/*

 * Copyright (c) 2005, 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 "classfile/classLoader.hpp"

#include "classfile/javaClasses.hpp"

#include "gc_implementation/shared/vmGCOperations.hpp"

#include "memory/gcLocker.inline.hpp"

#include "memory/genCollectedHeap.hpp"

#include "memory/oopFactory.hpp"

#include "oops/instanceKlass.hpp"

#include "oops/instanceRefKlass.hpp"

#include "runtime/handles.inline.hpp"

#include "runtime/init.hpp"

#include "runtime/interfaceSupport.hpp"

#include "utilities/dtrace.hpp"

#include "utilities/preserveException.hpp"

#include "utilities/macros.hpp"

#if INCLUDE_ALL_GCS

#include "gc_implementation/g1/g1CollectedHeap.inline.hpp"

#endif // INCLUDE_ALL_GCS

// 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) {

  HOTSPOT_GC_BEGIN(

                   full);

  HS_DTRACE_WORKAROUND_TAIL_CALL_BUG();

}

void VM_GC_Operation::notify_gc_end() {

  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 signaled,

// 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");

  assert(((_gc_cause != GCCause::_no_gc) &&

          (_gc_cause != GCCause::_no_cause_specified)), "Illegal GCCause");

  // To be able to handle a GC the VM initialization needs to be completed.

  if (!is_init_completed()) {

    vm_exit_during_initialization(

      err_msg("GC triggered before VM initialization completed. Try increasing "

              "NewSize, current value " UINTX_FORMAT "%s.",

              byte_size_in_proper_unit(NewSize),

              proper_unit_for_byte_size(NewSize)));

  }

  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;

}

bool VM_GC_HeapInspection::collect() {

  if (GC_locker::is_active()) {

    return false;

  }

  Universe::heap()->collect_as_vm_thread(GCCause::_heap_inspection);

  return true;

}

void VM_GC_HeapInspection::doit() {

  HandleMark hm;

  Universe::heap()->ensure_parsability(false); // must happen, even if collection does

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

                                               // or _full_gc being false

  if (_full_gc) {

    if (!collect()) {

      // The collection attempt was skipped because 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.

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

    }

  }

  HeapInspection inspect(_csv_format, _print_help, _print_class_stats,

                         _columns);

  inspect.heap_inspection(_out);

}

void VM_GenCollectForAllocation::doit() {

  SvcGCMarker sgcm(SvcGCMarker::MINOR);

  GenCollectedHeap* gch = GenCollectedHeap::heap();

  GCCauseSetter gccs(gch, _gc_cause);

    set_gc_locked();

  }

}

void VM_GenCollectFull::doit() {

  SvcGCMarker sgcm(SvcGCMarker::FULL);

  GenCollectedHeap* gch = GenCollectedHeap::heap();

  GCCauseSetter gccs(gch, _gc_cause);

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

}

// Returns true iff concurrent GCs unloads metadata.

bool VM_CollectForMetadataAllocation::initiate_concurrent_GC() {

#if INCLUDE_ALL_GCS

  if (UseConcMarkSweepGC && CMSClassUnloadingEnabled) {

    MetaspaceGC::set_should_concurrent_collect(true);

    return true;

  }

  if (UseG1GC && ClassUnloadingWithConcurrentMark) {

    G1CollectedHeap* g1h = G1CollectedHeap::heap();

    g1h->g1_policy()->set_initiate_conc_mark_if_possible();

    GCCauseSetter x(g1h, _gc_cause);

    // At this point we are supposed to start a concurrent cycle. We

    // will do so if one is not already in progress.

    bool should_start = g1h->g1_policy()->force_initial_mark_if_outside_cycle(_gc_cause);

    if (should_start) {

      double pause_target = g1h->g1_policy()->max_pause_time_ms();

      g1h->do_collection_pause_at_safepoint(pause_target);

    }

    return true;

  }

#endif

  return false;

}

static void log_metaspace_alloc_failure_for_concurrent_GC() {

  if (Verbose && PrintGCDetails) {

    if (UseConcMarkSweepGC) {

      gclog_or_tty->print_cr("\nCMS full GC for Metaspace");

    } else if (UseG1GC) {

      gclog_or_tty->print_cr("\nG1 full GC for Metaspace");

    }

  }

}

void VM_CollectForMetadataAllocation::doit() {

  SvcGCMarker sgcm(SvcGCMarker::FULL);

  CollectedHeap* heap = Universe::heap();

  GCCauseSetter gccs(heap, _gc_cause);

  // Check again if the space is available.  Another thread

  // may have similarly failed a metadata allocation and induced

  // a GC that freed space for the allocation.

  if (!MetadataAllocationFailALot) {

    _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype);

    if (_result != NULL) {

      return;

    }

  }

  if (initiate_concurrent_GC()) {

    // For CMS and G1 expand since the collection is going to be concurrent.

    _result = _loader_data->metaspace_non_null()->expand_and_allocate(_size, _mdtype);

    if (_result != NULL) {

      return;

    }

    log_metaspace_alloc_failure_for_concurrent_GC();

  }

  // Don't clear the soft refs yet.

  heap->collect_as_vm_thread(GCCause::_metadata_GC_threshold);

  // After a GC try to allocate without expanding.  Could fail

  // and expansion will be tried below.

  _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype);

  if (_result != NULL) {

    return;

  }

  // If still failing, allow the Metaspace to expand.

  // See delta_capacity_until_GC() for explanation of the

  // amount of the expansion.

  // This should work unless there really is no more space

  // or a MaxMetaspaceSize has been specified on the command line.

  _result = _loader_data->metaspace_non_null()->expand_and_allocate(_size, _mdtype);

  if (_result != NULL) {

    return;

  }

  // If expansion failed, do a last-ditch collection and try allocating

  // again.  A last-ditch collection will clear softrefs.  This

  // behavior is similar to the last-ditch collection done for perm

  // gen when it was full and a collection for failed allocation

  // did not free perm gen space.

  heap->collect_as_vm_thread(GCCause::_last_ditch_collection);

  _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype);

  if (_result != NULL) {

    return;

  }

  if (Verbose && PrintGCDetails) {

    gclog_or_tty->print_cr("\nAfter Metaspace GC failed to allocate size "

                           SIZE_FORMAT, _size);

  }

  if (GC_locker::is_active_and_needs_gc()) {

    set_gc_locked();

  }

}