/*

 * Copyright 2009 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 *

 */

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");

}

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>

Stack<E>::Stack(size_t segment_size, size_t max_cache_size, size_t max_size):

  StackBase(adjust_segment_size(segment_size), max_cache_size, max_size)

{

  reset(true);

}

template <class E>

void Stack<E>::push(E item)

{

  assert(!is_full(), "pushing onto a full stack");

  if (_cur_seg_size == _seg_size) {

    push_segment();

  }

  _cur_seg[_cur_seg_size] = item;

  ++_cur_seg_size;

}

template <class E>

E Stack<E>::pop()

{

  assert(!is_empty(), "popping from an empty stack");

  if (_cur_seg_size == 1) {

    E tmp = _cur_seg[--_cur_seg_size];

    pop_segment();

    return tmp;

  }

  return _cur_seg[--_cur_seg_size];

}

template <class E>

void Stack<E>::clear(bool clear_cache)

{

  free_segments(_cur_seg);

  if (clear_cache) free_segments(_cache);

  reset(clear_cache);

}

template <class E>

size_t Stack<E>::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>

size_t Stack<E>::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>

size_t Stack<E>::link_offset() const

{

  return align_size_up(_seg_size * sizeof(E), sizeof(E*));

}

template <class E>

size_t Stack<E>::segment_bytes() const

{

  return link_offset() + sizeof(E*);

}

template <class E>

E** Stack<E>::link_addr(E* seg) const

{

  return (E**) ((char*)seg + link_offset());

}

template <class E>

E* Stack<E>::get_link(E* seg) const

{

  return *link_addr(seg);

}

template <class E>

E* Stack<E>::set_link(E* new_seg, E* old_seg)

{

  *link_addr(new_seg) = old_seg;

  return new_seg;

}

template <class E>

E* Stack<E>::alloc(size_t bytes)

{

  return (E*) NEW_C_HEAP_ARRAY(char, bytes);

}

template <class E>

void Stack<E>::free(E* addr, size_t bytes)

{

  FREE_C_HEAP_ARRAY(char, (char*) addr);

}

template <class E>

void Stack<E>::push_segment()

{

  assert(_cur_seg_size == _seg_size, "current segment is not full");

  E* next;

  if (_cache_size > 0) {

    // Use a cached segment.

    next = _cache;

    _cache = get_link(_cache);

    --_cache_size;

  } else {

    next = alloc(segment_bytes());

    DEBUG_ONLY(zap_segment(next, true);)

  }

  const bool at_empty_transition = is_empty();

  _cur_seg = set_link(next, _cur_seg);

  _cur_seg_size = 0;

  _full_seg_size += at_empty_transition ? 0 : _seg_size;

  DEBUG_ONLY(verify(at_empty_transition);)

}

template <class E>

void Stack<E>::pop_segment()

{

  assert(_cur_seg_size == 0, "current segment is not empty");

  E* const prev = get_link(_cur_seg);

  if (_cache_size < _max_cache_size) {

    // Add the current segment to the cache.

    DEBUG_ONLY(zap_segment(_cur_seg, false);)

    _cache = set_link(_cur_seg, _cache);

    ++_cache_size;

  } else {

    DEBUG_ONLY(zap_segment(_cur_seg, true);)

    free(_cur_seg, segment_bytes());

  }

  const bool at_empty_transition = prev == NULL;

  _cur_seg = prev;

  _cur_seg_size = _seg_size;

  _full_seg_size -= at_empty_transition ? 0 : _seg_size;

  DEBUG_ONLY(verify(at_empty_transition);)

}

template <class E>

void Stack<E>::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>

void Stack<E>::reset(bool reset_cache)

{

  _cur_seg_size = _seg_size; // So push() will alloc a new segment.

  _full_seg_size = 0;

  _cur_seg = NULL;

  if (reset_cache) {

    _cache_size = 0;

    _cache = NULL;

  }

}

#ifdef ASSERT

template <class E>

void Stack<E>::verify(bool at_empty_transition) const

{

  assert(size() <= max_size(), "stack exceeded bounds");

  assert(cache_size() <= max_cache_size(), "cache exceeded bounds");

  assert(_cur_seg_size <= segment_size(), "segment index exceeded bounds");

  assert(_full_seg_size % _seg_size == 0, "not a multiple");

  assert(at_empty_transition || is_empty() == (size() == 0), "mismatch");

  assert((_cache == NULL) == (cache_size() == 0), "mismatch");

  if (is_empty()) {

    assert(_cur_seg_size == segment_size(), "sanity");

  }

}

template <class E>

void Stack<E>::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>

E* ResourceStack<E>::alloc(size_t bytes)

{

  return (E*) resource_allocate_bytes(bytes);

}

template <class E>

void ResourceStack<E>::free(E* addr, size_t bytes)

{

  resource_free_bytes((char*) addr, bytes);

}

template <class E>

void StackIterator<E>::sync()

{

  _full_seg_size = _stack._full_seg_size;

  _cur_seg_size = _stack._cur_seg_size;

  _cur_seg = _stack._cur_seg;

}

template <class E>

E* StackIterator<E>::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;

}