1 /*

     2  * Copyright (c) 2014, 2016, 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_G1_G1CODECACHEREMSET_HPP

    26 #define SHARE_VM_GC_G1_G1CODECACHEREMSET_HPP

    27 

    28 #include "memory/allocation.hpp"

    29 

    30 class CodeBlobClosure;

    31 class G1CodeRootSetTable;

    32 class HeapRegion;

    33 class nmethod;

    34 

    35 // Implements storage for a set of code roots.

    36 // All methods that modify the set are not thread-safe except if otherwise noted.

    37 class G1CodeRootSet VALUE_OBJ_CLASS_SPEC {

    38   friend class G1CodeRootSetTest;

    39  private:

    40 

    41   const static size_t SmallSize = 32;

    42   const static size_t Threshold = 24;

    43   const static size_t LargeSize = 512;

    44 

    45   G1CodeRootSetTable* _table;

    46   G1CodeRootSetTable* load_acquire_table();

    47 

    48   size_t _length;

    49 

    50   void move_to_large();

    51   void allocate_small_table();

    52 

    53  public:

    54   G1CodeRootSet() : _table(NULL), _length(0) {}

    55   ~G1CodeRootSet();

    56 

    57   static void purge();

    58 

    59   static size_t static_mem_size();

    60 

    61   void add(nmethod* method);

    62 

    63   bool remove(nmethod* method);

    64 

    65   // Safe to call without synchronization, but may return false negatives.

    66   bool contains(nmethod* method);

    67 

    68   void clear();

    69 

    70   void nmethods_do(CodeBlobClosure* blk) const;

    71 

    72   // Remove all nmethods which no longer contain pointers into our "owner" region

    73   void clean(HeapRegion* owner);

    74 

    75   bool is_empty() {

    76     bool empty = length() == 0;

    77     assert(empty == (_table == NULL), "is empty only if table is deallocated");

    78     return empty;

    79   }

    80 

    81   // Length in elements

    82   size_t length() const { return _length; }

    83 

    84   // Memory size in bytes taken by this set.

    85   size_t mem_size();

    86 

    87 };

    88 

    89 #endif // SHARE_VM_GC_G1_G1CODECACHEREMSET_HPP