Java example source code file (stack.inline.hpp)

This example Java source code file (stack.inline.hpp) 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

assert, debug_only, free_c_heap_array, memflags, new_c_heap_array, null, resourcestack, share_vm_utilities_stack_inline_hpp, stack, stackbase, stackiterator, zapstacksegments

The stack.inline.hpp Java example source code

/*
 * Copyright (c) 2009, 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.
 *
 */

#ifndef SHARE_VM_UTILITIES_STACK_INLINE_HPP
#define SHARE_VM_UTILITIES_STACK_INLINE_HPP

#include "utilities/stack.hpp"

template <MEMFLAGS F> StackBase::StackBase(size_t segment_size, size_t max_cache_size,
                     size_t max_size):
  _seg_size(segment_size),
  _max_cache_size(max_cache_size),
  _max_size(adjust_max_size(max_size, segment_size))
{
  assert(_max_size % _seg_size == 0, "not a multiple");
}

template <MEMFLAGS F> size_t StackBase::adjust_max_size(size_t max_size, size_t seg_size)
{
  assert(seg_size > 0, "cannot be 0");
  assert(max_size >= seg_size || max_size == 0, "max_size too small");
  const size_t limit = max_uintx - (seg_size - 1);
  if (max_size == 0 || max_size > limit) {
    max_size = limit;
  }
  return (max_size + seg_size - 1) / seg_size * seg_size;
}

template <class E, MEMFLAGS F>
Stack<E, F>::Stack(size_t segment_size, size_t max_cache_size, size_t max_size):
  StackBase<F>(adjust_segment_size(segment_size), max_cache_size, max_size)
{
  reset(true);
}

template <class E, MEMFLAGS F>
void Stack<E, F>::push(E item)
{
  assert(!is_full(), "pushing onto a full stack");
  if (this->_cur_seg_size == this->_seg_size) {
    push_segment();
  }
  this->_cur_seg[this->_cur_seg_size] = item;
  ++this->_cur_seg_size;
}

template <class E, MEMFLAGS F>
E Stack<E, F>::pop()
{
  assert(!is_empty(), "popping from an empty stack");
  if (this->_cur_seg_size == 1) {
    E tmp = _cur_seg[--this->_cur_seg_size];
    pop_segment();
    return tmp;
  }
  return this->_cur_seg[--this->_cur_seg_size];
}

template <class E, MEMFLAGS F>
void Stack<E, F>::clear(bool clear_cache)
{
  free_segments(_cur_seg);
  if (clear_cache) free_segments(_cache);
  reset(clear_cache);
}

template <class E, MEMFLAGS F>
size_t Stack<E, F>::default_segment_size()
{
  // Number of elements that fit in 4K bytes minus the size of two pointers
  // (link field and malloc header).
  return (4096 - 2 * sizeof(E*)) / sizeof(E);
}

template <class E, MEMFLAGS F>
size_t Stack<E, F>::adjust_segment_size(size_t seg_size)
{
  const size_t elem_sz = sizeof(E);
  const size_t ptr_sz = sizeof(E*);
  assert(elem_sz % ptr_sz == 0 || ptr_sz % elem_sz == 0, "bad element size");
  if (elem_sz < ptr_sz) {
    return align_size_up(seg_size * elem_sz, ptr_sz) / elem_sz;
  }
  return seg_size;
}

template <class E, MEMFLAGS F>
size_t Stack<E, F>::link_offset() const
{
  return align_size_up(this->_seg_size * sizeof(E), sizeof(E*));
}

template <class E, MEMFLAGS F>
size_t Stack<E, F>::segment_bytes() const
{
  return link_offset() + sizeof(E*);
}

template <class E, MEMFLAGS F>
E** Stack<E, F>::link_addr(E* seg) const
{
  return (E**) ((char*)seg + link_offset());
}

template <class E, MEMFLAGS F>
E* Stack<E, F>::get_link(E* seg) const
{
  return *link_addr(seg);
}

template <class E, MEMFLAGS F>
E* Stack<E, F>::set_link(E* new_seg, E* old_seg)
{
  *link_addr(new_seg) = old_seg;
  return new_seg;
}

template <class E, MEMFLAGS F>
E* Stack<E, F>::alloc(size_t bytes)
{
  return (E*) NEW_C_HEAP_ARRAY(char, bytes, F);
}

template <class E, MEMFLAGS F>
void Stack<E, F>::free(E* addr, size_t bytes)
{
  FREE_C_HEAP_ARRAY(char, (char*) addr, F);
}

