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Add tracked arena allocator

Browse Source 
Available under -DZEND_TRACK_ARENA_ALLOC. This will use the system
allocator combined with arena checkpointing & release semantics
and allows analyzing arena usage under asan/valgrind.

I've sacrificed the duplicate arena implementation in mysqlnd, as
the integration with mysqlnd alloc is not worth the code duplication
to me.
This commit is contained in:
Nikita Popov 2019-06-28 10:19:18 +02:00
parent 645ca710d7
commit 7632a411e3
2 changed files with 117 additions and 83 deletions
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104
Zend/zend_arena.h
View File

@ -21,6 +21,8 @@
#include "zend.h"
#ifndef ZEND_TRACK_ARENA_ALLOC
typedef struct _zend_arena zend_arena;
struct _zend_arena {
@ -48,8 +50,6 @@ static zend_always_inline void zend_arena_destroy(zend_arena *arena)
} while (arena);
}
#define ZEND_ARENA_ALIGNMENT 8U
static zend_always_inline void* zend_arena_alloc(zend_arena **arena_ptr, size_t size)
{
zend_arena *arena = *arena_ptr;
@ -121,4 +121,104 @@ static zend_always_inline zend_bool zend_arena_contains(zend_arena *arena, void
return 0;
}
#else
/* Use normal allocations and keep track of them for mass-freeing.
* This is intended for use with asan/valgrind. */
typedef struct _zend_arena zend_arena;
struct _zend_arena {
void **ptr;
void **end;
struct _zend_arena *prev;
void *ptrs[0];
};
#define ZEND_TRACKED_ARENA_SIZE 1000
static zend_always_inline zend_arena *zend_arena_create(size_t _size)
{
zend_arena *arena = (zend_arena*) emalloc(
sizeof(zend_arena) + sizeof(void *) * ZEND_TRACKED_ARENA_SIZE);
arena->ptr = &arena->ptrs[0];
arena->end = &arena->ptrs[ZEND_TRACKED_ARENA_SIZE];
arena->prev = NULL;
return arena;
}
static zend_always_inline void zend_arena_destroy(zend_arena *arena)
{
do {
zend_arena *prev = arena->prev;
void **ptr;
for (ptr = arena->ptrs; ptr < arena->ptr; ptr++) {
efree(*ptr);
}
efree(arena);
arena = prev;
} while (arena);
}
static zend_always_inline void *zend_arena_alloc(zend_arena **arena_ptr, size_t size)
{
zend_arena *arena = *arena_ptr;
if (arena->ptr == arena->end) {
*arena_ptr = zend_arena_create(0);
(*arena_ptr)->prev = arena;
arena = *arena_ptr;
}
return *arena->ptr++ = emalloc(size);
}
static zend_always_inline void* zend_arena_calloc(zend_arena **arena_ptr, size_t count, size_t unit_size)
{
int overflow;
size_t size;
void *ret;
size = zend_safe_address(unit_size, count, 0, &overflow);
if (UNEXPECTED(overflow)) {
zend_error(E_ERROR, "Possible integer overflow in zend_arena_calloc() (%zu * %zu)", unit_size, count);
}
ret = zend_arena_alloc(arena_ptr, size);
memset(ret, 0, size);
return ret;
}
static zend_always_inline void* zend_arena_checkpoint(zend_arena *arena)
{
return arena->ptr;
}
static zend_always_inline void zend_arena_release(zend_arena **arena_ptr, void *checkpoint)
{
while (1) {
zend_arena *arena = *arena_ptr;
zend_arena *prev = arena->prev;
while (1) {
if (arena->ptr == (void **) checkpoint) {
return;
}
if (arena->ptr == arena->ptrs) {
break;
}
arena->ptr--;
efree(*arena->ptr);
}
efree(arena);
*arena_ptr = prev;
ZEND_ASSERT(*arena_ptr);
}
}
static zend_always_inline zend_bool zend_arena_contains(zend_arena *arena, void *ptr)
{
/* TODO: Dummy */
return 1;
}
#endif
#endif /* _ZEND_ARENA_H_ */

