0ad/source/tools/atlas/GameInterface/MessagePasserImpl.cpp

#include "precompiled.h"

#include "MessagePasserImpl.h"
#include "Messages.h"

#include "lib/timer.h"

using namespace AtlasMessage;


MessagePasserImpl::MessagePasserImpl()
: m_Trace(false)
{
}

void MessagePasserImpl::Add(IMessage* msg)
{
	debug_assert(msg);
	debug_assert(msg->GetType() == IMessage::Message);

	if (m_Trace)
		debug_printf("%8.3f add message: %s\n", get_time(), msg->GetName());

	m_Mutex.Lock();
	m_Queue.push(msg);
	m_Mutex.Unlock();
}

IMessage* MessagePasserImpl::Retrieve()
{
	// (It should be fairly easy to use a more efficient thread-safe queue,
	// since there's only one thread adding items and one thread consuming;
	// but it's not worthwhile yet.)

	m_Mutex.Lock();

	IMessage* msg = NULL;
	if (! m_Queue.empty())
	{
		msg = m_Queue.front();
		m_Queue.pop();
	}

	m_Mutex.Unlock();

//	if (m_Trace && msg) debug_printf("%8.3f retrieved message: %s\n", get_time(), msg->GetType());

	return msg;
}

void MessagePasserImpl::Query(QueryMessage* qry)
{
	debug_assert(qry);
	debug_assert(qry->GetType() == IMessage::Query);

	if (m_Trace)
		debug_printf("%8.3f add query: %s\n", get_time(), qry->GetName());

	// Initialise a semaphore, so we can block until the query has been handled
	int err;
	sem_t sem;
	err = sem_init(&sem, 0, 0);
	if (err != 0)
	{
		// Probably-fatal error
		debug_warn("sem_init failed");
		return;
	}
	qry->m_Semaphore = (void*)&sem;

	m_Mutex.Lock();
	m_Queue.push(qry);
	m_Mutex.Unlock();

	// Wait until the query handler has handled the query and called sem_post
	while (0 != (err = sem_wait(&sem)))
	{
		// Keep retrying while EINTR
		if (errno != EINTR)
		{
			// Other errors are probably fatal
			debug_warn("sem_wait failed");
			return;
		}
	}

	// Clean up
	qry->m_Semaphore = NULL;
	sem_destroy(&sem);
}

bool MessagePasserImpl::IsEmpty()
{
	m_Mutex.Lock();
	bool empty = m_Queue.empty();
	m_Mutex.Unlock();
	return empty;
}

void MessagePasserImpl::SetTrace(bool t)
{
	m_Trace = t;
}