关于PHP源码中HashTable的解析
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2022-03-15 17:48:44
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PHP源码中HashTable的简单示例 前些日子看了那篇对hasttable的介绍，于是也想自己运行一下，可是对于源码的调试不是太在行。 所以想了个办法：自己把PHP源码中的一些简单操作提取出来，自己运行一下，查看输出或调试。 于是花费了三天的空闲时间把一些相关的东西提取出来，主要是Zend目录下的zend_alloc.c,zend_alloc.h,zend_hash.c,zend_hash.h四个文件。 将与PHP相关的内存分配去掉，默认使用系统自带的内存分配方式。 另外：一些注释是http://www.phppan.com/2009/12/zend-hashtable/中所引用文章中的相关信息。 作者地址：http://www.phpinternals.com 下面的代码是一个可以运行的C程序，它初始化一个容量为50的hashtable（实际上分配了64个），然后将30到68，写入hash table，并将这个hash table 打印出来。 相信这会给一些想学习源码的童鞋一些帮助。 源代码如下：
<!-- #include <stdio.h-->#include #include typedef unsigned long ulong;typedef unsigned int uint;typedef unsigned char zend_bool;typedef unsigned int size_t;typedef void (*dtor_func_t)(void *pDest);typedef ulong (*hash_func_t)(char *arKey, uint nKeyLength);#define SUCCESS 0#define FAILURE -1 /* this MUST stay a negative number, or it may affect functions! */ #define HASH_UPDATE (1<<0)#define HASH_ADD (1<<1)#define HASH_NEXT_INSERT(1<<2) #define HASH_DEL_KEY 0 #define perealloc_recoverable(ptr, size, persistent) (__zend_realloc((ptr), (size)))#define pefree_rel(ptr, persistent)(free(ptr))//此处省略了使用PHP的内存分配函数#define pemalloc_rel(size, persistent) (__zend_malloc(size))#define perealloc_rel(ptr, size, persistent) (__zend_realloc((ptr), (size)))#define pemalloc(size, persistent) (__zend_malloc(size))#define pefree(ptr, persistent) (free(ptr)) inline static void * __zend_malloc(size_t len) {
void *tmp = malloc(len);
if (tmp) {
return tmp;
}
fprintf(stderr, "Out of memory\n");
exit(1);}
inline static void * __zend_realloc(void *p, size_t len) {
p = realloc(p, len);
if (p) {
return p;
}
fprintf(stderr, "Out of memory\n");
exit(1);}
typedef struct bucket {
ulong h; /* Used for numeric indexing */
uint nKeyLength; /* key 长度 */
void *pData; /* 指向Bucket中保存的数据的指针 */
void *pDataPtr; /* 指针数据 */
struct bucket *pListNext; /* 指向HashTable桶列中下一个元素 */
struct bucket *pListLast; /* 指向HashTable桶列中前一个元素 */
struct bucket *pNext; /* 指向具有同一个hash值的桶列的后一个元素 */
struct bucket *pLast; /* 指向具有同一个hash值的桶列的前一个元素 */
char arKey[1]; /* 必须是最后一个成员，key名称*/} Bucket;
typedef struct _hashtable {
uint nTableSize;/*指定了HashTable的大小，同时它限定了HashTable中能保存Bucket的最大数量
此 数越大，系统为HashTable分配的内存就越多。为了提高计算效率，
系统自动会将nTableSize调整到最小一个不小于nTableSize的2 的整数次方*/
uint nTableMask;/*nTableMask的值永远是nTableSize – 1，引入这个字段的主要目的是为了提高计算效率*/
uint nNumOfElements;/*记录HashTable当前保存的数据元素的个数*/
ulong nNextFreeElement;/*记录HashTable中下一个可用于插入数据元素的arBuckets的索引*/
Bucket *pInternalPointer;/* Used for element traversal */
Bucket *pListHead;/*Bucket双向链表的第一个元素*/
Bucket *pListTail;/*Bucket双向链表的最后一元素*/
Bucket **arBuckets;/*存储Bucket双向链表*/
dtor_func_t pDestructor;/*函数指针，在HashTable的增加、修改、删除Bucket时自动调用，用于处理相关数据的清理工作*/
zend_bool persistent;/*指出了Bucket内存分配的方式。如果persisient为TRUE，则使用操作系统本身的内存分配函数为Bucket分配内存，否则使用PHP的内存分配函数。*/
unsigned char nApplyCount;/*nApplyCount与bApplyProtection结合提供了一个防止在遍历HashTable时进入递归循环时的一种机制*/
zend_bool bApplyProtection;} HashTable;
typedef struct _zend_hash_key {
char *arKey;
uint nKeyLength;
ulong h;} zend_hash_key; typedef zend_bool (*merge_checker_func_t)(HashTable *target_ht, void *source_data, zend_hash_key *hash_key, void *pParam);
#define CONNECT_TO_BUCKET_DLLIST(element, list_head) \
(element)->pNext = (list_head); \
(element)->pLast = NULL; \
