libpandabase/mem/arena.h

/**
 * Copyright (c) 2021-2022 Huawei Device Co., Ltd.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef LIBPANDABASE_MEM_ARENA_H
#define LIBPANDABASE_MEM_ARENA_H

#include "mem.h"

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namespace panda {

constexpr size_t ARENA_DEFAULT_SIZE = SIZE_1M;
constexpr Alignment ARENA_DEFAULT_ALIGNMENT = DEFAULT_ALIGNMENT;

class Arena {
public:
    Arena(size_t buff_size, void *buff);
    virtual ~Arena();
    DEFAULT_MOVE_SEMANTIC(Arena);
    DEFAULT_COPY_SEMANTIC(Arena);

    /**
     * \brief Allocates memory with size \param size and aligned with \param alignment
     * @param size - size of the allocated memory
     * @param alignment - alignment of the allocated memory
     * @return pointer to the allocated memory on success, or nullptr on fail
     */
    void *Alloc(size_t size, Alignment alignment = ARENA_DEFAULT_ALIGNMENT);

    /**
     * \brief Links this Arena to the \param arena
     * @param arena - Arena which will be linked as next to the current
     */
    void LinkTo(Arena *arena);

    /**
     * \brief Clear link to the next arena
     */
    void ClearNextLink();

    /**
     * \brief Returns next linked Arena
     * @return next linked Arena or nullptr
     */
    Arena *GetNextArena() const;

    /**
     * @return Size of free area in the arena
     */
    size_t GetFreeSize() const;

    /**
     * @return Size of an occupied area in the arena
     */
    size_t GetOccupiedSize() const;

    /**
     * @return A pointer to the first byte not in the arena
     */
    void *GetArenaEnd() const;

    /**
     * @return A pointer to the first not allocated byte
     */
    void *GetAllocatedEnd() const;

    /**
     * @return A pointer to the first allocated byte
     */
    void *GetAllocatedStart() const;

    /**
     * @return A pointer to the raw memory inside arena
     */
    void *GetMem() const
    {
        return buff_;
    }

    void *GetTop() const
    {
        return curPos_;
    }

    size_t GetSize() const
    {
        return size_;
    }

    /**
     * \brief Check that \param mem is stored inside this Arena
     * @return true on success, or false on fail
     */
    bool InArena(const void *mem) const;

    /**
     * \brief Mark all memory after \param mem as free. Check that \param mem is stored inside this arena.
     */
    void Free(void *mem);

    /**
     * \brief Set occupied memory size to \param new_size.
     */
    void Resize(size_t new_size);

    /*
     * \brief empties arena
     */
    void Reset();

    /*
     * \brief Expand arena. The new memory must be located just after the current buffer.
     * @param extra_buff - pointer to the extra buffer located just after the current.
     * @param size - the size of the extra buffer
     */
    void ExpandArena(const void *extra_buff, size_t size);

protected:
    Arena(size_t buff_size, void *buff, Alignment start_alignment);
    /**
     * \brief Fast allocates memory with size \param size
     * @param size - size of the allocated memory, must be \param alignment aligned
     * @param alignment - alignment of the allocated memory, used only for debug
     * @return pointer to the allocated memory on success, or nullptr on fail
     */
    void *AlignedAlloc(size_t size, Alignment alignment);

    void *GetStartPos() const
    {
        return startPos_;
    }

private:
    Arena *next_ = nullptr;
    void *buff_ = nullptr;
    void *startPos_ = nullptr;
    void *curPos_ = nullptr;
    size_t size_ = 0;
};

template <Alignment AlignmentT>
class AlignedArena : public Arena {
public:
    AlignedArena(size_t buff_size, void *buff) : Arena(buff_size, buff, AlignmentT) {}

    ~AlignedArena() override = default;

    void *Alloc(size_t size)
    {
        return Arena::AlignedAlloc(size, AlignmentT);
    }

private:
    DEFAULT_MOVE_SEMANTIC(AlignedArena);
    DEFAULT_COPY_SEMANTIC(AlignedArena);
};

template <Alignment AlignmentT>
class DoubleLinkedAlignedArena : public AlignedArena<AlignmentT> {
public:
    DoubleLinkedAlignedArena(size_t buff_size, void *buff) : AlignedArena<AlignmentT>(buff_size, buff) {}

    /**
     * \brief Links this Arena to the next \param arena
     * @param arena - Arena which will be linked as next to the current
     */
    void LinkNext(DoubleLinkedAlignedArena *arena)
    {
        Arena::LinkTo(static_cast<Arena *>(arena));
    }

    /**
     * \brief Links this Arena to the prev \param arena
     * @param arena - Arena which will be linked as prev to the current
     */
    void LinkPrev(DoubleLinkedAlignedArena *arena)
    {
        ASSERT(prev_ == nullptr);
        prev_ = arena;
    }

    /**
     * \brief Returns next linked Arena
     * @return next linked Arena or nullptr
     */
    DoubleLinkedAlignedArena *GetNextArena() const
    {
        return static_cast<DoubleLinkedAlignedArena *>(Arena::GetNextArena());
    }

    /**
     * \brief Returns prev linked Arena
     * @return prev linked Arena or nullptr
     */
    DoubleLinkedAlignedArena *GetPrevArena() const
    {
        return prev_;
    }

    /**
     * \brief Clear link to the prev arena
     */
    void ClearPrevLink()
    {
        prev_ = nullptr;
    }

    ~DoubleLinkedAlignedArena() override = default;

    DEFAULT_MOVE_SEMANTIC(DoubleLinkedAlignedArena);
    DEFAULT_COPY_SEMANTIC(DoubleLinkedAlignedArena);

private:
    DoubleLinkedAlignedArena *prev_ = nullptr;
};

}  // namespace panda

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#endif  // LIBPANDABASE_MEM_ARENA_H