src/mutex.c

#define	JEMALLOC_MUTEX_C_
#include "jemalloc/internal/jemalloc_internal.h"

#if defined(JEMALLOC_LAZY_LOCK) && !defined(_WIN32)
#include <dlfcn.h>
#endif

#ifndef _CRT_SPINCOUNT
#define	_CRT_SPINCOUNT 4000
#endif

/******************************************************************************/
/* Data. */

#ifdef JEMALLOC_LAZY_LOCK
bool isthreaded = false;
#endif
#ifdef JEMALLOC_MUTEX_INIT_CB
static bool		postpone_init = true;
static malloc_mutex_t	*postponed_mutexes = NULL;
#endif

#if defined(JEMALLOC_LAZY_LOCK) && !defined(_WIN32)
static void	pthread_create_once(void);
#endif

/******************************************************************************/
/*
 * We intercept pthread_create() calls in order to toggle isthreaded if the
 * process goes multi-threaded.
 */

#if defined(JEMALLOC_LAZY_LOCK) && !defined(_WIN32)
static int (*pthread_create_fptr)(pthread_t *__restrict, const pthread_attr_t *,
    void *(*)(void *), void *__restrict);

static void
pthread_create_once(void)
{

	pthread_create_fptr = dlsym(RTLD_NEXT, "pthread_create");
	if (pthread_create_fptr == NULL) {
		malloc_write("<jemalloc>: Error in dlsym(RTLD_NEXT, "
		    "\"pthread_create\")\n");
		abort();
	}

	isthreaded = true;
}

JEMALLOC_EXPORT int
pthread_create(pthread_t *__restrict thread,
    const pthread_attr_t *__restrict attr, void *(*start_routine)(void *),
    void *__restrict arg)
{
	static pthread_once_t once_control = PTHREAD_ONCE_INIT;

	pthread_once(&once_control, pthread_create_once);

	return (pthread_create_fptr(thread, attr, start_routine, arg));
}
#endif

/******************************************************************************/

#ifdef JEMALLOC_MUTEX_INIT_CB
JEMALLOC_EXPORT int	_pthread_mutex_init_calloc_cb(pthread_mutex_t *mutex,
    void *(calloc_cb)(size_t, size_t));
#endif

bool
malloc_mutex_init(malloc_mutex_t *mutex, const char *name, witness_rank_t rank)
{

#ifdef _WIN32
#  if _WIN32_WINNT >= 0x0600
	InitializeSRWLock(&mutex->lock);
#  else
	if (!InitializeCriticalSectionAndSpinCount(&mutex->lock,
	    _CRT_SPINCOUNT))
		return (true);
#  endif
#elif (defined(JEMALLOC_OS_UNFAIR_LOCK))
	mutex->lock = OS_UNFAIR_LOCK_INIT;
#elif (defined(JEMALLOC_OSSPIN))
	mutex->lock = 0;
#elif (defined(JEMALLOC_MUTEX_INIT_CB))
	if (postpone_init) {
		mutex->postponed_next = postponed_mutexes;
		postponed_mutexes = mutex;
	} else {
		if (_pthread_mutex_init_calloc_cb(&mutex->lock,
		    bootstrap_calloc) != 0)
			return (true);
	}
#else
	pthread_mutexattr_t attr;

	if (pthread_mutexattr_init(&attr) != 0)
		return (true);
	pthread_mutexattr_settype(&attr, MALLOC_MUTEX_TYPE);
	if (pthread_mutex_init(&mutex->lock, &attr) != 0) {
		pthread_mutexattr_destroy(&attr);
		return (true);
	}
	pthread_mutexattr_destroy(&attr);
#endif
	if (config_debug)
		witness_init(&mutex->witness, name, rank, NULL);
	return (false);
}

void
malloc_mutex_prefork(tsdn_t *tsdn, malloc_mutex_t *mutex)
{

	malloc_mutex_lock(tsdn, mutex);
}

void
malloc_mutex_postfork_parent(tsdn_t *tsdn, malloc_mutex_t *mutex)
{

	malloc_mutex_unlock(tsdn, mutex);
}

void
malloc_mutex_postfork_child(tsdn_t *tsdn, malloc_mutex_t *mutex)
{

#ifdef JEMALLOC_MUTEX_INIT_CB
	malloc_mutex_unlock(tsdn, mutex);
#else
	if (malloc_mutex_init(mutex, mutex->witness.name,
	    mutex->witness.rank)) {
		malloc_printf("<jemalloc>: Error re-initializing mutex in "
		    "child\n");
		if (opt_abort)
			abort();
	}
#endif
}

bool
malloc_mutex_boot(void)
{

#ifdef JEMALLOC_MUTEX_INIT_CB
	postpone_init = false;
	while (postponed_mutexes != NULL) {
		if (_pthread_mutex_init_calloc_cb(&postponed_mutexes->lock,
		    bootstrap_calloc) != 0)
			return (true);
		postponed_mutexes = postponed_mutexes->postponed_next;
	}
#endif
	return (false);
}