assimp/contrib/openddlparser/include/openddlparser/TPoolAllocator.h

/*-----------------------------------------------------------------------------------------------
The MIT License (MIT)

Copyright (c) 2014-2019 Kim Kulling

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-----------------------------------------------------------------------------------------------*/
#pragma once

#include <openddlparser/OpenDDLCommon.h>
#include <string>

BEGIN_ODDLPARSER_NS

//-------------------------------------------------------------------------------------------------
///	@class		TPoolAllocator
///	@ingroup	CPPCore
///
///	@brief  This class implements a simple pool-based allocation scheme.
/// Initially you have to define its size. Each allocation will be done from this initially created
/// pool. You have to release all pooled instances after the usage.
/// This allocation scheme is fast and does no call any new-calls during the lifetime of the
/// allocator.
//-------------------------------------------------------------------------------------------------
template <class T>
class TPoolAllocator {
public:
    TPoolAllocator();
    TPoolAllocator(size_t numItems);
    ~TPoolAllocator();
    T *alloc();
    void release();
    void reserve(size_t size);
    void clear();
    size_t capacity() const;
    size_t reservedMem() const;
    size_t freeMem() const;
    void dumpAllocations(std::string &allocs);
    void resize(size_t growSize);

    CPPCORE_NONE_COPYING(TPoolAllocator)

private:
    struct Pool {
        size_t m_poolsize;
        T *m_pool;
        size_t m_currentIdx;
        Pool *m_next;

        Pool() :
                m_poolsize(0u), m_pool(nullptr), m_currentIdx(0u), m_next(nullptr) {
            // empty
        }

        Pool(size_t numItems, Pool *prev) :
                m_poolsize(numItems), m_pool(nullptr), m_currentIdx(0u), m_next(prev) {
            m_pool = new T[m_poolsize];
        }

        ~Pool() {
            delete[] m_pool;
            m_pool = nullptr;
        }

        CPPCORE_NONE_COPYING(Pool)
    };

    Pool *getFreePool() {
        Pool *current(m_freeList);
        if (nullptr != m_freeList) {
            m_freeList = m_freeList->m_next;
        }
        return current;
    }

    Pool *m_first;
    Pool *m_current;
    Pool *m_freeList;
    size_t m_capacity;
};

template <class T>
inline TPoolAllocator<T>::TPoolAllocator() :
        m_first(nullptr), m_current(nullptr), m_freeList(nullptr), m_capacity(0L) {
    // empty
}

template <class T>
inline TPoolAllocator<T>::TPoolAllocator(size_t numItems) :
        m_first(nullptr), m_current(nullptr), m_freeList(nullptr), m_capacity(0L) {
    m_first = new Pool(numItems);
    m_capacity += numItems;
    m_current = m_first;
}

template <class T>
inline TPoolAllocator<T>::~TPoolAllocator() {
    clear();
}

template <class T>
inline T *TPoolAllocator<T>::alloc() {
    if (nullptr == m_current) {
        return nullptr;
    }

    if (m_current->m_currentIdx == m_current->m_poolsize) {
        resize(m_current->m_poolsize);
    }

    T *ptr(&m_current->m_pool[m_current->m_currentIdx]);
    m_current->m_currentIdx++;

    return ptr;
}

template <class T>
inline void TPoolAllocator<T>::release() {
    if (nullptr == m_current) {
        return;
    }

    Pool *current(m_first);
    while (nullptr != current) {
        current->m_currentIdx = 0;
        current = current->m_next;
    }
    m_freeList = m_first->m_next;
    m_current = m_first;
}

template <class T>
inline void TPoolAllocator<T>::reserve(size_t size) {
    clear();

    m_first = new Pool(size, nullptr);
    m_current = m_first;

    m_current->m_pool = new T[size];
    m_current->m_poolsize = size;

    m_capacity = size;
}

template <class T>
inline void TPoolAllocator<T>::clear() {
    if (nullptr == m_current) {
        return;
    }

    Pool *next(m_first);
    while (nullptr != next) {
        Pool *current = next;
        next = current->m_next;
        delete current;
    }
    m_current = nullptr;
    m_freeList = nullptr;
}

template <class T>
inline size_t TPoolAllocator<T>::capacity() const {
    return m_capacity;
}

template <class T>
inline size_t TPoolAllocator<T>::reservedMem() const {
    return m_capacity * sizeof(T);
}

template <class T>
inline size_t TPoolAllocator<T>::freeMem() const {
    if (nullptr == m_current) {
        return 0L;
    }

    return (m_current->m_poolsize - m_current->m_currentIdx);
}

template <class T>
inline void TPoolAllocator<T>::dumpAllocations(std::string &allocs) {
    allocs.clear();
    allocs += "Number allocations = ";
    allocs += std::to_string(m_current->m_currentIdx);
    allocs += "\n";
}

template <class T>
inline void TPoolAllocator<T>::resize(size_t growSize) {
    if (nullptr != m_current) {
        if (growSize < m_current->m_poolsize) {
            return;
        }
    }

    if (nullptr == m_first) {
        m_first = new Pool(growSize, nullptr);
        m_current = m_first;
        m_capacity += m_current->m_poolsize;
    } else {
        Pool *pool = getFreePool();
        if (nullptr == pool) {
            pool = new Pool(growSize, nullptr);
            m_capacity += growSize;
        }
        m_current->m_next = pool;
        m_current = m_current->m_next;
    }
}

END_ODDLPARSER_NS