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View Code? Open in Web Editor NEW一个极简内存池实现
License: MIT License
一个极简内存池实现
License: MIT License
初始化内存池时,此时内存池作为一个大的空闲块,其尾部也应该有指针指向首地址,此次没有相应操作
像这样:
*(mp_chunk**)((char*)ck + ck->size - MP_CHUNK_POINTER) = ck;
#define MP_INIT_MEMORY_STRUCT(mm, mempool_sz) \
do { \
mm->mempool_size = mempool_sz; \
mm->alloc_mem = 0; \
mm->alloc_prog_mem = 0; \
mm->free_list = (_MP_Chunk*) mm->start; \
mm->free_list->is_free = 1; \
mm->free_list->alloc_mem = mempool_sz; \
mm->free_list->prev = NULL; \
mm->free_list->next = NULL; \
mm->alloc_list = NULL; \
} while (0)
static int merge_free_chunk(MemoryPool* mp, _MP_Memory* mm, _MP_Chunk* c) {
_MP_Chunk *p0 = c, *p1 = c;
while (p0->is_free) {
p1 = p0;
// bug:向前面搜索邻接内存块貌似有错?p0是作为内存块_MP_Chunk首地址,而不是分配给用户的内存空间的首地址,因此不应该减去MP_CHUNKHEADER
// ++if ((char*) p0 - MP_CHUNKHEADER <= mm->start) break;
// --if ((char*) p0 - MP_CHUNKEND - MP_CHUNKHEADER <= mm->start) break;
p0 = *(_MP_Chunk**) ((char*) p0 - MP_CHUNKEND);
}
p0 = (_MP_Chunk*) ((char*) p1 + p1->alloc_mem);
while ((char*) p0 < mm->start + mp->mempool_size && p0->is_free) {
MP_DLINKLIST_DEL(mm->free_list, p0);
p1->alloc_mem += p0->alloc_mem;
p0 = (_MP_Chunk*) ((char*) p0 + p0->alloc_mem);
}
*(_MP_Chunk**) ((char*) p1 + p1->alloc_mem - MP_CHUNKEND) = p1;
#ifdef _Z_MEMORYPOOL_THREAD_
MP_UNLOCK(mp);
#endif
return 0;
}
是否保证线程安全
使用windows的wchar_t分配内存后释放存在问题,本来我是分配的2G,释放之后只有几百个字节可用
为什么要将list分成三个区,chunk结构体区,实际数据区,指向chunk的指针区。感觉第三个部分多余了吧。
你好:
关注和使用你的项目一段时间了,感谢你的分享,给我们带来了便利!
但是,我们在使用的过程中,通过get_mempool_usage方法获取使用率,一直能正确获取,但是有时会突然返回一个很大的值,由于是个异常,不太好抓,但是真的出现了!我找了一段时间没找到原因,不知道你是否有时间看看!(我用在嵌入式Linux上)
如果释放的内存为第一块申请出来的内存,在使用自动扩展后,在释放时:merge_free_chunk函数中,Chunk *p0 = *(Chunk **)((char *)c - CHUNKEND), *p1 = c;
while ((char *)p0 >= mm->start && p0->is_free)
{
.........
}
c操作任然会获取到错误的地址。
建议增加每个管理数据段的结束地址校验,比如
while ((char *)p0 >= mm->start && *(char )p0 < mm->end && p0->is_free)
end在每次调用系统malloc的时候进行记录
大哥 help 代码有毒
使用自动扩展后,merge_free_chunk会报错,while ((char *)p0 >= mm->start && p0->is_free),从调试来看,内存访问都是无法获取的状态
MemoryPool* MemoryPoolInit(mem_size_t maxmempoolsize, mem_size_t mempoolsize) {
if (mempoolsize > maxmempoolsize) {
// printf("[MemoryPool_Init] MemPool Init ERROR! Mempoolsize is too big!
// \n");
return NULL;
}
MemoryPool* mp = (MemoryPool*) malloc(sizeof(MemoryPool));
if (!mp) return NULL;
mp->last_id = 0;
if (mempoolsize < maxmempoolsize) mp->auto_extend = 1;
mp->max_mem_pool_size = maxmempoolsize;
mp->total_mem_pool_size = mp->mem_pool_size = mempoolsize;
#ifdef _Z_MEMORYPOOL_THREAD_
pthread_mutex_init(&mp->lock, NULL);
#endif
char* s = (char*) malloc(sizeof(_MP_Memory) +
sizeof(char) * mp->mem_pool_size);
if (!s) return NULL; //HERE!!!!!!!!!!!!!!!!!!!!, leads mem leak as mp is not free yet :-)
......
}
if (mp->auto_extend) {
// 超过总内存限制
if (mp->alloc_mempool_size + total_needed_size > mp->max_mempool_size) {
goto err_out;
}
// 问题1:
mem_size_t add_mem_sz = mp->max_mempool_size - mp->mempool_size;
// 如果空间足够则按 mempool_size 新增, 不足则分配剩下所有内存
add_mem_sz = add_mem_sz >= mp->mempool_size ? mp->mempool_size
: add_mem_sz;
if (!extend_memory_list(mp, add_mem_sz)) goto err_out;
// 更新实际分配内存
mp->alloc_mempool_size += add_mem_sz;
goto FIND_FREE_CHUNK;
}
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