/* Heaps with user defined storage */
typedef struct _zend_mm_storage zend_mm_storage;
 
typedef struct _zend_mm_segment {
    size_t    size;
    struct _zend_mm_segment *next_segment;
} zend_mm_segment;
 
typedef struct _zend_mm_mem_handlers {
    const char *name;
    zend_mm_storage* (*init)(void *params);    //    初始化函数
    void (*dtor)(zend_mm_storage *storage);    //    析构函数
    void (*compact)(zend_mm_storage *storage);
    zend_mm_segment* (*_alloc)(zend_mm_storage *storage, size_t size);    //    内存分配函数
    zend_mm_segment* (*_realloc)(zend_mm_storage *storage, zend_mm_segment *ptr, size_t size);    //    重新分配内存函数
    void (*_free)(zend_mm_storage *storage, zend_mm_segment *ptr);    //    释放内存函数
} zend_mm_mem_handlers;
 
struct _zend_mm_storage {
    const zend_mm_mem_handlers *handlers;    //    处理函数集
    void *data;
};

/* 使用mmap内存映射函数分配内存 写入时拷贝的私有映射，并且匿名映射，映射区不与任何文件关联。*/
# define ZEND_MM_MEM_MMAP_ANON_DSC {"mmap_anon", zend_mm_mem_dummy_init, zend_mm_mem_dummy_dtor, zend_mm_mem_dummy_compact, zend_mm_mem_mmap_anon_alloc, zend_mm_mem_mmap_realloc, zend_mm_mem_mmap_free}

/* 使用mmap内存映射函数分配内存 写入时拷贝的私有映射，并且映射到/dev/zero。*/
# define ZEND_MM_MEM_MMAP_ZERO_DSC {"mmap_zero", zend_mm_mem_mmap_zero_init, zend_mm_mem_mmap_zero_dtor, zend_mm_mem_dummy_compact, zend_mm_mem_mmap_zero_alloc, zend_mm_mem_mmap_realloc, zend_mm_mem_mmap_free}

/* 使用HeapAlloc分配内存 windows版本 关于这点，注释中写的是VirtualAlloc() to allocate memory，实际在程序中使用的是HeapAlloc*/
# define ZEND_MM_MEM_WIN32_DSC {"win32", zend_mm_mem_win32_init, zend_mm_mem_win32_dtor, zend_mm_mem_win32_compact, zend_mm_mem_win32_alloc, zend_mm_mem_win32_realloc, zend_mm_mem_win32_free}

/* 使用malloc分配内存 默认为此种分配 如果有加ZEND_WIN32宏，则使用win32的分配方案*/
# define ZEND_MM_MEM_MALLOC_DSC {"malloc", zend_mm_mem_dummy_init, zend_mm_mem_dummy_dtor, zend_mm_mem_dummy_compact, zend_mm_mem_malloc_alloc, zend_mm_mem_malloc_realloc, zend_mm_mem_malloc_free}

static const zend_mm_mem_handlers mem_handlers[] = {
#ifdef HAVE_MEM_WIN32
    ZEND_MM_MEM_WIN32_DSC,
#endif
#ifdef HAVE_MEM_MALLOC
    ZEND_MM_MEM_MALLOC_DSC,
#endif
#ifdef HAVE_MEM_MMAP_ANON
    ZEND_MM_MEM_MMAP_ANON_DSC,
#endif
#ifdef HAVE_MEM_MMAP_ZERO
    ZEND_MM_MEM_MMAP_ZERO_DSC,
#endif
    {NULL, NULL, NULL, NULL, NULL, NULL}
};

WINBASEAPI
__out_opt
HANDLE
WINAPI
HeapCreate(
	__in DWORD flOptions,
	__in SIZE_T dwInitialSize,
	__in SIZE_T dwMaximumSize
	);
 
WINBASEAPI
BOOL
WINAPI
HeapDestroy(
	__in HANDLE hHeap
	);
 
WINBASEAPI
__bcount(dwBytes)
LPVOID
WINAPI
HeapAlloc(
	__in HANDLE hHeap,
	__in DWORD dwFlags,
	__in SIZE_T dwBytes
	);
 
 
WINBASEAPI
BOOL
WINAPI
HeapFree(
	__inout HANDLE hHeap,
	__in	DWORD dwFlags,
	__deref LPVOID lpMem
	);
 
WINBASEAPI
SIZE_T
WINAPI
HeapSize(
	__in HANDLE hHeap,
	__in DWORD dwFlags,
	__in LPCVOID lpMem
	);

ZEND_API zend_mm_heap *zend_mm_startup(void)
{
    int i;
    size_t seg_size;
    char *mem_type = getenv("ZEND_MM_MEM_TYPE");
    char *tmp;
    const zend_mm_mem_handlers *handlers;
    zend_mm_heap *heap;
 
    if (mem_type == NULL) {
   	 i = 0;
    } else {
   	 for (i = 0; mem_handlers[i].name; i++) {
   		 if (strcmp(mem_handlers[i].name, mem_type) == 0) {
   			 break;
   		 }
   	 }
   	 if (!mem_handlers[i].name) {
   		 fprintf(stderr, "Wrong or unsupported zend_mm storage type '%s'\n", mem_type);
   		 fprintf(stderr, "  supported types:\n");
   		 for (i = 0; mem_handlers[i].name; i++) {
   			 fprintf(stderr, "	'%s'\n", mem_handlers[i].name);
   		 }
   		 exit(255);
   	 }
    }
    handlers = &mem_handlers[i];
 
    tmp = getenv("ZEND_MM_SEG_SIZE");
    if (tmp) {
   	 seg_size = zend_atoi(tmp, 0);
   	 if (zend_mm_low_bit(seg_size) != zend_mm_high_bit(seg_size)) {
   		 fprintf(stderr, "ZEND_MM_SEG_SIZE must be a power of two\n");
   		 exit(255);
   	 } else if (seg_size < ZEND_MM_ALIGNED_SEGMENT_SIZE + ZEND_MM_ALIGNED_HEADER_SIZE) {
   		 fprintf(stderr, "ZEND_MM_SEG_SIZE is too small\n");
   		 exit(255);
   	 }
    } else {
   	 seg_size = ZEND_MM_SEG_SIZE;
    }
 
    //....代码省略
}