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【iceoryx 零拷贝】 内存管理_roudi内存管理

作者：盐析白兔 | 2024-06-12 02:54:31

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roudi内存管理

iceoryx RouDi 内存管理 一

一、 RouDi进程的main

int main(int argc, char* argv[]) noexcept
{
    using iox::roudi::IceOryxRouDiApp;
    iox::config::CmdLineParserConfigFileOption cmdLineParser;
    auto cmdLineArgs = cmdLineParser.parse(argc, argv);
    iox::config::TomlRouDiConfigFileProvider configFileProvider(cmdLineArgs.value());
    auto roudiConfig = configFileProvider.parse();
    IceOryxRouDiApp roudi(cmdLineArgs.value(), roudiConfig.value());
    return roudi.run();
}

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1 解析传入的 xxx.toml 文件

iox::config::TomlRouDiConfigFileProvider configFileProvider(cmdLineArgs.value());

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2 IceOryxRouDiApp 的构造

传入的参数为 传入的 cfg 文件

IceOryxRouDiApp roudi(cmdLineArgs.value(), roudiConfig.value());

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构造函数里仅仅 又 构造了一个 RouDiApp

IceOryxRouDiApp::IceOryxRouDiApp(const config::CmdLineArgs_t& cmdLineArgs, const RouDiConfig_t& roudiConfig) noexcept
    : RouDiApp(cmdLineArgs, roudiConfig)

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3 RouDiApp 的构造

给一些主要成员赋值，设置Log等级。。。

m_logLevel(cmdLineArgs.logLevel)
m_config(config)

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4 看一下 roudi.run()

uint8_t IceOryxRouDiApp::run() noexcept
{
    if (m_run)
    {
        static cxx::optional<IceOryxRouDiComponents> m_rouDiComponents;  //<1>       
        auto componentsScopeGuard = cxx::makeScopedStatic(m_rouDiComponents, m_config); //<2>

        static cxx::optional<RouDi> roudi;
        auto roudiScopeGuard =
            cxx::makeScopedStatic(roudi,                                 //<3>
                                  m_rouDiComponents.value().rouDiMemoryManager,
                                  m_rouDiComponents.value().portManager,
                                  RouDi::RoudiStartupParameters{m_monitoringMode,
                                                                true,
                                                                RouDi::RuntimeMessagesThreadStart::IMMEDIATE,
                                                                m_compatibilityCheckLevel,
                                                                m_processKillDelay});
        waitForSignal();
    }
    return EXIT_SUCCESS;
}

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4.1 <1>构建了一个模板为 IceOryxRouDiComponents的optional对象：

template <typename T>
inline optional<T>::optional() noexcept
    : optional(nullopt_t())
{
}

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4.2 <2>处初始化 m_rouDiComponents ，调用了optional的emplace方法：

template <typename T, typename... CTorArgs>
inline GenericRAII makeScopedStatic(T& memory, CTorArgs&&... ctorArgs) noexcept
{
    memory.emplace(std::forward<CTorArgs>(ctorArgs)...);
    return GenericRAII([] {}, [&memory] { memory.reset(); });
}

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相当于开辟了一块sizeof ( IceOryxRouDiComponents )大小的空间，用 m_config 填充,将(void *)m_data指向这块空间，并将m_data强转为 IceOryxRouDiComponents * ，

inline void optional<T>::construct_value(Targs&&... args) noexcept
{
    new (static_cast<T*>(static_cast<void*>(m_data))) T(std::forward<Targs>(args)...);
    m_hasValue = true;
}


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此处会调用 IceOryxRouDiComponents 的构造，这个构造至关重要：

IceOryxRouDiComponents::IceOryxRouDiComponents(const RouDiConfig_t& roudiConfig) noexcept
    : rouDiMemoryManager(roudiConfig)
    , portManager([&]() -> IceOryxRouDiMemoryManager* {
        runtime::IpcInterfaceBase::cleanupOutdatedIpcChannel(roudi::IPC_CHANNEL_ROUDI_NAME);  //<1>
        rouDiMemoryManager.createAndAnnounceMemory().or_else([](RouDiMemoryManagerError error) { //<2>
            LogFatal() << "Could not create SharedMemory! Error: " << error;
            errorHandler(PoshError::ROUDI_COMPONENTS__SHARED_MEMORY_UNAVAILABLE, iox::ErrorLevel::FATAL);
        });
        return &rouDiMemoryManager;
    }())
{
}

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<1>处清理 过期的 IPC channel 。
<2>处创建内存池
先看一下 IceOryxRouDiMemoryManager 的构造

