1 /*
   2  * Copyright (c) 2014, 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_IMPLEMENTATION_G1_G1CODECACHEREMSET_HPP
  26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1CODECACHEREMSET_HPP
  27 
  28 #include "memory/allocation.hpp"
  29 
  30 class CodeBlobClosure;
  31 class CodeRootSetTable;
  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   CodeRootSetTable* _table;
  46   CodeRootSetTable* 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_IMPLEMENTATION_G1_G1CODECACHEREMSET_HPP