inline std::pair<T, bool> dequeue_and_begin_critical_section_on_success() {
m_mutex.lock();
T elem = T();
bool success = false;
// Wait while the queue is empty and this queue is alive
while(m_queue.empty() && m_alive) {
sleeping++;
m_conditional.wait(m_mutex);
sleeping--;
}
// An element has been added or a signal was raised
if(!m_queue.empty()) {
success = true;
elem = m_queue.front();
m_queue.pop_front();
if (m_queue.empty() && sleeping_on_empty) {
m_empty_conditional.signal();
}
}
if (!success) m_mutex.unlock();
return std::make_pair(elem, success);
}
static inline void
finish (bool output_fired,
bd_t bda,
bd_t bdb)
{
if (action_.automaton.get () != 0) {
// We were executing an action of this automaton.
switch (action_.action->type) {
case INPUT:
// We were executing an input. Move to the next input.
++input_action_pos_;
proceed_to_input ();
// -EEE
input_action_list_.front ()->output_action.automaton->unlock_execution ();
finish_output ();
break;
case OUTPUT:
// We were executing an output ...
if (output_fired) {
// ... and the output output did something.
output_buffer_a_ = action_.automaton->lookup_buffer (bda);
// Synchronize the buffers.
if (output_buffer_a_.get () != 0) {
output_buffer_a_->sync (0, output_buffer_a_->size ());
}
output_buffer_b_ = action_.automaton->lookup_buffer (bdb);
if (output_buffer_b_.get () != 0) {
output_buffer_b_->sync (0, output_buffer_b_->size ());
}
// Proceed to execute the inputs.
input_action_pos_ = input_action_list_.begin ();
// This does not return if there are inputs.
proceed_to_input ();
}
// No input actions to execute.
// -EEE
action_.automaton->unlock_execution ();
finish_output ();
break;
case INTERNAL:
case SYSTEM:
// -EEE
action_.automaton->unlock_execution ();
break;
}
}
// We are done with the current action.
action_.automaton = shared_ptr<automaton> ();
for (;;) {
irq_handler::process_interrupts ();
while (!ready_queue_.empty ()) {
// Get the automaton context and remove it from the ready queue.
automaton_context* c = ready_queue_.front ();
ready_queue_.pop_front ();
// Load the action.
action_ = c->front ();
c->pop_front ();
// The automaton exists. Continue loading and execute.
switch (action_.action->type) {
case INPUT:
// Error. Not a local action.
kpanic ("Non-local action on execution queue");
break;
case OUTPUT:
{
kassert (input_action_list_.empty ());
// Copy the bindings.
action_.automaton->copy_bound_inputs (action_, back_inserter (input_action_list_));
// Sort the bindings by input automaton.
sort (input_action_list_.begin (), input_action_list_.end (), sort_bindings_by_input ());
// We lock the automata in order. This is called Havender's Principle.
bool output_locked = false;
for (input_action_list_type::const_iterator pos = input_action_list_.begin ();
pos != input_action_list_.end ();
++pos) {
shared_ptr<automaton> input_automaton = (*pos)->input_action.automaton;
if (!output_locked && action_.automaton->aid () < input_automaton->aid ()) {
// +EEE
action_.automaton->lock_execution ();
output_locked = true;
}
// +FFF
input_automaton->lock_execution ();
}
if (!output_locked) {
// +EEE
action_.automaton->lock_execution ();
output_locked = true;
}
input_action_pos_ = input_action_list_.begin ();
}
break;
case INTERNAL:
case SYSTEM:
// +EEE
action_.automaton->lock_execution ();
break;
}
if (!c->empty ()) {
// Automaton has more actions, return to ready queue.
ready_queue_.push_back (c);
}
action_.automaton->execute (*action_.action, action_.parameter, output_buffer_a_, output_buffer_b_);
}
// Out of actions.
action_.automaton = shared_ptr<automaton> ();
irq_handler::wait_for_interrupt ();
}
}
