experimental destroy_on_exit option for statically linked mimalloc in a dynamically unloaded DLL

include/mimalloc-internal.h

@@ -139,6 +139,7 @@ uint8_t    _mi_bin(size_t size);                // for stats
 void       _mi_heap_destroy_pages(mi_heap_t* heap);
 void       _mi_heap_collect_abandon(mi_heap_t* heap);
 void       _mi_heap_set_default_direct(mi_heap_t* heap);
+void       _mi_heap_destroy_all(void);
 
 // "stats.c"
 void       _mi_stats_done(mi_stats_t* stats);

include/mimalloc.h

@@ -335,6 +335,7 @@ typedef enum mi_option_e {
   mi_option_max_errors,
   mi_option_max_warnings,
   mi_option_max_segment_reclaim,
+  mi_option_destroy_on_exit,          
   _mi_option_last
 } mi_option_t;
 

src/heap.c

@@ -327,7 +327,20 @@ void mi_heap_destroy(mi_heap_t* heap) {
   }
 }
 
-
+void _mi_heap_destroy_all(void) {
+  mi_heap_t* bheap = mi_heap_get_backing();
+  mi_heap_t* curr = bheap->tld->heaps;
+  while (curr != NULL) {
+    mi_heap_t* next = curr->next;
+    if (curr->no_reclaim) {
+      mi_heap_destroy(curr);
+    }
+    else {
+      _mi_heap_destroy_pages(curr);
+    }
+    curr = next;
+  }
+}
 
 /* -----------------------------------------------------------
   Safe Heap delete

src/init.c

@@ -598,7 +598,7 @@ static void mi_cdecl mi_process_done(void) {
   #if defined(_WIN32) && !defined(MI_SHARED_LIB)
   FlsFree(mi_fls_key);  // call thread-done on all threads (except the main thread) to prevent dangling callback pointer if statically linked with a DLL; Issue #208
   #endif
-  
+
   #ifndef MI_SKIP_COLLECT_ON_EXIT
     #if (MI_DEBUG != 0) || !defined(MI_SHARED_LIB)  
     // free all memory if possible on process exit. This is not needed for a stand-alone process
@@ -608,6 +608,11 @@ static void mi_cdecl mi_process_done(void) {
     #endif
   #endif
 
+  if (mi_option_is_enabled(mi_option_destroy_on_exit)) {
+    _mi_heap_destroy_all();                          // forcefully release all memory held by all heaps (of this thread only!)
+    _mi_mem_collect(&_mi_heap_main_get()->tld->os);  // release all regions
+  }
+
   if (mi_option_is_enabled(mi_option_show_stats) || mi_option_is_enabled(mi_option_verbose)) {
     mi_stats_print(NULL);
   }

src/options.c

@@ -93,7 +93,8 @@ static mi_option_desc_t options[_mi_option_last] =
   { 100, UNINIT, MI_OPTION(os_tag) },            // only apple specific for now but might serve more or less related purpose
   { 16,  UNINIT, MI_OPTION(max_errors) },        // maximum errors that are output
   { 16,  UNINIT, MI_OPTION(max_warnings) },      // maximum warnings that are output
-  { 8,   UNINIT, MI_OPTION(max_segment_reclaim)} // max. number of segment reclaims from the abandoned segments per try.
+  { 8,   UNINIT, MI_OPTION(max_segment_reclaim)},// max. number of segment reclaims from the abandoned segments per try.
+  { 0,   UNINIT, MI_OPTION(destroy_on_exit)}     // release all OS memory on process exit; careful with dangling pointer or after-exit frees!
 };
 
 static void mi_option_init(mi_option_desc_t* desc);

test/main-override-static.c

@@ -32,7 +32,7 @@ int main() {
   // invalid_free();
   // test_reserved();
   // negative_stat();
-  test_heap_walk();
+  // test_heap_walk();
   // alloc_huge();
   
   void* p1 = malloc(78);