Danny Robson
0e3fa05f05
ipp files weren't a great way of keeping things clean, and IDEs have a little trouble dealing with the split configuration. this simplifies debugging a great deal.
137 lines
4.0 KiB
C++
137 lines
4.0 KiB
C++
/*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* Copyright 2011-2016 Danny Robson <danny@nerdcruft.net>
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*/
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#ifndef CRUFT_UTIL_POOL_HPP
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#define CRUFT_UTIL_POOL_HPP
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#include "nocopy.hpp"
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#include "debug.hpp"
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#include <cstdlib>
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#include <cstdint>
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namespace util {
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/// a simple pre-allocated pool for storage of PODs.
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///
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/// non-POD types can be stored, but there are no guarantees for calling
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/// item destructors at pool destruction time.
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template <typename T>
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class pool : public nocopy {
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protected:
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union alignas (T) node {
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node *_node;
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char _data[sizeof (T)];
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};
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node *m_head; // root address of allocation
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node *m_next; // next available entry in the linked list
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const size_t m_capacity;
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size_t m_size;
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public:
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explicit
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pool (unsigned int _capacity):
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m_capacity (_capacity),
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m_size (0u)
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{
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static_assert (sizeof (T) >= sizeof (uintptr_t),
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"pool<T>'s chained block system requires that T be at least pointer sized");
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// allocate the memory and note the base address for deletion in destructor
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m_next = m_head = new node[m_capacity]; // static_cast<node *> (operator new (sizeof (T) * m_capacity));
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// initialise the linked list of nodes
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for (unsigned int i = 0; i < m_capacity - 1; ++i)
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m_next[i]._node = m_next + i + 1;
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m_next[m_capacity - 1]._node = nullptr;
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}
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~pool ()
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{
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// don't check if everything's been returned as pools are often used
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// for PODs which don't need to be destructed via calling release.
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delete [] m_head;
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}
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// Data management
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template <typename ...Args>
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T* acquire (Args&... args)
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{
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// double check we have enough capacity left
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if (!m_next)
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throw std::bad_alloc ();
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CHECK_LT (m_size, m_capacity);
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// save what will become the next node shortly. it could be overwritten
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// in the constructor we're about to call.
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node *newnext = m_next->_node;
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T *data = reinterpret_cast<T*> (m_next);
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// try to construct the returnable object.
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try {
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new (data) T (args...);
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} catch (...) {
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// the constructor may have overwritten the node linkages before
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// throwing. fix this up before forwarding the exception.
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m_next->_node = newnext;
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throw;
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}
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// the object is valid. save the new linked list head and bump the
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// stats for availability.
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m_next = newnext;
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m_size++;
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return data;
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}
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void release (T *data)
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{
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CHECK_NEZ (m_size);
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data->~T();
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node *newnode = reinterpret_cast<node *> (data);
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newnode->_node = m_next;
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m_next = newnode;
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m_size--;
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}
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size_t capacity (void) const
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{
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return m_capacity;
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}
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size_t size (void) const
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{
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return m_size;
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}
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bool empty (void) const
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{
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return m_size == m_capacity;
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}
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// Indexing
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size_t index (const T*) const;
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T& operator[] (size_t idx) &;
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const T& operator[] (size_t idx) const&;
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};
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}
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#endif
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