SLists使用了无锁算法来保证原子同步,以提升系统性能,避免了诸如优先级挂和互锁的问题。
注意:所有的链表项必须对齐到MEMORY_ALLOCATION_ALIGNMENT。否则会出现奇葩的错误。
(PS:看英文MSDN的API解释,我感觉这是从前插又从前取,是个栈的样子。)
InitializeSListHead,创建一个空栈
void WINAPI InitializeSListHead(
__inout PSLIST_HEADER ListHead//SLIST_HEADER类型的链头,供系统使用。
);
InterlockedFlushSList,清空栈(感觉这个返回值没什么用的样子,难道可以先全部得到,然后根据链表中元素数量再一个一个地用?求解释。)
PSLIST_ENTRY WINAPI InterlockedFlushSList(
__inout PSLIST_HEADER ListHead//创建空栈时用的那个链头
);
InterlockedPushEntrySList,在头添加(区别于从尾部添加),返回值为之前的第一项,如果之前为空链,则返回NULL。
PSLIST_ENTRY WINAPI InterlockedPushEntrySList(
__inout PSLIST_HEADER ListHead,//创建空栈时用的那个链头
__inout PSLIST_ENTRY ListEntry//插入项
);
InterlockedPopEntrySList,在头取出(区别于从尾部取出),返回值就是取的那个项的指针,如果之前为空链,则返回NULL。
PSLIST_ENTRY WINAPI InterlockedPopEntrySList(
__inout PSLIST_HEADER ListHead
);
QueryDepthSList,返回元素的数量。
USHORT WINAPI QueryDepthSList(
__in PSLIST_HEADER ListHead
);
微软的MSDN上有个例子,我复制了下来,链接:http://msdn.microsoft.com/en-us/library/windows/desktop/ms686962。代码如下。
#include <windows.h>
#include <malloc.h>
#include <stdio.h> // Structure to be used for a list item; the first member is the
// SLIST_ENTRY structure, and additional members are used for data.
// Here, the data is simply a signature for testing purposes. typedef struct _PROGRAM_ITEM {
SLIST_ENTRY ItemEntry;
ULONG Signature;
} PROGRAM_ITEM, *PPROGRAM_ITEM; int main( )
{
ULONG Count;
PSLIST_ENTRY pFirstEntry, pListEntry;
PSLIST_HEADER pListHead;
PPROGRAM_ITEM pProgramItem; // Initialize the list header to a MEMORY_ALLOCATION_ALIGNMENT boundary.
pListHead = (PSLIST_HEADER)_aligned_malloc(sizeof(SLIST_HEADER),
MEMORY_ALLOCATION_ALIGNMENT);
if( NULL == pListHead )
{
printf("Memory allocation failed.\n");
return -1;
}
InitializeSListHead(pListHead); // Insert 10 items into the list.
for( Count = 1; Count <= 10; Count += 1 )
{
pProgramItem = (PPROGRAM_ITEM)_aligned_malloc(sizeof(PROGRAM_ITEM),
MEMORY_ALLOCATION_ALIGNMENT);
if( NULL == pProgramItem )
{
printf("Memory allocation failed.\n");
return -1;
}
pProgramItem->Signature = Count;
pFirstEntry = InterlockedPushEntrySList(pListHead,
&(pProgramItem->ItemEntry));
} // Remove 10 items from the list and display the signature.
for( Count = 10; Count >= 1; Count -= 1 )
{
pListEntry = InterlockedPopEntrySList(pListHead); if( NULL == pListEntry )
{
printf("List is empty.\n");
return -1;
} pProgramItem = (PPROGRAM_ITEM)pListEntry;
printf("Signature is %d\n", pProgramItem->Signature); // This example assumes that the SLIST_ENTRY structure is the
// first member of the structure. If your structure does not
// follow this convention, you must compute the starting address
// of the structure before calling the free function. _aligned_free(pListEntry);
} // Flush the list and verify that the items are gone.
pListEntry = InterlockedFlushSList(pListHead);
pFirstEntry = InterlockedPopEntrySList(pListHead);
if (pFirstEntry != NULL)
{
printf("Error: List is not empty.\n");
return -1;
} _aligned_free(pListHead); return 1;
}
这里略微解释下吧!
微软自己定义的那个结构体PROGRAM_ITEM的第一项是SLIST_ENTRY类型的变量。
往InterlockedPushEntrySList和InterlockedPopEntrySList传递时传递的是自定义结构体的第一项。
结构体的地址和它的第一项的地址是同一个。