/*

 * Copyright (c) 2019, 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

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 */

#ifndef SHARE_MEMORY_ARCHIVEUTILS_HPP

#define SHARE_MEMORY_ARCHIVEUTILS_HPP

#include "logging/log.hpp"

#include "runtime/arguments.hpp"

#include "utilities/bitMap.hpp"

// ArchivePtrMarker is used to mark the location of pointers embedded in a CDS archive. E.g., when an

// InstanceKlass k is dumped, we mark the location of the k->_name pointer by effectively calling

// mark_pointer(/*ptr_loc=*/&k->_name). It's required that (_prt_base <= ptr_loc < _ptr_end). _ptr_base is

// fixed, but _ptr_end can be expanded as more objects are dumped.

class ArchivePtrMarker : AllStatic {

  static CHeapBitMap* _ptrmap;

  static address*     _ptr_base;

  static address*     _ptr_end;

  // Once _ptrmap is compacted, we don't allow bit marking anymore. This is to

  // avoid unintentional copy operations after the bitmap has been finalized and written.

  static bool         _compacted;

public:

  static void initialize(CHeapBitMap* ptrmap, address* ptr_base, address* ptr_end);

  static void mark_pointer(address* ptr_loc);

  static void compact(address relocatable_base, address relocatable_end);

  static void compact(size_t max_non_null_offset);

  template <typename T>

  static void mark_pointer(T* ptr_loc) {

    mark_pointer((address*)ptr_loc);

  }

  static void expand_ptr_end(address *new_ptr_end) {

    assert(_ptr_end <= new_ptr_end, "must be");

    _ptr_end = new_ptr_end;

  }

  static CHeapBitMap* ptrmap() {

    return _ptrmap;

  }

};

// SharedDataRelocator is used to shift pointers in the CDS archive.

//

// The CDS archive is basically a contiguous block of memory (divided into several regions)

// that contains multiple objects. The objects may contain direct pointers that point to other objects

// within the archive (e.g., InstanceKlass::_name points to a Symbol in the archive). During dumping, we

// built a bitmap that marks the locations of all these pointers (using ArchivePtrMarker, see comments above).

//

// The contents of the archive assumes that it’s mapped at the default SharedBaseAddress (e.g. 0x800000000).

// If the archive ends up being mapped at a different address (e.g. 0x810000000), SharedDataRelocator

// is used to shift each marked pointer by a delta (0x10000000 in this example), so that it points to

// the actually mapped location of the target object.

template <bool COMPACTING>

class SharedDataRelocator: public BitMapClosure {

  // for all (address** p), where (is_marked(p) && _patch_base <= p && p < _patch_end) { *p += delta; }

  // Patch all pointers within this region that are marked.

  address* _patch_base;

  address* _patch_end;

  // Before patching, all pointers must point to this region.

  address _valid_old_base;

  address _valid_old_end;

  // After patching, all pointers must point to this region.

  address _valid_new_base;

  address _valid_new_end;

  // How much to relocate for each pointer.

  intx _delta;

  // The following fields are used only when COMPACTING == true;

  // The highest offset (inclusive) in the bitmap that contains a non-null pointer.

  // This is used at dump time to reduce the size of the bitmap (which may have been over-allocated).

  size_t _max_non_null_offset;

  CHeapBitMap* _ptrmap;

 public:

  SharedDataRelocator(address* patch_base, address* patch_end,

                      address valid_old_base, address valid_old_end,

                      address valid_new_base, address valid_new_end, intx delta,

                      CHeapBitMap* ptrmap = NULL) :

    _patch_base(patch_base), _patch_end(patch_end),

    _valid_old_base(valid_old_base), _valid_old_end(valid_old_end),

    _valid_new_base(valid_new_base), _valid_new_end(valid_new_end),

    _delta(delta) {

    log_debug(cds, reloc)("SharedDataRelocator::_patch_base     = " PTR_FORMAT, p2i(_patch_base));

    log_debug(cds, reloc)("SharedDataRelocator::_patch_end      = " PTR_FORMAT, p2i(_patch_end));

    log_debug(cds, reloc)("SharedDataRelocator::_valid_old_base = " PTR_FORMAT, p2i(_valid_old_base));

    log_debug(cds, reloc)("SharedDataRelocator::_valid_old_end  = " PTR_FORMAT, p2i(_valid_old_end));

    log_debug(cds, reloc)("SharedDataRelocator::_valid_new_base = " PTR_FORMAT, p2i(_valid_new_base));

    log_debug(cds, reloc)("SharedDataRelocator::_valid_new_end  = " PTR_FORMAT, p2i(_valid_new_end));

    if (COMPACTING) {

      assert(ptrmap != NULL, "must be");

      _max_non_null_offset = 0;

      _ptrmap = ptrmap;

    } else {

      // Don't touch the _max_non_null_offset and _ptrmap fields. Hopefully a good C++ compiler can

      // elide them.

      assert(ptrmap == NULL, "must be");

    }

  }

  size_t max_non_null_offset() {

    assert(COMPACTING, "must be");

    return _max_non_null_offset;

  }

  inline bool do_bit(size_t offset);

};

#endif // SHARE_MEMORY_ARCHIVEUTILS_HPP