hakmem/core/box/smallobject_hotbox_v4_box.h

// smallobject_hotbox_v4_box.h - SmallObject HotHeap v4 (型スケルトン)
//
// 役割:
//   - v4 のページ / クラス / TLS コンテキスト型と API 宣言だけを定義する箱。
//   - 挙動はまだ v3/v1 のまま。alloc/free 本体は後続フェーズで実装する。
#pragma once

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

#include "tiny_geometry_box.h"

#ifndef SMALLOBJECT_NUM_CLASSES
#define SMALLOBJECT_NUM_CLASSES TINY_NUM_CLASSES
#endif

struct SmallSegment;  // Forward declaration, defined in smallsegment_v4_box.h

// ============================================================================
// SmallObject v4 HotBox Type Definitions
// ============================================================================

// SmallPageMeta: Page metadata for v4 HotBox
typedef struct SmallPageMeta {
    void* freelist;
    uint16_t used;
    uint16_t capacity;
    uint8_t class_idx;
    uint8_t flags;
    uint32_t block_size;
    uint8_t* base;
    void* slab_ref;  // Superslab / lease token (box boundary)
    struct SmallSegment* segment;  // Segment owner (NULL if Tiny v1 path)
    struct SmallPageMeta* next;
} SmallPageMeta;

// SmallClassHeap: Per-class heap state (current / partial / full lists)
typedef struct SmallClassHeap {
    SmallPageMeta* current;
    SmallPageMeta* partial_head;
    SmallPageMeta* full_head;
    uint32_t partial_count;
} SmallClassHeap;

// SmallHeapCtx: TLS heap context (per-thread)
typedef struct SmallHeapCtx {
    SmallClassHeap cls[SMALLOBJECT_NUM_CLASSES];
} SmallHeapCtx;

// SmallC6FastState: TLS fastlist state for C6 (Phase v4-mid-6)
typedef struct SmallC6FastState {
    void* freelist;       // C6 fastlist head
    void* page_base;      // Current C6 page base address
    uint32_t used;        // Usage count (synced to page->used on switch)
    uint32_t capacity;    // Page capacity
    SmallPageMeta* meta;  // Back-pointer to page metadata
} SmallC6FastState;

// Backward compatibility aliases (deprecated, use SmallXxx directly)
typedef SmallPageMeta small_page_v4;
typedef SmallClassHeap small_class_heap_v4;
typedef SmallHeapCtx small_heap_ctx_v4;

small_heap_ctx_v4* small_heap_ctx_v4_get(void);

// Hot path API (C7-only stub; later phases will expand)
void* small_heap_alloc_fast_v4(small_heap_ctx_v4* ctx, int class_idx);
void small_heap_free_fast_v4(small_heap_ctx_v4* ctx, int class_idx, void* ptr);
int smallobject_hotbox_v4_can_own(int class_idx, void* ptr);