Java example source code file (freeChunk.cpp)

This example Java source code file (freeChunk.cpp) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

copy::fill_to_words, freechunk\:\:header_size, freechunk\:\:mangleallocated, freechunk\:\:print_on, freechunk\:\:verifylist, heapword, heapword\*, heapwordsize, minchunksize, need, next, null, prev, ptr_format

The freeChunk.cpp Java example source code

/*
 * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

#include "precompiled.hpp"
#include "gc_implementation/concurrentMarkSweep/freeChunk.hpp"
#include "memory/freeBlockDictionary.hpp"
#include "utilities/copy.hpp"

#ifndef PRODUCT

#define baadbabeHeapWord badHeapWordVal
#define deadbeefHeapWord 0xdeadbeef

size_t const FreeChunk::header_size() {
  return sizeof(FreeChunk)/HeapWordSize;
}

void FreeChunk::mangleAllocated(size_t size) {
  // mangle all but the header of a just-allocated block
  // of storage
  assert(size >= MinChunkSize, "smallest size of object");
  // we can't assert that _size == size because this may be an
  // allocation out of a linear allocation block
  assert(sizeof(FreeChunk) % HeapWordSize == 0,
         "shouldn't write beyond chunk");
  HeapWord* addr = (HeapWord*)this;
  size_t hdr = header_size();
  Copy::fill_to_words(addr + hdr, size - hdr, baadbabeHeapWord);
}

void FreeChunk::mangleFreed(size_t sz) {
  assert(baadbabeHeapWord != deadbeefHeapWord, "Need distinct patterns");
  // mangle all but the header of a just-freed block of storage
  // just prior to passing it to the storage dictionary
  assert(sz >= MinChunkSize, "smallest size of object");
  assert(sz == size(), "just checking");
  HeapWord* addr = (HeapWord*)this;
  size_t hdr = header_size();
  Copy::fill_to_words(addr + hdr, sz - hdr, deadbeefHeapWord);
}

void FreeChunk::verifyList() const {
  FreeChunk* nextFC = next();
  if (nextFC != NULL) {
    assert(this == nextFC->prev(), "broken chain");
    assert(size() == nextFC->size(), "wrong size");
    nextFC->verifyList();
  }
}
#endif

void FreeChunk::print_on(outputStream* st) {
  st->print_cr("Next: " PTR_FORMAT " Prev: " PTR_FORMAT " %s",
    next(), prev(), cantCoalesce() ? "[can't coalesce]" : "");
}