bool SystemProperties::Wait(const prop_info* pi, uint32_t old_serial, uint32_t* new_serial_ptr,
const timespec* relative_timeout) {
// Are we waiting on the global serial or a specific serial?
atomic_uint_least32_t* serial_ptr;
if (pi == nullptr) {
if (!initialized_) {
return -1;
}
prop_area* serial_pa = contexts_->GetSerialPropArea();
if (serial_pa == nullptr) {
return -1;
}
serial_ptr = serial_pa->serial();
} else {
serial_ptr = const_cast<atomic_uint_least32_t*>(&pi->serial);
}
uint32_t new_serial;
do {
int rc;
if ((rc = __futex_wait(serial_ptr, old_serial, relative_timeout)) != 0 && rc == -ETIMEDOUT) {
return false;
}
new_serial = load_const_atomic(serial_ptr, memory_order_acquire);
} while (new_serial == old_serial);
*new_serial_ptr = new_serial;
return true;
}
int __system_property_wait(const prop_info *pi)
{
if (pi == 0) {
prop_area *pa = __system_property_area__;
const uint32_t n = pa->serial;
do {
__futex_wait(&pa->serial, n, NULL);
} while (n == pa->serial);
} else {
const uint32_t n = pi->serial;
do {
__futex_wait((volatile void *)&pi->serial, n, NULL);
} while(n == pi->serial);
}
return 0;
}
int __system_property_read(const prop_info *pi, char *name, char *value)
{
unsigned serial, len;
if (__predict_false(compat_mode)) {
return __system_property_read_compat(pi, name, value);
}
for(;;) {
serial = pi->serial;
while(SERIAL_DIRTY(serial)) {
__futex_wait((volatile void *)&pi->serial, serial, NULL);
serial = pi->serial;
}
len = SERIAL_VALUE_LEN(serial);
memcpy(value, pi->value, len + 1);
ANDROID_MEMBAR_FULL();
if(serial == pi->serial) {
if(name != 0) {
strcpy(name, pi->name);
}
return len;
}
}
}
bool mb__system_property_wait(const prop_info* pi,
uint32_t old_serial,
uint32_t* new_serial_ptr,
const timespec* relative_timeout) {
// Are we waiting on the global serial or a specific serial?
atomic_uint_least32_t* serial_ptr;
if (pi == nullptr) {
if (mb__system_property_area__ == nullptr) return -1;
serial_ptr = mb__system_property_area__->serial();
} else {
serial_ptr = const_cast<atomic_uint_least32_t*>(&pi->serial);
}
uint32_t new_serial;
do {
int rc;
if ((rc = __futex_wait(serial_ptr, old_serial, relative_timeout)) != 0 && rc == -ETIMEDOUT) {
return false;
}
new_serial = load_const_atomic(serial_ptr, memory_order_acquire);
} while (new_serial == old_serial);
*new_serial_ptr = new_serial;
return true;
}
int __system_property_wait(const prop_info *pi)
{
unsigned n;
if(pi == 0) {
prop_area *pa = __system_property_area__;
n = pa->serial;
do {
__futex_wait(&pa->serial, n, 0);
} while(n == pa->serial);
} else {
n = pi->serial;
do {
__futex_wait((volatile void *)&pi->serial, n, 0);
} while(n == pi->serial);
}
return 0;
}
int futex_wait(volatile void *ftx, int val, const struct timespec *timeout)
{
#ifdef ANDROID
return __futex_wait(ftx, val, timeout);
#else
nanosleep(timeout, NULL);
return 0;
#endif
}
unsigned int __system_property_wait_any(unsigned int serial)
{
prop_area *pa = __system_property_area__;
do {
__futex_wait(&pa->serial, serial, NULL);
} while(pa->serial == serial);
return pa->serial;
}
// Wait for non-locked serial, and retrieve it with acquire semantics.
unsigned int __system_property_serial(const prop_info *pi)
{
uint32_t serial = load_const_atomic(&pi->serial, memory_order_acquire);
while (SERIAL_DIRTY(serial)) {
__futex_wait(const_cast<volatile void *>(
reinterpret_cast<const void *>(&pi->serial)),
serial, NULL);
serial = load_const_atomic(&pi->serial, memory_order_acquire);
}
return serial;
}
unsigned int __system_property_wait_any(unsigned int serial)
{
prop_area *pa = __system_property_area__;
uint32_t my_serial;
do {
__futex_wait(&pa->serial, serial, NULL);
my_serial = atomic_load_explicit(&pa->serial, memory_order_acquire);
} while (my_serial == serial);
return my_serial;
}
/*
* Poll an event to see if it has been signaled. Set timeout to -1 to block indefinatly.
* If timeout is 0 this function does not block but returns immediately.
*/
BOOL event_poll( EVENT * event, DWORD timeout )
{
#ifdef _WIN32
if( event == NULL )
return FALSE;
if( WaitForSingleObject( event->handle, timeout ) == WAIT_OBJECT_0 )
return TRUE;
return FALSE;
#else
BOOL result = FALSE;
// DWORD WINAPI WaitForSingleObject(
// __in HANDLE hHandle,
// __in DWORD dwMilliseconds
// );
// http://msdn.microsoft.com/en-us/library/ms687032(VS.85).aspx
if( event == NULL )
return FALSE;
if(timeout) {
struct timespec ts;
// XXX, need to verify for -1. below modified from bionic/pthread.c
// and maybe loop if needed ;\
ts.tv_sec = timeout / 1000;
ts.tv_nsec = (timeout%1000)*1000000;
if (ts.tv_nsec >= 1000000000) {
ts.tv_sec++;
ts.tv_nsec -= 1000000000;
}
// atomically checks if event->handle is 0, if so,
// it sleeps for timeout. if event->handle is 1, it
// returns straight away.
