hakmem/core/box/ss_tls_bind_box.h

// ss_tls_bind_box.h - TLS Bind Box
//
// Purpose:
//   - Encapsulate the logic for binding a SuperSlab slab to a thread's TLS.
//   - Ensures consistent initialization (superslab_init_slab) and TLS state updates.
//   - Acts as a "public-ish" internal API for Shared Pool, Warm Pool, and Page Box.

#ifndef HAK_SS_TLS_BIND_BOX_H
#define HAK_SS_TLS_BIND_BOX_H

#include "../hakmem_tiny_superslab.h"
#include "../tiny_tls.h"
#include "../hakmem_tiny_config.h"
#include "../box/tiny_page_box.h"  // For tiny_page_box_on_new_slab()
#include <stdio.h>
#include <stdatomic.h>

// Forward declaration if not included
// CRITICAL FIX: type must match core/hakmem_tiny_config.h (const size_t, not uint16_t)
extern const size_t g_tiny_class_sizes[TINY_NUM_CLASSES];

// TLS Bind Box: initialize one slab within a SuperSlab and bind it to TLS.
// Returns 1 on success, 0 on failure (TLS is left in a safe state).
//
// Arguments:
//   class_idx: Target size class index (0-7)
//   tls:       Pointer to thread-local TLS slab state (e.g. &g_tls_slabs[class_idx])
//   ss:        Target SuperSlab
//   slab_idx:  Index of the slab within the SuperSlab
//   owner_tid: Thread ID of the caller (used for slab ownership initialization)
//
// Pre-conditions:
//   - ss and slab_idx must be valid and acquired by the caller.
//   - tls must be the correct TLS state for the current thread/class.
//
// Post-conditions:
//   - On success: TLS is updated to point to the new slab, and the slab is initialized.
//   - On failure: TLS is reset to a clean empty state.
//
// Future Usage:
//   - Shared Pool: superslab_refill() calls this after acquiring from global pool.
//   - Warm Pool:   Will call this after popping a warm SuperSlab to re-bind it to TLS.
//   - Page Box:    Will call this to bind a specific page (slab) chosen from its list.
static inline int ss_tls_bind_one(int class_idx,
                                  TinyTLSSlab* tls,
                                  SuperSlab* ss,
                                  int slab_idx,
                                  uint32_t owner_tid)
{
    if (!ss || slab_idx < 0 || class_idx < 0 || class_idx >= TINY_NUM_CLASSES) {
        return 0;
    }

    // Initialize slab metadata for this class/thread.
    // NOTE:
    //  - superslab_init_slab must not recursively call superslab_refill().
    //  - class_idx will be reflected in slab_meta->class_idx.
    superslab_init_slab(ss,
                        slab_idx,
                        g_tiny_class_sizes[class_idx],
                        owner_tid);

    // CRITICAL FIX: Ensure class_idx is set after init.
    // New SuperSlabs start with meta->class_idx=0 (mmap zero-init).
    // superslab_init_slab() only sets it if meta->class_idx==255.
    // We must explicitly set it to the requested class to avoid C0/C7 confusion.
    TinySlabMeta* meta = &ss->slabs[slab_idx];
    uint8_t old_cls = meta->class_idx;
    meta->class_idx = (uint8_t)class_idx;
#if !HAKMEM_BUILD_RELEASE
    if (class_idx == 7 && old_cls != class_idx) {
        fprintf(stderr, "[SUPERSLAB_REFILL_FIX_C7] ss=%p slab=%d old_cls=%u new_cls=%d\n",
                (void*)ss, slab_idx, old_cls, class_idx);
    }
#endif

#if HAKMEM_BUILD_RELEASE
    static _Atomic int rel_c7_bind_logged = 0;
    if (class_idx == 7 &&
        atomic_load_explicit(&rel_c7_bind_logged, memory_order_relaxed) == 0) {
        fprintf(stderr,
                "[REL_C7_BIND] ss=%p slab=%d cls=%u cap=%u used=%u carved=%u\n",
                (void*)ss,
                slab_idx,
                (unsigned)meta->class_idx,
                (unsigned)meta->capacity,
                (unsigned)meta->used,
                (unsigned)meta->carved);
        atomic_store_explicit(&rel_c7_bind_logged, 1, memory_order_relaxed);
    }
#else
    static __thread int dbg_c7_bind_logged = 0;
    if (class_idx == 7 && dbg_c7_bind_logged == 0) {
        fprintf(stderr,
                "[DBG_C7_BIND] ss=%p slab=%d old_cls=%u new_cls=%u cap=%u used=%u carved=%u\n",
                (void*)ss,
                slab_idx,
                (unsigned)old_cls,
                (unsigned)meta->class_idx,
                (unsigned)meta->capacity,
                (unsigned)meta->used,
                (unsigned)meta->carved);
        dbg_c7_bind_logged = 1;
    }
#endif

    // Bind this slab to TLS for fast subsequent allocations.
    // Inline implementation of tiny_tls_bind_slab() to avoid header dependencies.
    // Original logic:
    //   tls->ss = ss;
    //   tls->slab_idx = (uint8_t)slab_idx;
    //   tls->meta = &ss->slabs[slab_idx];
    //   tls->slab_base = tiny_slab_base_for(ss, slab_idx);
    //   tiny_page_box_on_new_slab(tls);
    
    tls->ss = ss;
    tls->slab_idx = (uint8_t)slab_idx;
    tls->meta = meta; // already computed above
    tls->slab_base = tiny_slab_base_for(ss, slab_idx);

    // Notify Tiny Page Box (if enabled for this class)
    tiny_page_box_on_new_slab(tls);

    // Sanity check: TLS must now describe this slab for this class.
    // On failure, revert TLS to safe state and return 0.
    if (!(tls->ss == ss &&
          tls->slab_idx == (uint8_t)slab_idx &&
          tls->meta != NULL &&
          tls->meta->class_idx == (uint8_t)class_idx &&
          tls->slab_base != NULL)) {
        tls->ss = NULL;
        tls->meta = NULL;
        tls->slab_base = NULL;
        tls->slab_idx = 0;
        return 0;
    }

    return 1;
}

#endif // HAK_SS_TLS_BIND_BOX_H