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 /*

  * Copyright (c) 2002, 2011, 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

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  */

 #include "precompiled.hpp"

 #include "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp"

 #include "gc_implementation/parallelScavenge/psOldGen.hpp"

 #include "gc_implementation/parallelScavenge/psPromotionManager.inline.hpp"

 #include "gc_implementation/parallelScavenge/psScavenge.inline.hpp"

 #include "gc_implementation/shared/mutableSpace.hpp"

 #include "memory/memRegion.hpp"

 #include "oops/oop.inline.hpp"

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

 PSPromotionManager**         PSPromotionManager::_manager_array = NULL;

 OopStarTaskQueueSet*         PSPromotionManager::_stack_array_depth = NULL;

 PSOldGen*                    PSPromotionManager::_old_gen = NULL;

 MutableSpace*                PSPromotionManager::_young_space = NULL;

 void PSPromotionManager::initialize() {

   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();

   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");

   _old_gen = heap->old_gen();

   _young_space = heap->young_gen()->to_space();

   assert(_manager_array == NULL, "Attempt to initialize twice");

   _manager_array = NEW_C_HEAP_ARRAY(PSPromotionManager*, ParallelGCThreads+1 );

   guarantee(_manager_array != NULL, "Could not initialize promotion manager");

   _stack_array_depth = new OopStarTaskQueueSet(ParallelGCThreads);

   guarantee(_stack_array_depth != NULL, "Cound not initialize promotion manager");

   // Create and register the PSPromotionManager(s) for the worker threads.

   for(uint i=0; i<ParallelGCThreads; i++) {

     _manager_array[i] = new PSPromotionManager();

     guarantee(_manager_array[i] != NULL, "Could not create PSPromotionManager");

     stack_array_depth()->register_queue(i, _manager_array[i]->claimed_stack_depth());

   }

   // The VMThread gets its own PSPromotionManager, which is not available

   // for work stealing.

   _manager_array[ParallelGCThreads] = new PSPromotionManager();

   guarantee(_manager_array[ParallelGCThreads] != NULL, "Could not create PSPromotionManager");

 }

 PSPromotionManager* PSPromotionManager::gc_thread_promotion_manager(int index) {

   assert(index >= 0 && index < (int)ParallelGCThreads, "index out of range");

   assert(_manager_array != NULL, "Sanity");

   return _manager_array[index];

 }

 PSPromotionManager* PSPromotionManager::vm_thread_promotion_manager() {

   assert(_manager_array != NULL, "Sanity");

   return _manager_array[ParallelGCThreads];

 }

 void PSPromotionManager::pre_scavenge() {

   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();

   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");

   _young_space = heap->young_gen()->to_space();

   for(uint i=0; i<ParallelGCThreads+1; i++) {

     manager_array(i)->reset();

   }

 }

 void PSPromotionManager::post_scavenge() {

   TASKQUEUE_STATS_ONLY(if (PrintGCDetails && ParallelGCVerbose) print_stats());

   for (uint i = 0; i < ParallelGCThreads + 1; i++) {

     PSPromotionManager* manager = manager_array(i);

     assert(manager->claimed_stack_depth()->is_empty(), "should be empty");

     manager->flush_labs();

   }

 }

 #if TASKQUEUE_STATS

 void

 PSPromotionManager::print_taskqueue_stats(uint i) const {

   tty->print("%3u ", i);

   _claimed_stack_depth.stats.print();

   tty->cr();

 }

 void

 PSPromotionManager::print_local_stats(uint i) const {

   #define FMT " " SIZE_FORMAT_W(10)

   tty->print_cr("%3u" FMT FMT FMT FMT, i, _masked_pushes, _masked_steals,

                 _arrays_chunked, _array_chunks_processed);

   #undef FMT

 }

 static const char* const pm_stats_hdr[] = {

   "    --------masked-------     arrays      array",

   "thr       push      steal    chunked     chunks",

   "--- ---------- ---------- ---------- ----------"

 };

 void

 PSPromotionManager::print_stats() {

   tty->print_cr("== GC Tasks Stats, GC %3d",

                 Universe::heap()->total_collections());

   tty->print("thr "); TaskQueueStats::print_header(1); tty->cr();

   tty->print("--- "); TaskQueueStats::print_header(2); tty->cr();

   for (uint i = 0; i < ParallelGCThreads + 1; ++i) {

     manager_array(i)->print_taskqueue_stats(i);

