musl/src/thread/pthread_key_create.c

#include "pthread_impl.h"

volatile size_t __pthread_tsd_size = sizeof(void *) * PTHREAD_KEYS_MAX;
void *__pthread_tsd_main[PTHREAD_KEYS_MAX] = { 0 };

static void (*volatile keys[PTHREAD_KEYS_MAX])(void *);

static void nodtor(void *dummy)
{
}

int __pthread_key_create(pthread_key_t *k, void (*dtor)(void *))
{
	unsigned i = (uintptr_t)&k / 16 % PTHREAD_KEYS_MAX;
	unsigned j = i;
	pthread_t self = __pthread_self();

	/* This can only happen in the main thread before
	 * pthread_create has been called. */
	if (!self->tsd) self->tsd = __pthread_tsd_main;

	if (!dtor) dtor = nodtor;
	do {
		if (!a_cas_p(keys+j, 0, (void *)dtor)) {
			*k = j;
			return 0;
		}
	} while ((j=(j+1)%PTHREAD_KEYS_MAX) != i);
	return EAGAIN;
}

int __pthread_key_delete(pthread_key_t k)
{
	keys[k] = 0;
	return 0;
}

void __pthread_tsd_run_dtors()
{
	pthread_t self = __pthread_self();
	int i, j, not_finished = self->tsd_used;
	for (j=0; not_finished && j<PTHREAD_DESTRUCTOR_ITERATIONS; j++) {
		not_finished = 0;
		for (i=0; i<PTHREAD_KEYS_MAX; i++) {
			if (self->tsd[i] && keys[i]) {
				void *tmp = self->tsd[i];
				self->tsd[i] = 0;
				keys[i](tmp);
				not_finished = 1;
			}
		}
	}
}

weak_alias(__pthread_key_delete, pthread_key_delete);
weak_alias(__pthread_key_create, pthread_key_create);