How to restore the initial state of the module?

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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
#include
#include
#include
#include
#include

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.

Start by reading the API documentation for mi_manage_os_memory_ex(), mi_heap_delete(), mi_heap_destroy(), and mi_heap_new_in_arena(). Compare their ownership and lifecycle semantics with the supplied mmap example, including the change to mi_option_show_errors. Done means the four questions have definitive, documented answers.

Written by the indexing model from the issue text.