/*----------------------------------------------------------------------
| NPT_Win32SharedVariable::WaitWhileOrUntilEquals
+---------------------------------------------------------------------*/
NPT_Result
NPT_Win32SharedVariable::WaitWhileOrUntilEquals(int value, NPT_Timeout timeout, bool until)
{
do {
m_Lock.Lock();
if (until) {
if (m_Value == value) break;
} else {
if (m_Value != value) break;
}
++m_Waiters;
m_Lock.Unlock();
NPT_Result result = m_Event.Wait(timeout);
bool last_waiter = true;
m_Lock.Lock();
if (--m_Waiters == 0) {
m_Event.Reset();
} else {
last_waiter = false;
}
m_Lock.Unlock();
if (NPT_FAILED(result)) return result;
// FIXME: this is suboptimal, but we need it to ensure we don't busy-loop
if (!last_waiter) {
Sleep(10);
}
} while (true);
m_Lock.Unlock();
return NPT_SUCCESS;
}
/*----------------------------------------------------------------------
| NPT_Win32Queue::Peek
+---------------------------------------------------------------------*/
NPT_Result
NPT_Win32Queue::Peek(NPT_QueueItem*& item, NPT_Timeout timeout)
{
// default value
item = NULL;
// lock the mutex that protects the list
NPT_CHECK(m_Mutex.Lock());
NPT_Result result = NPT_SUCCESS;
NPT_List<NPT_QueueItem*>::Iterator head = m_Items.GetFirstItem();
if (timeout) {
while (!head) {
// no item in the list, wait for one
// reset the condition to indicate that the queue is empty
m_CanPopCondition->Reset();
// unlock the mutex so that another thread can push
m_Mutex.Unlock();
// wait for the condition to signal that we can pop
NPT_Result result = m_CanPopCondition->Wait(timeout);
if (NPT_FAILED(result)) return result;
// relock the mutex so that we can check the list again
NPT_CHECK(m_Mutex.Lock());
// try again
head = m_Items.GetFirstItem();
}
} else {
if (!head) result = NPT_ERROR_LIST_EMPTY;
}
if (head) item = *head;
// unlock the mutex
m_Mutex.Unlock();
return result;
}
/*----------------------------------------------------------------------
| NPT_Win32Queue::Pop
+---------------------------------------------------------------------*/
NPT_Result
NPT_Win32Queue::Pop(NPT_QueueItem*& item, NPT_Timeout timeout)
{
// default value
item = NULL;
// lock the mutex that protects the list
NPT_CHECK(m_Mutex.Lock());
NPT_Result result;
if (timeout) {
while ((result = m_Items.PopHead(item)) == NPT_ERROR_LIST_EMPTY) {
// no item in the list, wait for one
// reset the condition to indicate that the queue is empty
m_CanPopCondition->Reset();
// unlock the mutex so that another thread can push
m_Mutex.Unlock();
// wait for the condition to signal that we can pop
NPT_Result result = m_CanPopCondition->Wait(timeout);
if (NPT_FAILED(result)) return result;
// relock the mutex so that we can check the list again
NPT_CHECK(m_Mutex.Lock());
}
} else {
result = m_Items.PopHead(item);
}
if (m_MaxItems && (result == NPT_SUCCESS)) {
// wake up the threads waiting to push
m_CanPushCondition->Signal();
}
// unlock the mutex
m_Mutex.Unlock();
return result;
}
/*----------------------------------------------------------------------
| NPT_Win32Queue::Push
+---------------------------------------------------------------------*/
NPT_Result
NPT_Win32Queue::Push(NPT_QueueItem* item, NPT_Timeout timeout)
{
// lock the mutex that protects the list
NPT_CHECK(m_Mutex.Lock());
// check that we have not exceeded the max
if (m_MaxItems) {
while (m_Items.GetItemCount() >= m_MaxItems) {
// we must wait until some items have been removed
// reset the condition to indicate that the queue is full
m_CanPushCondition->Reset();
// unlock the mutex so that another thread can pop
m_Mutex.Unlock();
// wait for the condition to signal that we can push
NPT_Result result = m_CanPushCondition->Wait(timeout);
if (NPT_FAILED(result)) return result;
// relock the mutex so that we can check the list again
NPT_CHECK(m_Mutex.Lock());
}
}
// add the item to the list
m_Items.Add(item);
// wake up the threads waiting to pop
m_CanPopCondition->Signal();
// unlock the mutex
m_Mutex.Unlock();
return NPT_SUCCESS;
}