/*

 * 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.

 *

 */

HS_DTRACE_PROBE_DECL1(hotspot, gc__begin, bool);

HS_DTRACE_PROBE_DECL(hotspot, gc__end);

// The same dtrace probe can't be inserted in two different files, so we

// have to call it here, so it's only in one file.  Can't create new probes

// for the other file anymore.   The dtrace probes have to remain stable.

void VM_GC_Operation::notify_gc_begin(bool full) {

  HS_DTRACE_PROBE1(hotspot, gc__begin, full);

  HS_DTRACE_WORKAROUND_TAIL_CALL_BUG();

}

void VM_GC_Operation::notify_gc_end() {

  HS_DTRACE_PROBE(hotspot, gc__end);

  HS_DTRACE_WORKAROUND_TAIL_CALL_BUG();

}

void VM_GC_Operation::acquire_pending_list_lock() {

  // we may enter this with pending exception set

  instanceRefKlass::acquire_pending_list_lock(&_pending_list_basic_lock);

}

void VM_GC_Operation::release_and_notify_pending_list_lock() {

  instanceRefKlass::release_and_notify_pending_list_lock(&_pending_list_basic_lock);

}

// Allocations may fail in several threads at about the same time,

// resulting in multiple gc requests.  We only want to do one of them.

// In case a GC locker is active and the need for a GC is already signalled,

// we want to skip this GC attempt altogether, without doing a futile

// safepoint operation.

bool VM_GC_Operation::skip_operation() const {

  bool skip = (_gc_count_before != Universe::heap()->total_collections());

  if (_full && skip) {

    skip = (_full_gc_count_before != Universe::heap()->total_full_collections());

  }

  if (!skip && GC_locker::is_active_and_needs_gc()) {

    skip = Universe::heap()->is_maximal_no_gc();

    assert(!(skip && (_gc_cause == GCCause::_gc_locker)),

           "GC_locker cannot be active when initiating GC");

  }

  return skip;

}

bool VM_GC_Operation::doit_prologue() {

  assert(Thread::current()->is_Java_thread(), "just checking");

  acquire_pending_list_lock();

  // If the GC count has changed someone beat us to the collection

  // Get the Heap_lock after the pending_list_lock.

  Heap_lock->lock();

  // Check invocations

  if (skip_operation()) {

    // skip collection

    Heap_lock->unlock();

    release_and_notify_pending_list_lock();

    _prologue_succeeded = false;

  } else {

    _prologue_succeeded = true;

    SharedHeap* sh = SharedHeap::heap();

    if (sh != NULL) sh->_thread_holds_heap_lock_for_gc = true;

  }

  return _prologue_succeeded;

}

void VM_GC_Operation::doit_epilogue() {

  assert(Thread::current()->is_Java_thread(), "just checking");

  // Release the Heap_lock first.

  SharedHeap* sh = SharedHeap::heap();

  if (sh != NULL) sh->_thread_holds_heap_lock_for_gc = false;

  Heap_lock->unlock();

  release_and_notify_pending_list_lock();

}

bool VM_GC_HeapInspection::doit_prologue() {

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

    return VM_GC_Operation::doit_prologue();

  } else {

    return false;

  }

}

bool VM_GC_HeapInspection::skip_operation() const {

  assert(Universe::heap()->supports_heap_inspection(), "huh?");

  return false;

}

void VM_GC_HeapInspection::doit() {

  HandleMark hm;

  CollectedHeap* ch = Universe::heap();

  ch->ensure_parsability(false); // must happen, even if collection does

                                 // not happen (e.g. due to GC_locker)

  if (_full_gc) {

    // The collection attempt below would be skipped anyway if

    // the gc locker is held. The following dump may then be a tad

    // misleading to someone expecting only live objects to show

    // up in the dump (see CR 6944195). Just issue a suitable warning

    // in that case and do not attempt to do a collection.

    // The latter is a subtle point, because even a failed attempt

    // to GC will, in fact, induce one in the future, which we

    // probably want to avoid in this case because the GC that we may

    // be about to attempt holds value for us only

    // if it happens now and not if it happens in the eventual

    // future.

    if (GC_locker::is_active()) {

      warning("GC locker is held; pre-dump GC was skipped");

    } else {

      ch->collect_as_vm_thread(GCCause::_heap_inspection);

    }

  }

  HeapInspection::heap_inspection(_out, _need_prologue /* need_prologue */);

}

void VM_GenCollectForAllocation::doit() {

  JvmtiGCForAllocationMarker jgcm;

  notify_gc_begin(false);

  GenCollectedHeap* gch = GenCollectedHeap::heap();

  GCCauseSetter gccs(gch, _gc_cause);

  _res = gch->satisfy_failed_allocation(_size, _tlab);

  assert(gch->is_in_reserved_or_null(_res), "result not in heap");

  if (_res == NULL && GC_locker::is_active_and_needs_gc()) {

    set_gc_locked();

  }

  notify_gc_end();

}

void VM_GenCollectFull::doit() {

  JvmtiGCFullMarker jgcm;

  notify_gc_begin(true);

  GenCollectedHeap* gch = GenCollectedHeap::heap();

  GCCauseSetter gccs(gch, _gc_cause);

  gch->do_full_collection(gch->must_clear_all_soft_refs(), _max_level);

  notify_gc_end();

}

void VM_GenCollectForPermanentAllocation::doit() {

  JvmtiGCForAllocationMarker jgcm;

  notify_gc_begin(true);

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

  GCCauseSetter gccs(heap, _gc_cause);

  switch (heap->kind()) {

    case (CollectedHeap::GenCollectedHeap): {

      GenCollectedHeap* gch = (GenCollectedHeap*)heap;

      gch->do_full_collection(gch->must_clear_all_soft_refs(),

                              gch->n_gens() - 1);

      break;

    }

#ifndef SERIALGC

    case (CollectedHeap::G1CollectedHeap): {

      G1CollectedHeap* g1h = (G1CollectedHeap*)heap;

      g1h->do_full_collection(_gc_cause == GCCause::_last_ditch_collection);

      break;

    }

#endif // SERIALGC

    default:

      ShouldNotReachHere();

  }

  _res = heap->perm_gen()->allocate(_size, false);

  assert(heap->is_in_reserved_or_null(_res), "result not in heap");

  if (_res == NULL && GC_locker::is_active_and_needs_gc()) {

    set_gc_locked();

  }

  notify_gc_end();

}