/*

 * Copyright (c) 2001, 2012, 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_implementation/shared/vmGCOperations.hpp"

#include "gc_interface/collectedHeap.hpp"

#include "gc_interface/collectedHeap.inline.hpp"

#include "oops/oop.inline.hpp"

#include "oops/instanceMirrorKlass.hpp"

#include "runtime/init.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(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());

  if (before) {

    Universe::print_heap_before_gc(&st, true);

  } else {

    Universe::print_heap_after_gc(&st, true);

  }

}

// Memory state functions.

CollectedHeap::CollectedHeap() : _n_par_threads(0)

{

  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);

  _barrier_set = NULL;

  _is_gc_active = false;

  _total_collections = _total_full_collections = 0;

  _gc_cause = _gc_lastcause = GCCause::_no_gc;

  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);

  }

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

  // 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

  }

}

MetaWord* CollectedHeap::satisfy_failed_metadata_allocation(

                                              ClassLoaderData* loader_data,

                                              size_t size, Metaspace::MetadataType mdtype) {

  return collector_policy()->satisfy_failed_metadata_allocation(loader_data, size, mdtype);

}

void CollectedHeap::pre_initialize() {

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

  // otherwise remains unused.

#ifdef COMPILER2

  _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(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;

  }

  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");

}

// 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, err_msg("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.

#ifdef _LP64

  // A single array can fill ~8G, so multiple objects are needed only in 64-bit.

  // First fill with arrays, ensuring that any remaining space is big enough to

  // fill.  The remainder is filled with a single object.

  const size_t min = min_fill_size();

  const size_t max = filler_array_max_size();

  while (words > max) {

    const size_t cur = words - max >= min ? max : max - min;

    fill_with_array(start, cur, zap);

    start += cur;

    words -= cur;

  }

#endif

  fill_with_object_impl(start, words, zap);

}

HeapWord* CollectedHeap::allocate_new_tlab(size_t size) {

  guarantee(false, "thread-local allocation buffers not supported");

  return NULL;

}

void CollectedHeap::ensure_parsability(bool retire_tlabs) {

  // The second disjunct in the assertion below makes a concession

  // for the start-up verification done while the VM is being

  // created. Callers be careful that you know that mutators

  // aren't going to interfere -- for instance, this is permissible

  // if we are still single-threaded and have either not yet

  // started allocating (nothing much to verify) or we have

  // started allocating but are now a full-fledged JavaThread

  // (and have thus made our TLAB's) available for filling.

  assert(SafepointSynchronize::is_at_safepoint() ||

         !is_init_completed(),

         "Should only be called at a safepoint or at start-up"

         " otherwise concurrent mutator activity may make heap "

         " unparsable again");

  const bool use_tlab = UseTLAB;

  const bool deferred = _defer_initial_card_mark;

  // The main thread starts allocating via a TLAB even before it

  // has added itself to the threads list at vm boot-up.

  assert(!use_tlab || Threads::first() != NULL,

         "Attempt to fill tlabs before main thread has been added"

         " to threads list is doomed to failure!");

  for (JavaThread *thread = Threads::first(); thread; thread = thread->next()) {

     if (use_tlab) thread->tlab().make_parsable(retire_tlabs);

#ifdef COMPILER2

     // The deferred store barriers must all have been flushed to the

     // card-table (or other remembered set structure) before GC starts

     // processing the card-table (or other remembered set).

     if (deferred) flush_deferred_store_barrier(thread);

#else

     assert(!deferred, "Should be false");

     assert(thread->deferred_card_mark().is_empty(), "Should be empty");

#endif

  }

}

void CollectedHeap::accumulate_statistics_all_tlabs() {

  if (UseTLAB) {

    assert(SafepointSynchronize::is_at_safepoint() ||

         !is_init_completed(),

         "should only accumulate statistics on tlabs at safepoint");

    ThreadLocalAllocBuffer::accumulate_statistics_before_gc();

  }

}

void CollectedHeap::resize_all_tlabs() {

  if (UseTLAB) {

    assert(SafepointSynchronize::is_at_safepoint() ||

         !is_init_completed(),

         "should only resize tlabs at safepoint");

    ThreadLocalAllocBuffer::resize_all_tlabs();

  }

}

void CollectedHeap::pre_full_gc_dump() {

  if (HeapDumpBeforeFullGC) {

    TraceTime tt("Heap Dump (before full gc): ", PrintGCDetails, false, gclog_or_tty);

    // We are doing a "major" collection and a heap dump before

    // major collection has been requested.

    HeapDumper::dump_heap();

  }

  if (PrintClassHistogramBeforeFullGC) {

    TraceTime tt("Class Histogram (before full gc): ", PrintGCDetails, true, gclog_or_tty);

    VM_GC_HeapInspection inspector(gclog_or_tty, false /* ! full gc */, false /* ! prologue */);

    inspector.doit();

  }

}

void CollectedHeap::post_full_gc_dump() {

  if (HeapDumpAfterFullGC) {

    TraceTime tt("Heap Dump (after full gc): ", PrintGCDetails, false, gclog_or_tty);

    HeapDumper::dump_heap();

  }

  if (PrintClassHistogramAfterFullGC) {

    TraceTime tt("Class Histogram (after full gc): ", PrintGCDetails, true, gclog_or_tty);

    VM_GC_HeapInspection inspector(gclog_or_tty, false /* ! full gc */, false /* ! prologue */);

    inspector.doit();

  }

}

oop CollectedHeap::Class_obj_allocate(KlassHandle klass, int size, KlassHandle real_klass, TRAPS) {

  debug_only(check_for_valid_allocation_state());

  assert(!Universe::heap()->is_gc_active(), "Allocation during gc not allowed");

  assert(size >= 0, "int won't convert to size_t");

  HeapWord* obj;

    assert(ScavengeRootsInCode > 0, "must be");

    obj = common_mem_allocate_init(size, CHECK_NULL);

  post_allocation_setup_common(klass, obj);

  assert(Universe::is_bootstrapping() ||

         !((oop)obj)->is_array(), "must not be an array");

  NOT_PRODUCT(Universe::heap()->check_for_bad_heap_word_value(obj, size));

  oop mirror = (oop)obj;