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Implementaion of optional thread safety
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@alex-schneider
alex-schneider committed Feb 6, 2019
1 parent b7ff387 commit 8ddf071
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1 change: 1 addition & 0 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@ for structs in tokenization applications.
## Features

* Written in pure `C`.
* Supports thread safety.
* Doesn't require any external libraries.
* Optimized for 32 and 64 bit systems on little-endian machines.
* Prevents internal memory space fragmentation (freed memory space is reusable).
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148 changes: 95 additions & 53 deletions src/mpz_alloc.c
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Expand Up @@ -14,13 +14,10 @@

#define MPZ_ALLOC_ALIGNMENT (2 * sizeof(mpz_void_t *))

#define MPZ_CHECK_VOID(p) ({ if (NULL == (p)) return; })
#define MPZ_CHECK_NULL(p) ({ if (NULL == (p)) return NULL; })

#ifdef MPZ_RAISE_SIGSEGV_ON_MEM_ERRORS
# define MPZ_SLOT_OVERHEAD (sizeof(mpz_uint32_t) * 2)
#define MPZ_SLOT_OVERHEAD (sizeof(mpz_uint32_t) * 2)
#else
# define MPZ_SLOT_OVERHEAD (sizeof(mpz_uint32_t) * 1)
#define MPZ_SLOT_OVERHEAD (sizeof(mpz_uint32_t) * 1)
#endif /* MPZ_RAISE_SIGSEGV_ON_MEM_ERRORS */

#define MPZ_SLOT_SIZE (sizeof(mpz_slot_t *) + MPZ_SLOT_OVERHEAD)
Expand All @@ -38,36 +35,25 @@
#define MPZ_POOL_MIN_ALLOC (MPZ_SLOTS_ALIGNMENT)
#define MPZ_POOL_MAX_ALLOC ((mpz_cuint32_t)((1 << 29) - 1))

#define MPZ_SLOT_READ_HEAD(s) ( \
#define MPZ_SLOT_READ_HEAD(s) ( \
(mpz_uint32_t *)(s) \
)
#define MPZ_SLOT_READ_SIZE(s) ( \
#define MPZ_SLOT_READ_SIZE(s) ( \
(mpz_uint32_t)((*MPZ_SLOT_READ_HEAD(s) << 2) >> 2) \
)

#ifdef MPZ_RAISE_SIGSEGV_ON_MEM_ERRORS
#define MPZ_FOOTER_MARK (0xFFFFFFFF)

#define MPZ_FOOTER_MARK (0xFFFFFFFF)

#define MPZ_SLOT_GOTO_FOOT(sl, si) ( \
(mpz_uint32_t *)((mpz_uchar_t *)(sl) + sizeof(mpz_uint32_t) + (si)) \
)
#define MPZ_SLOT_READ_FOOT(s) ( \
(mpz_uint32_t *)MPZ_SLOT_GOTO_FOOT((s), MPZ_SLOT_READ_SIZE(s)) \
)
#define MPZ_SLOT_GOTO_FOOT(sl, si) ( \
(mpz_uint32_t *)((mpz_uchar_t *)(sl) + sizeof(mpz_uint32_t) + (si)) \
)

#define MPZ_SLOT_READ_FOOT(s) ( \
(mpz_uint32_t *)MPZ_SLOT_GOTO_FOOT((s), MPZ_SLOT_READ_SIZE(s)) \
)
#endif /* MPZ_RAISE_SIGSEGV_ON_MEM_ERRORS */

#if defined (__cplusplus) || defined (__STDC_VERSION__) && __STDC_VERSION__ >= 199901L /* C99 */
# ifdef __GNUC__
# define MPZ_FORCE_INLINE static inline __attribute__((always_inline))
# else
# define MPZ_FORCE_INLINE static inline
# endif /* __GNUC__ */
#else
# define MPZ_FORCE_INLINE static
#endif /* __STDC_VERSION__ */

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

MPZ_FORCE_INLINE mpz_void_t _mpz_pool_gc(
Expand Down Expand Up @@ -104,8 +90,8 @@ MPZ_FORCE_INLINE mpz_void_t _mpz_slot_init(
mpz_pool_t *mpz_pool_create(
mpz_void_t
) {
mpz_pool_t *pool;
mpz_uint_t idx;
mpz_pool_t *pool;
mpz_uint_t idx;

MPZ_CHECK_NULL(pool = mpz_memalign(MPZ_ALLOC_ALIGNMENT, MPZ_POOL_SIZE));

Expand All @@ -115,21 +101,54 @@ mpz_pool_t *mpz_pool_create(

pool->slabs = NULL;

