/* Run the global destruction phase. */
void MVM_gc_global_destruction(MVMThreadContext *tc) {
char *nursery_tmp;
/* Fake a nursery collection run by swapping the semi-
* space nurseries. */
nursery_tmp = tc->nursery_fromspace;
tc->nursery_fromspace = tc->nursery_tospace;
tc->nursery_tospace = nursery_tmp;
/* Run the objects' finalizers */
MVM_gc_collect_free_nursery_uncopied(tc, tc->nursery_alloc);
MVM_gc_root_gen2_cleanup(tc);
MVM_gc_collect_free_gen2_unmarked(tc, 1);
MVM_gc_collect_free_stables(tc);
}
/* Run the global destruction phase. */
void MVM_gc_global_destruction(MVMThreadContext *tc) {
char *nursery_tmp;
/* Must wait until we're the only thread... */
while (tc->instance->num_user_threads) {
GC_SYNC_POINT(tc);
MVM_platform_thread_yield();
}
/* Fake a nursery collection run by swapping the semi-
* space nurseries. */
nursery_tmp = tc->nursery_fromspace;
tc->nursery_fromspace = tc->nursery_tospace;
tc->nursery_tospace = nursery_tmp;
/* Run the objects' finalizers */
MVM_gc_collect_free_nursery_uncopied(tc, tc->nursery_alloc);
MVM_gc_root_gen2_cleanup(tc);
MVM_gc_collect_free_gen2_unmarked(tc);
MVM_gc_collect_free_stables(tc);
}
static void finish_gc(MVMThreadContext *tc, MVMuint8 gen, MVMuint8 is_coordinator) {
MVMuint32 i, did_work;
/* Do any extra work that we have been passed. */
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE,
"Thread %d run %d : doing any work in thread in-trays\n");
did_work = 1;
while (did_work) {
did_work = 0;
for (i = 0; i < tc->gc_work_count; i++)
did_work += process_in_tray(tc->gc_work[i].tc, gen);
}
/* Decrement gc_finish to say we're done, and wait for termination. */
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : Voting to finish\n");
MVM_decr(&tc->instance->gc_finish);
while (MVM_load(&tc->instance->gc_finish)) {
for (i = 0; i < 1000; i++)
; /* XXX Something HT-efficienter. */
/* XXX Here we can look to see if we got passed any work, and if so
* try to un-vote. */
}
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE, "Thread %d run %d : Termination agreed\n");
/* Co-ordinator should do final check over all the in-trays, and trigger
* collection until all is settled. Rest should wait. Additionally, after
* in-trays are settled, coordinator walks threads looking for anything
* that needs adding to the finalize queue. It then will make another
* iteration over in-trays to handle cross-thread references to objects
* needing finalization. For full collections, collected objects are then
* cleaned from all inter-generational sets, and finally any objects to
* be freed at the fixed size allocator's next safepoint are freed. */
if (is_coordinator) {
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE,
"Thread %d run %d : Co-ordinator handling in-tray clearing completion\n");
clear_intrays(tc, gen);
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE,
"Thread %d run %d : Co-ordinator handling finalizers\n");
MVM_finalize_walk_queues(tc, gen);
clear_intrays(tc, gen);
if (gen == MVMGCGenerations_Both) {
MVMThread *cur_thread = (MVMThread *)MVM_load(&tc->instance->threads);
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE,
"Thread %d run %d : Co-ordinator handling inter-gen root cleanup\n");
while (cur_thread) {
if (cur_thread->body.tc)
MVM_gc_root_gen2_cleanup(cur_thread->body.tc);
cur_thread = cur_thread->body.next;
}
}
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE,
"Thread %d run %d : Co-ordinator handling fixed-size allocator safepoint frees\n");
MVM_fixed_size_safepoint(tc, tc->instance->fsa);
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE,
"Thread %d run %d : Co-ordinator signalling in-trays clear\n");
MVM_store(&tc->instance->gc_intrays_clearing, 0);
}
else {
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE,
