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 /*

  * Copyright (c) 2014, 2016, Oracle and/or its affiliates. All rights reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

  * questions.

  *

  */

 #include "precompiled.hpp"

 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"

 #include "gc_implementation/g1/g1OopClosures.inline.hpp"

 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp"

 #include "oops/oop.inline.hpp"

 #include "oops/oop.pcgc.inline.hpp"

 #include "runtime/prefetch.inline.hpp"

 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num, ReferenceProcessor* rp)

   : _g1h(g1h),

     _refs(g1h->task_queue(queue_num)),

     _dcq(&g1h->dirty_card_queue_set()),

     _ct_bs(g1h->g1_barrier_set()),

     _g1_rem(g1h->g1_rem_set()),

     _hash_seed(17), _queue_num(queue_num),

     _term_attempts(0),

     _tenuring_threshold(g1h->g1_policy()->tenuring_threshold()),

     _age_table(false), _scanner(g1h, rp),

     _strong_roots_time(0), _term_time(0) {

   _scanner.set_par_scan_thread_state(this);

   // we allocate G1YoungSurvRateNumRegions plus one entries, since

   // we "sacrifice" entry 0 to keep track of surviving bytes for

   // non-young regions (where the age is -1)

   // We also add a few elements at the beginning and at the end in

   // an attempt to eliminate cache contention

   uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();

   uint array_length = PADDING_ELEM_NUM +

                       real_length +

                       PADDING_ELEM_NUM;

   _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);

   if (_surviving_young_words_base == NULL)

     vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,

                           "Not enough space for young surv histo.");

   _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;

   memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));

   _g1_par_allocator = G1ParGCAllocator::create_allocator(_g1h);

   _dest[InCSetState::NotInCSet]    = InCSetState::NotInCSet;

   // The dest for Young is used when the objects are aged enough to

   // need to be moved to the next space.

   _dest[InCSetState::Young]        = InCSetState::Old;

   _dest[InCSetState::Old]          = InCSetState::Old;

   _start = os::elapsedTime();

 }

 G1ParScanThreadState::~G1ParScanThreadState() {

   _g1_par_allocator->retire_alloc_buffers();

   delete _g1_par_allocator;

   FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base, mtGC);

 }

 void

 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)

 {

   st->print_raw_cr("GC Termination Stats");

   st->print_raw_cr("     elapsed  --strong roots-- -------termination-------"

                    " ------waste (KiB)------");

   st->print_raw_cr("thr     ms        ms      %        ms      %    attempts"

                    "  total   alloc    undo");

   st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"

                    " ------- ------- -------");

 }

 void

 G1ParScanThreadState::print_termination_stats(int i,

                                               outputStream* const st) const

 {

   const double elapsed_ms = elapsed_time() * 1000.0;

   const double s_roots_ms = strong_roots_time() * 1000.0;

   const double term_ms    = term_time() * 1000.0;

   const size_t alloc_buffer_waste = _g1_par_allocator->alloc_buffer_waste();

   const size_t undo_waste         = _g1_par_allocator->undo_waste();

   st->print_cr("%3d %9.2f %9.2f %6.2f "

                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "

                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),

                i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,

                term_ms, term_ms * 100 / elapsed_ms, term_attempts(),

                (alloc_buffer_waste + undo_waste) * HeapWordSize / K,

                alloc_buffer_waste * HeapWordSize / K,

                undo_waste * HeapWordSize / K);

 }

 #ifdef ASSERT

 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {

   assert(ref != NULL, "invariant");

   assert(UseCompressedOops, "sanity");

   assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, p2i(ref)));

   oop p = oopDesc::load_decode_heap_oop(ref);

   assert(_g1h->is_in_g1_reserved(p),

          err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p)));

   return true;

 }

 bool G1ParScanThreadState::verify_ref(oop* ref) const {

   assert(ref != NULL, "invariant");

   if (has_partial_array_mask(ref)) {

     // Must be in the collection set--it's already been copied.

     oop p = clear_partial_array_mask(ref);

     assert(_g1h->obj_in_cs(p),

            err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p)));

   } else {

     oop p = oopDesc::load_decode_heap_oop(ref);

     assert(_g1h->is_in_g1_reserved(p),

            err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p)));

   }

   return true;

 }

 bool G1ParScanThreadState::verify_task(StarTask ref) const {

   if (ref.is_narrow()) {

     return verify_ref((narrowOop*) ref);

   } else {

     return verify_ref((oop*) ref);

   }

 }

 #endif // ASSERT

 void G1ParScanThreadState::trim_queue() {

   assert(_evac_failure_cl != NULL, "not set");

   StarTask ref;

   do {

     // Drain the overflow stack first, so other threads can steal.

     while (_refs->pop_overflow(ref)) {

       if (!_refs->try_push_to_taskqueue(ref)) {

         dispatch_reference(ref);

       }

     }

     while (_refs->pop_local(ref)) {

       dispatch_reference(ref);

     }

   } while (!_refs->is_empty());

 }

 HeapWord* G1ParScanThreadState::allocate_in_next_plab(InCSetState const state,

                                                       InCSetState* dest,

                                                       size_t word_sz,

                                                       AllocationContext_t const context) {

   assert(state.is_in_cset_or_humongous(), err_msg("Unexpected state: " CSETSTATE_FORMAT, state.value()));

   assert(dest->is_in_cset_or_humongous(), err_msg("Unexpected dest: " CSETSTATE_FORMAT, dest->value()));

   // Right now we only have two types of regions (young / old) so

   // let's keep the logic here simple. We can generalize it when necessary.

   if (dest->is_young()) {

     HeapWord* const obj_ptr = _g1_par_allocator->allocate(InCSetState::Old,

                                                           word_sz, context);

     if (obj_ptr == NULL) {

       return NULL;

     }

     // Make sure that we won't attempt to copy any other objects out

     // of a survivor region (given that apparently we cannot allocate

     // any new ones) to avoid coming into this slow path.

