/* Adds a chunk of work to another thread's in-tray. */
static void push_work_to_thread_in_tray(MVMThreadContext *tc, MVMuint32 target, MVMGCPassedWork *work) {
MVMGCPassedWork * volatile *target_tray;
/* Locate the thread to pass the work to. */
MVMThreadContext *target_tc = NULL;
if (target == 1) {
/* It's going to the main thread. */
target_tc = tc->instance->main_thread;
}
else {
MVMThread *t = (MVMThread *)MVM_load(&tc->instance->threads);
do {
if (t->body.tc && t->body.tc->thread_id == target) {
target_tc = t->body.tc;
break;
}
} while ((t = t->body.next));
if (!target_tc)
MVM_panic(MVM_exitcode_gcnursery, "Internal error: invalid thread ID %d in GC work pass", target);
}
/* Pass the work, chaining any other in-tray entries for the thread
* after us. */
target_tray = &target_tc->gc_in_tray;
while (1) {
MVMGCPassedWork *orig = *target_tray;
work->next = orig;
if (MVM_casptr(target_tray, orig, work) == orig)
return;
}
}
/* Takes work in a thread's in-tray, if any, and adds it to the worklist. */
static void add_in_tray_to_worklist(MVMThreadContext *tc, MVMGCWorklist *worklist) {
MVMGCPassedWork * volatile *in_tray = &tc->gc_in_tray;
MVMGCPassedWork *head;
/* Get work to process. */
while (1) {
/* See if there's anything in the in-tray; if not, we're done. */
head = *in_tray;
if (head == NULL)
return;
/* Otherwise, try to take it. */
if (MVM_casptr(in_tray, head, NULL) == head)
break;
}
/* Go through list, adding to worklist. */
while (head) {
MVMGCPassedWork *next = head->next;
MVMuint32 i;
for (i = 0; i < head->num_items; i++)
MVM_gc_worklist_add(tc, worklist, head->items[i]);
MVM_free(head);
head = next;
}
}
/* Adds a chunk of work to another thread's in-tray. */
static void push_work_to_thread_in_tray(MVMThreadContext *tc, MVMuint32 target, MVMGCPassedWork *work) {
MVMint32 j;
MVMGCPassedWork * volatile *target_tray;
/* Locate the thread to pass the work to. */
MVMThreadContext *target_tc = NULL;
if (target == 0) {
/* It's going to the main thread. */
target_tc = tc->instance->main_thread;
}
else {
MVMThread *t = (MVMThread *)MVM_load(&tc->instance->threads);
do {
if (t->body.tc->thread_id == target) {
target_tc = t->body.tc;
break;
}
} while ((t = t->body.next));
if (!target_tc)
MVM_panic(MVM_exitcode_gcnursery, "Internal error: invalid thread ID in GC work pass");
}
/* push to sent_items list */
if (tc->gc_sent_items) {
tc->gc_sent_items->next_by_sender = work;
work->last_by_sender = tc->gc_sent_items;
}
/* queue it up to check if the check list isn't clear */
if (!MVM_load(&tc->gc_next_to_check)) {
MVM_store(&tc->gc_next_to_check, work);
}
tc->gc_sent_items = work;
/* Pass the work, chaining any other in-tray entries for the thread
* after us. */
target_tray = &target_tc->gc_in_tray;
while (1) {
MVMGCPassedWork *orig = *target_tray;
work->next = orig;
if (MVM_casptr(target_tray, orig, work) == orig)
return;
}
}
/* This is called when the allocator finds it has run out of memory and wants
* to trigger a GC run. In this case, it's possible (probable, really) that it
* will need to do that triggering, notifying other running threads that the
* time has come to GC. */
void MVM_gc_enter_from_allocator(MVMThreadContext *tc) {
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : Entered from allocate\n");
/* Try to start the GC run. */
if (MVM_trycas(&tc->instance->gc_start, 0, 1)) {
MVMThread *last_starter = NULL;
MVMuint32 num_threads = 0;
MVMuint32 is_full;
/* Need to wait for other threads to reset their gc_status. */
while (MVM_load(&tc->instance->gc_ack)) {
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE,
"Thread %d run %d : waiting for other thread's gc_ack\n");
MVM_platform_thread_yield();
}
/* We are the winner of the GC starting race. This gives us some
* extra responsibilities as well as doing the usual things.