__futex_wait(&(event->handle), 0, &ts);
}
// We should behave like an auto-reset event
result = event->handle ? TRUE : FALSE;
if( result )
event->handle = (HANDLE)0;
return result;
#endif
}
int pthread_join(pthread_t t, void** return_value) {
if (t == pthread_self()) {
return EDEADLK;
}
pid_t tid;
volatile int* tid_ptr;
{
pthread_accessor thread(t);
if (thread.get() == NULL) {
return ESRCH;
}
if ((thread->attr.flags & PTHREAD_ATTR_FLAG_DETACHED) != 0) {
return EINVAL;
}
if ((thread->attr.flags & PTHREAD_ATTR_FLAG_JOINED) != 0) {
return EINVAL;
}
// Okay, looks like we can signal our intention to join.
thread->attr.flags |= PTHREAD_ATTR_FLAG_JOINED;
tid = thread->tid;
tid_ptr = &thread->tid;
}
// We set the PTHREAD_ATTR_FLAG_JOINED flag with the lock held,
// so no one is going to remove this thread except us.
// Wait for the thread to actually exit, if it hasn't already.
while (*tid_ptr != 0) {
__futex_wait(tid_ptr, tid, NULL);
}
// Take the lock again so we can pull the thread's return value
// and remove the thread from the list.
pthread_accessor thread(t);
if (return_value) {
*return_value = thread->return_value;
}
_pthread_internal_remove_locked(thread.get());
return 0;
}
int __system_property_read(const prop_info *pi, char *name, char *value)
{
unsigned serial, len;
for(;;) {
serial = *(unsigned*)((char*)pi + prop_name_max);
while(SERIAL_DIRTY(serial)) {
__futex_wait((volatile void *)((char*)pi + prop_name_max), serial, 0);
serial = *(unsigned*)((char*)pi + prop_name_max);
}
len = SERIAL_VALUE_LEN(serial);
memcpy(value, (char*)pi + prop_name_max + sizeof(pi->serial), len + 1);
if(serial == *(unsigned*)((char*)pi + prop_name_max)) {
if(name != 0) {
strcpy(name, pi->name);
}
return len;
}
}
}
extern "C" int __cxa_guard_acquire(_guard_t* gv)
{
// 0 -> pending, return 1
// pending -> waiting, wait and return 0
// waiting: untouched, wait and return 0
// ready: untouched, return 0
retry:
if (__atomic_cmpxchg(0, pending, &gv->state) == 0) {
ANDROID_MEMBAR_FULL();
return 1;
}
__atomic_cmpxchg(pending, waiting, &gv->state); // Indicate there is a waiter
__futex_wait(&gv->state, waiting, NULL);
if (gv->state != ready) // __cxa_guard_abort was called, let every thread try since there is no return code for this condition
goto retry;
ANDROID_MEMBAR_FULL();
return 0;
}
int pthread_join(pthread_t t, void** return_value) {
if (t == pthread_self()) {
return EDEADLK;
}
pid_t tid;
volatile int* tid_ptr;
{
pthread_accessor thread(t);
if (thread.get() == NULL) {
return ESRCH;
}
if ((thread->attr.flags & PTHREAD_ATTR_FLAG_DETACHED) != 0) {
return EINVAL;
}
if ((thread->attr.flags & PTHREAD_ATTR_FLAG_JOINED) != 0) {
return EINVAL;
}
// Okay, looks like we can signal our intention to join.
thread->attr.flags |= PTHREAD_ATTR_FLAG_JOINED;
tid = thread->tid;
tid_ptr = &thread->tid;
}
// We set the PTHREAD_ATTR_FLAG_JOINED flag with the lock held,
// so no one is going to remove this thread except us.
// Wait for the thread to actually exit, if it hasn't already.
while (*tid_ptr != 0) {
// ARC MOD BEGIN
// Use __nacl_irt_sched_yield instead of __futex_wait.
// __nacl_irt_thread_exit does not give us a notice with
// futex_wait, so we will yield and poll until thread completes.
//
// Note that nacl-glibc's has similar code in nptl/pthread_join.c
// and sysdeps/nacl/lowlevellock.h.
#if defined(HAVE_ARC)
__nacl_irt_sched_yield();
#else
// ARC MOD END
__futex_wait(tid_ptr, tid, NULL);
// ARC MOD BEGIN
#endif
// ARC MOD END
}
// Take the lock again so we can pull the thread's return value
// and remove the thread from the list.
pthread_accessor thread(t);
if (return_value) {
*return_value = thread->return_value;
}
// ARC MOD BEGIN
// Unmap stack if PTHREAD_ATTR_FLAG_USER_STACK is not
// set. Upstream bionic unmaps the stack in thread which are about
// to exit, but we cannot do this on NaCl because the stack should
// be available when we call __nacl_irt_thread_exit. Instead, we
// unmap the stack from the thread which calls pthread_join.
#if defined(HAVE_ARC)
if (!thread->user_allocated_stack() &&
thread->attr.stack_base) {
if (munmap(thread->attr.stack_base, thread->attr.stack_size) != 0) {
static const int kStderrFd = 2;
static const char kMsg[] = "failed to unmap the stack!\n";
write(kStderrFd, kMsg, sizeof(kMsg) - 1);
abort();
}
// Clear the pointer to unmapped stack so pthread_join from
// other threads will not try to unmap this region again.
thread->attr.stack_base = NULL;
thread->attr.stack_size = 0;
thread->tls = NULL;
}
#endif // HAVE_ARC
// ARC MOD END
_pthread_internal_remove_locked(thread.get());
return 0;
}