"Thread %d run %d : Waiting for in-tray clearing completion\n");
while (MVM_load(&tc->instance->gc_intrays_clearing))
for (i = 0; i < 1000; i++)
; /* XXX Something HT-efficienter. */
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE,
"Thread %d run %d : Got in-tray clearing complete notice\n");
}
/* Reset GC status flags. This is also where thread destruction happens,
* and it needs to happen before we acknowledge this GC run is finished. */
for (i = 0; i < tc->gc_work_count; i++) {
MVMThreadContext *other = tc->gc_work[i].tc;
MVMThread *thread_obj = other->thread_obj;
if (MVM_load(&thread_obj->body.stage) == MVM_thread_stage_clearing_nursery) {
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE,
"Thread %d run %d : transferring gen2 of thread %d\n", other->thread_id);
MVM_gc_gen2_transfer(other, tc);
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE,
"Thread %d run %d : destroying thread %d\n", other->thread_id);
MVM_tc_destroy(other);
tc->gc_work[i].tc = thread_obj->body.tc = NULL;
MVM_store(&thread_obj->body.stage, MVM_thread_stage_destroyed);
}
else {
if (MVM_load(&thread_obj->body.stage) == MVM_thread_stage_exited) {
/* Don't bother freeing gen2; we'll do it next time */
MVM_store(&thread_obj->body.stage, MVM_thread_stage_clearing_nursery);
GCDEBUG_LOG(tc, MVM_GC_DEBUG_ORCHESTRATE,
"Thread %d run %d : set thread %d clearing nursery stage to %d\n",
other->thread_id, (int)MVM_load(&thread_obj->body.stage));
}
MVM_cas(&other->gc_status, MVMGCStatus_STOLEN, MVMGCStatus_UNABLE);
MVM_cas(&other->gc_status, MVMGCStatus_INTERRUPT, MVMGCStatus_NONE);
}
}
/* Signal acknowledgement of completing the cleanup,
* except for STables, and if we're the final to do
* so, free the STables, which have been linked. */
if (MVM_decr(&tc->instance->gc_ack) == 2) {
/* Set it to zero (we're guaranteed the only ones trying to write to
* it here). Actual STable free in MVM_gc_enter_from_allocator. */
MVM_store(&tc->instance->gc_ack, 0);
}
}
/* Does a garbage collection run. Exactly what it does is configured by the
* couple of arguments that it takes.
*
* The what_to_do argument specifies where it should look for things to add
* to the worklist: everywhere, just at thread local stuff, or just in the
* thread's in-tray.
*
* The gen argument specifies whether to collect the nursery or both of the
* generations. Nursery collection is done by semi-space copying. Once an
* object is seen/copied once in the nursery (may be tuned in the future to
* twice or so - we'll see) then it is not copied to tospace, but instead
* promoted to the second generation. If we are collecting generation 2 also,
* then objects that are alive in the second generation are simply marked.
* Since the second generation is managed as a set of sized pools, there is
* much less motivation for any kind of copying/compaction; the internal
* fragmentation that makes finding a right-sized gap problematic will not
* happen.
*
* Note that it adds the roots and processes them in phases, to try to avoid
* building up a huge worklist. */
void MVM_gc_collect(MVMThreadContext *tc, MVMuint8 what_to_do, MVMuint8 gen) {
/* Create a GC worklist. */
MVMGCWorklist *worklist = MVM_gc_worklist_create(tc, gen != MVMGCGenerations_Nursery);
/* Initialize work passing data structure. */
WorkToPass wtp;
wtp.num_target_threads = 0;
wtp.target_work = NULL;
/* If we're starting a run (as opposed to just coming back here to do a
* little more work we got after we first thought we were done...) */
if (what_to_do != MVMGCWhatToDo_InTray) {
/* Swap fromspace and tospace. */
void * fromspace = tc->nursery_tospace;
void * tospace = tc->nursery_fromspace;
tc->nursery_fromspace = fromspace;
tc->nursery_tospace = tospace;
/* Reset nursery allocation pointers to the new tospace. */
