/*

 * Copyright (c) 2013, 2015, 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/metadataOnStackMark.hpp"

#include "code/codeCache.hpp"

#include "compiler/compileBroker.hpp"

#include "oops/metadata.hpp"

#include "prims/jvmtiImpl.hpp"

#include "runtime/synchronizer.hpp"

#include "runtime/thread.hpp"

#include "services/threadService.hpp"

#include "utilities/chunkedList.hpp"

MetadataOnStackBuffer* MetadataOnStackMark::_used_buffers = NULL;

MetadataOnStackBuffer* MetadataOnStackMark::_free_buffers = NULL;

MetadataOnStackBuffer* MetadataOnStackMark::_current_buffer = NULL;

NOT_PRODUCT(bool MetadataOnStackMark::_is_active = false;)

// Walk metadata on the stack and mark it so that redefinition doesn't delete

// it.  Class unloading only deletes in-error class files, methods created by

// the relocator and dummy constant pools.  None of these appear anywhere except

// in metadata Handles.

MetadataOnStackMark::MetadataOnStackMark(bool redefinition_walk) {

  assert(SafepointSynchronize::is_at_safepoint(), "sanity check");

  assert(_used_buffers == NULL, "sanity check");

  assert(!_is_active, "MetadataOnStackMarks do not nest");

  NOT_PRODUCT(_is_active = true;)

  Threads::metadata_handles_do(Metadata::mark_on_stack);

  if (redefinition_walk) {

    Threads::metadata_do(Metadata::mark_on_stack);

    CodeCache::alive_nmethods_do(nmethod::mark_on_stack);

    CompileBroker::mark_on_stack();

    JvmtiCurrentBreakpoints::metadata_do(Metadata::mark_on_stack);

    ThreadService::metadata_do(Metadata::mark_on_stack);

  }

}

MetadataOnStackMark::~MetadataOnStackMark() {

  assert(SafepointSynchronize::is_at_safepoint(), "sanity check");

  // Unmark everything that was marked.   Can't do the same walk because

  // redefine classes messes up the code cache so the set of methods

  // might not be the same.

  retire_current_buffer();

  MetadataOnStackBuffer* buffer = _used_buffers;

  while (buffer != NULL) {

    // Clear on stack state for all metadata.

    size_t size = buffer->size();

    for (size_t i  = 0; i < size; i++) {

      Metadata* md = buffer->at(i);

      md->set_on_stack(false);

    }

    MetadataOnStackBuffer* next = buffer->next_used();

    // Move the buffer to the free list.

    buffer->clear();

    buffer->set_next_used(NULL);

    buffer->set_next_free(_free_buffers);

    _free_buffers = buffer;

    // Step to next used buffer.

    buffer = next;

  }

  _used_buffers = NULL;

  NOT_PRODUCT(_is_active = false;)

}

void MetadataOnStackMark::retire_buffer(MetadataOnStackBuffer* buffer) {

  if (buffer == NULL) {

    return;

  }

  buffer->set_next_used(_used_buffers);

  _used_buffers = buffer;

}

// Current buffer is full or we're ready to walk them, add it to the used list.

void MetadataOnStackMark::retire_current_buffer() {

  retire_buffer(_current_buffer);

  _current_buffer = NULL;

}

// Get buffer off free list.

MetadataOnStackBuffer* MetadataOnStackMark::allocate_buffer() {

  MetadataOnStackBuffer* allocated = _free_buffers;

  if (allocated != NULL) {

    _free_buffers = allocated->next_free();

  }

  if (allocated == NULL) {

    allocated = new MetadataOnStackBuffer();

  }

  return allocated;

}

// Record which objects are marked so we can unmark the same objects.

void MetadataOnStackMark::record(Metadata* m) {

  assert(_is_active, "metadata on stack marking is active");

  MetadataOnStackBuffer* buffer = _current_buffer;

  if (buffer != NULL && buffer->is_full()) {

    retire_buffer(buffer);

    buffer = NULL;

  }

  if (buffer == NULL) {

    buffer = allocate_buffer();

    _current_buffer = buffer;

  }

  buffer->push(m);

}