/*

 * Copyright (c) 2001, 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 "classfile/systemDictionary.hpp"

#include "gc/shared/allocTracer.hpp"

#include "gc/shared/barrierSet.inline.hpp"

#include "gc/shared/collectedHeap.hpp"

#include "gc/shared/collectedHeap.inline.hpp"

#include "gc/shared/gcHeapSummary.hpp"

#include "gc/shared/gcTrace.hpp"

#include "gc/shared/gcTraceTime.inline.hpp"

#include "gc/shared/gcWhen.hpp"

#include "gc/shared/vmGCOperations.hpp"

#include "logging/log.hpp"

#include "memory/metaspace.hpp"

#include "oops/instanceMirrorKlass.hpp"

#include "oops/oop.inline.hpp"

#include "runtime/init.hpp"

#include "runtime/thread.inline.hpp"

#include "services/heapDumper.hpp"

#ifdef ASSERT

int CollectedHeap::_fire_out_of_memory_count = 0;

#endif

size_t CollectedHeap::_filler_array_max_size = 0;

template <>

void EventLogBase<GCMessage>::print(outputStream* st, GCMessage& m) {

  st->print_cr("GC heap %s", m.is_before ? "before" : "after");

  st->print_raw(m);

}

void GCHeapLog::log_heap(CollectedHeap* heap, bool before) {

  if (!should_log()) {

    return;

  }

  double timestamp = fetch_timestamp();

  MutexLockerEx ml(&_mutex, Mutex::_no_safepoint_check_flag);

  int index = compute_log_index();

  _records[index].thread = NULL; // Its the GC thread so it's not that interesting.

  _records[index].timestamp = timestamp;

  _records[index].data.is_before = before;

  stringStream st(_records[index].data.buffer(), _records[index].data.size());

  st.print_cr("{Heap %s GC invocations=%u (full %u):",

                 before ? "before" : "after",

                 heap->total_collections(),

                 heap->total_full_collections());

  heap->print_on(&st);

  st.print_cr("}");

}

VirtualSpaceSummary CollectedHeap::create_heap_space_summary() {

  size_t capacity_in_words = capacity() / HeapWordSize;

  return VirtualSpaceSummary(

    reserved_region().start(), reserved_region().start() + capacity_in_words, reserved_region().end());

}

GCHeapSummary CollectedHeap::create_heap_summary() {

  VirtualSpaceSummary heap_space = create_heap_space_summary();

  return GCHeapSummary(heap_space, used());

}

MetaspaceSummary CollectedHeap::create_metaspace_summary() {

  const MetaspaceSizes meta_space(

      MetaspaceAux::committed_bytes(),

      MetaspaceAux::used_bytes(),

      MetaspaceAux::reserved_bytes());

  const MetaspaceSizes data_space(

      MetaspaceAux::committed_bytes(Metaspace::NonClassType),

      MetaspaceAux::used_bytes(Metaspace::NonClassType),

      MetaspaceAux::reserved_bytes(Metaspace::NonClassType));

  const MetaspaceSizes class_space(

      MetaspaceAux::committed_bytes(Metaspace::ClassType),

      MetaspaceAux::used_bytes(Metaspace::ClassType),

      MetaspaceAux::reserved_bytes(Metaspace::ClassType));

  const MetaspaceChunkFreeListSummary& ms_chunk_free_list_summary =

    MetaspaceAux::chunk_free_list_summary(Metaspace::NonClassType);

  const MetaspaceChunkFreeListSummary& class_chunk_free_list_summary =

    MetaspaceAux::chunk_free_list_summary(Metaspace::ClassType);

  return MetaspaceSummary(MetaspaceGC::capacity_until_GC(), meta_space, data_space, class_space,

                          ms_chunk_free_list_summary, class_chunk_free_list_summary);

}

void CollectedHeap::print_heap_before_gc() {

  Universe::print_heap_before_gc();

  if (_gc_heap_log != NULL) {

    _gc_heap_log->log_heap_before(this);

  }

}

void CollectedHeap::print_heap_after_gc() {

  Universe::print_heap_after_gc();

  if (_gc_heap_log != NULL) {

    _gc_heap_log->log_heap_after(this);

  }

}

void CollectedHeap::print_on_error(outputStream* st) const {

  st->print_cr("Heap:");

  print_extended_on(st);

  st->cr();

  _barrier_set->print_on(st);

}

void CollectedHeap::register_nmethod(nmethod* nm) {

  assert_locked_or_safepoint(CodeCache_lock);

}

void CollectedHeap::unregister_nmethod(nmethod* nm) {

  assert_locked_or_safepoint(CodeCache_lock);

}

void CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {

  const GCHeapSummary& heap_summary = create_heap_summary();

  gc_tracer->report_gc_heap_summary(when, heap_summary);

  const MetaspaceSummary& metaspace_summary = create_metaspace_summary();

  gc_tracer->report_metaspace_summary(when, metaspace_summary);

}

void CollectedHeap::trace_heap_before_gc(const GCTracer* gc_tracer) {

  trace_heap(GCWhen::BeforeGC, gc_tracer);

}

void CollectedHeap::trace_heap_after_gc(const GCTracer* gc_tracer) {

  trace_heap(GCWhen::AfterGC, gc_tracer);

}

// Memory state functions.

