1 /*
   2  * Copyright (c) 2018, 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
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  24 
  25 #ifndef SHARE_MEMORY_METASPACE_METASPACEGC_HPP
  26 #define SHARE_MEMORY_METASPACE_METASPACEGC_HPP
  27 
  28 #include "memory/allocation.hpp"
  29 #include "utilities/globalDefinitions.hpp"
  30 
  31 namespace metaspace {
  32 
  33 // Metaspace are deallocated when their class loader are GC'ed.
  34 // This class implements a policy for inducing GC's to recover
  35 // Metaspaces.
  36 
  37 class MetaspaceGC : public AllStatic {
  38 
  39   // The current high-water-mark for inducing a GC.
  40   // When committed memory of all metaspaces reaches this value,
  41   // a GC is induced and the value is increased. Size is in bytes.
  42   static volatile size_t _capacity_until_GC;
  43 
  44   // For a CMS collection, signal that a concurrent collection should
  45   // be started.
  46   static bool _should_concurrent_collect;
  47 
  48   static uint _shrink_factor;
  49 
  50   static size_t shrink_factor() { return _shrink_factor; }
  51   void set_shrink_factor(uint v) { _shrink_factor = v; }
  52 
  53  public:
  54 
  55   static void initialize();
  56   static void post_initialize();
  57 
  58   static size_t capacity_until_GC();
  59   static bool inc_capacity_until_GC(size_t v,
  60                                     size_t* new_cap_until_GC = NULL,
  61                                     size_t* old_cap_until_GC = NULL,
  62                                     bool* can_retry = NULL);
  63   static size_t dec_capacity_until_GC(size_t v);
  64 
  65   static bool should_concurrent_collect() { return _should_concurrent_collect; }
  66   static void set_should_concurrent_collect(bool v) {
  67     _should_concurrent_collect = v;
  68   }
  69 
  70   // The amount to increase the high-water-mark (_capacity_until_GC)
  71   static size_t delta_capacity_until_GC(size_t bytes);
  72 
  73   // Tells if we have can expand metaspace without hitting set limits.
  74   static bool can_expand(size_t words, bool is_class);
  75 
  76   // Returns amount that we can expand without hitting a GC,
  77   // measured in words.
  78   static size_t allowed_expansion();
  79 
  80   // Calculate the new high-water mark at which to induce
  81   // a GC.
  82   static void compute_new_size();
  83 };
  84 
  85 } // namespace metaspace
  86 
  87 #endif // SHARE_MEMORY_METASPACE_METASPACEGC_HPP