zend_weakrefs.h

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/*
   +----------------------------------------------------------------------+
   | Copyright (c) The PHP Group                                          |
   +----------------------------------------------------------------------+
   | This source file is subject to version 2.00 of the Zend license,     |
   | that is bundled with this package in the file LICENSE, and is        |
   | available through the world-wide-web at the following url:           |
   | http://www.zend.com/license/2_00.txt.                                |
   | If you did not receive a copy of the Zend license and are unable to  |
   | obtain it through the world-wide-web, please send a note to          |
   | license@zend.com so we can mail you a copy immediately.              |
   +----------------------------------------------------------------------+
   | Authors: krakjoe@php.net                                             |
   +----------------------------------------------------------------------+
*/
 
#ifndef ZEND_WEAKREFS_H
#define ZEND_WEAKREFS_H
 
#include "zend_alloc.h"
 
BEGIN_EXTERN_C()
 
extern ZEND_API zend_class_entry *zend_ce_weakref;
 
void zend_register_weakref_ce(void);
 
void zend_weakrefs_init(void);
void zend_weakrefs_shutdown(void);
 
ZEND_API void zend_weakrefs_notify(zend_object *object);
 
ZEND_API zval *zend_weakrefs_hash_add(HashTable *ht, zend_object *key, zval *pData);
ZEND_API zend_result zend_weakrefs_hash_del(HashTable *ht, zend_object *key);
static zend_always_inline void *zend_weakrefs_hash_add_ptr(HashTable *ht, zend_object *key, void *ptr) {
    zval tmp, *zv;
    ZVAL_PTR(&tmp, ptr);
    if ((zv = zend_weakrefs_hash_add(ht, key, &tmp))) {
        return Z_PTR_P(zv);
    } else {
        return NULL;
    }
}
 
/* Because php uses the raw numbers as a hash function, raw pointers will lead to hash collisions.
 * We have a guarantee that the lowest ZEND_MM_ALIGNED_OFFSET_LOG2 bits of a pointer are zero.
 *
 * E.g. On most 64-bit platforms, pointers are aligned to 8 bytes, so the least significant 3 bits are always 0 and can be discarded.
 *
 * NOTE: This function is only used for EG(weakrefs) and zend_weakmap->ht.
 * It is not used for the HashTable instances associated with ZEND_WEAKREF_TAG_HT tags (created in zend_weakref_register, which uses ZEND_WEAKREF_ENCODE instead).
 * The ZEND_WEAKREF_TAG_HT instances are used to disambiguate between multiple weak references to the same zend_object.
 */
static zend_always_inline zend_ulong zend_object_to_weakref_key(const zend_object *object)
{
    ZEND_ASSERT(((uintptr_t)object) % ZEND_MM_ALIGNMENT == 0);
    return ((uintptr_t) object) >> ZEND_MM_ALIGNMENT_LOG2;
}
 
static zend_always_inline zend_object *zend_weakref_key_to_object(zend_ulong key)
{
    return (zend_object *) (((uintptr_t) key) << ZEND_MM_ALIGNMENT_LOG2);
}
 
HashTable *zend_weakmap_get_gc(zend_object *object, zval **table, int *n);
HashTable *zend_weakmap_get_key_entry_gc(zend_object *object, zval **table, int *n);
HashTable *zend_weakmap_get_entry_gc(zend_object *object, zval **table, int *n);
HashTable *zend_weakmap_get_object_key_entry_gc(zend_object *object, zval **table, int *n);
HashTable *zend_weakmap_get_object_entry_gc(zend_object *object, zval **table, int *n);
 
END_EXTERN_C()
 
#endif