hakmem/core/hakmem_config.h

// hakmem_config.h - Mode-based Configuration System
// Purpose: Centralize configuration and provide simple presets

#ifndef HAKMEM_CONFIG_H
#define HAKMEM_CONFIG_H

#include <stddef.h>  // for size_t
#include "hakmem_features.h"

// ===========================================================================
// Configuration Modes
// ===========================================================================

typedef enum {
    HAKMEM_MODE_MINIMAL = 0,   // Baseline: malloc/mmap only
    HAKMEM_MODE_FAST,          // Production: pool fast-path + FROZEN learning
    HAKMEM_MODE_BALANCED,      // Default: BigCache + ELO FROZEN + Batch
    HAKMEM_MODE_LEARNING,      // Development: ELO LEARN + adaptive
    HAKMEM_MODE_RESEARCH,      // Debug: All features + verbose logging
} HakemMode;

// ===========================================================================
// Free Policy (from Phase 6.4 P1)
// ===========================================================================

typedef enum {
    FREE_POLICY_BATCH,      // Default: BigCache miss → batch
    FREE_POLICY_KEEP,       // Keep VA mapped, no madvise (HOT strategy)
    FREE_POLICY_ADAPTIVE    // Adaptive: Hot/Warm/Cold based on size
} FreePolicy;

// ===========================================================================
// THP Policy (from Phase 6.4 P4)
// ===========================================================================

typedef enum {
    THP_POLICY_OFF,     // No THP (MADV_NOHUGEPAGE for all)
    THP_POLICY_AUTO,    // Auto: >=2MB → MADV_HUGEPAGE, <2MB → MADV_NOHUGEPAGE
    THP_POLICY_ON       // Force THP for all (MADV_HUGEPAGE for all >= 1MB)
} THPPolicy;

// ===========================================================================
// Evolution Phase (from Phase 6.5)
// ===========================================================================

typedef enum {
    EVO_PHASE_LEARN,    // Learning mode: collect data, select strategies
    EVO_PHASE_FROZEN,   // Frozen mode: use confirmed strategy, no learning
    EVO_PHASE_CANARY,   // Canary mode: test new candidate, roll back if bad
} EvoPhase;

// ===========================================================================
// Global Configuration
// ===========================================================================

typedef struct {
    // Mode
    HakemMode mode;
    const char* mode_name;  // For logging

    // Features (bitflags)
    HakemFeatureSet features;

    // Policies
    FreePolicy free_policy;
    THPPolicy thp_policy;
    EvoPhase evo_phase;

    // Parameters
    int elo_frozen_strategy;    // Strategy ID for FROZEN mode (0-11)
    size_t batch_threshold;     // Minimum size for batch madvise

    // Debug
    int verbose;  // 0=off, 1=minimal, 2=verbose
    int ace_trace; // 0=off, 1=on (log OOM failures)
} HakemConfig;

// ===========================================================================
// Global Instance
// ===========================================================================

extern HakemConfig g_hakem_config;

// ===========================================================================
// Initialization
// ===========================================================================

// Initialize configuration from environment variables
// Priority: HAKMEM_MODE > individual env vars > defaults
void hak_config_init(void);

// Apply a mode preset
void hak_config_apply_mode(HakemMode mode);

// Print current configuration (for debugging)
void hak_config_print(void);

// ===========================================================================
// Mode Presets (Implementation in hakmem_config.c)
// ===========================================================================

// Mode name strings
const char* hak_mode_name(HakemMode mode);

// Check if a specific feature is enabled
#define HAK_ENABLED_ALLOC(f)    hak_has_feature_alloc(&g_hakem_config.features, (f))
#define HAK_ENABLED_CACHE(f)    hak_has_feature_cache(&g_hakem_config.features, (f))
#define HAK_ENABLED_LEARNING(f) hak_has_feature_learning(&g_hakem_config.features, (f))
#define HAK_ENABLED_MEMORY(f)   hak_has_feature_memory(&g_hakem_config.features, (f))
#define HAK_ENABLED_DEBUG(f)    hak_has_feature_debug(&g_hakem_config.features, (f))

#endif // HAKMEM_CONFIG_H