#ifdef MPZ_ENABLE_THREAD_SAFETY
mpz_mutex_init(&pool->mutex, NULL);
#endif /* MPZ_ENABLE_THREAD_SAFETY */

return pool;
}

mpz_void_t mpz_pool_reset(
mpz_int_t mpz_pool_reset(
mpz_pool_t *pool
) {
#ifdef MPZ_ENABLE_THREAD_SAFETY
MPZ_CHECK_INT(pool, MPZ_FAILURE);

if (0 != mpz_mutex_lock(&pool->mutex)) {
return MPZ_FAILURE;
}
#endif /* MPZ_ENABLE_THREAD_SAFETY */

_mpz_pool_gc(pool, 1);

#ifdef MPZ_ENABLE_THREAD_SAFETY
mpz_mutex_unlock(&pool->mutex);
#endif /* MPZ_ENABLE_THREAD_SAFETY */

return MPZ_SUCCESS;
}

mpz_void_t mpz_pool_destroy(
mpz_int_t mpz_pool_destroy(
mpz_pool_t *pool
) {
#ifdef MPZ_ENABLE_THREAD_SAFETY
MPZ_CHECK_INT(pool, MPZ_FAILURE);

if (0 != mpz_mutex_lock(&pool->mutex)) {
return MPZ_FAILURE;
}
#endif /* MPZ_ENABLE_THREAD_SAFETY */

_mpz_pool_gc(pool, 0);

#ifdef MPZ_ENABLE_THREAD_SAFETY
mpz_mutex_unlock(&pool->mutex);
mpz_mutex_destroy(&pool->mutex);
#endif /* MPZ_ENABLE_THREAD_SAFETY */

free(pool);

return MPZ_SUCCESS;
}

mpz_void_t *mpz_pmalloc(
Expand All @@ -144,41 +163,49 @@ mpz_void_t *mpz_pcalloc(
return _mpz_palloc(pool, size, 1);
}

mpz_void_t mpz_free(
mpz_int_t mpz_free(
mpz_pool_t *pool, mpz_cvoid_t *data
) {
mpz_slot_t *slot;
mpz_uint32_t *head, size;
mpz_uint_t idx;
mpz_slot_t *slot;
mpz_uint32_t *head, size;
mpz_uint_t idx;

MPZ_CHECK_VOID(pool);
MPZ_CHECK_VOID(data);
MPZ_CHECK_INT(pool, MPZ_FAILURE);
MPZ_CHECK_INT(data, MPZ_FAILURE);

#ifdef MPZ_ENABLE_THREAD_SAFETY
if (0 != mpz_mutex_lock(&pool->mutex)) {
return MPZ_FAILURE;
}
#endif /* MPZ_ENABLE_THREAD_SAFETY */

slot = MPZ_DATA_TO_SLOT(data);
head = MPZ_SLOT_READ_HEAD(slot);

#ifdef MPZ_RAISE_SIGSEGV_ON_MEM_ERRORS

/* Check both "segmentation faults" and "double free" errors. */
if ((MPZ_FOOTER_MARK != *MPZ_SLOT_READ_FOOT(slot)) || (!(*head & MPZ_SLOT_FLAG_USED))) {
raise(SIGSEGV);
}

#endif /* MPZ_RAISE_SIGSEGV_ON_MEM_ERRORS */

if (*head & MPZ_SLOT_FLAG_HUGE) {
return _mpz_slab_free(pool, slot);
_mpz_slab_free(pool, slot);

#ifdef MPZ_ENABLE_THREAD_SAFETY
mpz_mutex_unlock(&pool->mutex);
#endif /* MPZ_ENABLE_THREAD_SAFETY */

return MPZ_SUCCESS;
}

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

size = MPZ_SLOT_READ_SIZE(slot);

#ifdef MPZ_RAISE_SIGSEGV_ON_MEM_ERRORS

/* Remove the "used" mark. */
_mpz_slot_init(slot, size, 0);

#endif /* MPZ_RAISE_SIGSEGV_ON_MEM_ERRORS */

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
Expand All @@ -189,6 +216,12 @@ mpz_void_t mpz_free(
slot->next = pool->bins[idx];

pool->bins[idx] = slot;

#ifdef MPZ_ENABLE_THREAD_SAFETY
mpz_mutex_unlock(&pool->mutex);
#endif /* MPZ_ENABLE_THREAD_SAFETY */

return MPZ_SUCCESS;
}

/* ==================================================================================================== */
Expand All @@ -197,9 +230,9 @@ mpz_void_t mpz_free(
MPZ_FORCE_INLINE mpz_void_t _mpz_pool_gc(
mpz_pool_t *pool, mpz_cuint_t soft
) {
mpz_slab_t *slab, *next;
mpz_slot_t *slot;
mpz_uint_t idx;
mpz_slab_t *slab, *next;
mpz_slot_t *slot;
mpz_uint_t idx;

MPZ_CHECK_VOID(pool);
MPZ_CHECK_VOID(pool->slabs);
Expand Down Expand Up @@ -240,9 +273,9 @@ MPZ_FORCE_INLINE mpz_void_t _mpz_pool_gc(
MPZ_FORCE_INLINE mpz_void_t *_mpz_palloc(
mpz_pool_t *pool, mpz_size_t size, mpz_cuint_t zeroize
) {
mpz_slab_t *slab;
mpz_slot_t *slot;
mpz_uint_t idx;
mpz_slab_t *slab;
mpz_slot_t *slot;
mpz_uint_t idx;