CollectedHeap::CollectedHeap() :

  _barrier_set(NULL),

  _is_gc_active(false),

  _total_collections(0),

  _total_full_collections(0),

  _gc_cause(GCCause::_no_gc),

  _gc_lastcause(GCCause::_no_gc),

  _defer_initial_card_mark(false) // strengthened by subclass in pre_initialize() below.

{

  const size_t max_len = size_t(arrayOopDesc::max_array_length(T_INT));

  const size_t elements_per_word = HeapWordSize / sizeof(jint);

  _filler_array_max_size = align_object_size(filler_array_hdr_size() +

                                             max_len / elements_per_word);

  NOT_PRODUCT(_promotion_failure_alot_count = 0;)

  NOT_PRODUCT(_promotion_failure_alot_gc_number = 0;)

  if (UsePerfData) {

    EXCEPTION_MARK;

    // create the gc cause jvmstat counters

    _perf_gc_cause = PerfDataManager::create_string_variable(SUN_GC, "cause",

                             80, GCCause::to_string(_gc_cause), CHECK);

    _perf_gc_lastcause =

                PerfDataManager::create_string_variable(SUN_GC, "lastCause",

                             80, GCCause::to_string(_gc_lastcause), CHECK);

  }

  // Create the ring log

  if (LogEvents) {

    _gc_heap_log = new GCHeapLog();

  } else {

    _gc_heap_log = NULL;

  }

}

// This interface assumes that it's being called by the

// vm thread. It collects the heap assuming that the

// heap lock is already held and that we are executing in

// the context of the vm thread.

void CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {

  assert(Thread::current()->is_VM_thread(), "Precondition#1");

  assert(Heap_lock->is_locked(), "Precondition#2");

  GCCauseSetter gcs(this, cause);

  switch (cause) {

    case GCCause::_heap_inspection:

    case GCCause::_heap_dump:

    case GCCause::_metadata_GC_threshold : {

      HandleMark hm;

      do_full_collection(false);        // don't clear all soft refs

      break;

    }

    case GCCause::_last_ditch_collection: {

      HandleMark hm;

      do_full_collection(true);         // do clear all soft refs

      break;

    }

    default:

      ShouldNotReachHere(); // Unexpected use of this function

  }

}

void CollectedHeap::set_barrier_set(BarrierSet* barrier_set) {

  _barrier_set = barrier_set;

  oopDesc::set_bs(_barrier_set);

}

void CollectedHeap::pre_initialize() {

  // Used for ReduceInitialCardMarks (when COMPILER2 is used);

  // otherwise remains unused.

#if defined(COMPILER2) || INCLUDE_JVMCI

  _defer_initial_card_mark =    ReduceInitialCardMarks && can_elide_tlab_store_barriers()

                             && (DeferInitialCardMark || card_mark_must_follow_store());

#else

  assert(_defer_initial_card_mark == false, "Who would set it?");

#endif

}

#ifndef PRODUCT

void CollectedHeap::check_for_bad_heap_word_value(HeapWord* addr, size_t size) {

  if (CheckMemoryInitialization && ZapUnusedHeapArea) {

    for (size_t slot = 0; slot < size; slot += 1) {

      assert((*(intptr_t*) (addr + slot)) != ((intptr_t) badHeapWordVal),

             "Found badHeapWordValue in post-allocation check");

    }

  }

}

void CollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr, size_t size) {

  if (CheckMemoryInitialization && ZapUnusedHeapArea) {

    for (size_t slot = 0; slot < size; slot += 1) {

      assert((*(intptr_t*) (addr + slot)) == ((intptr_t) badHeapWordVal),

             "Found non badHeapWordValue in pre-allocation check");

    }

  }

}

#endif // PRODUCT

#ifdef ASSERT

void CollectedHeap::check_for_valid_allocation_state() {

  Thread *thread = Thread::current();

  // How to choose between a pending exception and a potential

  // OutOfMemoryError?  Don't allow pending exceptions.