96
ext/mysqlnd/mysqlnd_block_alloc.c
View File

@ -24,83 +24,13 @@
#include "mysqlnd_debug.h"
#include "mysqlnd_priv.h"
/* {{{ mysqlnd_arena_create */
static zend_always_inline zend_arena* mysqlnd_arena_create(size_t size)
{
zend_arena *arena = (zend_arena*)mnd_emalloc(size);
arena->ptr = (char*) arena + ZEND_MM_ALIGNED_SIZE(sizeof(zend_arena));
arena->end = (char*) arena + size;
arena->prev = NULL;
return arena;
}
/* }}} */
/* {{{ mysqlnd_arena_destroy */
static zend_always_inline void mysqlnd_arena_destroy(zend_arena *arena)
{
do {
zend_arena *prev = arena->prev;
mnd_efree(arena);
arena = prev;
} while (arena);
}
/* }}} */
/* {{{ mysqlnd_arena_alloc */
static zend_always_inline void* mysqlnd_arena_alloc(zend_arena **arena_ptr, size_t size)
{
zend_arena *arena = *arena_ptr;
char *ptr = arena->ptr;
size = ZEND_MM_ALIGNED_SIZE(size);
if (EXPECTED(size <= (size_t)(arena->end - ptr))) {
arena->ptr = ptr + size;
} else {
size_t arena_size =
UNEXPECTED((size + ZEND_MM_ALIGNED_SIZE(sizeof(zend_arena))) > (size_t)(arena->end - (char*) arena)) ?
(size + ZEND_MM_ALIGNED_SIZE(sizeof(zend_arena))) :
(size_t)(arena->end - (char*) arena);
zend_arena *new_arena = (zend_arena*)mnd_emalloc(arena_size);
ptr = (char*) new_arena + ZEND_MM_ALIGNED_SIZE(sizeof(zend_arena));
new_arena->ptr = (char*) new_arena + ZEND_MM_ALIGNED_SIZE(sizeof(zend_arena)) + size;
new_arena->end = (char*) new_arena + arena_size;
new_arena->prev = arena;
*arena_ptr = new_arena;
}
return (void*) ptr;
}
/* }}} */
static zend_always_inline void* mysqlnd_arena_checkpoint(zend_arena *arena)
{
return arena->ptr;
}
static zend_always_inline void mysqlnd_arena_release(zend_arena **arena_ptr, void *checkpoint)
{
zend_arena *arena = *arena_ptr;
while (UNEXPECTED((char*)checkpoint > arena->end) ||
UNEXPECTED((char*)checkpoint <= (char*)arena)) {
zend_arena *prev = arena->prev;
mnd_efree(arena);
*arena_ptr = arena = prev;
}
ZEND_ASSERT((char*)checkpoint > (char*)arena && (char*)checkpoint <= arena->end);
arena->ptr = (char*)checkpoint;
}
/* {{{ mysqlnd_mempool_free_chunk */
static void
mysqlnd_mempool_free_chunk(MYSQLND_MEMORY_POOL * pool, void * ptr)
{
DBG_ENTER("mysqlnd_mempool_free_chunk");
/* Try to back-off and guess if this is the last block allocated */
#ifndef ZEND_TRACK_ARENA_ALLOC
if (ptr == pool->last) {
/*
This was the last allocation. Lucky us, we can free
@ -109,6 +39,7 @@ mysqlnd_mempool_free_chunk(MYSQLND_MEMORY_POOL * pool, void * ptr)
pool->arena->ptr = (char*)ptr;
pool->last = NULL;
}
#endif
DBG_VOID_RETURN;
}
/* }}} */
@ -120,6 +51,7 @@ mysqlnd_mempool_resize_chunk(MYSQLND_MEMORY_POOL * pool, void * ptr, size_t old_
{
DBG_ENTER("mysqlnd_mempool_resize_chunk");
#ifndef ZEND_TRACK_ARENA_ALLOC
/* Try to back-off and guess if this is the last block allocated */
if (ptr == pool->last
&& (ZEND_MM_ALIGNED_SIZE(size) <= ((char*)pool->arena->end - (char*)ptr))) {
@ -128,11 +60,13 @@ mysqlnd_mempool_resize_chunk(MYSQLND_MEMORY_POOL * pool, void * ptr, size_t old_
a bit of memory from the pool. Next time we will return from the same ptr.
*/
pool->arena->ptr = (char*)ptr + ZEND_MM_ALIGNED_SIZE(size);
} else {
void *new_ptr = mysqlnd_arena_alloc(&pool->arena, size);
memcpy(new_ptr, ptr, MIN(old_size, size));
pool->last = ptr = new_ptr;
DBG_RETURN(ptr);
}
#endif
void *new_ptr = zend_arena_alloc(&pool->arena, size);
memcpy(new_ptr, ptr, MIN(old_size, size));
pool->last = ptr = new_ptr;
DBG_RETURN(ptr);
}
/* }}} */
@ -145,7 +79,7 @@ mysqlnd_mempool_get_chunk(MYSQLND_MEMORY_POOL * pool, size_t size)
void *ptr = NULL;
DBG_ENTER("mysqlnd_mempool_get_chunk");
ptr = mysqlnd_arena_alloc(&pool->arena, size);
ptr = zend_arena_alloc(&pool->arena, size);
pool->last = ptr;
DBG_RETURN(ptr);
@ -161,8 +95,8 @@ mysqlnd_mempool_create(size_t arena_size)
MYSQLND_MEMORY_POOL * ret;
DBG_ENTER("mysqlnd_mempool_create");
arena = mysqlnd_arena_create(MAX(arena_size, sizeof(zend_arena)));
ret = mysqlnd_arena_alloc(&arena, sizeof(MYSQLND_MEMORY_POOL));
arena = zend_arena_create(MAX(arena_size, sizeof(zend_arena)));
ret = zend_arena_alloc(&arena, sizeof(MYSQLND_MEMORY_POOL));
ret->arena = arena;
ret->last = NULL;
ret->checkpoint = NULL;
@ -180,7 +114,7 @@ mysqlnd_mempool_destroy(MYSQLND_MEMORY_POOL * pool)
{
DBG_ENTER("mysqlnd_mempool_destroy");
/* mnd_free will reference LOCK_access and might crash, depending on the caller...*/
mysqlnd_arena_destroy(pool->arena);
zend_arena_destroy(pool->arena);
DBG_VOID_RETURN;
}
/* }}} */
@ -190,7 +124,7 @@ PHPAPI void
mysqlnd_mempool_save_state(MYSQLND_MEMORY_POOL * pool)
{
DBG_ENTER("mysqlnd_mempool_save_state");
pool->checkpoint = mysqlnd_arena_checkpoint(pool->arena);
pool->checkpoint = zend_arena_checkpoint(pool->arena);
DBG_VOID_RETURN;
}
/* }}} */
@ -201,7 +135,7 @@ mysqlnd_mempool_restore_state(MYSQLND_MEMORY_POOL * pool)
{
DBG_ENTER("mysqlnd_mempool_restore_state");
if (pool->checkpoint) {
mysqlnd_arena_release(&pool->arena, pool->checkpoint);
zend_arena_release(&pool->arena, pool->checkpoint);
pool->last = NULL;
pool->checkpoint = NULL;
}