How to restore the initial state of the module?

[gongshuaiqi]

I want to new a heap for a module. To avoid memory fragmentation, when the module is idle, I want to restore the initial state of the heap. How should I do this? Thank you.

#include <sys/mman.h>
#include <mimalloc.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>

int main() {
const size_t size = 1UL << 30; // 1GB
int protection = PROT_READ | PROT_WRITE;
int flags = MAP_ANONYMOUS | MAP_SHARED;
void* addr = mmap(NULL, size, protection, flags, -1, 0);

if (addr == MAP_FAILED) {
    fprintf(stderr, "Error: mmap failed\n");
    return 1;
}

memset(addr, 0, size);
printf("addr: %p, end:%p\n", addr, (char*)addr + size);

// Tell mimalloc we (the user) own the region (own=false).
// => We are responsible for calling munmap.
mi_arena_id_t arena_id;
bool ok = mi_manage_os_memory_ex(addr, size,
                                 /*commit?*/ true,
                                 /*allow_large?*/ false,
                                 /*is_pinned?*/ false,
                                 /*alignment*/ -1,
                                 /*own?*/ false, 
                                 &arena_id);
if (!ok) {
    fprintf(stderr, "Error: mi_manage_os_memory_ex failed\n");
    munmap(addr, size);
    return 1;
}

// Create a custom heap in that arena
mi_heap_t* my_heap = mi_heap_new_in_arena(arena_id);
if (!my_heap) {
    fprintf(stderr, "Error: could not create heap\n");
    munmap(addr, size);
    return 1;
}

// Allocate memory from our custom heap
void* p1 = mi_heap_malloc(my_heap, 1 * 1024 * 1024); // 1MB
void* p2 = mi_heap_malloc(my_heap, 1 * 1024 * 1024); // 1MB
printf("p1=%p, p2=%p\n", p1, p2);

// Free the allocated blocks
mi_free(p1);
mi_free(p2);

// Delete the heap
mi_heap_delete(my_heap);

// Now we can safely unmap, since mimalloc doesn't "own" the region
munmap(addr, size);

return 0;

}

（1）When the "own" parameter of mi_manage_os_memory_ex() is set to true, Do I still need to munmap?

（2）Should I use mi_heap_delete or mi_heap_destroy to restore the initial state of the heap?

（3）After restoring to the initial state, should I call mi_heap_new_in_arena(arena_id) to re-allocate a heap?

（4）I found that after calling mi_heap_destroy and mi_heap_new_in_arena(arena_id), mi_option_is_enabled(mi_option_show_errors) changed from 0 to 1.