.NET深入学习笔记(1)：DataSet和SqlDataReader性能差异深入剖析与测试(2)

protected virtual int Fill(DataSet dataSet, string srcTable, IDataReader dataReader, int startRecord, int maxRecords)
{
int num;
IntPtr ptr;
Bid.ScopeEnter(out ptr, "<comm.DataAdapter.Fill|API> %d#, dataSet, srcTable, dataReader, startRecord, maxRecords\n", this.ObjectID);
try
{
if (dataSet == null)
{
throw ADP.FillRequires("dataSet");
}
if (ADP.IsEmpty(srcTable))
{
throw ADP.FillRequiresSourceTableName("srcTable");
}
if (dataReader == null)
{
throw ADP.FillRequires("dataReader");
}
if (startRecord < 0)
{
throw ADP.InvalidStartRecord("startRecord", startRecord);
}
if (maxRecords < 0)
{
throw ADP.InvalidMaxRecords("maxRecords", maxRecords);
}
if (dataReader.IsClosed)
{
return 0;
}
DataReaderContainer container = DataReaderContainer.Create(dataReader, this.ReturnProviderSpecificTypes);
num = this.FillFromReader(dataSet, null, srcTable, container, startRecord, maxRecords, null, null);
}
finally
{
Bid.ScopeLeave(ref ptr);
}
return num;
}

另外一个SqlCommand 的ExecuteReader方法最终调用Run方法代码如下：

internal bool Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj)
{
if ((TdsParserState.Broken == this.State) || (this.State == TdsParserState.Closed))
{
return true;
}
bool flag = false;
Label_0016:
if (stateObj._internalTimeout)
{
runBehavior = RunBehavior.Attention;
}
if ((TdsParserState.Broken == this.State) || (this.State == TdsParserState.Closed))
{
goto Label_06DF;
}
byte token = stateObj.ReadByte();
if ((((((token != 170) && (token != 0xab)) && ((token != 0xad) && (token != 0xe3))) && (((token != 0xac) && (token != 0x79)) && ((token != 160) && (token != 0xa1)))) && ((((token != 0x81) && (token != 0x88)) && ((token != 0xa4) && (token != 0xa5))) && (((token != 0xa9) && (token != 0xd3)) && ((token != 0xd1) && (token != 0xfd))))) && ((((token != 0xfe) && (token != 0xff)) && ((token != 0x39) && (token != 0xed))) && (((token != 0xae) && (token != 0x7c)) && ((token != 120) && (token != 0xed)))))
{
this._state = TdsParserState.Broken;
this._connHandler.BreakConnection();
throw SQL.ParsingError();
}
int tokenLength = this.GetTokenLength(token, stateObj);
switch (token)
{
case 0xa4:
if (dataStream == null)
{
this.SkipBytes(tokenLength, stateObj);
}
else
{
dataStream.TableNames = this.ProcessTableName(tokenLength, stateObj);
}
goto Label_06AF;

case 0xa5:
if (dataStream == null)
{
this.SkipBytes(tokenLength, stateObj);
}
else
{
_SqlMetaDataSet metaData = this.ProcessColInfo(dataStream.MetaData, dataStream, stateObj);
dataStream.SetMetaData(metaData, false);
dataStream.BrowseModeInfoConsumed = true;
}
goto Label_06AF;

case 0xa9:
this.SkipBytes(tokenLength, stateObj);
goto Label_06AF;

case 170:
case 0xab:
{
if (token == 170)
{
stateObj._errorTokenReceived = true;
}
SqlError error = this.ProcessError(token, stateObj);
if (RunBehavior.Clean == (RunBehavior.Clean & runBehavior))
{
if (error.Class >= 20)
{
this.Errors.Add(error);
}
}
else if (((this._connHandler != null) && (this._connHandler.Connection != null)) && (this._connHandler.Connection.FireInfoMessageEventOnUserErrors && (error.Class <= 0x10)))
{
this.FireInfoMessageEvent(stateObj, error);
}
else if (error.Class < 11)
{
this.Warnings.Add(error);
}
else if (error.Class <= 0x10)
{
this.Errors.Add(error);
if ((dataStream != null) && !dataStream.IsInitialized)
{
runBehavior = RunBehavior.UntilDone;
}
}
else
{
this.Errors.Add(error);
runBehavior = RunBehavior.UntilDone;
}
goto Label_06AF;
}
case 0xac:
{
SqlReturnValue rec = this.ProcessReturnValue(tokenLength, stateObj);
if (cmdHandler != null)
{
cmdHandler.OnReturnValue(rec);
}
goto Label_06AF;
}
case 0xad:
{
SqlLoginAck ack = this.ProcessLoginAck(stateObj);
this._connHandler.OnLoginAck(ack);
goto Label_06AF;
}
case 0x88:
{
if (stateObj._cleanupAltMetaDataSetArray == null)
{
stateObj._cleanupAltMetaDataSetArray = new _SqlMetaDataSetCollection();
}
_SqlMetaDataSet altMetaDataSet = this.ProcessAltMetaData(tokenLength, stateObj);
stateObj._cleanupAltMetaDataSetArray.Add(altMetaDataSet);
if (dataStream != null)
{
dataStream.SetAltMetaDataSet(altMetaDataSet, 0x88 != stateObj.PeekByte());
}
goto Label_06AF;
}
case 0x79:
{
int status = stateObj.ReadInt32();
if (cmdHandler != null)
{
cmdHandler.OnReturnStatus(status);
}
goto Label_06AF;
}
case 0x81:
if (tokenLength != 0xffff)
{
stateObj._cleanupMetaData = this.ProcessMetaData(tokenLength, stateObj);
}
else if (cmdHandler != null)
{
stateObj._cleanupMetaData = cmdHandler.MetaData;
}
if (dataStream != null)
{
byte num5 = stateObj.PeekByte();
dataStream.SetMetaData(stateObj._cleanupMetaData, (0xa4 == num5) || (0xa5 == num5));
}
else if (bulkCopyHandler != null)
{
bulkCopyHandler.SetMetaData(stateObj._cleanupMetaData);
}
goto Label_06AF;

