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SMFac::Execute和SMFac::ExecuteForCheckpoint应该消除不必要的string拷贝 #231

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SMFac::Execute和SMFac::ExecuteForCheckpoint应该消除不必要的string拷贝#231
@dyx2025

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@dyx2025
dyx2025
opened on Mar 5, 2026

SMFac::Execute和SMFac::ExecuteForCheckpoint分别是状态机执行和checkpoint执行的热路径，应该消除不必要的string拷贝。

原代码路径：
src/sm-base/sm_base.cpp

// ...

bool SMFac :: Execute(const int iGroupIdx, const uint64_t llInstanceID, const std::string & sPaxosValue, SMCtx * poSMCtx)
{
    if (sPaxosValue.size() < sizeof(int))
    {   
        PLG1Err("Value wrong, instanceid %lu size %zu", llInstanceID, sPaxosValue.size());
        //need do nothing, just skip
        return true;
    }   

    int iSMID = 0;
    memcpy(&iSMID, sPaxosValue.data(), sizeof(int));

    if (iSMID == 0)
    {   
        PLG1Imp("Value no need to do sm, just skip, instanceid %lu", llInstanceID);
        return true;
    }   

    // 先把body拷贝到string临时对象，再从string临时对象拷贝到sBodyValue。
    // 对于BatchExecute只用到从sPaxosValue.data() + sizeof(int)开始长度为sPaxosValue.size() - sizeof(int)的内容反序列化，没必要创建sBodyValue。
    // 对于DoExecute需要用到sBodyValue，但创建sBodyValue过程中没必要引入string临时对象。
    std::string sBodyValue = string(sPaxosValue.data() + sizeof(int), sPaxosValue.size() - sizeof(int));
    if (iSMID == BATCH_PROPOSE_SMID)
    {   
        BatchSMCtx * poBatchSMCtx = nullptr;
        if (poSMCtx != nullptr && poSMCtx->m_pCtx != nullptr)
        {   
            poBatchSMCtx = (BatchSMCtx *)poSMCtx->m_pCtx;
        }   
        return BatchExecute(iGroupIdx, llInstanceID, sBodyValue, poBatchSMCtx);
    }   
    else
    {   
        return DoExecute(iGroupIdx, llInstanceID, sBodyValue, iSMID, poSMCtx);
    }   
}

bool SMFac :: BatchExecute(const int iGroupIdx, const uint64_t llInstanceID, const std::string & sBodyValue, BatchSMCtx * poBatchSMCtx)
{
    BatchPaxosValues oBatchValues;
    bool bSucc = oBatchValues.ParseFromArray(sBodyValue.data(), sBodyValue.size());
    if (!bSucc)
    {   
        PLG1Err("ParseFromArray fail, valuesize %zu", sBodyValue.size());
        return false;
    }   

    if (poBatchSMCtx != nullptr) 
    {   
        if ((int)poBatchSMCtx->m_vecSMCtxList.size() != oBatchValues.values_size())
        {
            PLG1Err("values size %d not equal to smctx size %zu",
                    oBatchValues.values_size(), poBatchSMCtx->m_vecSMCtxList.size());
            return false;
        }
    }

    for (int i = 0; i < oBatchValues.values_size(); i++)
    {
        const PaxosValue & oValue = oBatchValues.values(i);
        SMCtx * poSMCtx = poBatchSMCtx != nullptr ? poBatchSMCtx->m_vecSMCtxList[i] : nullptr;
        bool bExecuteSucc = DoExecute(iGroupIdx, llInstanceID, oValue.value(), oValue.smid(), poSMCtx);
        if (!bExecuteSucc)
        {
            return false;
        }
    }

    return true;
}

// ...

bool SMFac :: ExecuteForCheckpoint(const int iGroupIdx, const uint64_t llInstanceID, const std::string & sPaxosValue)
{
    if (sPaxosValue.size() < sizeof(int))
    {
        PLG1Err("Value wrong, instanceid %lu size %zu", llInstanceID, sPaxosValue.size());
        //need do nothing, just skip
        return true;
    }

    int iSMID = 0;
    memcpy(&iSMID, sPaxosValue.data(), sizeof(int));

    if (iSMID == 0)
    {
        PLG1Imp("Value no need to do sm, just skip, instanceid %lu", llInstanceID);
        return true;
    }

