void lock()
{
while (state_.exchange(Locked, boost::memory_order_acquire) == Locked)
{
/* busy-wait */
}
}
/**
* The environment should be initialised exactly once during shared library initialisation.
* Prior to that, all operations work in pass-through mode.
* To overcome undefined global initialisation order, we use a local static variable.
* This variable is accesd by a single writer (lib (de)initialisation), and multiple readers (exported operations).
* Writer: toggle == true (toggles is_initialised)
* Reader: toggle == false (returns the current value of is_initialised)
*
* NOTE: pthread_once initialisation for the overlay leads to a deadlock due to a re-entry situation:
* - environment ctor is called the first time via pthread_once
* - which leads a write somewhere (probably to a socket during client initialisation)
* - which then enters the pthread_once initialisation mechanism again and blocks deadlocks
*/
bool overlay_initialized(bool toggle /* defaults to: false */) {
static boost::atomic<bool> is_initilized(false);
// writer
if(toggle) {
return is_initilized.exchange(!is_initilized.load());
}
// reader
return is_initilized.load();
}
/// Attempts to acquire ownership of the \a recursive_mutex.
/// Suspends the current HPX-thread until \a timeout if ownership cannot
/// be obtained immediately.
///
/// \returns \a true if ownership was acquired; otherwise, \a false.
///
/// \throws Throws \a hpx#bad_parameter if an error occurs while
/// suspending. Throws \a hpx#yield_aborted if the mutex is
/// destroyed while suspended. Throws \a hpx#null_thread_id if
/// called outside of a HPX-thread.
// template<typename Duration>
// bool timed_lock(Duration const& timeout)
// {
// return timed_lock(boost::get_system_time() + timeout);
// }
//
// bool timed_lock(boost::xtime const& timeout)
// {
// return timed_lock(boost::posix_time::ptime(timeout));
// }
//
/// Release ownership of the \a recursive_mutex.
///
/// \throws Throws \a hpx#bad_parameter if an error occurs while
/// releasing the mutex. Throws \a hpx#null_thread_id if called
/// outside of a HPX-thread.
void unlock()
{
util::unregister_lock(this);
if (0 == --recursion_count)
{
locking_thread_id.exchange(thread_id_from_mutex<Mutex>
::invalid_id());
util::reset_ignored(&mtx);
mtx.unlock();
}
}
bool try_basic_lock(thread_id_type current_thread_id)
{
if (mtx.try_lock())
{
locking_thread_id.exchange(current_thread_id);
util::ignore_lock(&mtx);
util::register_lock(this);
recursion_count.store(1);
return true;
}
return false;
}
/// Acquires ownership of the \a recursive_mutex. Suspends the
/// current HPX-thread if ownership cannot be obtained immediately.
///
/// \throws Throws \a hpx#bad_parameter if an error occurs while
/// suspending. Throws \a hpx#yield_aborted if the mutex is
/// destroyed while suspended. Throws \a hpx#null_thread_id if
/// called outside of a HPX-thread.
void lock()
{
thread_id_type const id = thread_id_from_mutex<Mutex>::call();
HPX_ASSERT(id != thread_id_from_mutex<Mutex>::invalid_id());
if (!try_recursive_lock(id))
{
mtx.lock();
locking_thread_id.exchange(id);
util::ignore_lock(&mtx);
util::register_lock(this);
recursion_count.store(1);
}
}
void push_back(T elem) {
// Construct an element to hold it
synclist_item<T>* itm = new synclist_item<T>();
itm->value = elem;
itm->prev.store(m_last.load(boost::memory_order_release), boost::memory_order_acquire);
itm->next.store(NULL, boost::memory_order_acquire);
// Insert the element in the list
synclist_item<T>* tmpItm = itm;
synclist_item<T>* prevLast = m_last.exchange(tmpItm, boost::memory_order_consume);
tmpItm = itm;
synclist_item<T>* null = NULL;
m_first.compare_exchange_strong(null, tmpItm, boost::memory_order_consume, boost::memory_order_acquire);
if(prevLast != NULL) {
prevLast->next.store(itm, boost::memory_order_consume);
}
m_length.fetch_add(1, boost::memory_order_consume);
}
IntrusivePtr& swap(IntrusivePtr&& other) {
T* old = ptr.exchange(other.ptr);
other.ptr = old;
return other;
}
~IntrusivePtr() {
T* _p = ptr.exchange(NULL);
if(_p)
intrusive_ptr_release(_p);
}
void swap( boost::atomic<T>& lhs, boost::atomic<T>& rhs )
{
lhs.store(rhs.exchange(lhs.load()));
}
/** Swap the atomic value with value.
* \return the previously held value
*/
T swap(T value)
{ return _value.exchange(value); }