// hakmem_debug.h - Debug Timing Infrastructure (Box理論: 計測箱)
// Purpose: Lightweight timing measurement for performance analysis
//
// License: MIT
// Date: 2025-10-21

#pragma once
#include <stdint.h>
#include <time.h>

#ifdef __cplusplus
extern "C" {
#endif

// ============================================================================
// Configuration (環境変数で制御可能)
// ============================================================================

// Build-time guard: HAKMEM_DEBUG_TIMING=1 enables all timing code
#ifndef HAKMEM_DEBUG_TIMING
#define HAKMEM_DEBUG_TIMING 0  // Default: OFF (zero overhead)
#endif

// Runtime guard: HAKMEM_TIMING=1 enables timing at runtime
// Sampling rate: HAKMEM_TIMING_SAMPLE=N (default: 64, means 1/64 sampling)

// ============================================================================
// Timing Categories (計測カテゴリID)
// ============================================================================

typedef enum {
    // Syscalls and fallbacks
    HKM_CAT_SYSCALL_MMAP = 0,
    HKM_CAT_SYSCALL_MUNMAP,
    HKM_CAT_SYSCALL_MADVISE,
    HKM_CAT_FALLBACK_MALLOC,

    // Whale Fast-Path
    HKM_CAT_WHALE_GET,
    HKM_CAT_WHALE_PUT,

    // L2.5 Pool (Phase 6.11.3: Added for profiling)
    HKM_CAT_L25_GET,
    HKM_CAT_L25_PUT,
    HKM_CAT_L25_REFILL,

    // Tiny Pool (Phase 6.11.3: Added for profiling)
    HKM_CAT_TINY_ALLOC,
    HKM_CAT_TINY_FREE,
    HKM_CAT_TINY_SLAB_SEARCH,

    // BigCache (Phase 6.11.3: Added for profiling)
    HKM_CAT_BIGCACHE_GET,
    HKM_CAT_BIGCACHE_PUT,
    HKM_CAT_BIGCACHE_EVICT_SCAN,

    // Site Rules (Phase 6.11.3: Added for profiling)
    HKM_CAT_SITE_RULES_LOOKUP,
    HKM_CAT_SITE_RULES_ADOPT,

    // ELO Learning (Phase 6.11.3: Added for profiling)
    HKM_CAT_ELO_SELECT,
    HKM_CAT_ELO_UPDATE,

    // Top-level API (Phase 6.11.3: Added for profiling)
    HKM_CAT_HAK_ALLOC,
    HKM_CAT_HAK_FREE,

    // Legacy (keep for compatibility)
    HKM_CAT_REGION_GET,
    HKM_CAT_REGION_PUT,
    HKM_CAT_HASH_FNV1A,

    // Mid (L2 Pool) fine-grained
    HKM_CAT_POOL_GET,
    HKM_CAT_POOL_LOCK,
    HKM_CAT_POOL_REFILL,
    HKM_CAT_TC_DRAIN,
    HKM_CAT_TLS_FAST,
    HKM_CAT_SHARD_STEAL,
    // Additional Mid (L2) fine-grained (NEW)
    HKM_CAT_POOL_TLS_RING_POP,
    HKM_CAT_POOL_TLS_LIFO_POP,
    HKM_CAT_POOL_REMOTE_PUSH,
    HKM_CAT_POOL_ALLOC_TLS_PAGE,

    // L2.5 (LargePool) fine-grained (NEW)
    HKM_CAT_L25_LOCK,
    HKM_CAT_L25_TLS_RING_POP,
    HKM_CAT_L25_TLS_LIFO_POP,
    HKM_CAT_L25_TC_DRAIN,
    HKM_CAT_L25_REMOTE_PUSH,
    HKM_CAT_L25_ALLOC_TLS_PAGE,
    HKM_CAT_L25_SHARD_STEAL,

    HKM_CAT_MAX  // Total number of categories
} HkmTimingCategory;

// ============================================================================
// Timing Statistics (TLS per-thread)
// ============================================================================

typedef struct {
    uint64_t count;     // Number of calls
    uint64_t cycles;    // Total cycles (TSC or nanoseconds)
} HkmTimingStat;

// ============================================================================
// Public API
// ============================================================================

// Initialize timing subsystem (called from hak_init)
void hkm_timing_init(void);

// Shutdown timing subsystem (called from hak_shutdown, dumps stats)
void hkm_timing_shutdown(void);

// Get current timestamp (TSC or clock_gettime)
static inline uint64_t hkm_tsc_now(void);

// Increment counter for category
void hkm_count_inc(HkmTimingCategory cat);

// Add cycles to category
void hkm_cycles_add(HkmTimingCategory cat, uint64_t cycles);

// Dump all statistics (called at exit or on demand)
void hkm_timing_dump(void);

// ============================================================================
// Timing Macros (inline化、ビルド時に消える)
// ============================================================================

#if HAKMEM_DEBUG_TIMING

// HKM_TIME_START(var) - Start timing, stores start time in var
#define HKM_TIME_START(var) \
    uint64_t var = hkm_tsc_now()

// HKM_TIME_END(cat, var) - End timing, add elapsed time to category
#define HKM_TIME_END(cat, var) \
    do { \
        uint64_t _end = hkm_tsc_now(); \
        hkm_cycles_add(cat, _end - var); \
        hkm_count_inc(cat); \
    } while (0)

// HKM_CNT(cat) - Increment count only (no timing)
#define HKM_CNT(cat) \
    hkm_count_inc(cat)

#else

// Build-time disabled: declare variables but no timing code (zero overhead)
#define HKM_TIME_START(var) \
    uint64_t var = 0

#define HKM_TIME_END(cat, var) \
    do { (void)(cat); (void)(var); } while (0)

#define HKM_CNT(cat) \
    do { (void)(cat); } while (0)

#endif

// ============================================================================
// Internal: TSC/Clock Implementation (inline for zero overhead)
// ============================================================================

#if HAKMEM_DEBUG_TIMING

static inline uint64_t hkm_tsc_now(void) {
#if defined(__x86_64__) || defined(__i386__)
    // x86/x64: Use RDTSC (fast, ~10 cycles)
    uint32_t lo, hi;
    __asm__ __volatile__ ("rdtsc" : "=a"(lo), "=d"(hi));
    return ((uint64_t)hi << 32) | lo;
#else
    // Non-x86: Use clock_gettime (slower, but portable)
    struct timespec ts;
    clock_gettime(CLOCK_MONOTONIC_RAW, &ts);
    return (uint64_t)ts.tv_sec * 1000000000ULL + (uint64_t)ts.tv_nsec;
#endif
}

#else

// Build-time disabled: empty inline function
static inline uint64_t hkm_tsc_now(void) {
    return 0;
}

#endif

#ifdef __cplusplus
}
#endif