IceOryxRouDiMemoryManager::IceOryxRouDiMemoryManager(const RouDiConfig_t& roudiConfig) noexcept
    : m_defaultMemory(roudiConfig)
{
    m_defaultMemory.m_managementShm.addMemoryBlock(&m_portPoolBlock).or_else([](auto) {
        errorHandler(PoshError::ICEORYX_ROUDI_MEMORY_MANAGER__FAILED_TO_ADD_PORTPOOL_MEMORY_BLOCK, ErrorLevel::FATAL);
    });
    m_memoryManager.addMemoryProvider(&m_defaultMemory.m_managementShm).or_else([](auto) {  //<3>
        errorHandler(PoshError::ICEORYX_ROUDI_MEMORY_MANAGER__FAILED_TO_ADD_MANAGEMENT_MEMORY_BLOCK, ErrorLevel::FATAL);
    });
}

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初始化了成员 m_defaultMemory（DefaultRouDiMemory） ，很重要 ：

DefaultRouDiMemory::DefaultRouDiMemory(const RouDiConfig_t& roudiConfig) noexcept
    : m_introspectionMemPoolBlock(introspectionMemPoolConfig())
    , m_segmentManagerBlock(roudiConfig)
    , m_managementShm(SHM_NAME, posix::AccessMode::READ_WRITE, posix::OpenMode::PURGE_AND_CREATE) //<4>
{
    m_managementShm.addMemoryBlock(&m_introspectionMemPoolBlock).or_else([](auto) {   //<7>
        errorHandler(PoshError::ROUDI__DEFAULT_ROUDI_MEMORY_FAILED_TO_ADD_INTROSPECTION_MEMORY_BLOCK,
                     ErrorLevel::FATAL);
    });
    m_managementShm.addMemoryBlock(&m_segmentManagerBlock).or_else([](auto) {         //<8>
        errorHandler(PoshError::ROUDI__DEFAULT_ROUDI_MEMORY_FAILED_TO_ADD_SEGMENT_MANAGER_MEMORY_BLOCK,
                     ErrorLevel::FATAL);
    });
}

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主要看<4> m_defaultMemory.m_shmName 为 SHM_NAME “iceoryx_mgmt”，会在 /dev/shm/下看到。
<7>、<8>处 m_managementShm.m_memoryBlocks.push_back(memoryBlock )了两次，一块用来缓存Topic，一块是cfg.toml文件中的内存池配置。
<3>处将 m_managementShm push 进 IceOryxRouDiMemoryManager::m_memoryManager 。

cxx::expected<RouDiMemoryManagerError> IceOryxRouDiMemoryManager::createAndAnnounceMemory() noexcept
{
    auto result = m_memoryManager.createAndAnnounceMemory();
    auto portPool = m_portPoolBlock.portPool();
    if (!result.has_error() && portPool.has_value())
    {
        m_portPool.emplace(*portPool.value());
    }
    return result;
}

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调用：

cxx::expected<RouDiMemoryManagerError> RouDiMemoryManager::createAndAnnounceMemory() noexcept
{
    for (auto memoryProvider : m_memoryProvider)
    {
        auto result = memoryProvider->create(); //<5>
    }
    for (auto memoryProvider : m_memoryProvider)
    {
        memoryProvider->announceMemoryAvailable(); //<6>
    }
    return cxx::success<>();
}

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4.3 <5>处执行一次，因为<3>处仅 push了一个 MemoryProvider。执行 MemoryProvider::create()

    uint64_t totalSize = 0u;
    uint64_t maxAlignment = 1;
    for (auto memoryBlock : m_memoryBlocks)
    {
        auto alignment = memoryBlock->alignment();
        if (alignment > maxAlignment)
        {
            maxAlignment = alignment;
        }

        // just in case the memory block doesn't calculate its size as multiple of the alignment
        // this shouldn't be necessary, but also doesn't harm
        auto size = cxx::align(memoryBlock->size(), alignment);
        totalSize = cxx::align(totalSize, alignment) + size;
    }

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<7><8>处push了两块 memoryBlock ，这里全部取出，对齐(留出sizeof>8)，计算出 totalSize 。

auto memoryResult = createMemory(totalSize, maxAlignment);