   }

   const uint hlines = sizeof(pm_stats_hdr) / sizeof(pm_stats_hdr[0]);

   for (uint i = 0; i < hlines; ++i) tty->print_cr(pm_stats_hdr[i]);

   for (uint i = 0; i < ParallelGCThreads + 1; ++i) {

     manager_array(i)->print_local_stats(i);

   }

 }

 void

 PSPromotionManager::reset_stats() {

   claimed_stack_depth()->stats.reset();

   _masked_pushes = _masked_steals = 0;

   _arrays_chunked = _array_chunks_processed = 0;

 }

 #endif // TASKQUEUE_STATS

 PSPromotionManager::PSPromotionManager() {

   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();

   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");

   // We set the old lab's start array.

   _old_lab.set_start_array(old_gen()->start_array());

   uint queue_size;

   claimed_stack_depth()->initialize();

   queue_size = claimed_stack_depth()->max_elems();

   _totally_drain = (ParallelGCThreads == 1) || (GCDrainStackTargetSize == 0);

   if (_totally_drain) {

     _target_stack_size = 0;

   } else {

     // don't let the target stack size to be more than 1/4 of the entries

     _target_stack_size = (uint) MIN2((uint) GCDrainStackTargetSize,

                                      (uint) (queue_size / 4));

   }

   _array_chunk_size = ParGCArrayScanChunk;

   // let's choose 1.5x the chunk size

   _min_array_size_for_chunking = 3 * _array_chunk_size / 2;

   reset();

 }

 void PSPromotionManager::reset() {

   assert(stacks_empty(), "reset of non-empty stack");

   // We need to get an assert in here to make sure the labs are always flushed.

   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();

   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");

   // Do not prefill the LAB's, save heap wastage!

   HeapWord* lab_base = young_space()->top();

   _young_lab.initialize(MemRegion(lab_base, (size_t)0));

   _young_gen_is_full = false;

   lab_base = old_gen()->object_space()->top();

   _old_lab.initialize(MemRegion(lab_base, (size_t)0));

   _old_gen_is_full = false;

   TASKQUEUE_STATS_ONLY(reset_stats());

 }

 void PSPromotionManager::drain_stacks_depth(bool totally_drain) {

   totally_drain = totally_drain || _totally_drain;

 #ifdef ASSERT

   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();

   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");

   MutableSpace* to_space = heap->young_gen()->to_space();

   MutableSpace* old_space = heap->old_gen()->object_space();

   MutableSpace* perm_space = heap->perm_gen()->object_space();

 #endif /* ASSERT */

   OopStarTaskQueue* const tq = claimed_stack_depth();

   do {

     StarTask p;

     // Drain overflow stack first, so other threads can steal from

     // claimed stack while we work.

     while (tq->pop_overflow(p)) {

       process_popped_location_depth(p);

     }

     if (totally_drain) {

       while (tq->pop_local(p)) {

         process_popped_location_depth(p);

       }

     } else {

       while (tq->size() > _target_stack_size && tq->pop_local(p)) {

         process_popped_location_depth(p);

       }

     }

   } while (totally_drain && !tq->taskqueue_empty() || !tq->overflow_empty());

   assert(!totally_drain || tq->taskqueue_empty(), "Sanity");

   assert(totally_drain || tq->size() <= _target_stack_size, "Sanity");

   assert(tq->overflow_empty(), "Sanity");

 }

 void PSPromotionManager::flush_labs() {

   assert(stacks_empty(), "Attempt to flush lab with live stack");

   // If either promotion lab fills up, we can flush the

   // lab but not refill it, so check first.

   assert(!_young_lab.is_flushed() || _young_gen_is_full, "Sanity");

   if (!_young_lab.is_flushed())

     _young_lab.flush();

   assert(!_old_lab.is_flushed() || _old_gen_is_full, "Sanity");

   if (!_old_lab.is_flushed())

     _old_lab.flush();

   // Let PSScavenge know if we overflowed

   if (_young_gen_is_full) {

     PSScavenge::set_survivor_overflow(true);

   }

 }

 //

 // This method is pretty bulky. It would be nice to split it up

 // into smaller submethods, but we need to be careful not to hurt

 // performance.