    // 先把body拷贝到string临时对象，再从string临时对象拷贝到sBodyValue。
    // 对于BatchExecuteForCheckpoint只用到从sPaxosValue.data() + sizeof(int)开始长度为sPaxosValue.size() - sizeof(int)的内容反序列化，没必要创建sBodyValue。
    // **对于DoExecuteForCheckpoint需要用到sBodyValue，但创建sBodyValue过程中没必要引入string临时对象。**
    std::string sBodyValue = string(sPaxosValue.data() + sizeof(int), sPaxosValue.size() - sizeof(int));
    if (iSMID == BATCH_PROPOSE_SMID)
    {
        return BatchExecuteForCheckpoint(iGroupIdx, llInstanceID, sBodyValue);
    }
    else
    {
        return DoExecuteForCheckpoint(iGroupIdx, llInstanceID, sBodyValue, iSMID);
    }
}

bool SMFac :: BatchExecuteForCheckpoint(const int iGroupIdx, const uint64_t llInstanceID, 
        const std::string & sBodyValue)
{
    BatchPaxosValues oBatchValues;
    bool bSucc = oBatchValues.ParseFromArray(sBodyValue.data(), sBodyValue.size());
    if (!bSucc)
    {
        PLG1Err("ParseFromArray fail, valuesize %zu", sBodyValue.size());
        return false;
    }

    for (int i = 0; i < oBatchValues.values_size(); i++)
    {
        const PaxosValue & oValue = oBatchValues.values(i);
        bool bExecuteSucc = DoExecuteForCheckpoint(iGroupIdx, llInstanceID, oValue.value(), oValue.smid());
        if (!bExecuteSucc)
        {
            return false;
        }
    }

    return true;
}

修改后代码路径：
src/sm-base/sm_base.h

// ...

/*
    bool BatchExecute(const int iGroupIdx, const uint64_t llInstanceID,                                                                                                             
            const std::string & sBodyValue, BatchSMCtx * poBatchSMCtx);
*/

    bool BatchExecute(const int iGroupIdx, const uint64_t llInstanceID,                                                                                                             
            const char* body, size_t body_len, BatchSMCtx * poBatchSMCtx);

/*
    bool BatchExecuteForCheckpoint(const int iGroupIdx, const uint64_t llInstanceID, 
            const std::string & sBodyValue);
*/

    bool BatchExecuteForCheckpoint(const int iGroupIdx, const uint64_t llInstanceID, 
            const char* body, size_t body_len);

// ...

src/sm-base/sm_base.cpp

// ...

bool SMFac :: Execute(const int iGroupIdx, const uint64_t llInstanceID, const std::string & sPaxosValue, SMCtx * poSMCtx)
{
    if (sPaxosValue.size() < sizeof(int))
    {   
        PLG1Err("Value wrong, instanceid %lu size %zu", llInstanceID, sPaxosValue.size());
        //need do nothing, just skip
        return true;
    }   

    int iSMID = 0;
    memcpy(&iSMID, sPaxosValue.data(), sizeof(int));

    if (iSMID == 0)
    {   
        PLG1Imp("Value no need to do sm, just skip, instanceid %lu", llInstanceID);
        return true;
    }   

    // std::string sBodyValue = string(sPaxosValue.data() + sizeof(int), sPaxosValue.size() - sizeof(int));
    if (iSMID == BATCH_PROPOSE_SMID)
    {   
        BatchSMCtx * poBatchSMCtx = nullptr;
        if (poSMCtx != nullptr && poSMCtx->m_pCtx != nullptr)
        {   
            poBatchSMCtx = (BatchSMCtx *)poSMCtx->m_pCtx;
        }
        // return BatchExecute(iGroupIdx, llInstanceID, sBodyValue, poBatchSMCtx);
        // 没有创建sBodyValue   
        return BatchExecute(iGroupIdx, llInstanceID, sPaxosValue.data() + sizeof(int), sPaxosValue.size() - sizeof(int), poBatchSMCtx);
    }   
    else
    {
        // 创建sBodyValue，没有临时string对象 
        std::string sBodyValue(sPaxosValue.data() + sizeof(int), sPaxosValue.size() - sizeof(int);   
        return DoExecute(iGroupIdx, llInstanceID, sBodyValue, iSMID, poSMCtx);
    }   
}