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实际调用：

cxx::expected<void*, MemoryProviderError> PosixShmMemoryProvider::createMemory(const uint64_t size,
                                                                               const uint64_t alignment) noexcept
{
    if (!posix::SharedMemoryObjectBuilder()
             .name(m_shmName)
             .memorySizeInBytes(size)
             .accessMode(m_accessMode)
             .openMode(m_openMode)
             .permissions(SHM_MEMORY_PERMISSIONS)
             .create()
             .and_then([this](auto& sharedMemoryObject) {
                 sharedMemoryObject.finalizeAllocation();
                 m_shmObject.emplace(std::move(sharedMemoryObject));
             }))
    {
        return cxx::error<MemoryProviderError>(MemoryProviderError::MEMORY_CREATION_FAILED);
    }

    auto baseAddress = m_shmObject->getBaseAddress();
    return cxx::success<void*>(baseAddress);
}


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关键方法：

SharedMemoryObjectBuilder::create()

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依次调用：

    auto sharedMemory = SharedMemoryBuilder()
                            .name(m_name)
                            .accessMode(m_accessMode)
                            .openMode(m_openMode)
                            .filePermissions(m_permissions)
                            .size(m_memorySizeInBytes)
                            .create();

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实质是 shm_open(name, oflag, mode) 创建 /dev/shm/iceoryx_mgmt 设备，并返回 sharedMemoryFileHandle 句柄
然后：

    auto memoryMap = MemoryMapBuilder()
                         .baseAddressHint((m_baseAddressHint) ? *m_baseAddressHint : nullptr)
                         .length(m_memorySizeInBytes)
                         .fileDescriptor(sharedMemory->getHandle())
                         .accessMode(m_accessMode)
                         .flags(MemoryMapFlags::SHARE_CHANGES)
                         .offset(0)
                         .create();

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调用mmap(void* addr, size_t length, int prot, int flags, int fd, off_t offset) 将文件映射成一个虚拟地址，并返回一个MemoryMap实例，包含这块内存的baseAddress、length。

return cxx::success<MemoryMap>(MemoryMap(result.value().value, m_length));
MemoryMap::MemoryMap(void* const baseAddress, const uint64_t length) noexcept
    : m_baseAddress(baseAddress)
    , m_length(length)

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接下来构造一个 Allocator ，用于计算地址偏移：

 Allocator allocator(memoryMap->getBaseAddress(), m_memorySizeInBytes);

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返回：

return cxx::success<SharedMemoryObject>(
        SharedMemoryObject(std::move(*sharedMemory), std::move(*memoryMap), std::move(allocator), m_memorySizeInBytes));

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之后 获取每个 memoryBlock 的 m_memory

 iox::posix::Allocator allocator(m_memory, m_size);

    for (auto memoryBlock : m_memoryBlocks)
    {
        memoryBlock->m_memory = allocator.allocate(memoryBlock->size(), memoryBlock->alignment());
    }


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(void *)m_memory = m_startAddress + alignedPosition;
至此 <5> 讲完。

4.4 下面看<6>

void MemoryProvider::announceMemoryAvailable() noexcept
{
    if (!m_memoryAvailableAnnounced)
    {
        for (auto memoryBlock : m_memoryBlocks)
        {
            memoryBlock->onMemoryAvailable(memoryBlock->m_memory);
        }

        m_memoryAvailableAnnounced = true;
    }
}

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关注一下 MemPoolSegmentManagerMemoryBlock::onMemoryAvailable。即 m_defaultMemory ：

void MemPoolSegmentManagerMemoryBlock::onMemoryAvailable(cxx::not_null<void*> memory) noexcept
{
    posix::Allocator allocator(memory, size());
    auto segmentManager = allocator.allocate(sizeof(mepoo::SegmentManager<>), alignof(mepoo::SegmentManager<>));
    m_segmentManager = new (segmentManager) mepoo::SegmentManager<>(m_segmentConfig, &allocator);
}

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在这里实例化了一个 SegmentManager 类型的 m_segmentManager ，传入的 m_segmentConfig 即 xxx.toml里的配置，注意 这里的 allocator 的 m_currentPosition 向后偏移了 sizeof(mepoo::SegmentManager<>)

inline SegmentManager<SegmentType>::SegmentManager(const SegmentConfig& segmentConfig,
                                                   posix::Allocator* managementAllocator) noexcept
    : m_managementAllocator(managementAllocator)
{
    cxx::Expects(segmentConfig.m_sharedMemorySegments.capacity() <= m_segmentContainer.capacity());
    for (const auto& segmentEntry : segmentConfig.m_sharedMemorySegments) //<1>
    {
        createSegment(segmentEntry);
    }
}

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要说清楚 <1> 需要 看一下 解析cfg.toml的过程,在 roudi_config_toml_file_provider.cpp文件的 TomlRouDiConfigFileProvider::parse()：

[general]
version = 1

[[segment]]