 //

 oop PSPromotionManager::copy_to_survivor_space(oop o) {

   assert(PSScavenge::should_scavenge(&o), "Sanity");

   oop new_obj = NULL;

   // NOTE! We must be very careful with any methods that access the mark

   // in o. There may be multiple threads racing on it, and it may be forwarded

   // at any time. Do not use oop methods for accessing the mark!

   markOop test_mark = o->mark();

   // The same test as "o->is_forwarded()"

   if (!test_mark->is_marked()) {

     bool new_obj_is_tenured = false;

     size_t new_obj_size = o->size();

     // Find the objects age, MT safe.

     int age = (test_mark->has_displaced_mark_helper() /* o->has_displaced_mark() */) ?

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

     // Try allocating obj in to-space (unless too old)

     if (age < PSScavenge::tenuring_threshold()) {

       new_obj = (oop) _young_lab.allocate(new_obj_size);

       if (new_obj == NULL && !_young_gen_is_full) {

         // Do we allocate directly, or flush and refill?

         if (new_obj_size > (YoungPLABSize / 2)) {

           // Allocate this object directly

           new_obj = (oop)young_space()->cas_allocate(new_obj_size);

         } else {

           // Flush and fill

           _young_lab.flush();

           HeapWord* lab_base = young_space()->cas_allocate(YoungPLABSize);

           if (lab_base != NULL) {

             _young_lab.initialize(MemRegion(lab_base, YoungPLABSize));

             // Try the young lab allocation again.

             new_obj = (oop) _young_lab.allocate(new_obj_size);

           } else {

             _young_gen_is_full = true;

           }

         }

       }

     }

     // Otherwise try allocating obj tenured

     if (new_obj == NULL) {

 #ifndef PRODUCT

       if (Universe::heap()->promotion_should_fail()) {

         return oop_promotion_failed(o, test_mark);

       }

 #endif  // #ifndef PRODUCT

       new_obj = (oop) _old_lab.allocate(new_obj_size);

       new_obj_is_tenured = true;

       if (new_obj == NULL) {

         if (!_old_gen_is_full) {

           // Do we allocate directly, or flush and refill?

           if (new_obj_size > (OldPLABSize / 2)) {

             // Allocate this object directly

             new_obj = (oop)old_gen()->cas_allocate(new_obj_size);

           } else {

             // Flush and fill

             _old_lab.flush();

             HeapWord* lab_base = old_gen()->cas_allocate(OldPLABSize);

             if(lab_base != NULL) {

               _old_lab.initialize(MemRegion(lab_base, OldPLABSize));

               // Try the old lab allocation again.

               new_obj = (oop) _old_lab.allocate(new_obj_size);

             }

           }

         }

         // This is the promotion failed test, and code handling.

         // The code belongs here for two reasons. It is slightly

         // different thatn the code below, and cannot share the

         // CAS testing code. Keeping the code here also minimizes

         // the impact on the common case fast path code.

         if (new_obj == NULL) {

           _old_gen_is_full = true;

           return oop_promotion_failed(o, test_mark);

         }

       }

     }

     assert(new_obj != NULL, "allocation should have succeeded");

     // Copy obj

     Copy::aligned_disjoint_words((HeapWord*)o, (HeapWord*)new_obj, new_obj_size);

     // Now we have to CAS in the header.

     if (o->cas_forward_to(new_obj, test_mark)) {

       // We won any races, we "own" this object.

       assert(new_obj == o->forwardee(), "Sanity");

       // Increment age if obj still in new generation. Now that

       // we're dealing with a markOop that cannot change, it is

       // okay to use the non mt safe oop methods.

       if (!new_obj_is_tenured) {

         new_obj->incr_age();

         assert(young_space()->contains(new_obj), "Attempt to push non-promoted obj");

       }

       // Do the size comparison first with new_obj_size, which we

       // already have. Hopefully, only a few objects are larger than

       // _min_array_size_for_chunking, and most of them will be arrays.

