// pool_stats_box.h — Box: Pool Statistics & Monitoring
//
// Purpose: Pool allocator statistics tracking for all phases
// Pattern: Atomic counters + dump on destructor
// Multi-phase design: Supports future phase extensions (POOL-MID-DN-BATCH, etc)

#ifndef POOL_STATS_BOX_H
#define POOL_STATS_BOX_H

#include "pool_config_box.h"  // For hak_pool_v1_flatten_stats_enabled(), etc
#include <stdio.h>
#include <stdint.h>
#include <stdatomic.h>

// ============================================================================
// Pool V1 Flatten Statistics
// ============================================================================
// Tracks allocation/free path hits + rejection reasons
// Multi-phase design: Each phase adds fields without disrupting others

typedef struct PoolV1FlattenStats {
    // Flatten hot path stats (basic alloc/free tracking)
    _Atomic uint64_t alloc_tls_hit;
    _Atomic uint64_t alloc_fallback_v1;
    _Atomic uint64_t free_tls_hit;
    _Atomic uint64_t free_fallback_v1;
    _Atomic uint64_t free_fb_page_null;
    _Atomic uint64_t free_fb_not_mine;
    _Atomic uint64_t free_fb_other;

    // Phase POOL-FREE-V1-OPT Step 1: v2 reject reasons
    _Atomic uint64_t v2_reject_total;      // Total v2 free rejects (fell through to v1)
    _Atomic uint64_t v2_reject_ptr_null;   // ptr == NULL

    // Phase POOL-FREE-V1-OPT Step 2: fast split stats
    _Atomic uint64_t fastsplit_fast_hit;   // Fast path taken
    _Atomic uint64_t fastsplit_slow_hit;   // Slow path taken (fast predicate failed)
    _Atomic uint64_t v2_reject_not_init;   // pool not initialized
    _Atomic uint64_t v2_reject_desc_null;  // mid_desc_lookup returned NULL
    _Atomic uint64_t v2_reject_mf2_null;   // MF2 path but mf2_addr_to_page returned NULL
} PoolV1FlattenStats;

// Global stats instance (shared by all phases)
static PoolV1FlattenStats g_pool_v1_flat_stats = {0};

// ============================================================================
// Statistics Dump & Monitoring
// ============================================================================

static inline void pool_v1_flat_stats_dump(void) {
    if (!hak_pool_v1_flatten_stats_enabled() && !hak_pool_free_v1_reject_stats_enabled()) return;

    if (hak_pool_v1_flatten_stats_enabled()) {
        fprintf(stderr,
                "[POOL_V1_FLAT] alloc_tls_hit=%llu alloc_fb=%llu free_tls_hit=%llu free_fb=%llu page_null=%llu not_mine=%llu other=%llu\n",
                (unsigned long long)atomic_load_explicit(&g_pool_v1_flat_stats.alloc_tls_hit,
                                                         memory_order_relaxed),
                (unsigned long long)atomic_load_explicit(&g_pool_v1_flat_stats.alloc_fallback_v1,
                                                         memory_order_relaxed),
                (unsigned long long)atomic_load_explicit(&g_pool_v1_flat_stats.free_tls_hit,
                                                         memory_order_relaxed),
                (unsigned long long)atomic_load_explicit(&g_pool_v1_flat_stats.free_fallback_v1,
                                                         memory_order_relaxed),
                (unsigned long long)atomic_load_explicit(&g_pool_v1_flat_stats.free_fb_page_null,
                                                         memory_order_relaxed),
                (unsigned long long)atomic_load_explicit(&g_pool_v1_flat_stats.free_fb_not_mine,
                                                         memory_order_relaxed),
                (unsigned long long)atomic_load_explicit(&g_pool_v1_flat_stats.free_fb_other,
                                                         memory_order_relaxed));
    }

    // Phase POOL-FREE-V1-OPT Step 1: v2 reject stats
    if (hak_pool_free_v1_reject_stats_enabled()) {
        fprintf(stderr,
                "[POOL_V2_REJECT] total=%llu ptr_null=%llu not_init=%llu desc_null=%llu mf2_null=%llu\n",
                (unsigned long long)atomic_load_explicit(&g_pool_v1_flat_stats.v2_reject_total,
                                                         memory_order_relaxed),
                (unsigned long long)atomic_load_explicit(&g_pool_v1_flat_stats.v2_reject_ptr_null,
                                                         memory_order_relaxed),
                (unsigned long long)atomic_load_explicit(&g_pool_v1_flat_stats.v2_reject_not_init,
                                                         memory_order_relaxed),
                (unsigned long long)atomic_load_explicit(&g_pool_v1_flat_stats.v2_reject_desc_null,
                                                         memory_order_relaxed),
                (unsigned long long)atomic_load_explicit(&g_pool_v1_flat_stats.v2_reject_mf2_null,
                                                         memory_order_relaxed));
    }

    // Phase POOL-FREE-V1-OPT Step 2: fastsplit stats
    if (hak_pool_v1_flatten_stats_enabled() && hak_pool_v1_free_fastsplit_enabled()) {
        fprintf(stderr,
                "[POOL_V1_FASTSPLIT] fast_hit=%llu slow_hit=%llu\n",
                (unsigned long long)atomic_load_explicit(&g_pool_v1_flat_stats.fastsplit_fast_hit,
                                                         memory_order_relaxed),
                (unsigned long long)atomic_load_explicit(&g_pool_v1_flat_stats.fastsplit_slow_hit,
                                                         memory_order_relaxed));
    }
}

// Dump stats on program exit (destructor attribute)
__attribute__((destructor)) static void pool_v1_flatten_stats_destructor(void) {
    pool_v1_flat_stats_dump();
}

#endif  // POOL_STATS_BOX_H