1 /*
   2  * Copyright (c) 2019, 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_JFR_RECORDER_STORAGE_JFRMEMORYSPACERETRIEVAL_HPP
  26 #define SHARE_VM_JFR_RECORDER_STORAGE_JFRMEMORYSPACERETRIEVAL_HPP
  27 
  28 #include "memory/allocation.hpp"
  29 #include "jfr/recorder/storage/jfrBuffer.hpp"
  30 #include "jfr/recorder/repository/jfrChunkWriter.hpp"
  31 #include "jfr/utilities/jfrAllocation.hpp"
  32 #include "jfr/utilities/jfrTypes.hpp"
  33 
  34 /*
  35 * Some policy classes for getting mspace memory
  36 */
  37 
  38 template <typename Mspace>
  39 class JfrMspaceRetrieval : AllStatic {
  40  public:
  41   typedef typename Mspace::Type Type;
  42   static Type* get(size_t size, Mspace* mspace, typename Mspace::Iterator& iterator, Thread* thread) {
  43     while (iterator.has_next()) {
  44       Type* const t = iterator.next();
  45       if (t->retired()) continue;
  46       if (t->try_acquire(thread)) {
  47         assert(!t->retired(), "invariant");
  48         if (t->free_size() >= size) {
  49           return t;
  50         }
  51         t->set_retired();
  52         mspace->register_full(t, thread);
  53       }
  54     }
  55     return NULL;
  56   }
  57 };
  58 
  59 template <typename Mspace>
  60 class JfrMspaceAlternatingRetrieval {
  61  private:
  62    // provides stochastic distribution over "deque" endpoints; racy is ok here
  63   static bool _last_access;
  64  public:
  65   typedef typename Mspace::Type Type;
  66   static Type* get(size_t size, Mspace* mspace, Thread* thread) {
  67     typename Mspace::Iterator iterator(mspace->free(), (_last_access = !_last_access) ? forward : backward);
  68     return JfrMspaceRetrieval<Mspace>::get(size, mspace, iterator, thread);
  69   }
  70 };
  71 
  72 template <typename Mspace>
  73 bool JfrMspaceAlternatingRetrieval<Mspace>::_last_access = false;
  74 
  75 template <typename Mspace>
  76 class JfrMspaceSequentialRetrieval {
  77  public:
  78   typedef typename Mspace::Type Type;
  79   static Type* get(size_t size, Mspace* mspace, Thread* thread) {
  80     typename Mspace::Iterator iterator(mspace->free());
  81     return JfrMspaceRetrieval<Mspace>::get(size, mspace, iterator, thread);
  82   }
  83 };
  84 
  85 #endif // SHARE_VM_JFR_RECORDER_STORAGE_JFRMEMORYSPACERETRIEVAL_HPP