  // This is a VM policy failure, so how do we exhaustively test it?

  assert(!thread->has_pending_exception(),

         "shouldn't be allocating with pending exception");

  if (StrictSafepointChecks) {

    assert(thread->allow_allocation(),

           "Allocation done by thread for which allocation is blocked "

           "by No_Allocation_Verifier!");

    // Allocation of an oop can always invoke a safepoint,

    // hence, the true argument

    thread->check_for_valid_safepoint_state(true);

  }

}

#endif

HeapWord* CollectedHeap::allocate_from_tlab_slow(KlassHandle klass, Thread* thread, size_t size) {

  // Retain tlab and allocate object in shared space if

  // the amount free in the tlab is too large to discard.

  if (thread->tlab().free() > thread->tlab().refill_waste_limit()) {

    thread->tlab().record_slow_allocation(size);

    return NULL;

  }

  // Discard tlab and allocate a new one.

  // To minimize fragmentation, the last TLAB may be smaller than the rest.

  size_t new_tlab_size = thread->tlab().compute_size(size);

  thread->tlab().clear_before_allocation();

  if (new_tlab_size == 0) {

    return NULL;

  }

  // Allocate a new TLAB...

  HeapWord* obj = Universe::heap()->allocate_new_tlab(new_tlab_size);

  if (obj == NULL) {

    return NULL;

  }

  AllocTracer::send_allocation_in_new_tlab_event(klass, new_tlab_size * HeapWordSize, size * HeapWordSize);

  if (ZeroTLAB) {

    // ..and clear it.

    Copy::zero_to_words(obj, new_tlab_size);

  } else {

    // ...and zap just allocated object.

#ifdef ASSERT

    // Skip mangling the space corresponding to the object header to

    // ensure that the returned space is not considered parsable by

    // any concurrent GC thread.

    size_t hdr_size = oopDesc::header_size();

    Copy::fill_to_words(obj + hdr_size, new_tlab_size - hdr_size, badHeapWordVal);

#endif // ASSERT

  }

  thread->tlab().fill(obj, obj + size, new_tlab_size);

  return obj;

}

void CollectedHeap::flush_deferred_store_barrier(JavaThread* thread) {

  MemRegion deferred = thread->deferred_card_mark();

  if (!deferred.is_empty()) {

    assert(_defer_initial_card_mark, "Otherwise should be empty");

    {

      // Verify that the storage points to a parsable object in heap

      DEBUG_ONLY(oop old_obj = oop(deferred.start());)

      assert(is_in(old_obj), "Not in allocated heap");

      assert(!can_elide_initializing_store_barrier(old_obj),

             "Else should have been filtered in new_store_pre_barrier()");

      assert(old_obj->is_oop(true), "Not an oop");

      assert(deferred.word_size() == (size_t)(old_obj->size()),

             "Mismatch: multiple objects?");

    }

    BarrierSet* bs = barrier_set();

    assert(bs->has_write_region_opt(), "No write_region() on BarrierSet");

    bs->write_region(deferred);

    // "Clear" the deferred_card_mark field

    thread->set_deferred_card_mark(MemRegion());

  }

  assert(thread->deferred_card_mark().is_empty(), "invariant");

}

size_t CollectedHeap::max_tlab_size() const {

  // TLABs can't be bigger than we can fill with a int[Integer.MAX_VALUE].

  // This restriction could be removed by enabling filling with multiple arrays.

  // If we compute that the reasonable way as

  //    header_size + ((sizeof(jint) * max_jint) / HeapWordSize)

  // we'll overflow on the multiply, so we do the divide first.

  // We actually lose a little by dividing first,

  // but that just makes the TLAB  somewhat smaller than the biggest array,

  // which is fine, since we'll be able to fill that.

  size_t max_int_size = typeArrayOopDesc::header_size(T_INT) +

              sizeof(jint) *

              ((juint) max_jint / (size_t) HeapWordSize);

  return align_size_down(max_int_size, MinObjAlignment);

}

// Helper for ReduceInitialCardMarks. For performance,

// compiled code may elide card-marks for initializing stores

// to a newly allocated object along the fast-path. We

// compensate for such elided card-marks as follows:

// (a) Generational, non-concurrent collectors, such as

//     GenCollectedHeap(ParNew,DefNew,Tenured) and

//     ParallelScavengeHeap(ParallelGC, ParallelOldGC)

//     need the card-mark if and only if the region is

//     in the old gen, and do not care if the card-mark

//     succeeds or precedes the initializing stores themselves,

//     so long as the card-mark is completed before the next

//     scavenge. For all these cases, we can do a card mark

//     at the point at which we do a slow path allocation

//     in the old gen, i.e. in this call.

// (b) GenCollectedHeap(ConcurrentMarkSweepGeneration) requires

//     in addition that the card-mark for an old gen allocated

//     object strictly follow any associated initializing stores.

