1 /*
   2  * Copyright (c) 2017, 2018, 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 #include "precompiled.hpp"
  26 #include "jfr/leakprofiler/sampling/objectSample.hpp"
  27 #include "jfr/leakprofiler/sampling/sampleList.hpp"
  28 #include "oops/oop.inline.hpp"
  29 
  30 SampleList::SampleList(size_t limit, size_t cache_size) :
  31   _free_list(),
  32   _in_use_list(),
  33   _last_resolved(NULL),
  34   _limit(limit),
  35   _cache_size(cache_size),
  36   _allocated(0) {
  37 }
  38 
  39 SampleList::~SampleList() {
  40   deallocate_samples(_free_list);
  41   deallocate_samples(_in_use_list);
  42 }
  43 
  44 ObjectSample* SampleList::last() const {
  45   return _in_use_list.head();
  46 }
  47 
  48 ObjectSample* SampleList::first() const {
  49   return _in_use_list.tail();
  50 }
  51 
  52 const ObjectSample* SampleList::last_resolved() const {
  53   return _last_resolved;
  54 }
  55 
  56 void SampleList::set_last_resolved(const ObjectSample* sample) {
  57   assert(last() == sample, "invariant");
  58   _last_resolved = sample;
  59 }
  60 
  61 void SampleList::link(ObjectSample* sample) {
  62   assert(sample != NULL, "invariant");
  63   _in_use_list.prepend(sample);
  64 }
  65 
  66 void SampleList::unlink(ObjectSample* sample) {
  67   assert(sample != NULL, "invariant");
  68   if (_last_resolved == sample) {
  69     _last_resolved = sample->next();
  70   }
  71   reset(_in_use_list.remove(sample));
  72 }
  73 
  74 ObjectSample* SampleList::reuse(ObjectSample* sample) {
  75   assert(sample != NULL, "invariant");
  76   unlink(sample);
  77   link(sample);
  78   return sample;
  79 }
  80 
  81 void SampleList::populate_cache() {
  82   if (_free_list.count() < _cache_size) {
  83     const size_t cache_delta = _cache_size - _free_list.count();
  84     for (size_t i = 0; i < cache_delta; ++i) {
  85       ObjectSample* sample = newSample();
  86       if (sample != NULL) {
  87         _free_list.append(sample);
  88       }
  89     }
  90   }
  91 }
  92 
  93 ObjectSample* SampleList::newSample() const {
  94   if (_limit == _allocated) {
  95     return NULL;
  96   }
  97   ++_allocated;
  98   return new ObjectSample();
  99 }
 100 
 101 ObjectSample* SampleList::get() {
 102   ObjectSample* sample = _free_list.head();
 103   if (sample != NULL) {
 104     link(_free_list.remove(sample));
 105   } else {
 106     sample = newSample();
 107     if (sample != NULL) {
 108       _in_use_list.prepend(sample);
 109     }
 110   }
 111   if (_cache_size > 0 && sample != NULL) {
 112     populate_cache();
 113   }
 114   return sample;
 115 }
 116 
 117 void SampleList::release(ObjectSample* sample) {
 118   assert(sample != NULL, "invariant");
 119   unlink(sample);
 120   _free_list.append(sample);
 121 }
 122 
 123 void SampleList::deallocate_samples(List& list) {
 124   if (list.count() > 0) {
 125     ObjectSample* sample = list.head();
 126     while (sample != NULL) {
 127       list.remove(sample);
 128       delete sample;
 129       sample = list.head();
 130     }
 131   }
 132   assert(list.count() == 0, "invariant");
 133 }
 134 
 135 void SampleList::reset(ObjectSample* sample) {
 136   assert(sample != NULL, "invariant");
 137   sample->reset();
 138 }
 139 
 140 bool SampleList::is_full() const {
 141   return _in_use_list.count() == _limit;
 142 }
 143 
 144 size_t SampleList::count() const {
 145   return _in_use_list.count();
 146 }