case 0xd1:
if (bulkCopyHandler == null)
{
if (RunBehavior.ReturnImmediately != (RunBehavior.ReturnImmediately & runBehavior))
{
this.SkipRow(stateObj._cleanupMetaData, stateObj);
}
break;
}
this.ProcessRow(stateObj._cleanupMetaData, bulkCopyHandler.CreateRowBuffer(), bulkCopyHandler.CreateIndexMap(), stateObj);
break;

case 0xd3:
if (RunBehavior.ReturnImmediately != (RunBehavior.ReturnImmediately & runBehavior))
{
int num8 = stateObj.ReadUInt16();
this.SkipRow(stateObj._cleanupAltMetaDataSetArray[num8], stateObj);
}
flag = true;
goto Label_06AF;

case 0xe3:
{
SqlEnvChange[] changeArray = this.ProcessEnvChange(tokenLength, stateObj);
for (int i = 0; i < changeArray.Length; i++)
{
if (changeArray[i] == null)
{
continue;
}
switch (changeArray[i].type)
{
case 8:
case 11:
this._currentTransaction = this._pendingTransaction;
this._pendingTransaction = null;
if (this._currentTransaction == null)
{
break;
}
this._currentTransaction.TransactionId = changeArray[i].newLongValue;
goto Label_048E;

case 9:
case 12:
case 0x11:
this._retainedTransactionId = 0L;
goto Label_04D1;

case 10:
goto Label_04D1;

default:
goto Label_0551;
}
TransactionType type = (8 == changeArray[i].type) ? TransactionType.LocalFromTSQL : TransactionType.Distributed;
this._currentTransaction = new SqlInternalTransaction(this._connHandler, type, null, changeArray[i].newLongValue);
Label_048E:
if ((this._statistics != null) && !this._statisticsIsInTransaction)
{
this._statistics.SafeIncrement(ref this._statistics._transactions);
}
this._statisticsIsInTransaction = true;
this._retainedTransactionId = 0L;
continue;
Label_04D1:
if (this._currentTransaction != null)
{
if (9 == changeArray[i].type)
{
this._currentTransaction.Completed(TransactionState.Committed);
}
else if (10 == changeArray[i].type)
{
if (this._currentTransaction.IsDistributed && this._currentTransaction.IsActive)
{
this._retainedTransactionId = changeArray[i].oldLongValue;
}
this._currentTransaction.Completed(TransactionState.Aborted);
}
else
{
this._currentTransaction.Completed(TransactionState.Unknown);
}
this._currentTransaction = null;
}
this._statisticsIsInTransaction = false;
continue;
Label_0551:
this._connHandler.OnEnvChange(changeArray[i]);
}
goto Label_06AF;
}
case 0xfd:
case 0xfe:
case 0xff:
this.ProcessDone(cmdHandler, dataStream, ref runBehavior, stateObj);
if ((token == 0xfe) && (cmdHandler != null))
{
cmdHandler.OnDoneProc();
}
goto Label_06AF;

case 0xed:
this.ProcessSSPI(tokenLength);
goto Label_06AF;

default:
goto Label_06AF;
}
if (this._statistics != null)
{
this._statistics.WaitForDoneAfterRow = true;
}
flag = true;
Label_06AF:
if ((stateObj._pendingData && (RunBehavior.ReturnImmediately != (RunBehavior.ReturnImmediately & runBehavior))) || ((!stateObj._pendingData && stateObj._attentionSent) && !stateObj._attentionReceived))
{
goto Label_0016;
}
Label_06DF:
if (!stateObj._pendingData && (this.CurrentTransaction != null))
{
this.CurrentTransaction.Activate();
}
if (stateObj._attentionSent && stateObj._attentionReceived)
{
stateObj._attentionSent = false;
stateObj._attentionReceived = false;
if ((RunBehavior.Clean != (RunBehavior.Clean & runBehavior)) && !stateObj._internalTimeout)
{
this.Errors.Add(new SqlError(0, 0, 11, this._server, SQLMessage.OperationCancelled(), "", 0));
}
}
if ((this._errors != null) || (this._warnings != null))
{
this.ThrowExceptionAndWarning(stateObj);
}
return flag;
}

我已经使用Reflector查看了SQLDataAdapter类型的Fill方法以及SqlCommand.ExecuteReader 方法代码。确实有使用DataReader的地方。他们是真正负责处理查询并装在数据。DataReader和DataSet应该都是数据容器。做个类比的话，应该是茶壶和茶杯的关系。至于查询数据，除了取决于容器，还和具体负责查询和装载数据的类有关系。 我文章的标题，应该说是有问题的，这种比较忽略了一个数据查询和装载的过程。有不合理的地方。现在更正。