1 /*

     2  * Copyright (c) 2014, 2015, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    20  * or visit www.oracle.com if you need additional information or have any

    21  * questions.

    22  *

    23  */

    24 

    25 #ifndef SHARE_VM_GC_SHARED_CARDGENERATION_HPP

    26 #define SHARE_VM_GC_SHARED_CARDGENERATION_HPP

    27 

    28 // Class CardGeneration is a generation that is covered by a card table,

    29 // and uses a card-size block-offset array to implement block_start.

    30 

    31 #include "gc/shared/generation.hpp"

    32 

    33 class BlockOffsetSharedArray;

    34 class CompactibleSpace;

    35 

    36 class CardGeneration: public Generation {

    37   friend class VMStructs;

    38  protected:

    39   // This is shared with other generations.

    40   CardTableRS* _rs;

    41   // This is local to this generation.

    42   BlockOffsetSharedArray* _bts;

    43 

    44   // Current shrinking effect: this damps shrinking when the heap gets empty.

    45   size_t _shrink_factor;

    46 

    47   size_t _min_heap_delta_bytes;   // Minimum amount to expand.

    48 

    49   // Some statistics from before gc started.

    50   // These are gathered in the gc_prologue (and should_collect)

    51   // to control growing/shrinking policy in spite of promotions.

    52   size_t _capacity_at_prologue;

    53   size_t _used_at_prologue;

    54 

    55   CardGeneration(ReservedSpace rs, size_t initial_byte_size, CardTableRS* remset);

    56 

    57   virtual void assert_correct_size_change_locking() = 0;

    58 

    59   virtual CompactibleSpace* space() const = 0;

    60 

    61  public:

    62 

    63   // Attempt to expand the generation by "bytes".  Expand by at a

    64   // minimum "expand_bytes".  Return true if some amount (not

    65   // necessarily the full "bytes") was done.

    66   virtual bool expand(size_t bytes, size_t expand_bytes);

    67 

    68   // Shrink generation with specified size

    69   virtual void shrink(size_t bytes);

    70 

    71   virtual void compute_new_size();

    72 

    73   virtual void clear_remembered_set();

    74 

    75   virtual void invalidate_remembered_set();

    76 

    77   virtual void prepare_for_verify();

    78 

    79   // Grow generation with specified size (returns false if unable to grow)

    80   bool grow_by(size_t bytes);

    81   // Grow generation to reserved size.

    82   bool grow_to_reserved();

    83 

    84   size_t capacity() const;

    85   size_t used() const;

    86   size_t free() const;

    87   MemRegion used_region() const;

    88 

    89   void space_iterate(SpaceClosure* blk, bool usedOnly = false);

    90 

    91   void younger_refs_iterate(OopsInGenClosure* blk, uint n_threads);

    92 

    93   bool is_in(const void* p) const;

    94 

    95   CompactibleSpace* first_compaction_space() const;

    96 };

    97 

    98 #endif // SHARE_VM_GC_SHARED_CARDGENERATION_HPP