persistent_ptr.hpp

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/*
 * Copyright 2015-2019, Intel Corporation
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in
 *       the documentation and/or other materials provided with the
 *       distribution.
 *
 *     * Neither the name of the copyright holder nor the names of its
 *       contributors may be used to endorse or promote products derived
 *       from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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 */

#ifndef LIBPMEMOBJ_CPP_PERSISTENT_PTR_HPP
#define LIBPMEMOBJ_CPP_PERSISTENT_PTR_HPP

#include <cassert>
#include <limits>
#include <memory>
#include <ostream>

#include <libpmemobj++/detail/common.hpp>
#include <libpmemobj++/detail/persistent_ptr_base.hpp>
#include <libpmemobj++/detail/specialization.hpp>
#include <libpmemobj++/pool.hpp>
#include <libpmemobj/base.h>

namespace pmem
{

namespace obj
{

template <typename T>
class pool;

template <typename T>
class persistent_ptr;

/*
 * persistent_ptr void specialization.
 */
template <>
class persistent_ptr<void> : public detail::persistent_ptr_base<void> {
public:
    persistent_ptr() = default;
    using detail::persistent_ptr_base<void>::persistent_ptr_base;
    using detail::persistent_ptr_base<void>::operator=;
};

/*
 * persistent_ptr const void specialization.
 */
template <>
class persistent_ptr<const void>
    : public detail::persistent_ptr_base<const void> {
public:
    persistent_ptr() = default;
    using detail::persistent_ptr_base<const void>::persistent_ptr_base;
    using detail::persistent_ptr_base<const void>::operator=;
};

template <typename T>
class persistent_ptr : public detail::persistent_ptr_base<T> {
public:
    persistent_ptr() = default;
    using detail::persistent_ptr_base<T>::persistent_ptr_base;

    explicit persistent_ptr(persistent_ptr<void> const &rhs) noexcept
        : detail::persistent_ptr_base<T>(rhs.raw())
    {
    }

    explicit persistent_ptr(persistent_ptr<const void> const &rhs) noexcept
        : detail::persistent_ptr_base<T>(rhs.raw())
    {
    }

    operator persistent_ptr<void>() const noexcept
    {
        return this->get();
    }

    typename pmem::detail::sp_dereference<T>::type operator*() const
        noexcept
    {
        return *this->get();
    }

    typename pmem::detail::sp_member_access<T>::type operator->() const
        noexcept
    {
        return this->get();
    }

    template <typename = typename std::enable_if<!std::is_void<T>::value>>
    typename pmem::detail::sp_array_access<T>::type
    operator[](std::ptrdiff_t i) const noexcept
    {
        assert(i >= 0 &&
               (i < pmem::detail::sp_extent<T>::value ||
            pmem::detail::sp_extent<T>::value == 0) &&
               "persistent array index out of bounds");

        return this->get()[i];
    }

    inline persistent_ptr<T> &
    operator++()
    {
        detail::conditional_add_to_tx(this);
        this->oid.off += sizeof(T);

        return *this;
    }

    inline persistent_ptr<T>
    operator++(int)
    {
        PMEMoid noid = this->oid;
        ++(*this);

        return persistent_ptr<T>(noid);
    }

    inline persistent_ptr<T> &
    operator--()
    {
        detail::conditional_add_to_tx(this);
        this->oid.off -= sizeof(T);

        return *this;
    }

    inline persistent_ptr<T>
    operator--(int)
    {
        PMEMoid noid = this->oid;
        --(*this);

        return persistent_ptr<T>(noid);
    }

    inline persistent_ptr<T> &
    operator+=(std::ptrdiff_t s)
    {
        detail::conditional_add_to_tx(this);
        this->oid.off += static_cast<std::uint64_t>(s) * sizeof(T);

        return *this;
    }

    inline persistent_ptr<T> &
    operator-=(std::ptrdiff_t s)
    {
        detail::conditional_add_to_tx(this);
        this->oid.off -= static_cast<std::uint64_t>(s) * sizeof(T);

        return *this;
    }

    void
    persist(pool_base &pop)
    {
        pop.persist(this->get(), sizeof(T));
    }

    void
    persist(void)
    {
        pmemobjpool *pop = pmemobj_pool_by_oid(this->raw());

        if (pop == nullptr)
            throw pmem::pool_error(
                "Cannot get pool from persistent pointer");

        pmemobj_persist(pop, this->get(), sizeof(T));
    }

    void
    flush(pool_base &pop)
    {
        pop.flush(this->get(), sizeof(T));
    }

    void
    flush(void)
    {
        pmemobjpool *pop = pmemobj_pool_by_oid(this->raw());

        if (pop == nullptr)
            throw pmem::pool_error(
                "Cannot get pool from persistent pointer");

        pmemobj_flush(pop, this->get(), sizeof(T));
    }

    /*
     * Pointer traits related.
     */

    static persistent_ptr<T>
    pointer_to(T &ref)
    {
        return persistent_ptr<T>(std::addressof(ref), 0);
    }

    template <class U>
    using rebind = pmem::obj::persistent_ptr<U>;

    using persistency_type = p<T>;

    using bool_type = bool;

