How the method SqlDataReader.Read() work?

Question

下面是reflector看到的代码， 这里的实现看的我一头雾水， 它应该是从socket取得来的数据吧，  socket  ---------(中间过程)-------------->    SqlDataReader.GetString(...)取数据
这个中间过程怎么样的？Can someone explain more? Thanks in advance.
public override bool Read()
{
    return this.ReadInternal(true);
} private bool ReadInternal(bool setTimeout)
{
    bool flag;
    SqlStatistics statistics = null;
    IntPtr ptr;
    Bid.ScopeEnter(out ptr, "<sc.SqlDataReader.Read|API> %d#", this.ObjectID);
    RuntimeHelpers.PrepareConstrainedRegions();
    try
    {
        statistics = SqlStatistics.StartTimer(this.Statistics);
        if (this._parser == null)
        {
            goto Label_017B;
        }
        if (setTimeout)
        {
            this.SetTimeout();
        }
        if (this._dataReady)
        {
            this.CleanPartialRead();
        }
        this._dataReady = false;
        SqlBuffer.Clear(this._data);
        this._nextColumnHeaderToRead = 0;
        this._nextColumnDataToRead = 0;
        this._columnDataBytesRemaining = -1L;
        if (this._haltRead)
        {
            goto Label_016A;
        }
        if (this.HasMoreRows())
        {
            while (this._stateObj._pendingData)
            {
                if (this._altRowStatus != ALTROWSTATUS.AltRow)
                {
                    this._dataReady = this._parser.Run(RunBehavior.ReturnImmediately, this._command, this, null, this._stateObj);
                    if (!this._dataReady)
                    {
                        continue;
                    }
                }
                else
                {
                    this._altRowStatus = ALTROWSTATUS.Done;
                    this._dataReady = true;
                }
                break;
            }
            if (this._dataReady)
            {
                this._haltRead = this.IsCommandBehavior(CommandBehavior.SingleRow);
                return true;
            }
        }
        if (!this._stateObj._pendingData)
        {
            this.CloseInternal(false);
        }
        goto Label_018E;
    Label_010E:
        this._dataReady = this._parser.Run(RunBehavior.ReturnImmediately, this._command, this, null, this._stateObj);
    Label_012E:
        if (this._stateObj._pendingData && !this._dataReady)
        {
            goto Label_010E;
        }
        if (this._dataReady)
        {
            this.CleanPartialRead();
        }
        this._dataReady = false;
        SqlBuffer.Clear(this._data);
        this._nextColumnHeaderToRead = 0;
    Label_016A:
        if (this.HasMoreRows())
        {
            goto Label_012E;
        }
        this._haltRead = false;
        goto Label_018E;
    Label_017B:
        if (this.IsClosed)
        {
            throw ADP.DataReaderClosed("Read");
        }
    Label_018E:
        return false;
    }
    catch (OutOfMemoryException exception3)
    {
        this._isClosed = true;
        SqlConnection connection3 = this._connection;
        if (connection3 != null)
        {
            connection3.Abort(exception3);
        }
        throw;
    }
    catch (StackOverflowException exception2)
    {
        this._isClosed = true;
        SqlConnection connection2 = this._connection;
        if (connection2 != null)
        {
            connection2.Abort(exception2);
        }
        throw;
    }
    catch (ThreadAbortException exception)
    {
        this._isClosed = true;
        SqlConnection connection = this._connection;
        if (connection != null)
        {
            connection.Abort(exception);
        }
        throw;
    }
    finally
    {
        SqlStatistics.StopTimer(statistics);
        Bid.ScopeLeave(ref ptr);
    }
    return flag;
}  

Answer 1

private bool ReadInternal(bool setTimeout)
{
    bool flag;
    SqlStatistics statistics = null;
    IntPtr ptr;
    Bid.ScopeEnter(out ptr, "<sc.SqlDataReader.Read|API> %d#", this.ObjectID);
    RuntimeHelpers.PrepareConstrainedRegions();
    try
    {
        statistics = SqlStatistics.StartTimer(this.Statistics);
        if (this._parser == null)
        {
            if (this.IsClosed)
        {
            throw ADP.DataReaderClosed("Read");
        }
        return false;
        }
        if (setTimeout)
        {
            this.SetTimeout();
        }
//清除数据、初始化数据
        if (this._dataReady)
        {
            this.CleanPartialRead();
        }
        this._dataReady = false;
        SqlBuffer.Clear(this._data);
        this._nextColumnHeaderToRead = 0;
        this._nextColumnDataToRead = 0;
        this._columnDataBytesRemaining = -1L;
//如果是停止读取（已经读到最后一条记录了或者EOF）了
        if (this._haltRead) 
        {
            if (this.HasMoreRows())
        {
           while (this._stateObj._pendingData && !this._dataReady) //注意此处变为循环了，运行到第一条记录处或者BOF
        {
            this._dataReady = this._parser.Run(RunBehavior.ReturnImmediately, this._command, this, null, this._stateObj);
        }
        if (this._dataReady)
        {
            this.CleanPartialRead();
        }
        this._dataReady = false;
        SqlBuffer.Clear(this._data);
        this._nextColumnHeaderToRead = 0;
        }
        this._haltRead = false;
        return false;
        }        if (this.HasMoreRows())
        {
            while (this._stateObj._pendingData)
            {
                if (this._altRowStatus != ALTROWSTATUS.AltRow)
                {
                    this._dataReady = this._parser.Run(RunBehavior.ReturnImmediately, this._command, this, null, this._stateObj);
                    if (!this._dataReady)
                    {
                        continue;
                    }
                }
                else
                {
                    this._altRowStatus = ALTROWSTATUS.Done;
                    this._dataReady = true;
                }
                break;
            }
            if (this._dataReady)
            {
                this._haltRead = this.IsCommandBehavior(CommandBehavior.SingleRow);
                return true;
            }
        }
        if (!this._stateObj._pendingData)
        {
            this.CloseInternal(false);
        }
        return false; 
    }
    catch (OutOfMemoryException exception3)
    {
        this._isClosed = true;
        SqlConnection connection3 = this._connection;
        if (connection3 != null)
        {
            connection3.Abort(exception3);
        }
        throw;
    }
    catch (StackOverflowException exception2)
    {
        this._isClosed = true;
        SqlConnection connection2 = this._connection;
        if (connection2 != null)
        {
            connection2.Abort(exception2);
        }
        throw;
    }
    catch (ThreadAbortException exception)
    {
        this._isClosed = true;
        SqlConnection connection = this._connection;
        if (connection != null)
        {
            connection.Abort(exception);
        }
        throw;
    }
    finally
    {
        SqlStatistics.StopTimer(statistics);
        Bid.ScopeLeave(ref ptr);
    }
    return flag;
}

Answer 2

即有两种情况：一是已经读到最后一条记录了，返回false
二是正常读取下一条记录，填充数据到this._data，然后返回true