我认为比较理想的内存使用方式应该实现这几个特性：

1. 分配一块能满足大多数情况下需求的内存，比如80%的情况下都不需要再次分配内存。

2. 对另外20%需要较多内存的情况，可以通过动态链表按需追加新的内存块。

3. 要对总共消耗的内存有一个最大数量限制，比如200M。

下面就是一个比较理想的通过动态链表实现按需内存分配和使用的例子，取名MemChain

#define BudaMc(size) (char*)alloc(size)
#define BudaM(T) (T*)alloc(sizeof(T))
#define BudaMn(T, name) T *name = (T*)alloc(sizeof(T))
#define BudaZ(T, name) T name; memset(&name, 0, sizeof(name))
#define BudaFree(m) if(m){ free(m); m = NULL; }
#define BudaMax(a, b) ((a)<(b)?(b):(a))typedef struct mem_chain_block
{char *mem;struct mem_chain_block *next;int size;int used;
} MemChainBlock;
typedef struct mem_chain
{struct mem_chain_block *first;struct mem_chain_block *last;int max_size;int used;            // sum of allocated mem of blocksint blocks_used;     // sum of used bytes of blocksint block_min_size;int block_count;
} MemChain;// calloc memory, log fail message
void* alloc(int size);
// MUST use free_mem_chain to free heap mem used
MemChain* create_mem_chain(int max_size=100002048, int block_min_size=2048);
// destroy the whole mem_chain
void free_mem_chain(MemChain *mc);
// delete all the blocks except the first one, reset mem_chain to the beginning
void reset_mem_chain(MemChain *mc);
// return NULL if failed
MemChainBlock* mem_chain_add_block(MemChain *mc, int size);
// If the memory size to use is known to be size, use this function; otherwise, use the next function. 
// Return NULL if failed, return the start of used memory if succeed.
char* use_mem_chain(MemChain *mc, int size, char* content=NULL);
// Return NULL if failed, return the start of used memory if succeed.
char* use_mem_chain(MemChain *mc, const char* format, ...);namespace BUDA
{void* alloc(int size){if (size <= 0) { log("alloc size cannot be less than 1\n"); return NULL; }void* r = calloc(1, size); if (!r) { log("alloc %d bytes memory failed.\n", size); return NULL; }  return r;}MemChain* create_mem_chain(int max_size, int block_min_size){log("create_mem_chain %d/%d", max_size, block_min_size);BudaMn(MemChain, mc); BudaMn(MemChainBlock, mcb); if(mc==NULL || mcb == NULL) return NULL;mcb->mem=BudaMc(block_min_size); if(mcb->mem == NULL) return NULL; mcb->size=block_min_size; mc->max_size=max_size; mc->used+=mcb->size; mc->block_min_size=block_min_size; mc->first=mc->last=mcb; mc->block_count=1;return mc;}  MemChainBlock* mem_chain_add_block(MemChain *mc, int size){log("mem_chain_add_block %d", size);if(size+mc->used > mc->max_size) { log("mem_chain reached max_size: %d", mc->max_size); return NULL; }BudaMn(MemChainBlock, mcb); if(mcb == NULL) return NULL;mcb->mem=BudaMc(size); if(mcb->mem == NULL) return NULL; mcb->size=size; mc->used+=size; mc->block_count++; mc->last->next=mcb; mc->last=mcb;return mcb;}void free_mem_chain(MemChain *mc){log("free_mem_chain %d", mc->used);int remain_block_count = mc->block_count; MemChainBlock *mcb=mc->first, *next; BudaFree(mc);while(mcb) { next=mcb->next; BudaFree(mcb->mem); BudaFree(mcb); remain_block_count--; mcb=next; }if(remain_block_count) { log("MemChain block_count broken: %d", remain_block_count); }}void reset_mem_chain(MemChain *mc){log("reset_mem_chain %d/%d", mc->max_size, mc->block_min_size);MemChainBlock *first=mc->first; MemChainBlock *mcb=first->next, *next; while(mcb) { next=mcb->next; BudaFree(mcb->mem); BudaFree(mcb); mcb=next; }mc->block_count=1; mc->blocks_used=0; mc->last=first; mc->used=first->size;first->next=NULL; first->used=0;}char* use_mem_chain(MemChain *mc, int size, char* content){log("use_mem_chain %d bytes", size);MemChainBlock *last=mc->last;if(last->used + size > last->size){int asize=BudaMax(mc->block_min_size, size); last = mem_chain_add_block(mc, asize); if(last==NULL) return NULL;}char* write_start=last->mem + last->used; last->used += size; mc->blocks_used+=size;if(content) memcpy(write_start, content, size);return write_start;}char* use_mem_chain(MemChain *mc, const char* format, ...){//log("try use_mem_chain : %s", format);MemChainBlock *last=mc->last; int used=last->used; char *write_start=last->mem+used; int remain=last->size - used, len, asize=mc->block_min_size;write: va_list args; va_start(args, format); len = vsnprintf2(last->mem + used, remain, format, args); va_end(args);if(len == -1) {last = mem_chain_add_block(mc, asize); if(last==NULL) return NULL; used=0; write_start=last->mem; remain=asize; asize*=2; goto write;}else{last->used += len; mc->blocks_used+=len;log("use_mem_chain %d bytes : \n%s", len, write_start);}return write_start;}}

作者寄语

以上如有错漏之处，敬请大家指正。我是主修C/C++、Vue3，开发网站的程序员，我的联系方式：
微信：TobeBuda
Email/Paypal: jinmin.si@outlook.com
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参考资料

chatgpt

gemini

mistral

claude