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memorypool's Issues

merge_free_chunk报错

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

关于void* MemoryPoolAlloc(MemoryPool* mp, mem_size_t wantsize)部分的逻辑疑问

  1. 请问：mp->mempool_size代表的什么意思？是默认的一个标准内存池大小吗？
  2. 剩余可新增内存池大小不是应该等于mp->max_mempool_size - mp->alloc_mempool_size吗？
    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;
    }

issues for auto-extended

I think the extended feature has problem:
image
In above code, why compare with the value mem_pool_size?
max_mem_pool_size should be used instead here in my opinion.

Another place is:
image

In my opinion, it should be modified as below:
image

Please correct me if my understanding is wrong.

Type Chinese is also okay for me.

Thank you.

关于list分区

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。

在调用get_mempool_usage方法时，突然返回一个很大的值

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）

初始化时，空闲块尾指针应当指向首地址

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)

关于释放内存报错

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

bug：static int merge_free_chunk(MemoryPool* mp, _MP_Memory* mm, _MP_Chunk* c) 

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;
}

mem leak 

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 :-)
    ......
}

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