       // So, the is->objArray() test would be very infrequent.

       if (new_obj_size > _min_array_size_for_chunking &&

           new_obj->is_objArray() &&

           PSChunkLargeArrays) {

         // we'll chunk it

         oop* const masked_o = mask_chunked_array_oop(o);

         push_depth(masked_o);

         TASKQUEUE_STATS_ONLY(++_arrays_chunked; ++_masked_pushes);

       } else {

         // we'll just push its contents

         new_obj->push_contents(this);

       }

     }  else {

       // We lost, someone else "owns" this object

       guarantee(o->is_forwarded(), "Object must be forwarded if the cas failed.");

       // Try to deallocate the space.  If it was directly allocated we cannot

       // deallocate it, so we have to test.  If the deallocation fails,

       // overwrite with a filler object.

       if (new_obj_is_tenured) {

         if (!_old_lab.unallocate_object(new_obj)) {

           CollectedHeap::fill_with_object((HeapWord*) new_obj, new_obj_size);

         }

       } else if (!_young_lab.unallocate_object(new_obj)) {

         CollectedHeap::fill_with_object((HeapWord*) new_obj, new_obj_size);

       }

       // don't update this before the unallocation!

       new_obj = o->forwardee();

     }

   } else {

     assert(o->is_forwarded(), "Sanity");

     new_obj = o->forwardee();

   }

 #ifdef DEBUG

   // This code must come after the CAS test, or it will print incorrect

   // information.

   if (TraceScavenge) {

     gclog_or_tty->print_cr("{%s %s " PTR_FORMAT " -> " PTR_FORMAT " (" SIZE_FORMAT ")}",

        PSScavenge::should_scavenge(&new_obj) ? "copying" : "tenuring",

        new_obj->blueprint()->internal_name(), o, new_obj, new_obj->size());

   }

 #endif

   return new_obj;

 }

 template <class T> void PSPromotionManager::process_array_chunk_work(

                                                  oop obj,

                                                  int start, int end) {

   assert(start <= end, "invariant");

   T* const base      = (T*)objArrayOop(obj)->base();

   T* p               = base + start;

   T* const chunk_end = base + end;

   while (p < chunk_end) {

     if (PSScavenge::should_scavenge(p)) {

       claim_or_forward_depth(p);

     }

     ++p;

   }

 }

 void PSPromotionManager::process_array_chunk(oop old) {

   assert(PSChunkLargeArrays, "invariant");

   assert(old->is_objArray(), "invariant");

   assert(old->is_forwarded(), "invariant");

   TASKQUEUE_STATS_ONLY(++_array_chunks_processed);

   oop const obj = old->forwardee();

   int start;

   int const end = arrayOop(old)->length();

   if (end > (int) _min_array_size_for_chunking) {

     // we'll chunk more

     start = end - _array_chunk_size;

     assert(start > 0, "invariant");

     arrayOop(old)->set_length(start);

     push_depth(mask_chunked_array_oop(old));

     TASKQUEUE_STATS_ONLY(++_masked_pushes);

   } else {

     // this is the final chunk for this array

     start = 0;

     int const actual_length = arrayOop(obj)->length();

     arrayOop(old)->set_length(actual_length);

   }

   if (UseCompressedOops) {

     process_array_chunk_work<narrowOop>(obj, start, end);

   } else {

     process_array_chunk_work<oop>(obj, start, end);

   }

 }

 oop PSPromotionManager::oop_promotion_failed(oop obj, markOop obj_mark) {

   assert(_old_gen_is_full || PromotionFailureALot, "Sanity");

   // Attempt to CAS in the header.

   // This tests if the header is still the same as when

   // this started.  If it is the same (i.e., no forwarding

   // pointer has been installed), then this thread owns

   // it.

   if (obj->cas_forward_to(obj, obj_mark)) {

     // We won any races, we "own" this object.

     assert(obj == obj->forwardee(), "Sanity");

     obj->push_contents(this);

     // Save the mark if needed

     PSScavenge::oop_promotion_failed(obj, obj_mark);

   }  else {

     // We lost, someone else "owns" this object

     guarantee(obj->is_forwarded(), "Object must be forwarded if the cas failed.");

     // No unallocation to worry about.

     obj = obj->forwardee();

   }

 #ifdef DEBUG

   if (TraceScavenge) {

     gclog_or_tty->print_cr("{%s %s 0x%x (%d)}",

                            "promotion-failure",

                            obj->blueprint()->internal_name(),

                            obj, obj->size());

   }

 #endif

   return obj;

 }