used_chunk_list.hpp🔗

Namespaces🔗

Name
iox
iox::popo

Classes🔗

Name

class

iox::popo::UsedChunkList
This class is used to keep track of the chunks currently in use by the application. In case the application terminates while holding chunks, this list is used by RouDi to retain ownership of the chunks and prevent a chunk leak. In order to always be able to access the used chunks, neither a vector or list can be used, because these container could be corrupted when the application dies in the wrong moment. To be able to do the cleanup, RouDi needs to be able to access the list with the used chunk under all circumstances. This is achieved by storing the ChunkManagement pointer in an array which can always be accessed. Additionally, the type stored is this array must be less or equal to 64 bit in order to write it within one clock cycle to prevent torn writes, which would corrupt the list and could potentially crash RouDi.

Source code🔗

// Copyright (c) 2019 by Robert Bosch GmbH. All rights reserved.
// Copyright (c) 2021 by Apex.AI Inc. All rights reserved.
//
// 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.
//
// SPDX-License-Identifier: Apache-2.0
#ifndef IOX_POSH_POPO_USED_CHUNK_LIST_HPP
#define IOX_POSH_POPO_USED_CHUNK_LIST_HPP

#include "iceoryx_posh/internal/mepoo/shared_chunk.hpp"
#include "iceoryx_posh/internal/mepoo/shm_safe_unmanaged_chunk.hpp"
#include "iceoryx_posh/mepoo/chunk_header.hpp"

#include <atomic>
#include <cstdint>

namespace iox
{
namespace popo
{
template <uint32_t Capacity>
class UsedChunkList
{
    static_assert(Capacity > 0, "UsedChunkList Capacity must be larger than 0!");

  public:
    UsedChunkList() noexcept;

    bool insert(mepoo::SharedChunk chunk) noexcept;

    bool remove(const mepoo::ChunkHeader* chunkHeader, mepoo::SharedChunk& chunk) noexcept;

    void cleanup() noexcept;

  private:
    void init() noexcept;

  private:
    static constexpr uint32_t INVALID_INDEX{Capacity};

    using DataElement_t = mepoo::ShmSafeUnmanagedChunk;
    static constexpr DataElement_t DATA_ELEMENT_LOGICAL_NULLPTR{};

  private:
    std::atomic_flag m_synchronizer = ATOMIC_FLAG_INIT;
    uint32_t m_usedListHead{INVALID_INDEX};
    uint32_t m_freeListHead{0u};
    uint32_t m_listIndices[Capacity];
    DataElement_t m_listData[Capacity];
};

} // namespace popo
} // namespace iox

#include "used_chunk_list.inl"

#endif // IOX_POSH_POPO_USED_CHUNK_LIST_HPP

Updated on 31 May 2022 at 15:29:16 CEST