template <class E, MEMFLAGS F>
void Stack<E, F>::push_segment()
{
  assert(this->_cur_seg_size == this->_seg_size, "current segment is not full");
  E* next;
  if (this->_cache_size > 0) {
    // Use a cached segment.
    next = _cache;
    _cache = get_link(_cache);
    --this->_cache_size;
  } else {
    next = alloc(segment_bytes());
    DEBUG_ONLY(zap_segment(next, true);)
  }
  const bool at_empty_transition = is_empty();
  this->_cur_seg = set_link(next, _cur_seg);
  this->_cur_seg_size = 0;
  this->_full_seg_size += at_empty_transition ? 0 : this->_seg_size;
  DEBUG_ONLY(verify(at_empty_transition);)
}

template <class E, MEMFLAGS F>
void Stack<E, F>::pop_segment()
{
  assert(this->_cur_seg_size == 0, "current segment is not empty");
  E* const prev = get_link(_cur_seg);
  if (this->_cache_size < this->_max_cache_size) {
    // Add the current segment to the cache.
    DEBUG_ONLY(zap_segment(_cur_seg, false);)
    _cache = set_link(_cur_seg, _cache);
    ++this->_cache_size;
  } else {
    DEBUG_ONLY(zap_segment(_cur_seg, true);)
    free(_cur_seg, segment_bytes());
  }
  const bool at_empty_transition = prev == NULL;
  this->_cur_seg = prev;
  this->_cur_seg_size = this->_seg_size;
  this->_full_seg_size -= at_empty_transition ? 0 : this->_seg_size;
  DEBUG_ONLY(verify(at_empty_transition);)
}

template <class E, MEMFLAGS F>
void Stack<E, F>::free_segments(E* seg)
{
  const size_t bytes = segment_bytes();
  while (seg != NULL) {
    E* const prev = get_link(seg);
    free(seg, bytes);
    seg = prev;
  }
}

template <class E, MEMFLAGS F>
void Stack<E, F>::reset(bool reset_cache)
{
  this->_cur_seg_size = this->_seg_size; // So push() will alloc a new segment.
  this->_full_seg_size = 0;
  _cur_seg = NULL;
  if (reset_cache) {
    this->_cache_size = 0;
    _cache = NULL;
  }
}

#ifdef ASSERT
template <class E, MEMFLAGS F>
void Stack<E, F>::verify(bool at_empty_transition) const
{
  assert(size() <= this->max_size(), "stack exceeded bounds");
  assert(this->cache_size() <= this->max_cache_size(), "cache exceeded bounds");
  assert(this->_cur_seg_size <= this->segment_size(), "segment index exceeded bounds");

  assert(this->_full_seg_size % this->_seg_size == 0, "not a multiple");
  assert(at_empty_transition || is_empty() == (size() == 0), "mismatch");
  assert((_cache == NULL) == (this->cache_size() == 0), "mismatch");

  if (is_empty()) {
    assert(this->_cur_seg_size == this->segment_size(), "sanity");
  }
}

template <class E, MEMFLAGS F>
void Stack<E, F>::zap_segment(E* seg, bool zap_link_field) const
{
  if (!ZapStackSegments) return;
  const size_t zap_bytes = segment_bytes() - (zap_link_field ? 0 : sizeof(E*));
  uint32_t* cur = (uint32_t*)seg;
  const uint32_t* end = cur + zap_bytes / sizeof(uint32_t);
  while (cur < end) {
    *cur++ = 0xfadfaded;
  }
}
#endif

template <class E, MEMFLAGS F>
E* ResourceStack<E, F>::alloc(size_t bytes)
{
  return (E*) resource_allocate_bytes(bytes);
}

template <class E, MEMFLAGS F>
void ResourceStack<E, F>::free(E* addr, size_t bytes)
{
  resource_free_bytes((char*) addr, bytes);
}

template <class E, MEMFLAGS F>
void StackIterator<E, F>::sync()
{
  _full_seg_size = _stack._full_seg_size;
  _cur_seg_size = _stack._cur_seg_size;
  _cur_seg = _stack._cur_seg;
}

template <class E, MEMFLAGS F>
E* StackIterator<E, F>::next_addr()
{
  assert(!is_empty(), "no items left");
  if (_cur_seg_size == 1) {
    E* addr = _cur_seg;
    _cur_seg = _stack.get_link(_cur_seg);
    _cur_seg_size = _stack.segment_size();
    _full_seg_size -= _stack.segment_size();
    return addr;
  }
  return _cur_seg + --_cur_seg_size;
}

#endif // SHARE_VM_UTILITIES_STACK_INLINE_HPP