[[segment.mempool]]
size = 128
count = 10000

[[segment.mempool]]
size = 1024
count = 5000

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for (auto segment : *segments)
{
  auto writer = segment->get_as<std::string>("writer").value_or(groupOfCurrentProcess);
  auto reader = segment->get_as<std::string>("reader").value_or(groupOfCurrentProcess);
  iox::mepoo::MePooConfig mempoolConfig;
  auto mempools = segment->get_table_array("mempool");
	for (auto mempool : *mempools)
	  {
	  	auto chunkSize = mempool->get_as<uint32_t>("size");
	      auto chunkCount = mempool->get_as<uint32_t>("count");
	      mempoolConfig.addMemPool({*chunkSize, *chunkCount}); // <2>            
	}
    parsedConfig.m_sharedMemorySegments.push_back(
          {iox::posix::PosixGroup::string_t(iox::cxx::TruncateToCapacity, reader),
           iox::posix::PosixGroup::string_t(iox::cxx::TruncateToCapacity, writer), mempoolConfig});             
}

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配置文件中只有一个 segment , 该 segment 有多个 mempool ，获取 mempool 的 chunkSize 、chunkCount 填充 mempoolConfig.m_mempoolConfig ,最后填充 cxx::vector<SegmentEntry, MAX_SHM_SEGMENTS> m_sharedMemorySegments; 这个vector 即 <1> 中的。
因此 <1>中取出的 segmentEntry 即 struct SegmentEntry 类型，构造：

  SegmentEntry(const posix::PosixGroup::string_t& readerGroup,
                     const posix::PosixGroup::string_t& writerGroup,
                     const MePooConfig& memPoolConfig,
                     iox::mepoo::MemoryInfo memoryInfo = iox::mepoo::MemoryInfo()) noexcept
            : m_readerGroup(readerGroup)
            , m_writerGroup(writerGroup)
            , m_mempoolConfig(memPoolConfig)
            , m_memoryInfo(memoryInfo)

        {
        }

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下面有个 填充 m_segmentContainer ，其类型为：

 cxx::vector<SegmentType, MAX_SHM_SEGMENTS> m_segmentContainer;

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SegmentType实际的类型为：

template <typename SegmentType = MePooSegment<>>

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因此 以下操作会调用 MePooSegment 的构造 ：

m_segmentContainer.emplace_back(
        segmentEntry.m_mempoolConfig, *m_managementAllocator, readerGroup, writerGroup, segmentEntry.m_memoryInfo);

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4.5 先看 MePooSegment 属性赋值部分 ：

inline MePooSegment<SharedMemoryObjectType, MemoryManagerType>::MePooSegment(
    const MePooConfig& mempoolConfig,
    posix::Allocator& managementAllocator,
    const posix::PosixGroup& readerGroup,
    const posix::PosixGroup& writerGroup,
    const iox::mepoo::MemoryInfo& memoryInfo) noexcept
    : m_sharedMemoryObject(std::move(createSharedMemoryObject(mempoolConfig, writerGroup))) //<3>
    , m_readerGroup(readerGroup)
    , m_writerGroup(writerGroup)
    , m_memoryInfo(memoryInfo)

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<3>处最重要 创建了 /dev/shm/whoami ,并地址映射：

inline SharedMemoryObjectType MePooSegment<SharedMemoryObjectType, MemoryManagerType>::createSharedMemoryObject(
    const MePooConfig& mempoolConfig, const posix::PosixGroup& writerGroup) noexcept
{
    std::cout<<"MePooSegment:"<<writerGroup.getName()<<std::endl;
    return std::move(
        typename SharedMemoryObjectType::Builder()
            .name(writerGroup.getName())                            //<4>
            .memorySizeInBytes(MemoryManager::requiredChunkMemorySize(mempoolConfig))   //<5>
            .accessMode(posix::AccessMode::READ_WRITE)
            .openMode(posix::OpenMode::PURGE_AND_CREATE)
            .permissions(SEGMENT_PERMISSIONS)
            .create()
            .and_then([this](auto& sharedMemoryObject) {
                this->setSegmentId(iox::rp::BaseRelativePointer::registerPtr(sharedMemoryObject.getBaseAddress(),
                                                                             sharedMemoryObject.getSizeInBytes()));

                LogDebug() << "Roudi registered payload data segment "
                           << iox::log::HexFormat(reinterpret_cast<uint64_t>(sharedMemoryObject.getBaseAddress()))
                           << " with size " << sharedMemoryObject.getSizeInBytes() << " to id " << m_segmentId;
            })
            .or_else([](auto&) { errorHandler(PoshError::MEPOO__SEGMENT_UNABLE_TO_CREATE_SHARED_MEMORY_OBJECT); })
            .value());
}


