pcb_t * proc_queue_remove(proc_queue_t * queue, pcb_t *pcb)
{
if (queue == NULL || pcb == NULL || proc_queue_is_empty(queue))
{
return NULL;
}
if (queue->head == pcb)
{
return proc_queue_dequeue(queue);
}
pcb_t *prev_node = queue->head;
pcb_t *curr_node = queue->head->next;
while (curr_node)
{
if (curr_node == pcb)
{
prev_node->next = curr_node->next;
curr_node->next = NULL;
return curr_node;
}
prev_node = curr_node;
curr_node = curr_node->next;
}
return NULL;
}
pcb_t * proc_queue_dequeue(proc_queue_t* queue)
{
if (queue == NULL || proc_queue_is_empty(queue))
{
return NULL;
}
pcb_t * pcb = queue->head;
if (queue->head == NULL)
{
queue->tail = NULL;
}
else
{
queue->head = queue->head->next;
}
pcb->next = NULL;
return pcb;
}
int proc_queue_enqueue(proc_queue_t * queue, pcb_t * pcb)
{
if (queue == NULL || pcb == NULL)
{
return ERROR_NULL_ARG;
}
assert(pcb->next == NULL);
if (proc_queue_is_empty(queue))
{
queue->head = pcb;
}
else
{
queue->tail->next = pcb;
}
queue->tail = pcb;
queue->tail->next = NULL;
return CODE_SUCCESS;
}
proc_t *scheduler_next(proc_t *current, int reds_left)
{
set_phase(PHASE_NEXT);
uint32_t reds_used = SLICE_REDUCTIONS -reds_left;
ssi(SYS_STATS_CTX_SWITCHES);
ssa(SYS_STATS_REDUCTIONS, reds_used);
current->total_reds += reds_used;
proc_t *next_proc = 0;
uint64_t ticks = monotonic_clock(); // freeze time
assert(current->my_queue == MY_QUEUE_NONE);
#ifdef PROFILE_HARNESS
static uint64_t proc_started_ns = 0;
if (proc_started_ns != 0)
prof_slice_complete(current->pid,
current->result.what, current->cap.ip, proc_started_ns, ticks);
#endif
proc_t *expired;
while ((expired = wait_list_expired(&queues.on_timed_receive, ticks)) != 0)
{
expired->cap.ip = expired->result.jump_to;
if (scheduler_park_runnable_N(expired) < 0)
scheduler_exit_process(expired, A_NO_MEMORY);
}
int memory_exhausted = 0;
switch (current->result.what)
{
case SLICE_RESULT_YIELD:
if (scheduler_park_runnable_N(current) < 0)
memory_exhausted = 1;
break;
case SLICE_RESULT_WAIT:
if (current->result.until_when == LING_INFINITY)
{
if (proc_list_put_N(&queues.on_infinite_receive, current) < 0)
memory_exhausted = 1;
else
current->my_queue = MY_QUEUE_INF_WAIT;
}
else
{
if (wait_list_put_N(&queues.on_timed_receive,
current, current->result.until_when) < 0)
memory_exhausted = 1;
else
current->my_queue = MY_QUEUE_TIMED_WAIT;
}
break;
case SLICE_RESULT_DONE:
scheduler_exit_process(current, A_NORMAL);
break;
case SLICE_RESULT_PURGE_PROCS:
// purge_module() call may have detected processes lingering on the old
// code - terminate them
if (scheduler_park_runnable_N(current) < 0)
memory_exhausted = 1;
for (int i = 0; i < num_purged; i++)
if (scheduler_signal_exit_N(purgatory[i], current->pid, A_KILL) < 0)
memory_exhausted = 1;
num_purged = 0;
break;
case SLICE_RESULT_EXIT:
scheduler_exit_process(current, current->result.reason);
// what about the returned value when main function just returns?
break;
case SLICE_RESULT_EXIT2:
// only needed to implement erlang:exit/2
if (scheduler_park_runnable_N(current) < 0 ||
(scheduler_signal_exit_N(current->result.victim,
current->pid,
current->result.reason2) < 0))
memory_exhausted = 1;
break;
case SLICE_RESULT_ERROR:
scheduler_exit_process(current, current->result.reason);
// how is this different from SLICE_RESULT_EXIT?
break;
case SLICE_RESULT_THROW:
scheduler_exit_process(current, current->result.reason);
// how is this different from SLICE_RESULT_EXIT?
break;
default:
{
assert(current->result.what == SLICE_RESULT_OUTLET_CLOSE);
if (scheduler_park_runnable_N(current) < 0)
memory_exhausted = 1;
outlet_t *closing = current->result.closing;
//assert(is_atom(current->result.why));
outlet_close(closing, current->result.why);
break;
}
}
if (memory_exhausted)
scheduler_exit_process(current, A_NO_MEMORY);
do_pending:
ticks = monotonic_clock();
while ((expired = wait_list_expired(&queues.on_timed_receive, ticks)) != 0)
{
expired->cap.ip = expired->result.jump_to;
if (scheduler_park_runnable_N(expired) < 0)
scheduler_exit_process(expired, A_NO_MEMORY);
}
set_phase(PHASE_EVENTS);
// software events/timeouts
net_check_timeouts();
etimer_expired(ticks);
// 'hardware' events
int nr_fired = events_do_pending();
update_event_times(nr_fired, ticks);
set_phase(PHASE_NEXT);
// select_runnable
if (!proc_queue_is_empty(&queues.high_prio))
next_proc = proc_queue_get(&queues.high_prio);
else if (normal_count < NORMAL_ADVANTAGE)
{
if (!proc_queue_is_empty(&queues.normal_prio))
next_proc = proc_queue_get(&queues.normal_prio);
else if (!proc_queue_is_empty(&queues.low_prio))
next_proc = proc_queue_get(&queues.low_prio);
normal_count++;
}
else
{
if (!proc_queue_is_empty(&queues.low_prio))
next_proc = proc_queue_get(&queues.low_prio);
else if (!proc_queue_is_empty(&queues.normal_prio))
next_proc = proc_queue_get(&queues.normal_prio);
normal_count = 0;
}
if (next_proc == 0)
{
// no runnable processes; poll for events from all three sources
// Beware that events_poll() reports events 5us after they occur. If
// a new event is expected very soon we are better off polling event
// bits manually (using events_do_pending())
// Devote a portion of time until the next event to gc waiting processes
garbage_collect_waiting_processes(expect_event_in_ns /2);
if (expect_event_in_ns < MANUAL_POLLING_THRESHOLD)
goto do_pending;
uint64_t next_ticks = wait_list_timeout(&queues.on_timed_receive);
uint64_t closest_timeout = etimer_closest_timeout();
if (closest_timeout < next_ticks)
next_ticks = closest_timeout;
closest_timeout = lwip_closest_timeout();
if (closest_timeout < next_ticks)
next_ticks = closest_timeout;
scheduler_runtime_update();
events_poll(next_ticks); // LING_INFINITY is big enough
scheduler_runtime_start();
goto do_pending;
}
next_proc->my_queue = MY_QUEUE_NONE;
//TODO: update stats
#ifdef PROFILE_HARNESS
proc_started_ns = ticks;
#endif
set_phase(PHASE_ERLANG);
return next_proc;
}