MPZ_CHECK_NULL(pool);

Expand All @@ -252,6 +285,12 @@ MPZ_FORCE_INLINE mpz_void_t *_mpz_palloc(
return NULL;
}

#ifdef MPZ_ENABLE_THREAD_SAFETY
if (0 != mpz_mutex_lock(&pool->mutex)) {
return NULL;
}
#endif /* MPZ_ENABLE_THREAD_SAFETY */

size += MPZ_SLOT_OVERHEAD;
size = mpz_align(size, MPZ_SLOTS_ALIGNMENT);

Expand All @@ -264,6 +303,10 @@ MPZ_FORCE_INLINE mpz_void_t *_mpz_palloc(
/* The new slab contains only a single huge slot. */
_mpz_slot_init(slot = MPZ_SLAB_TO_SLOT(slab), size, MPZ_SLOT_FLAG_HUGE|MPZ_SLOT_FLAG_USED);

#ifdef MPZ_ENABLE_THREAD_SAFETY
mpz_mutex_unlock(&pool->mutex);
#endif /* MPZ_ENABLE_THREAD_SAFETY */

return MPZ_SLOT_TO_DATA(slot);
}

Expand All @@ -288,16 +331,18 @@ MPZ_FORCE_INLINE mpz_void_t *_mpz_palloc(
pool->bins[idx] = slot->next;

#ifdef MPZ_RAISE_SIGSEGV_ON_MEM_ERRORS

/* Mark the slot as "used". */
_mpz_slot_init(slot, size, MPZ_SLOT_FLAG_USED);

#endif /* MPZ_RAISE_SIGSEGV_ON_MEM_ERRORS */

if (zeroize) {
mpz_memzero(MPZ_SLOT_TO_DATA(slot), size);
}

#ifdef MPZ_ENABLE_THREAD_SAFETY
mpz_mutex_unlock(&pool->mutex);
#endif /* MPZ_ENABLE_THREAD_SAFETY */

return MPZ_SLOT_TO_DATA(slot);
}

Expand All @@ -316,8 +361,8 @@ MPZ_FORCE_INLINE mpz_void_t *_mpz_slab_create(
MPZ_FORCE_INLINE mpz_void_t _mpz_slab_init(
mpz_pool_t *pool, mpz_slab_t *slab, mpz_cuint32_t size
) {
mpz_slot_t *slot = MPZ_SLAB_TO_SLOT(slab);
mpz_uint_t idx, i;
mpz_slot_t *slot = MPZ_SLAB_TO_SLOT(slab);
mpz_uint_t idx, i;

idx = MPZ_BIN_IDX(size);

Expand Down Expand Up @@ -392,9 +437,6 @@ MPZ_FORCE_INLINE mpz_void_t _mpz_slot_init(
*MPZ_SLOT_READ_HEAD(slot) = (0 | flags | size);

#ifdef MPZ_RAISE_SIGSEGV_ON_MEM_ERRORS

*MPZ_SLOT_GOTO_FOOT(slot, size) = MPZ_FOOTER_MARK;

#endif /* MPZ_RAISE_SIGSEGV_ON_MEM_ERRORS */

}
34 changes: 31 additions & 3 deletions src/mpz_alloc.h
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Original file line number Diff line number Diff line change
Expand Up @@ -10,15 +10,43 @@

/* ==================================================================================================== */

typedef struct _mpz_pool_s mpz_pool_t;
typedef struct _mpz_slab_s mpz_slab_t;
typedef struct _mpz_slot_s mpz_slot_t;

struct _mpz_slot_s
{
mpz_void_t *data;
mpz_slot_t *next;
};

struct _mpz_slab_s
{
mpz_slab_t *prev;
mpz_slab_t *next;
};

struct _mpz_pool_s
{
mpz_slot_t *bins[MPZ_BINS];
mpz_slab_t *slabs;

#ifdef MPZ_ENABLE_THREAD_SAFETY
mpz_mutex_t mutex;
#endif /* MPZ_ENABLE_THREAD_SAFETY */
};

/* ==================================================================================================== */

mpz_pool_t *mpz_pool_create(
mpz_void_t
);

mpz_void_t mpz_pool_reset(
mpz_int_t mpz_pool_reset(
mpz_pool_t *pool
);

mpz_void_t mpz_pool_destroy(
mpz_int_t mpz_pool_destroy(
mpz_pool_t *pool
);

Expand All @@ -30,7 +58,7 @@ mpz_void_t *mpz_pcalloc(
mpz_pool_t *pool, mpz_csize_t size
);

mpz_void_t mpz_free(
mpz_int_t mpz_free(
mpz_pool_t *pool, mpz_cvoid_t *data
);

Expand Down
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