if ((element)->pNext) { \
(element)->pNext->pLast = (element); \
} #define CONNECT_TO_GLOBAL_DLLIST(element, ht) \
(element)->pListLast = (ht)->pListTail; \
(ht)->pListTail = (element); \
(element)->pListNext = NULL; \
if ((element)->pListLast != NULL) { \
(element)->pListLast->pListNext = (element); \
} \
if (!(ht)->pListHead) { \
(ht)->pListHead = (element); \
} \
if ((ht)->pInternalPointer == NULL) { \
(ht)->pInternalPointer = (element); \
} #define ZEND_HASH_IF_FULL_DO_RESIZE(ht) \
if ((ht)->nNumOfElements > (ht)->nTableSize) {\
zend_hash_do_resize(ht); \
} int zend_hash_rehash(HashTable *ht) {
Bucket *p;
uint nIndex;
memset(ht->arBuckets, 0, ht->nTableSize * sizeof(Bucket *));
p = ht->pListHead;
while (p != NULL) {
nIndex = p->h & ht->nTableMask;
CONNECT_TO_BUCKET_DLLIST(p, ht->arBuckets[nIndex]);
ht->arBuckets[nIndex] = p;
p = p->pListNext;
}
return SUCCESS;} static int zend_hash_do_resize(HashTable *ht) {
Bucket **t; if ((ht->nTableSize << 1) > 0) {/* Let's double the table size */
t = (Bucket **) perealloc_recoverable(ht->arBuckets, (ht->nTableSize << 1) * sizeof(Bucket *), ht->persistent);
if (t) {
ht->arBuckets = t;
ht->nTableSize = (ht->nTableSize << 1);
ht->nTableMask = ht->nTableSize - 1;
zend_hash_rehash(ht);
return SUCCESS;
}
return FAILURE;
}
return SUCCESS;}
#define UPDATE_DATA(ht, p, pData, nDataSize) \
if (nDataSize == sizeof(void*)) { \
if ((p)->pData != &(p)->pDataPtr) { \
pefree_rel((p)->pData, (ht)->persistent); \
} \
memcpy(&(p)->pDataPtr, pData, sizeof(void *)); \
(p)->pData = &(p)->pDataPtr; \
} else { \
if ((p)->pData == &(p)->pDataPtr) { \
(p)->pData = (void *) pemalloc_rel(nDataSize, (ht)->persistent); \
(p)->pDataPtr=NULL; \
} else { \
(p)->pData = (void *) perealloc_rel((p)->pData, nDataSize, (ht)->persistent);\
/* (p)->pDataPtr is already NULL so no need to initialize it */ \
} \
memcpy((p)->pData, pData, nDataSize); \
} #define INIT_DATA(ht, p, pData, nDataSize); \
if (nDataSize == sizeof(void*)) { \
memcpy(&(p)->pDataPtr, pData, sizeof(void *)); \
(p)->pData = &(p)->pDataPtr; \
} else { \
(p)->pData = (void *) pemalloc_rel(nDataSize, (ht)->persistent);\
if (!(p)->pData) { \
pefree_rel(p, (ht)->persistent); \
return FAILURE; \
} \
memcpy((p)->pData, pData, nDataSize); \
(p)->pDataPtr=NULL; \
}
static inline ulong zend_inline_hash_func(char *arKey, uint nKeyLength) {
register ulong hash = 5381; /* variant with the hash unrolled eight times */
for (; nKeyLength >= 8; nKeyLength -= 8) {
hash = ((hash << 5) + hash) + *arKey++;
hash = ((hash << 5) + hash) + *arKey++;
hash = ((hash << 5) + hash) + *arKey++;
hash = ((hash << 5) + hash) + *arKey++;
hash = ((hash << 5) + hash) + *arKey++;
hash = ((hash << 5) + hash) + *arKey++;
hash = ((hash << 5) + hash) + *arKey++;
hash = ((hash << 5) + hash) + *arKey++;
}
switch (nKeyLength) {
case 7: hash = ((hash << 5) + hash) + *arKey++; /* fallthrough... */
case 6: hash = ((hash << 5) + hash) + *arKey++; /* fallthrough... */
case 5: hash = ((hash << 5) + hash) + *arKey++; /* fallthrough... */
case 4: hash = ((hash << 5) + hash) + *arKey++; /* fallthrough... */
case 3: hash = ((hash << 5) + hash) + *arKey++; /* fallthrough... */
case 2: hash = ((hash << 5) + hash) + *arKey++; /* fallthrough... */
case 1: hash = ((hash << 5) + hash) + *arKey++; break;
case 0: break;
}
return hash;}ulong zend_hash_func(char *arKey, uint nKeyLength) {