// bool SMFac :: BatchExecute(const int iGroupIdx, const uint64_t llInstanceID, const std::string & sBodyValue, BatchSMCtx * poBatchSMCtx)
bool SMFac :: BatchExecute(const int iGroupIdx, const uint64_t llInstanceID,  const char* body, size_t body_len, BatchSMCtx * poBatchSMCtx)
{
    BatchPaxosValues oBatchValues;
    // bool bSucc = oBatchValues.ParseFromArray(sBodyValue.data(), sBodyValue.size());
    bool bSucc = oBatchValues.ParseFromArray(body, body_len);
    if (!bSucc)
    {   
        // PLG1Err("ParseFromArray fail, valuesize %zu", sBodyValue.size());
        PLG1Err("ParseFromArray fail, valuesize %zu", body_len);
        return false;
    }   

    if (poBatchSMCtx != nullptr) 
    {   
        if ((int)poBatchSMCtx->m_vecSMCtxList.size() != oBatchValues.values_size())
        {
            PLG1Err("values size %d not equal to smctx size %zu",
                    oBatchValues.values_size(), poBatchSMCtx->m_vecSMCtxList.size());
            return false;
        }
    }

    for (int i = 0; i < oBatchValues.values_size(); i++)
    {
        const PaxosValue & oValue = oBatchValues.values(i);
        SMCtx * poSMCtx = poBatchSMCtx != nullptr ? poBatchSMCtx->m_vecSMCtxList[i] : nullptr;
        bool bExecuteSucc = DoExecute(iGroupIdx, llInstanceID, oValue.value(), oValue.smid(), poSMCtx);
        if (!bExecuteSucc)
        {
            return false;
        }
    }

    return true;
}

// ...

bool SMFac :: ExecuteForCheckpoint(const int iGroupIdx, const uint64_t llInstanceID, const std::string & sPaxosValue)
{
    if (sPaxosValue.size() < sizeof(int))
    {
        PLG1Err("Value wrong, instanceid %lu size %zu", llInstanceID, sPaxosValue.size());
        //need do nothing, just skip
        return true;
    }

    int iSMID = 0;
    memcpy(&iSMID, sPaxosValue.data(), sizeof(int));

    if (iSMID == 0)
    {
        PLG1Imp("Value no need to do sm, just skip, instanceid %lu", llInstanceID);
        return true;
    }

    // std::string sBodyValue = string(sPaxosValue.data() + sizeof(int), sPaxosValue.size() - sizeof(int));
    if (iSMID == BATCH_PROPOSE_SMID)
    {
        // return BatchExecuteForCheckpoint(iGroupIdx, llInstanceID, sBodyValue);
        // 没有创建sBodyValue
        return BatchExecuteForCheckpoint(iGroupIdx, llInstanceID, sPaxosValue.data() + sizeof(int), sPaxosValue.size() - sizeof(int));
    }
    else
    {
        // 创建sBodyValue，没有临时string对象 
        std::string sBodyValue(sPaxosValue.data() + sizeof(int), sPaxosValue.size() - sizeof(int); 
        return DoExecuteForCheckpoint(iGroupIdx, llInstanceID, sBodyValue, iSMID);
    }
}

/*
bool SMFac :: BatchExecuteForCheckpoint(const int iGroupIdx, const uint64_t llInstanceID, 
        const std::string & sBodyValue)
*/
bool SMFac :: BatchExecuteForCheckpoint(const int iGroupIdx, const uint64_t llInstanceID, 
        const char* body, size_t body_len)
{
    BatchPaxosValues oBatchValues;
    // bool bSucc = oBatchValues.ParseFromArray(sBodyValue.data(), sBodyValue.size());
    bool bSucc = oBatchValues.ParseFromArray(body, body_len);
    if (!bSucc)
    {
        // PLG1Err("ParseFromArray fail, valuesize %zu", sBodyValue.size());
        PLG1Err("ParseFromArray fail, valuesize %zu", body_len);
        return false;
    }

    for (int i = 0; i < oBatchValues.values_size(); i++)
    {
        const PaxosValue & oValue = oBatchValues.values(i);
        bool bExecuteSucc = DoExecuteForCheckpoint(iGroupIdx, llInstanceID, oValue.value(), oValue.smid());
        if (!bExecuteSucc)
        {
            return false;
        }
    }

    return true;
}

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