MemoryStream, XmlTextWriter and Warning 4 CA2202 : Microsoft.Usage
- by rasx
The Run Code Analysis command in Visual Studio 2010 Ultimate returns a warning when seeing a certain pattern with MemoryStream and XmlTextWriter.
This is the warning:
Warning 7 CA2202 : Microsoft.Usage :
Object 'ms' can be disposed more than
once in method
'KinteWritePages.GetXPathDocument(DbConnection)'.
To avoid generating a
System.ObjectDisposedException you
should not call Dispose more than one
time on an object.: Lines:
421 C:\Visual Studio
2010\Projects\Songhay.DataAccess.KinteWritePages\KinteWritePages.cs 421 Songhay.DataAccess.KinteWritePages
This is the form:
static XPathDocument GetXPathDocument(DbConnection connection)
{
XPathDocument xpDoc = null;
var ms = new MemoryStream();
try
{
using(XmlTextWriter writer = new XmlTextWriter(ms, Encoding.UTF8))
{
using(DbDataReader reader = CommonReader.GetReader(connection, Resources.KinteRssSql))
{
writer.WriteStartDocument();
writer.WriteStartElement("data");
do
{
while(reader.Read())
{
writer.WriteStartElement("item");
for(int i = 0; i < reader.FieldCount; i++)
{
writer.WriteRaw(String.Format("<{0}>{1}</{0}>", reader.GetName(i), reader[i].ToString()));
}
writer.WriteFullEndElement();
}
} while(reader.NextResult());
writer.WriteFullEndElement();
writer.WriteEndDocument();
writer.Flush();
ms.Position = 0;
xpDoc = new XPathDocument(ms);
}
}
}
finally
{
ms.Dispose();
}
return xpDoc;
}
The same kind of warning is produced for this form:
XPathDocument xpDoc = null;
using(var ms = new MemoryStream())
{
using(XmlTextWriter writer = new XmlTextWriter(ms, Encoding.UTF8))
{
using(DbDataReader reader = CommonReader.GetReader(connection, Resources.KinteRssSql))
{
//...
}
}
}
return xpDoc;
By the way, the following form produces another warning:
XPathDocument xpDoc = null;
var ms = new MemoryStream();
using(XmlTextWriter writer = new XmlTextWriter(ms, Encoding.UTF8))
{
using(DbDataReader reader = CommonReader.GetReader(connection, Resources.KinteRssSql))
{
//...
}
}
return xpDoc;
The above produces the warning:
Warning 7 CA2000 :
Microsoft.Reliability : In method
'KinteWritePages.GetXPathDocument(DbConnection)',
object 'ms' is not disposed along all
exception paths. Call
System.IDisposable.Dispose on object
'ms' before all references to it are
out of scope. C:\Visual Studio
2010\Projects\Songhay.DataAccess.KinteWritePages\KinteWritePages.cs 383 Songhay.DataAccess.KinteWritePages
In addition to the following, what are my options?:
Supress warning CA2202.
Supress warning CA2000 and hope that
Microsoft is disposing of
MemoryStream (because
Reflector is not showing me the source code).
Rewrite my legacy code to recognize
the wonderful XDocument and LINQ to
XML.