    /*
     * Random access iterator requirements (members)
     */

    using iterator_category = std::random_access_iterator_tag;

    using difference_type = std::ptrdiff_t;

    using value_type = T;

    using reference = T &;

    using pointer = persistent_ptr<T>;
};

template <class T>
inline void
swap(persistent_ptr<T> &a, persistent_ptr<T> &b)
{
    a.swap(b);
}

template <typename T, typename Y>
inline bool
operator==(persistent_ptr<T> const &lhs, persistent_ptr<Y> const &rhs) noexcept
{
    return OID_EQUALS(lhs.raw(), rhs.raw());
}

template <typename T, typename Y>
inline bool
operator!=(persistent_ptr<T> const &lhs, persistent_ptr<Y> const &rhs) noexcept
{
    return !(lhs == rhs);
}

template <typename T>
inline bool
operator==(persistent_ptr<T> const &lhs, std::nullptr_t) noexcept
{
    return lhs.get() == nullptr;
}

template <typename T>
inline bool
operator==(std::nullptr_t, persistent_ptr<T> const &lhs) noexcept
{
    return lhs.get() == nullptr;
}

template <typename T>
inline bool
operator!=(persistent_ptr<T> const &lhs, std::nullptr_t) noexcept
{
    return lhs.get() != nullptr;
}

template <typename T>
inline bool
operator!=(std::nullptr_t, persistent_ptr<T> const &lhs) noexcept
{
    return lhs.get() != nullptr;
}

template <typename T, typename Y>
inline bool
operator<(persistent_ptr<T> const &lhs, persistent_ptr<Y> const &rhs) noexcept
{
    if (lhs.raw().pool_uuid_lo == rhs.raw().pool_uuid_lo)
        return lhs.raw().off < rhs.raw().off;
    else
        return lhs.raw().pool_uuid_lo < rhs.raw().pool_uuid_lo;
}

template <typename T, typename Y>
inline bool
operator<=(persistent_ptr<T> const &lhs, persistent_ptr<Y> const &rhs) noexcept
{
    return !(rhs < lhs);
}

template <typename T, typename Y>
inline bool
operator>(persistent_ptr<T> const &lhs, persistent_ptr<Y> const &rhs) noexcept
{
    return (rhs < lhs);
}

template <typename T, typename Y>
inline bool
operator>=(persistent_ptr<T> const &lhs, persistent_ptr<Y> const &rhs) noexcept
{
    return !(lhs < rhs);
}

/* nullptr comparisons */

template <typename T>
inline bool
operator<(persistent_ptr<T> const &lhs, std::nullptr_t) noexcept
{
    return std::less<typename persistent_ptr<T>::element_type *>()(
        lhs.get(), nullptr);
}

template <typename T>
inline bool
operator<(std::nullptr_t, persistent_ptr<T> const &rhs) noexcept
{
    return std::less<typename persistent_ptr<T>::element_type *>()(
        nullptr, rhs.get());
}

template <typename T>
inline bool
operator<=(persistent_ptr<T> const &lhs, std::nullptr_t) noexcept
{
    return !(nullptr < lhs);
}

template <typename T>
inline bool
operator<=(std::nullptr_t, persistent_ptr<T> const &rhs) noexcept
{
    return !(rhs < nullptr);
}

template <typename T>
inline bool
operator>(persistent_ptr<T> const &lhs, std::nullptr_t) noexcept
{
    return nullptr < lhs;
}

template <typename T>
inline bool
operator>(std::nullptr_t, persistent_ptr<T> const &rhs) noexcept
{
    return rhs < nullptr;
}

template <typename T>
inline bool
operator>=(persistent_ptr<T> const &lhs, std::nullptr_t) noexcept
{
    return !(lhs < nullptr);
}

template <typename T>
inline bool
operator>=(std::nullptr_t, persistent_ptr<T> const &rhs) noexcept
{
    return !(nullptr < rhs);
}

template <typename T>
inline persistent_ptr<T>
operator+(persistent_ptr<T> const &lhs, std::ptrdiff_t s)
{
    PMEMoid noid;
    noid.pool_uuid_lo = lhs.raw().pool_uuid_lo;
    noid.off = lhs.raw().off + static_cast<std::uint64_t>(s) * sizeof(T);

    return persistent_ptr<T>(noid);
}

template <typename T>
inline persistent_ptr<T>
operator-(persistent_ptr<T> const &lhs, std::ptrdiff_t s)
{
    PMEMoid noid;
    noid.pool_uuid_lo = lhs.raw().pool_uuid_lo;
    noid.off = lhs.raw().off - static_cast<std::uint64_t>(s) * sizeof(T);

    return persistent_ptr<T>(noid);
}

template <typename T, typename Y,
      typename = typename std::enable_if<
          std::is_same<typename std::remove_cv<T>::type,
                   typename std::remove_cv<Y>::type>::value>>
inline ptrdiff_t
operator-(persistent_ptr<T> const &lhs, persistent_ptr<Y> const &rhs)
{
    assert(lhs.raw().pool_uuid_lo == rhs.raw().pool_uuid_lo);
    auto d = static_cast<std::ptrdiff_t>(lhs.raw().off - rhs.raw().off);

    return d / static_cast<std::ptrdiff_t>(sizeof(T));
}

template <typename T>
std::ostream &
operator<<(std::ostream &os, persistent_ptr<T> const &pptr)
{
    PMEMoid raw_oid = pptr.raw();
    os << std::hex << "0x" << raw_oid.pool_uuid_lo << ", 0x" << raw_oid.off
       << std::dec;
    return os;
}

} /* namespace obj */

} /* namespace pmem */

#endif /* LIBPMEMOBJ_CPP_PERSISTENT_PTR_HPP */