1 /*
   2  * Copyright (c) 2012, 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 #include "precompiled.hpp"
  26 #include "memory/allocation.hpp"
  27 #include "memory/metachunk.hpp"
  28 #include "utilities/copy.hpp"
  29 #include "utilities/debug.hpp"
  30 
  31 class VirtualSpaceNode;
  32 
  33 size_t Metachunk::object_alignment() {
  34   // Must align pointers and sizes to 8,
  35   // so that 64 bit types get correctly aligned.
  36   const size_t alignment = 8;
  37 
  38   // Make sure that the Klass alignment also agree.
  39   STATIC_ASSERT(alignment == (size_t)KlassAlignmentInBytes);
  40 
  41   return alignment;
  42 }
  43 
  44 size_t Metachunk::overhead() {
  45   return align_size_up(sizeof(Metachunk), object_alignment()) / BytesPerWord;
  46 }
  47 
  48 // Metachunk methods
  49 
  50 Metachunk::Metachunk(size_t word_size,
  51                      VirtualSpaceNode* container)
  52     : Metabase<Metachunk>(word_size),
  53     _top(NULL),
  54     _container(container)
  55 {
  56   _top = initial_top();
  57 #ifdef ASSERT
  58   set_is_tagged_free(false);
  59   mangle();
  60 #endif
  61 }
  62 
  63 MetaWord* Metachunk::allocate(size_t word_size) {
  64   MetaWord* result = NULL;
  65   // If available, bump the pointer to allocate.
  66   if (free_word_size() >= word_size) {
  67     result = _top;
  68     _top = _top + word_size;
  69   }
  70   return result;
  71 }
  72 
  73 // _bottom points to the start of the chunk including the overhead.
  74 size_t Metachunk::used_word_size() const {
  75   return pointer_delta(_top, bottom(), sizeof(MetaWord));
  76 }
  77 
  78 size_t Metachunk::free_word_size() const {
  79   return pointer_delta(end(), _top, sizeof(MetaWord));
  80 }
  81 
  82 void Metachunk::print_on(outputStream* st) const {
  83   st->print_cr("Metachunk:"
  84                " bottom " PTR_FORMAT " top " PTR_FORMAT
  85                " end " PTR_FORMAT " size " SIZE_FORMAT,
  86                p2i(bottom()), p2i(_top), p2i(end()), word_size());
  87   if (Verbose) {
  88     st->print_cr("    used " SIZE_FORMAT " free " SIZE_FORMAT,
  89                  used_word_size(), free_word_size());
  90   }
  91 }
  92 
  93 #ifndef PRODUCT
  94 void Metachunk::mangle(juint wordValue) {
  95   // Overwrite the payload of the chunk and not the links that
  96   // maintain list of chunks.
  97   HeapWord* start = (HeapWord*)initial_top();
  98   size_t size = word_size() - overhead();
  99   Copy::fill_to_words(start, size, wordValue);
 100 }
 101 #endif // PRODUCT
 102 
 103 void Metachunk::verify() {
 104 #ifdef ASSERT
 105   // Cannot walk through the blocks unless the blocks have
 106   // headers with sizes.
 107   assert(bottom() <= _top &&
 108          _top <= (MetaWord*)end(),
 109          "Chunk has been smashed");
 110 #endif
 111   return;
 112 }
 113 
 114 /////////////// Unit tests ///////////////
 115 
 116 #ifndef PRODUCT
 117 
 118 class TestMetachunk {
 119  public:
 120   static void test() {
 121     size_t size = 2 * 1024 * 1024;
 122     void* memory = malloc(size);
 123     assert(memory != NULL, "Failed to malloc 2MB");
 124 
 125     Metachunk* metachunk = ::new (memory) Metachunk(size / BytesPerWord, NULL);
 126 
 127     assert(metachunk->bottom() == (MetaWord*)metachunk, "assert");
 128     assert(metachunk->end() == (uintptr_t*)metachunk + metachunk->size(), "assert");
 129 
 130     // Check sizes
 131     assert(metachunk->size() == metachunk->word_size(), "assert");
 132     assert(metachunk->word_size() == pointer_delta(metachunk->end(), metachunk->bottom(),
 133         sizeof(MetaWord*)), "assert");
 134 
 135     // Check usage
 136     assert(metachunk->used_word_size() == metachunk->overhead(), "assert");
 137     assert(metachunk->free_word_size() == metachunk->word_size() - metachunk->used_word_size(), "assert");
 138     assert(metachunk->top() == metachunk->initial_top(), "assert");
 139     assert(metachunk->is_empty(), "assert");
 140 
 141     // Allocate
 142     size_t alloc_size = 64; // Words
 143     assert(is_size_aligned(alloc_size, Metachunk::object_alignment()), "assert");
 144 
 145     MetaWord* mem = metachunk->allocate(alloc_size);
 146 
 147     // Check post alloc
 148     assert(mem == metachunk->initial_top(), "assert");
 149     assert(mem + alloc_size == metachunk->top(), "assert");
 150     assert(metachunk->used_word_size() == metachunk->overhead() + alloc_size, "assert");
 151     assert(metachunk->free_word_size() == metachunk->word_size() - metachunk->used_word_size(), "assert");
 152     assert(!metachunk->is_empty(), "assert");
 153 
 154     // Clear chunk
 155     metachunk->reset_empty();
 156 
 157     // Check post clear
 158     assert(metachunk->used_word_size() == metachunk->overhead(), "assert");
 159     assert(metachunk->free_word_size() == metachunk->word_size() - metachunk->used_word_size(), "assert");
 160     assert(metachunk->top() == metachunk->initial_top(), "assert");
 161     assert(metachunk->is_empty(), "assert");
 162 
 163     free(memory);
 164   }
 165 };
 166 
 167 void TestMetachunk_test() {
 168   TestMetachunk::test();
 169 }
 170 
 171 #endif