1, memory_order_relaxed) < 128) {
        HAK_TRACE("[hak_alloc_at_enter]\n");
    }
    if (!g_initialized) hak_init();

    // Adaptive CAS: Register thread on first allocation
    hakmem_thread_register();

    uintptr_t site_id = (uintptr_t)site;

    // Phase 17-1: Small-Mid Front Box (256B-1KB) - TRY FIRST!
    // Strategy: Thin TLS cache layer, no backend (falls through on miss)
    // ENV: HAKMEM_SMALLMID_ENABLE=1 to enable (default: OFF)
    // CRITICAL: Must come BEFORE Tiny to avoid routing conflict
    // When enabled, auto-adjusts Tiny to C0-C5 (0-255B only)
    // PERF_OPT: unlikely hint - smallmid disabled by default
    if (__builtin_expect(smallmid_is_enabled() && smallmid_is_in_range(size), 0)) {
#if HAKMEM_DEBUG_TIMING
        HKM_TIME_START(t_smallmid);
#endif
        void* sm_ptr = smallmid_alloc(size);
#if HAKMEM_DEBUG_TIMING
        HKM_TIME_END(HKM_CAT_TINY_ALLOC, t_smallmid);
#endif
        // PERF_OPT: likely hint - smallmid usually succeeds when enabled
        if (__builtin_expect(sm_ptr != NULL, 1)) {
            hkm_ace_track_alloc();
            return sm_ptr;
        }
        // TLS miss: Fall through to Mid/ACE (Tiny skipped due to auto-adjust)
    }

    // Phase 16: Dynamic Tiny max size (ENV: HAKMEM_TINY_MAX_CLASS)
    // Default: 1023B (C0-C7), reduced to 255B (C0-C5) when Small-Mid enabled
    // Phase 17-1: Auto-adjusted to avoid overlap with Small-Mid
    if (__builtin_expect(size <= tiny_get_max_size(), 1)) {
#if HAKMEM_DEBUG_TIMING
        HKM_TIME_START(t_tiny);
#endif
        void* tiny_ptr = NULL;
#ifdef HAKMEM_TINY_PHASE6_BOX_REFACTOR
        tiny_ptr = hak_tiny_alloc_fast_wrapper(size);
#elif defined(HAKMEM_TINY_PHASE6_METADATA)
        tiny_ptr = hak_tiny_alloc_metadata(size);
#else
        tiny_ptr = hak_tiny_alloc(size);
#endif
#if HAKMEM_DEBUG_TIMING
        HKM_TIME_END(HKM_CAT_TINY_ALLOC, t_tiny);
#endif
        // PERF_OPT: likely hint - tiny allocations usually succeed (hot path)
        if (__builtin_expect(tiny_ptr != NULL, 1)) { hkm_ace_track_alloc(); return tiny_ptr; }

        // PHASE 7 CRITICAL FIX: No malloc fallback for Tiny failures
        // If Tiny fails for size <= tiny_get_max_size(), let it flow to Mid/ACE layers
        // This prevents mixed HAKMEM/libc allocation bugs
#if HAKMEM_TINY_HEADER_CLASSIDX
        if (!tiny_ptr && size <= tiny_get_max_size()) {
            #if !HAKMEM_BUILD_RELEASE
            // Tiny failed - log and continue to Mid/ACE (no early return!)
            static int log_count = 0;
            if (log_count < 3) {
                fprintf(stderr, "[DEBUG] Phase 7: tiny_alloc(%zu) failed, trying Mid/ACE layers (no malloc fallback)\n", size);
                log_count++;
            }
            #endif
            // Continue to Mid allocation below (do NOT fallback to malloc!)
        }
#else
        #if !HAKMEM_BUILD_RELEASE
        static int log_count = 0; if (log_count < 3) { fprintf(stderr, "[DEBUG] tiny_alloc(%zu) returned NULL, falling back\n", size); log_count++; }
        #endif
#endif
    }

    hkm_size_hist_record(size);

    // =========================================================================
    // Phase 2: Pool Lane (LANE_POOL: 1025B-52KB)
    // =========================================================================
    // Key fix: Route 1025-52KB to Pool BEFORE ACE
    // This eliminates the "unmanaged zone" (1025-2047B) that caused libc fragmentation
    //
    // Pool has 2KB as smallest class, so 1025-2047B requests use 2KB class
    // (internal fragmentation ~48%, but better than libc fragmentation!)

    if (HAK_LANE_IS_POOL(size)) {
#ifdef HAKMEM_POOL_TLS_PHASE1
        // Pool TLS fast path (8KB-52KB only, pool_tls.c classes)
        if (size >= 8192 && size <= 53248) {
            void* pool_ptr = pool_alloc(size);
            if (__builtin_expect(pool_ptr != NULL, 1)) return pool_ptr;
        }
#endif
        // Pool API path (1025B-52KB, hakmem_pool.c classes including 2KB)
        // This catches 1025-8191B range that Pool TLS doesn't handle
        void* pool_try = hak_pool_try_alloc(size, site_id);
        if (__builtin_expect(pool_try != NULL, 1)) return pool_try;
        // Fall through to ACE if Pool fails
    }