tc->nursery_alloc = tospace;
tc->nursery_alloc_limit = (char *)tc->nursery_alloc + MVM_NURSERY_SIZE;
MVM_gc_worklist_add(tc, worklist, &tc->thread_obj);
GCDEBUG_LOG(tc, MVM_GC_DEBUG_COLLECT, "Thread %d run %d : processing %d items from thread_obj\n", worklist->items);
process_worklist(tc, worklist, &wtp, gen);
/* Add permanent roots and process them; only one thread will do
* this, since they are instance-wide. */
if (what_to_do != MVMGCWhatToDo_NoInstance) {
MVM_gc_root_add_permanents_to_worklist(tc, worklist);
GCDEBUG_LOG(tc, MVM_GC_DEBUG_COLLECT, "Thread %d run %d : processing %d items from instance permanents\n", worklist->items);
process_worklist(tc, worklist, &wtp, gen);
MVM_gc_root_add_instance_roots_to_worklist(tc, worklist);
GCDEBUG_LOG(tc, MVM_GC_DEBUG_COLLECT, "Thread %d run %d : processing %d items from instance roots\n", worklist->items);
process_worklist(tc, worklist, &wtp, gen);
}
/* Add per-thread state to worklist and process it. */
MVM_gc_root_add_tc_roots_to_worklist(tc, worklist);
GCDEBUG_LOG(tc, MVM_GC_DEBUG_COLLECT, "Thread %d run %d : processing %d items from TC objects\n", worklist->items);
process_worklist(tc, worklist, &wtp, gen);
/* Add current frame to worklist. */
MVM_gc_worklist_add_frame(tc, worklist, tc->cur_frame);
GCDEBUG_LOG(tc, MVM_GC_DEBUG_COLLECT, "Thread %d run %d : processing %d items from current frame\n", worklist->items);
process_worklist(tc, worklist, &wtp, gen);
/* Add temporary roots and process them (these are per-thread). */
MVM_gc_root_add_temps_to_worklist(tc, worklist);
GCDEBUG_LOG(tc, MVM_GC_DEBUG_COLLECT, "Thread %d run %d : processing %d items from thread temps\n", worklist->items);
process_worklist(tc, worklist, &wtp, gen);
/* Add things that are roots for the first generation because they are
* pointed to by objects in the second generation and process them
* (also per-thread). Note we need not do this if we're doing a full
* collection anyway (in fact, we must not for correctness, otherwise
* the gen2 rooting keeps them alive forever). */
if (gen == MVMGCGenerations_Nursery) {
MVM_gc_root_add_gen2s_to_worklist(tc, worklist);
GCDEBUG_LOG(tc, MVM_GC_DEBUG_COLLECT, "Thread %d run %d : processing %d items from gen2 \n", worklist->items);
process_worklist(tc, worklist, &wtp, gen);
}
/* Find roots in frames and process them. */
if (tc->cur_frame) {
MVM_gc_worklist_add_frame(tc, worklist, tc->cur_frame);
GCDEBUG_LOG(tc, MVM_GC_DEBUG_COLLECT, "Thread %d run %d : processing %d items from cur_frame \n", worklist->items);
process_worklist(tc, worklist, &wtp, gen);
}
/* Process anything in the in-tray. */
add_in_tray_to_worklist(tc, worklist);
GCDEBUG_LOG(tc, MVM_GC_DEBUG_COLLECT, "Thread %d run %d : processing %d items from in tray \n", worklist->items);
process_worklist(tc, worklist, &wtp, gen);
/* At this point, we have probably done most of the work we will
* need to (only get more if another thread passes us more); zero
* out the remaining tospace. */
memset(tc->nursery_alloc, 0, (char *)tc->nursery_alloc_limit - (char *)tc->nursery_alloc);
}
else {
/* We just need to process anything in the in-tray. */
add_in_tray_to_worklist(tc, worklist);
GCDEBUG_LOG(tc, MVM_GC_DEBUG_COLLECT, "Thread %d run %d : processing %d items from in tray \n", worklist->items);
process_worklist(tc, worklist, &wtp, gen);
}
/* Destroy the worklist. */
MVM_gc_worklist_destroy(tc, worklist);
/* Pass any work for other threads we accumulated but that didn't trigger
* the work passing threshold, then cleanup work passing list. */
if (wtp.num_target_threads) {
pass_leftover_work(tc, &wtp);
free(wtp.target_work);
}
/* If it was a full collection, some of the things in gen2 that we root
* due to point to gen1 objects may be dead. */
if (gen != MVMGCGenerations_Nursery)
MVM_gc_root_gen2_cleanup(tc);
}
