消除AcceptorState::Load不必要的拷贝

[dyx2025]

消除AcceptorState::Load不必要的拷贝

AcceptorState::Load的m_sAcceptedValue可以通过移动oState的acceptednodeid，减少不必要的拷贝。#214 的测试数据支持这一做法。

原代码路径：
src/algorithm/acceptor.cpp

int AcceptorState :: Load(uint64_t & llInstanceID)
{
    int ret = m_oPaxosLog.GetMaxInstanceIDFromLog(m_poConfig->GetMyGroupIdx(), llInstanceID);
    if (ret != 0 && ret != 1)
    {   
        PLGErr("Load max instance id fail, ret %d", ret);
        return ret;
    }   

    if (ret == 1)
    {   
        PLGErr("empty database");
        llInstanceID = 0;
        return 0;
    }   

    AcceptorStateData oState;
    ret = m_oPaxosLog.ReadState(m_poConfig->GetMyGroupIdx(), llInstanceID, oState);
    if (ret != 0)
    {   
        return ret;
    }   
        
    m_oPromiseBallot.m_llProposalID = oState.promiseid();
    m_oPromiseBallot.m_llNodeID = oState.promisenodeid();
    m_oAcceptedBallot.m_llProposalID = oState.acceptedid();
    m_oAcceptedBallot.m_llNodeID = oState.acceptednodeid();
    m_sAcceptedValue = oState.acceptedvalue();  // 赋值，产生字符串拷贝
    m_iChecksum = oState.checksum();
        
    PLGImp("GroupIdx %d InstanceID %lu PromiseID %lu PromiseNodeID %lu"
           " AccectpedID %lu AcceptedNodeID %lu ValueLen %zu Checksum %u", 
            m_poConfig->GetMyGroupIdx(), llInstanceID, m_oPromiseBallot.m_llProposalID, 
            m_oPromiseBallot.m_llNodeID, m_oAcceptedBallot.m_llProposalID, 
            m_oAcceptedBallot.m_llNodeID, m_sAcceptedValue.size(), m_iChecksum);
        
    return 0;
} 

修改后的代码路径：
src/algorithm/acceptor.cpp

int AcceptorState :: Load(uint64_t & llInstanceID)
{
    int ret = m_oPaxosLog.GetMaxInstanceIDFromLog(m_poConfig->GetMyGroupIdx(), llInstanceID);
    if (ret != 0 && ret != 1)
    {   
        PLGErr("Load max instance id fail, ret %d", ret);
        return ret;
    }   

    if (ret == 1)
    {   
        PLGErr("empty database");
        llInstanceID = 0;
        return 0;
    }   

    AcceptorStateData oState;
    ret = m_oPaxosLog.ReadState(m_poConfig->GetMyGroupIdx(), llInstanceID, oState);
    if (ret != 0)
    {   
        return ret;
    }   
        
    m_oPromiseBallot.m_llProposalID = oState.promiseid();
    m_oPromiseBallot.m_llNodeID = oState.promisenodeid();
    m_oAcceptedBallot.m_llProposalID = oState.acceptedid();
    m_oAcceptedBallot.m_llNodeID = oState.acceptednodeid();
    // 修改代码
    // m_sAcceptedValue = oState.acceptedvalue();
    m_sAcceptedValue = std::move(*(oState.mutable_acceptedvalue()));
    m_iChecksum = oState.checksum();
        
    PLGImp("GroupIdx %d InstanceID %lu PromiseID %lu PromiseNodeID %lu"
           " AccectpedID %lu AcceptedNodeID %lu ValueLen %zu Checksum %u", 
            m_poConfig->GetMyGroupIdx(), llInstanceID, m_oPromiseBallot.m_llProposalID, 
            m_oPromiseBallot.m_llNodeID, m_oAcceptedBallot.m_llProposalID, 
            m_oAcceptedBallot.m_llNodeID, m_sAcceptedValue.size(), m_iChecksum);
        
    return 0;
}