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<4>处获取用户名 whoami ;<5> 处 计算 memorySize ：

uint64_t MemoryManager::requiredChunkMemorySize(const MePooConfig& mePooConfig) noexcept
{
    uint64_t memorySize{0};
    for (const auto& mempoolConfig : mePooConfig.m_mempoolConfig)   //<6>
    {
        memorySize += cxx::align(static_cast<uint64_t>(mempoolConfig.m_chunkCount)
                                     * MemoryManager::sizeWithChunkHeaderStruct(mempoolConfig.m_size),
                                 MemPool::CHUNK_MEMORY_ALIGNMENT);  //<7>
    }
    return memorySize;
}

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<6> 取出 [[segment.mempool]] size = 128 count = 10000 [[segment.mempool]] size = 1024 count = 5000
<7> 1000 * [128 + sizeof(ChunkHeader)] 再进行 CHUNK_MEMORY_ALIGNMENT 对齐。最终计算出 总的 size。
创建好 /dev/shm/whoami 并 mmap 后 ，返回一个 sharedMemoryObject 进行 registerPtr()注册获得 SegmentId。

4.6 MePooSegment 构造 下半部

    m_memoryManager.configureMemoryManager(mempoolConfig, managementAllocator, m_sharedMemoryObject.getAllocator());
    m_sharedMemoryObject.finalizeAllocation();

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MemoryManager 类型的 m_memoryManager

void MemoryManager::configureMemoryManager(const MePooConfig& mePooConfig,
                                           posix::Allocator& managementAllocator,
                                           posix::Allocator& chunkMemoryAllocator) noexcept
{
    for (auto entry : mePooConfig.m_mempoolConfig)
    {
        addMemPool(managementAllocator, chunkMemoryAllocator, entry.m_size, entry.m_chunkCount);
    }

    generateChunkManagementPool(managementAllocator); //<8>
}


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addMemPool 最终调用了 MemPool 的构造 ，填充 cxx::vector<MemPool, 32> m_memPoolVector;
看一下 MemPool ：

MemPool::MemPool(const cxx::greater_or_equal<uint32_t, CHUNK_MEMORY_ALIGNMENT> chunkSize,
                 const cxx::greater_or_equal<uint32_t, 1> numberOfChunks,
                 posix::Allocator& managementAllocator,
                 posix::Allocator& chunkMemoryAllocator) noexcept
    : m_chunkSize(chunkSize)
    , m_numberOfChunks(numberOfChunks)
    , m_minFree(numberOfChunks)
{
    if (isMultipleOfAlignment(chunkSize))
    {
        m_rawMemory = static_cast<uint8_t*>(chunkMemoryAllocator.allocate(
            static_cast<uint64_t>(m_numberOfChunks) * m_chunkSize, CHUNK_MEMORY_ALIGNMENT));
        auto memoryLoFFLi =
            managementAllocator.allocate(freeList_t::requiredIndexMemorySize(m_numberOfChunks), CHUNK_MEMORY_ALIGNMENT);
        m_freeIndices.init(static_cast<concurrent::LoFFLi::Index_t*>(memoryLoFFLi), m_numberOfChunks);
    }
}

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传入 4个参数 ： [[segment.mempool]] size (已经+ChunkHeader）、count 、managementAllocator(管理模块的指针，在/dev/shm/iceoryx_mgmt )、chunk池的指针(chunkMemoryAllocator 在 /dev/shm/whoami )
MemPool.m_rawMemory 指向 该 [[segment.mempool]] 的起始address。
MemPool.m_freeIndices 指向 (m_numberOfChunks * uint32_t )的首地址 ，实际是一个freelist

m_nextFreeIndex[i] = i + 1;

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相当于 每个uint32_t 代表一个chunk，起始 填入 1，2，3… m_numberOfChunks
<8>处如下：

void MemoryManager::generateChunkManagementPool(posix::Allocator& managementAllocator) noexcept
{
    m_denyAddMemPool = true;
    uint32_t chunkSize = sizeof(ChunkManagement);
    m_chunkManagementPool.emplace_back(chunkSize, m_totalNumberOfChunks, managementAllocator, managementAllocator);
}

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相当于在 /dev/shm/iceoryx_mgmt 上划分了 m_totalNumberOfChunks 个 ChunkManagement ，并做了 freelist。

二 、内存分配示意如下

补充： MemoryManager->size = sizeof(mepoo::SegmentManager<>) + m_totalNumberOfChunks * u32 + m_totalNumberOfChunks * sizeof(ChunkManagement) + m_totalNumberOfChunks * u32
在这里插入图片描述

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