* First, increment GC sequence number. */
MVM_incr(&tc->instance->gc_seq_number);
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE,
"Thread %d run %d : GC thread elected coordinator: starting gc seq %d\n",
(int)MVM_load(&tc->instance->gc_seq_number));
/* Decide if it will be a full collection. */
is_full = is_full_collection(tc);
/* If profiling, record that GC is starting. */
if (tc->instance->profiling)
MVM_profiler_log_gc_start(tc, is_full);
/* Ensure our stolen list is empty. */
tc->gc_work_count = 0;
/* Flag that we didn't agree on this run that all the in-trays are
* cleared (a responsibility of the co-ordinator. */
MVM_store(&tc->instance->gc_intrays_clearing, 1);
/* We'll take care of our own work. */
add_work(tc, tc);
/* Find other threads, and signal or steal. */
do {
MVMThread *threads = (MVMThread *)MVM_load(&tc->instance->threads);
if (threads && threads != last_starter) {
MVMThread *head = threads;
MVMuint32 add;
while ((threads = (MVMThread *)MVM_casptr(&tc->instance->threads, head, NULL)) != head) {
head = threads;
}
add = signal_all_but(tc, head, last_starter);
last_starter = head;
if (add) {
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : Found %d other threads\n", add);
MVM_add(&tc->instance->gc_start, add);
num_threads += add;
}
}
/* If there's an event loop thread, wake it up to participate. */
if (tc->instance->event_loop_wakeup)
uv_async_send(tc->instance->event_loop_wakeup);
} while (MVM_load(&tc->instance->gc_start) > 1);
/* Sanity checks. */
if (!MVM_trycas(&tc->instance->threads, NULL, last_starter))
MVM_panic(MVM_exitcode_gcorch, "threads list corrupted\n");
if (MVM_load(&tc->instance->gc_finish) != 0)
MVM_panic(MVM_exitcode_gcorch, "Finish votes was %"MVM_PRSz"\n", MVM_load(&tc->instance->gc_finish));
/* gc_ack gets an extra so the final acknowledger
* can also free the STables. */
MVM_store(&tc->instance->gc_finish, num_threads + 1);
MVM_store(&tc->instance->gc_ack, num_threads + 2);
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : finish votes is %d\n",
(int)MVM_load(&tc->instance->gc_finish));
/* Now we're ready to start, zero promoted since last full collection
* counter if this is a full collect. */
if (is_full)
MVM_store(&tc->instance->gc_promoted_bytes_since_last_full, 0);
/* Signal to the rest to start */
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : coordinator signalling start\n");
if (MVM_decr(&tc->instance->gc_start) != 1)
MVM_panic(MVM_exitcode_gcorch, "Start votes was %"MVM_PRSz"\n", MVM_load(&tc->instance->gc_start));
/* Start collecting. */
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : coordinator entering run_gc\n");
run_gc(tc, MVMGCWhatToDo_All);
/* Free any STables that have been marked for deletion. It's okay for
* us to muck around in another thread's fromspace while it's mutating
* tospace, really. */
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : Freeing STables if needed\n");
MVM_gc_collect_free_stables(tc);
/* If profiling, record that GC is over. */
if (tc->instance->profiling)
MVM_profiler_log_gc_end(tc);
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : GC complete (cooridnator)\n");
}
else {
/* Another thread beat us to starting the GC sync process. Thus, act as
* if we were interrupted to GC. */
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : Lost coordinator election\n");
MVM_gc_enter_from_interrupt(tc);
}
}
MVMObject * MVM_thread_start(MVMThreadContext *tc, MVMObject *invokee, MVMObject *result_type) {
int status;
ThreadStart *ts;
MVMObject *child_obj;
/* Create a thread object to wrap it up in. */
MVM_gc_root_temp_push(tc, (MVMCollectable **)&invokee);
child_obj = REPR(result_type)->allocate(tc, STABLE(result_type));
MVM_gc_root_temp_pop(tc);
if (REPR(child_obj)->ID == MVM_REPR_ID_MVMThread) {
MVMThread *child = (MVMThread *)child_obj;
MVMThread * volatile *threads;
/* Create a new thread context and set it up. */
MVMThreadContext *child_tc = MVM_tc_create(tc->instance);
child->body.tc = child_tc;
MVM_ASSIGN_REF(tc, child, child->body.invokee, invokee);
child_tc->thread_obj = child;
child_tc->thread_id = MVM_incr(&tc->instance->next_user_thread_id);
/* Create the thread. Note that we take a reference to the current frame,
* since it must survive to be the dynamic scope of where the thread was
* started, and there's no promises that the thread won't start before
* the code creating the thread returns. The count is decremented when
* the thread is done. */
ts = malloc(sizeof(ThreadStart));
ts->tc = child_tc;
ts->caller = MVM_frame_inc_ref(tc, tc->cur_frame);
ts->thread_obj = child_obj;
/* push this to the *child* tc's temp roots. */
MVM_gc_root_temp_push(child_tc, (MVMCollectable **)&ts->thread_obj);
/* Signal to the GC we have a childbirth in progress. The GC
* will null it for us. */
MVM_gc_mark_thread_blocked(child_tc);
MVM_ASSIGN_REF(tc, tc->thread_obj, tc->thread_obj->body.new_child, child);
/* push to starting threads list */
threads = &tc->instance->threads;
do {
MVMThread *curr = *threads;
MVM_ASSIGN_REF(tc, child, child->body.next, curr);
} while (MVM_casptr(threads, child->body.next, child) != child->body.next);
status = uv_thread_create(&child->body.thread, &start_thread, ts);
if (status < 0) {
MVM_panic(MVM_exitcode_compunit, "Could not spawn thread: errorcode %d", status);
}
/* need to run the GC to clear our new_child field in case we try
* try to launch another thread before the GC runs and before the
* thread starts. */
GC_SYNC_POINT(tc);
}
else {
MVM_exception_throw_adhoc(tc,
"Thread result type must have representation MVMThread");
}
return child_obj;
}
