pyobjc / pyobjc-core / Modules / objc / closure_pool.m

 * A simple allocator for closure. This assumes that most closures are kept
 * alive forever and we therefore don't have to return storage to the OS.
#include "pyobjc.h"

#include <sys/mman.h>

typedef struct freelist {
	struct freelist* next;
} freelist;

static freelist* closure_freelist = NULL;

static freelist* allocate_block(void)

	/* Allocate ffi_closure in groups of 10 VM pages */
#define BLOCKSIZE ((PAGE_SIZE*10)/sizeof(ffi_closure*))

	freelist* newblock = mmap(NULL, BLOCKSIZE * sizeof(ffi_closure),
	size_t i;

	if (newblock == (void*)-1) {
		return NULL;
	for (i = 0; i < BLOCKSIZE-1; i++) {
		((freelist*)(((ffi_closure*)newblock)+i))->next = 

	((freelist*)(((ffi_closure*)newblock)+(BLOCKSIZE-1)))->next = NULL;
	return newblock;

	if (closure_freelist == NULL) {
		closure_freelist = allocate_block();
		if (closure_freelist == NULL) {
			return NULL;
	ffi_closure* result = (ffi_closure*)closure_freelist;
	closure_freelist = closure_freelist->next;
	return result;

PyObjC_free_closure(ffi_closure* cl)
	((freelist*)cl)->next = closure_freelist;
	closure_freelist = (freelist*)cl;
	return 0;
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