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 /*

  * Copyright (c) 2014, 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),

     _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),

     _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),

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

     _strong_roots_time(0), _term_time(0),

     _alloc_buffer_waste(0), _undo_waste(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));

   _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;

   _alloc_buffers[GCAllocForTenured]  = &_tenured_alloc_buffer;

   _start = os::elapsedTime();

 }

 G1ParScanThreadState::~G1ParScanThreadState() {

   retire_alloc_buffers();

   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;

   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)) {

       dispatch_reference(ref);

     }

     while (_refs->pop_local(ref)) {

       dispatch_reference(ref);

     }

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

 }

 oop G1ParScanThreadState::copy_to_survivor_space(oop const old) {

   size_t word_sz = old->size();

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

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

   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" );

   G1CollectorPolicy* g1p = _g1h->g1_policy();

   markOop m = old->mark();

   int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()

                                            : m->age();

   GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,

                                                              word_sz);

   HeapWord* obj_ptr = allocate(alloc_purpose, word_sz);

 #ifndef PRODUCT

   // Should this evacuation fail?

   if (_g1h->evacuation_should_fail()) {

     if (obj_ptr != NULL) {

       undo_allocation(alloc_purpose, obj_ptr, word_sz);

       obj_ptr = NULL;

     }

   }

 #endif // !PRODUCT

   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);

   }

   oop obj = oop(obj_ptr);

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

   Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);

   oop forward_ptr = old->forward_to_atomic(obj);

   if (forward_ptr == NULL) {

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

     // alloc_purpose is just a hint to allocate() above, recheck the type of region

     // we actually allocated from and update alloc_purpose accordingly

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

     alloc_purpose = to_region->is_young() ? GCAllocForSurvived : GCAllocForTenured;

     if (g1p->track_object_age(alloc_purpose)) {

       // We could simply do obj->incr_age(). However, this causes a

       // performance issue. obj->incr_age() will first check whether

       // the object has a displaced mark by checking its mark word;

       // getting the mark word from the new location of the object

       // stalls. So, given that we already have the mark word and we

       // are about to install it anyway, it's better to increase the

       // age on the mark word, when the object does not have a

       // displaced mark word. We're not expecting many objects to have

       // a displaced marked word, so that case is not optimized

       // further (it could be...) and we simply call obj->incr_age().

       if (m->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(m);

         obj->incr_age();

       } else {

         m = m->incr_age();

         obj->set_mark(m);

       }

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

     } else {

       obj->set_mark(m);

     }

     if (G1StringDedup::is_enabled()) {

       G1StringDedup::enqueue_from_evacuation(from_region->is_young(),

                                              to_region->is_young(),

                                              queue_num(),

                                              obj);

     }

     size_t* 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 {

       // No point in using the slower heap_region_containing() method,

       // given that we know obj is in the heap.

       _scanner.set_region(_g1h->heap_region_containing_raw(obj));

       obj->oop_iterate_backwards(&_scanner);

     }

   } else {

     undo_allocation(alloc_purpose, obj_ptr, word_sz);

     obj = forward_ptr;

   }

   return obj;

 }

 HeapWord* G1ParScanThreadState::allocate_slow(GCAllocPurpose purpose, size_t word_sz) {

   HeapWord* obj = NULL;

   size_t gclab_word_size = _g1h->desired_plab_sz(purpose);

   if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {

     G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);

     add_to_alloc_buffer_waste(alloc_buf->words_remaining());

     alloc_buf->retire(false /* end_of_gc */, false /* retain */);

     HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size);

     if (buf == NULL) {

       return NULL; // Let caller handle allocation failure.

     }

     // Otherwise.

     alloc_buf->set_word_size(gclab_word_size);

     alloc_buf->set_buf(buf);

     obj = alloc_buf->allocate(word_sz);

     assert(obj != NULL, "buffer was definitely big enough...");

   } else {

     obj = _g1h->par_allocate_during_gc(purpose, word_sz);

   }

   return obj;

 }

 void G1ParScanThreadState::undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {

   if (alloc_buffer(purpose)->contains(obj)) {

     assert(alloc_buffer(purpose)->contains(obj + word_sz - 1),

            "should contain whole object");

     alloc_buffer(purpose)->undo_allocation(obj, word_sz);

   } else {

     CollectedHeap::fill_with_object(obj, word_sz);

     add_to_undo_waste(word_sz);

   }

 }

 HeapWord* G1ParScanThreadState::allocate(GCAllocPurpose purpose, size_t word_sz) {

   HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);

   if (obj != NULL) {

     return obj;

   }

   return allocate_slow(purpose, word_sz);

 }

 void G1ParScanThreadState::retire_alloc_buffers() {

   for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {

     size_t waste = _alloc_buffers[ap]->words_remaining();

     add_to_alloc_buffer_waste(waste);

     _alloc_buffers[ap]->flush_stats_and_retire(_g1h->stats_for_purpose((GCAllocPurpose)ap),

                                                true /* end_of_gc */,

                                                false /* retain */);

   }

 }