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 /*

  * Copyright (c) 2009, 2010, 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.

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  */

 #ifndef SHARE_VM_UTILITIES_STACK_INLINE_HPP

 #define SHARE_VM_UTILITIES_STACK_INLINE_HPP

 #include "utilities/stack.hpp"

 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;

 }

 #endif // SHARE_VM_UTILITIES_STACK_INLINE_HPP