#if HAKMEM_FEATURE_EVOLUTION
    if (g_evo_sample_mask > 0) {
        static _Atomic uint64_t tick_counter = 0;
        if ((atomic_fetch_add(&tick_counter, 1) & g_evo_sample_mask) == 0) {
            struct timespec now; clock_gettime(CLOCK_MONOTONIC, &now);
            uint64_t now_ns = now.tv_sec * 1000000000ULL + now.tv_nsec;
            if (hak_evo_tick(now_ns)) {
                int new_strategy = hak_elo_select_strategy();
                atomic_store(&g_cached_strategy_id, new_strategy);
            }
        }
    }
#endif

    // Phase 5-Step3: Use Mid/Large Config Box (compile-time constant in PGO mode)
    size_t threshold;
    if (MID_LARGE_ELO_ENABLED) {
        int strategy_id = atomic_load(&g_cached_strategy_id);
        threshold = hak_elo_get_threshold(strategy_id);
    } else {
        threshold = 2097152;
    }

    if (MID_LARGE_BIGCACHE_ENABLED && size >= threshold) {
        void* cached_ptr = NULL;
#if HAKMEM_DEBUG_TIMING
        HKM_TIME_START(t_bc);
#endif
        if (hak_bigcache_try_get(size, site_id, &cached_ptr)) {
#if HAKMEM_DEBUG_TIMING
            HKM_TIME_END(HKM_CAT_BIGCACHE_GET, t_bc);
#endif
            return cached_ptr;
        }
#if HAKMEM_DEBUG_TIMING
        HKM_TIME_END(HKM_CAT_BIGCACHE_GET, t_bc);
#endif
    }

    // =========================================================================
    // Phase 2: ACE Lane (LANE_ACE: 52KB-2MB) + HUGE Lane (2MB+)
    // =========================================================================
    // ACE handles sizes between Pool max (52KB) and huge threshold (2MB)
    // Sizes > 2MB go directly to mmap (LANE_HUGE)

    if (HAK_LANE_IS_ACE(size) || size > LANE_POOL_MAX) {
        const FrozenPolicy* pol = hkm_policy_get();
#if HAKMEM_DEBUG_TIMING
        HKM_TIME_START(t_ace);
#endif
        void* l1 = hkm_ace_alloc(size, site_id, pol);
#if HAKMEM_DEBUG_TIMING
        HKM_TIME_END(HKM_CAT_POOL_GET, t_ace);
#endif
        if (l1) return l1;
    }

    // =========================================================================
    // Phase 2: Final Fallback (mmap) - should be rare after Pool fix
    // =========================================================================
    // With Phase 2 Pool extension, 1025-52KB should be handled by Pool
    // This fallback is for:
    //   - LANE_HUGE (2MB+): Normal mmap path
    //   - Pool/ACE failures: Emergency fallback
    //   - LANE_TINY failures: Should not happen (design bug)

    extern _Atomic uint64_t g_final_fallback_mmap_count;

    void* ptr;
    if (HAK_LANE_IS_HUGE(size)) {
        // LANE_HUGE: Normal path for 2MB+ allocations
        atomic_fetch_add(&g_final_fallback_mmap_count, 1);
        ptr = hak_os_map_boundary(size, site_id);
    } else if (size > LANE_TINY_MAX) {
        // Pool or ACE failed for 1025B-2MB range - emergency mmap fallback
        atomic_fetch_add(&g_final_fallback_mmap_count, 1);
        static _Atomic int gap_alloc_count = 0;
        int count = atomic_fetch_add(&gap_alloc_count, 1);
        #if !HAKMEM_BUILD_RELEASE
        if (count < 5) {
            fprintf(stderr, "[HAKMEM] Phase 2 WARN: Pool/ACE fallback size=%zu (should be rare)\n", size);
        }
        #endif
        ptr = hak_os_map_boundary(size, site_id);
    } else {
        // LANE_TINY failed - this is a design bug!
        HAK_LANE_ASSERT_NO_FALLBACK(LANE_FALLBACK, size);
        static _Atomic int oom_count = 0;
        int count = atomic_fetch_add(&oom_count, 1);
        if (count < 10) {
            fprintf(stderr, "[HAKMEM] BUG: Tiny lane failed for size=%zu (should not happen)\n", size);
        }
        errno = ENOMEM;
        return NULL;
    }
    if (!ptr) return NULL;

    if (g_evo_sample_mask > 0) { hak_evo_record_size(size); }
    AllocHeader* hdr = (AllocHeader*)((char*)ptr - HEADER_SIZE);
    if (hdr->magic != HAKMEM_MAGIC) { fprintf(stderr, "[hakmem] ERROR: Invalid magic in allocated header!\n"); return ptr; }
    hdr->alloc_site = site_id;
    hdr->class_bytes = (size >= threshold) ? threshold : 0;
    // Guard byte for FrontGate V2: force ptr[-1] away from 0xA?/0xB? to avoid Tiny misclass
    ((uint8_t*)hdr)[HEADER_SIZE - 1] = HAKMEM_FG_GUARD_BYTE;

#if HAKMEM_DEBUG_TIMING
    HKM_TIME_END(HKM_CAT_HAK_ALLOC, t0);
#endif
    return ptr;
}

#endif // HAK_ALLOC_API_INC_H