     _tenuring_threshold = 0;

     dest->set_old();

     return obj_ptr;

   } else {

     assert(dest->is_old(), err_msg("Unexpected dest: " CSETSTATE_FORMAT, dest->value()));

     // no other space to try.

     return NULL;

   }

 }

 InCSetState G1ParScanThreadState::next_state(InCSetState const state, markOop const m, uint& age) {

   if (state.is_young()) {

     age = !m->has_displaced_mark_helper() ? m->age()

                                           : m->displaced_mark_helper()->age();

     if (age < _tenuring_threshold) {

       return state;

     }

   }

   return dest(state);

 }

 oop G1ParScanThreadState::copy_to_survivor_space(InCSetState const state,

                                                  oop const old,

                                                  markOop const old_mark) {

   const size_t word_sz = old->size();

   HeapRegion* const from_region = _g1h->heap_region_containing_raw(old);

   // +1 to make the -1 indexes valid...

   const int young_index = from_region->young_index_in_cset()+1;

   assert( (from_region->is_young() && young_index >  0) ||

          (!from_region->is_young() && young_index == 0), "invariant" );

   const AllocationContext_t context = from_region->allocation_context();

   uint age = 0;

   InCSetState dest_state = next_state(state, old_mark, age);

   HeapWord* obj_ptr = _g1_par_allocator->plab_allocate(dest_state, word_sz, context);

   // PLAB allocations should succeed most of the time, so we'll

   // normally check against NULL once and that's it.

   if (obj_ptr == NULL) {

     obj_ptr = _g1_par_allocator->allocate_direct_or_new_plab(dest_state, word_sz, context);

     if (obj_ptr == NULL) {

       obj_ptr = allocate_in_next_plab(state, &dest_state, word_sz, context);

       if (obj_ptr == NULL) {

         // This will either forward-to-self, or detect that someone else has

         // installed a forwarding pointer.

         return _g1h->handle_evacuation_failure_par(this, old);

       }

     }

   }

   assert(obj_ptr != NULL, "when we get here, allocation should have succeeded");

 #ifndef PRODUCT

   // Should this evacuation fail?

   if (_g1h->evacuation_should_fail()) {

     // Doing this after all the allocation attempts also tests the

     // undo_allocation() method too.

     _g1_par_allocator->undo_allocation(dest_state, obj_ptr, word_sz, context);

     return _g1h->handle_evacuation_failure_par(this, old);

   }

 #endif // !PRODUCT

   // We're going to allocate linearly, so might as well prefetch ahead.

   Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);

   const oop obj = oop(obj_ptr);

   const oop forward_ptr = old->forward_to_atomic(obj);

   if (forward_ptr == NULL) {

     Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);

     if (dest_state.is_young()) {

       if (age < markOopDesc::max_age) {

         age++;

       }

       if (old_mark->has_displaced_mark_helper()) {

         // In this case, we have to install the mark word first,

         // otherwise obj looks to be forwarded (the old mark word,

         // which contains the forward pointer, was copied)

         obj->set_mark(old_mark);

         markOop new_mark = old_mark->displaced_mark_helper()->set_age(age);

         old_mark->set_displaced_mark_helper(new_mark);

       } else {

         obj->set_mark(old_mark->set_age(age));

       }

       age_table()->add(age, word_sz);

     } else {

       obj->set_mark(old_mark);

     }

     if (G1StringDedup::is_enabled()) {

       const bool is_from_young = state.is_young();

       const bool is_to_young = dest_state.is_young();

       assert(is_from_young == _g1h->heap_region_containing_raw(old)->is_young(),

              "sanity");

       assert(is_to_young == _g1h->heap_region_containing_raw(obj)->is_young(),

              "sanity");

       G1StringDedup::enqueue_from_evacuation(is_from_young,

                                              is_to_young,

                                              queue_num(),

                                              obj);

     }

     size_t* const surv_young_words = surviving_young_words();

     surv_young_words[young_index] += word_sz;

     if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {

       // We keep track of the next start index in the length field of

       // the to-space object. The actual length can be found in the

       // length field of the from-space object.

       arrayOop(obj)->set_length(0);

       oop* old_p = set_partial_array_mask(old);

       push_on_queue(old_p);

     } else {

       HeapRegion* const to_region = _g1h->heap_region_containing_raw(obj_ptr);

       _scanner.set_region(to_region);

       obj->oop_iterate_backwards(&_scanner);

     }

     return obj;

   } else {

     _g1_par_allocator->undo_allocation(dest_state, obj_ptr, word_sz, context);

     return forward_ptr;

   }

 }