//     In these cases, the memRegion remembered below is

//     used to card-mark the entire region either just before the next

//     slow-path allocation by this thread or just before the next scavenge or

//     CMS-associated safepoint, whichever of these events happens first.

//     (The implicit assumption is that the object has been fully

//     initialized by this point, a fact that we assert when doing the

//     card-mark.)

// (c) G1CollectedHeap(G1) uses two kinds of write barriers. When a

//     G1 concurrent marking is in progress an SATB (pre-write-)barrier is

//     is used to remember the pre-value of any store. Initializing

//     stores will not need this barrier, so we need not worry about

//     compensating for the missing pre-barrier here. Turning now

//     to the post-barrier, we note that G1 needs a RS update barrier

//     which simply enqueues a (sequence of) dirty cards which may

//     optionally be refined by the concurrent update threads. Note

//     that this barrier need only be applied to a non-young write,

//     but, like in CMS, because of the presence of concurrent refinement

//     (much like CMS' precleaning), must strictly follow the oop-store.

//     Thus, using the same protocol for maintaining the intended

//     invariants turns out, serendepitously, to be the same for both

//     G1 and CMS.

//

// For any future collector, this code should be reexamined with

// that specific collector in mind, and the documentation above suitably

// extended and updated.

oop CollectedHeap::new_store_pre_barrier(JavaThread* thread, oop new_obj) {

  // If a previous card-mark was deferred, flush it now.

  flush_deferred_store_barrier(thread);

  if (can_elide_initializing_store_barrier(new_obj)) {

    // The deferred_card_mark region should be empty

    // following the flush above.

    assert(thread->deferred_card_mark().is_empty(), "Error");

  } else {

    MemRegion mr((HeapWord*)new_obj, new_obj->size());

    assert(!mr.is_empty(), "Error");

    if (_defer_initial_card_mark) {

      // Defer the card mark

      thread->set_deferred_card_mark(mr);

    } else {

      // Do the card mark

      BarrierSet* bs = barrier_set();

      assert(bs->has_write_region_opt(), "No write_region() on BarrierSet");

      bs->write_region(mr);

    }

  }

  return new_obj;

}

size_t CollectedHeap::filler_array_hdr_size() {

  return size_t(align_object_offset(arrayOopDesc::header_size(T_INT))); // align to Long

}

size_t CollectedHeap::filler_array_min_size() {

  return align_object_size(filler_array_hdr_size()); // align to MinObjAlignment

}

#ifdef ASSERT

void CollectedHeap::fill_args_check(HeapWord* start, size_t words)

{

  assert(words >= min_fill_size(), "too small to fill");

  assert(words % MinObjAlignment == 0, "unaligned size");

  assert(Universe::heap()->is_in_reserved(start), "not in heap");

  assert(Universe::heap()->is_in_reserved(start + words - 1), "not in heap");

}

void CollectedHeap::zap_filler_array(HeapWord* start, size_t words, bool zap)

{

  if (ZapFillerObjects && zap) {

    Copy::fill_to_words(start + filler_array_hdr_size(),

                        words - filler_array_hdr_size(), 0XDEAFBABE);

  }

}

#endif // ASSERT

void

CollectedHeap::fill_with_array(HeapWord* start, size_t words, bool zap)

{

  assert(words >= filler_array_min_size(), "too small for an array");

  assert(words <= filler_array_max_size(), "too big for a single object");

  const size_t payload_size = words - filler_array_hdr_size();

  const size_t len = payload_size * HeapWordSize / sizeof(jint);

  assert((int)len >= 0, "size too large " SIZE_FORMAT " becomes %d", words, (int)len);

  // Set the length first for concurrent GC.

  ((arrayOop)start)->set_length((int)len);

  post_allocation_setup_common(Universe::intArrayKlassObj(), start);

  DEBUG_ONLY(zap_filler_array(start, words, zap);)

}

void

CollectedHeap::fill_with_object_impl(HeapWord* start, size_t words, bool zap)

{

  assert(words <= filler_array_max_size(), "too big for a single object");

  if (words >= filler_array_min_size()) {

    fill_with_array(start, words, zap);

  } else if (words > 0) {

    assert(words == min_fill_size(), "unaligned size");

    post_allocation_setup_common(SystemDictionary::Object_klass(), start);

  }

}

void CollectedHeap::fill_with_object(HeapWord* start, size_t words, bool zap)

{

  DEBUG_ONLY(fill_args_check(start, words);)

  HandleMark hm;  // Free handles before leaving.

  fill_with_object_impl(start, words, zap);

}

void CollectedHeap::fill_with_objects(HeapWord* start, size_t words, bool zap)

{

  DEBUG_ONLY(fill_args_check(start, words);)

  HandleMark hm;  // Free handles before leaving.

  // Multiple objects may be required depending on the filler array maximum size. Fill