return zend_inline_hash_func(arKey, nKeyLength);} //省略了int zend_hash_init(HashTable *ht, uint nSize, hash_func_t pHashFunction, dtor_func_t pDestructor) {
uint i = 3;
Bucket **tmp;
zend_bool persistent = 1;
if (nSize >= 0x80000000) {/* prevent overflow */
ht->nTableSize = 0x80000000;
} else {
while ((1U << i) < nSize) {
i++;
}
ht->nTableSize = 1 << i;
}
ht->nTableMask = ht->nTableSize - 1;
ht->pDestructor = pDestructor;
ht->arBuckets = NULL;
ht->pListHead = NULL;
ht->pListTail = NULL;
ht->nNumOfElements = 0;
ht->nNextFreeElement = 0;
ht->pInternalPointer = NULL;
ht->persistent = persistent;
ht->nApplyCount = 0;
ht->bApplyProtection = 1;
tmp = (Bucket **) calloc(ht->nTableSize, sizeof(Bucket *));
if (!tmp) {
return FAILURE;
}
ht->arBuckets = tmp;
return SUCCESS;} int zend_hash_add_or_update(HashTable *ht, char *arKey, uint nKeyLength, void *pData, uint nDataSize, void **pDest, int flag) {
ulong h;
uint nIndex;
Bucket *p;
if (nKeyLength <= 0) {
return FAILURE;
}
h = zend_inline_hash_func(arKey, nKeyLength);
nIndex = h & ht->nTableMask;
p = ht->arBuckets[nIndex]; while (p != NULL) {
if ((p->h == h) && (p->nKeyLength == nKeyLength)) {
if (!memcmp(p->arKey, arKey, nKeyLength)) {
if (flag & HASH_ADD) {
return FAILURE;
} if (ht->pDestructor) {
ht->pDestructor(p->pData);
}
UPDATE_DATA(ht, p, pData, nDataSize);
if (pDest) {
*pDest = p->pData;
}
return SUCCESS;
}
}
p = p->pNext;}
p = (Bucket *) pemalloc(sizeof(Bucket) - 1 + nKeyLength, ht->persistent);if (!p) {
return FAILURE;}memcpy(p->arKey, arKey, nKeyLength);p->nKeyLength = nKeyLength;INIT_DATA(ht, p, pData, nDataSize);p->h = h;CONNECT_TO_BUCKET_DLLIST(p, ht->arBuckets[nIndex]);if (pDest) {*pDest = p->pData;}
CONNECT_TO_GLOBAL_DLLIST(p, ht);ht->arBuckets[nIndex] = p;
ht->nNumOfElements++;ZEND_HASH_IF_FULL_DO_RESIZE(ht); /* If the Hash table is full, resize it */return SUCCESS;} void zend_hash_destroy(HashTable *ht) {
Bucket *p, *q;
p = ht->pListHead;
while (p != NULL) {
q = p;
p = p->pListNext;
if (ht->pDestructor) {
ht->pDestructor(q->pData);
}
if (q->pData != &q->pDataPtr) {
pefree(q->pData, ht->persistent);
}
pefree(q, ht->persistent);
}
pefree(ht->arBuckets, ht->persistent); }
int zend_hash_find(HashTable *ht, char *arKey, uint nKeyLength, void **pData) {
ulong h;
uint nIndex;
Bucket *p;
h = zend_inline_hash_func(arKey, nKeyLength);
nIndex = h & ht->nTableMask;
p = ht->arBuckets[nIndex];
while (p != NULL) {
if ((p->h == h) && (p->nKeyLength == nKeyLength)) {
if (!memcmp(p->arKey, arKey, nKeyLength)) {
*pData = p->pData;
return SUCCESS;
}
}
p = p->pNext;}return FAILURE;}
void zend_hash_display(HashTable *ht) {
Bucket *p;
uint i;
int flag = 0 ; for (i = 0; i < ht->nTableSize; i++) {
p = ht->arBuckets[i];
flag = 0;
while (p != NULL) {
printf("(%d %s <==> 0x%lX %d) ", i, p->arKey, p->h, p->pNext);
p = p->pNext;
flag = 1;
}
if (flag == 1) {
printf("\n");
} }
p = ht->pListTail;
while (p != NULL) {
printf("%s <==> 0x%lX\n", p->arKey, p->h);
p = p->pListLast;
}}int main() {
int i;
char ch[20];
HashTable ht;
zend_hash_init(&ht, 50, NULL, NULL);
for (i = 30; i < 68; i++) {
sprintf(ch, "%d", i);
ch[strlen(ch) + 1] = '\0';
zend_hash_add_or_update(&ht, ch, strlen(ch) + 1, NULL, 0, NULL, 0);
}
zend_hash_display(&ht);
zend_hash_destroy(&ht);
return 0;}?>
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