MemoryPool.h

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// Copyright Onix Solutions Limited [OnixS]. All rights reserved.
//
// This software owned by Onix Solutions Limited [OnixS] and is
// protected by copyright law and international copyright treaties.
//
// Access to and use of the software is governed by the terms of the applicable
// OnixS Software Services Agreement (the Agreement) and Customer end user license
// agreements granting a non-assignable, non-transferable and non-exclusive license
// to use the software for it's own data processing purposes under the terms defined
// in the Agreement.
//
// Except as otherwise granted within the terms of the Agreement, copying or
// reproduction of any part of this source code or associated reference material
// to any other location for further reproduction or redistribution, and any
// amendments to this copyright notice, are expressly prohibited.
//
// Any reproduction or redistribution for sale or hiring of the Software not in
// accordance with the terms of the Agreement is a violation of copyright law.
//
 
#pragma once
 
#if defined(ONIXS_CMEMDH_ENABLE_TRACING)
#  include <ostream>
#endif
 
#include <cstddef>
#include <new>
#include <type_traits>
#include <utility>
 
#include <OnixS/CME/MDH/Bootstrap.h>
#include <OnixS/CME/MDH/MemoryPoolSettings.h>
#include <OnixS/CME/MDH/Utils.h>
 
ONIXS_CMEMDH_NAMESPACE_BEGIN

namespace details {
    ONIXS_CMEMDH_EXPORTED ONIXS_CMEMDH_NORETURN ONIXS_CMEMDH_COLDPATH
    void throwMemoryPoolAllocatorSizeTooLarge();
}

class ONIXS_CMEMDH_EXPORTED MemoryPool
{
public:
    virtual void release() noexcept = 0;

    ONIXS_CMEMDH_NODISCARD
    virtual void* allocate(size_t size) = 0;

    virtual void deallocate(void* block) noexcept = 0;
 
#if defined(ONIXS_CMEMDH_ENABLE_TRACING)
    virtual void trace(std::ostream& stream) = 0;
#endif
 
protected:
    MemoryPool() noexcept = default;

    virtual ~MemoryPool() noexcept = default;
 
private:
    // Copies are disallowed.
    MemoryPool(const MemoryPool&) noexcept = default;
 
    // Assignment is disallowed.
    MemoryPool& operator=(const MemoryPool&) noexcept = default;
};

template <class Object>
class MemoryPoolAllocator
{
public:
    using value_type = Object;

    using pointer = Object*;

    using const_pointer = const Object*;

    using reference = Object&;

    using const_reference = const Object&;

    using size_type = std::size_t;

    using difference_type = std::ptrdiff_t;

    template <class Other>
    struct rebind
    {
        using other = MemoryPoolAllocator<Other>;
    };

    MemoryPoolAllocator() noexcept
        : pool_(nullptr)
    {
    }

    MemoryPoolAllocator(MemoryPool& memoryPool) noexcept
        : pool_(&memoryPool)
    {
    }

    MemoryPoolAllocator(const MemoryPoolAllocator& other) noexcept = default;

    template <class Other>
    MemoryPoolAllocator(const MemoryPoolAllocator<Other>& other) noexcept
        : pool_(other.pool_)
    {
    }

    ~MemoryPoolAllocator() noexcept = default;

    ONIXS_CMEMDH_NODISCARD
    MemoryPool& memoryPool() const noexcept
    {
        return *pool_;
    }

    ONIXS_CMEMDH_NODISCARD
    pointer address(reference obj) const noexcept
    {
        return &obj;
    }

    ONIXS_CMEMDH_NODISCARD
    const_pointer address(const_reference x) const noexcept
    {
        return &x;
    }

    ONIXS_CMEMDH_NODISCARD
    pointer allocate(size_type qty)
    {
        static_assert(
            alignof(value_type) <= alignof(std::max_align_t),
            "value_type must not require extended alignment"
        );
 
        assert(nullptr != pool_);
 
        if ONIXS_CMEMDH_UNLIKELY(qty > max_size())
            ::ONIXS_CMEMDH_NAMESPACE::details::throwMemoryPoolAllocatorSizeTooLarge();
 
        return static_cast<pointer>(pool_->allocate(qty * sizeof(value_type)));
    }

    void deallocate(pointer block, size_type qty) noexcept
    {
        Utils::unusedArgs(qty);
 
        assert(nullptr != pool_);
 
        pool_->deallocate(block);
    }

    template <class Item, class... Args>
    void construct(Item* block, Args&&... args)
    {
        ::new (static_cast<void*>(block)) Item(std::forward<Args>(args)...);
    }

    void destroy(pointer obj) noexcept
    {
        static_assert(
            std::is_nothrow_destructible<value_type>::value,
            "value_type must be nothrow-destructible"
        );
 
        obj->~value_type();
        Utils::unusedArgs(obj);
    }

    ONIXS_CMEMDH_NODISCARD
    size_type max_size() const noexcept
    {
        return static_cast<size_type>(-1) / sizeof(value_type);
    }

    MemoryPoolAllocator& operator=(const MemoryPoolAllocator& other) noexcept = default;

    template <class Other>
    MemoryPoolAllocator& operator=(const MemoryPoolAllocator<Other>& other) noexcept
    {
        pool_ = other.pool_;
 
        return *this;
    }
 
private:
    template <class> friend class MemoryPoolAllocator;
 
    template <class LeftObject, class RightObject>
    friend bool operator==(
        const MemoryPoolAllocator<LeftObject>& left, const MemoryPoolAllocator<RightObject>& right) noexcept;
 
    MemoryPool* pool_;
};

template <class Object, class OtherObject>
ONIXS_CMEMDH_NODISCARD
inline bool operator==(const MemoryPoolAllocator<Object>& left, const MemoryPoolAllocator<OtherObject>& right) noexcept
{
    return (left.pool_ == right.pool_);
}

template <class Object, class OtherObject>
ONIXS_CMEMDH_NODISCARD
inline bool operator!=(const MemoryPoolAllocator<Object>& left, const MemoryPoolAllocator<OtherObject>& right) noexcept
{
    return !(left == right);
}

ONIXS_CMEMDH_EXPORTED
ONIXS_CMEMDH_NODISCARD
MemoryPool* makeMemoryPool(const MemoryPoolSettings& settings);

inline ONIXS_CMEMDH_NODISCARD
MemoryPool* makeMemoryPool(size_t blockIncrease, size_t increaseQty, size_t chunkSize, size_t chunkScaling)
{
    return makeMemoryPool(MemoryPoolSettings(blockIncrease, increaseQty, chunkSize, chunkScaling));
}
 
ONIXS_CMEMDH_NAMESPACE_END