94 lines
3.1 KiB
C
94 lines
3.1 KiB
C
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// ============================================================================
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// Phase 14 v1: Tiny tcache ENV Box (L0)
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// ============================================================================
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//
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// Purpose: ENV gate for tcache-style intrusive LIFO cache
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//
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// Design: docs/analysis/PHASE14_POINTER_CHASE_REDUCTION_1_DESIGN.md
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// Instructions: docs/analysis/PHASE14_POINTER_CHASE_REDUCTION_1_NEXT_INSTRUCTIONS.md
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//
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// Strategy:
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// - Add intrusive LIFO tcache layer before array-based UnifiedCache
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// - Reduce pointer-chase overhead (system malloc tcache pattern)
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// - Hit: head pointer + intrusive next only (no array access)
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//
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// ENV:
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// HAKMEM_TINY_TCACHE=0/1 (default: 0, opt-in)
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// HAKMEM_TINY_TCACHE_CAP=64 (default: 64, per-class capacity)
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//
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// API:
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// tiny_tcache_enabled() -> int
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// tiny_tcache_cap() -> uint16_t
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// tiny_tcache_env_refresh_from_env()
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//
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// Box Theory:
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// - L0: This file (ENV gate, reversible)
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// - L1: tiny_tcache_box.h (intrusive LIFO logic)
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// - L2: tiny_unified_cache.h (integration point)
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//
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// Safety:
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// - ENV-gated (default OFF, opt-in)
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// - Reversible (ENV toggle)
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// - No call site changes (integration inside unified_cache)
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//
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// ============================================================================
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#ifndef TINY_TCACHE_ENV_BOX_H
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#define TINY_TCACHE_ENV_BOX_H
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#include <stdint.h>
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#include <stdatomic.h>
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// ============================================================================
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// Global State (L0)
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// ============================================================================
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// Cached state: -1 (uninitialized), 0 (disabled), 1 (enabled)
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extern _Atomic int g_tiny_tcache_enabled;
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// Cached capacity: 0 (uninitialized), >0 (cap value)
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extern _Atomic uint16_t g_tiny_tcache_cap;
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// ============================================================================
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// Hot Inline API (L0)
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// ============================================================================
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// Check if tcache is enabled
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// Returns: 1 if enabled, 0 if disabled
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static inline int tiny_tcache_enabled(void) {
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int val = atomic_load_explicit(&g_tiny_tcache_enabled, memory_order_relaxed);
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if (__builtin_expect(val == -1, 0)) {
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// Lazy init: read ENV once
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extern int tiny_tcache_env_init(void);
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val = tiny_tcache_env_init();
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}
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return val;
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}
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// Get tcache capacity per class
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// Returns: capacity (default 64)
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static inline uint16_t tiny_tcache_cap(void) {
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uint16_t cap = atomic_load_explicit(&g_tiny_tcache_cap, memory_order_relaxed);
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if (__builtin_expect(cap == 0, 0)) {
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// Lazy init: read ENV once
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extern int tiny_tcache_env_init(void);
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tiny_tcache_env_init();
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cap = atomic_load_explicit(&g_tiny_tcache_cap, memory_order_relaxed);
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}
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return cap;
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}
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// ============================================================================
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// Cold API (L2)
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// ============================================================================
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// Refresh ENV cache (called from bench_profile after putenv)
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// Pattern: Same as Phase 8/13 (FREE_STATIC_ROUTE, C7_PRESERVE_HEADER)
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extern void tiny_tcache_env_refresh_from_env(void);
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#endif // TINY_TCACHE_ENV_BOX_H
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