Dispose Unmanaged resources

  • Thread starter Thread starter Curious
  • Start date Start date
C

Curious

We all know that in .NET, we don't need to worry about memory leak
becaseu GC does a nice job to collect it.

The only time we need to worry about memory leak is when we use
unmanaged resources, such as COM-based objects written in C++, for an
instance. Therefore, I've created the following sample code below to
illustrate the step necessary in disposing unmanaged resources.

I believe that to dispose unmanaged resources, we'll need to call the
Destructor of the COM object. However, I don't know what's the right
syntax. I'm looking for advice and input on the piece of code below.
Thanks!

using System;
using System.Runtime.InteropServices;

namespace iopmb
{


[DllImport("user32.dll", EntryPoint="MessageBoxW",
CharSet=CharSet.Auto, ExactSpelling=true)]
public static extern bool COMDbConnection (string connectionString,
bool useTrustedConnection, string, userName, string password);

COMDbConnection myConnection = new
COMDbConnection("Provider=sqloledb;Data Source=DataWarehouse;Initial
Catalog=Pace;", true, "sa", "password") ;

try
{
// do something with myConnection
}
catch
{
finally
{
myConnection.Dispose() ;
}

}


class COMDbConnection
{
protected override void Dispose(bool disposing)
{
if (disposing)
{
// Call distructor of the COM object. I know this is not right to
clean memory this way.
// But if anyone points out the right way, I'd appreciate it!
this.~COMDbConnection();
}
// This should be skipped
//base.Dispose(disposing);
}
}
 
We all know that in .NET, we don't need to worry about memory leak
becaseu GC does a nice job to collect it.

The only time we need to worry about memory leak is when we use
unmanaged resources, such as COM-based objects written in C++, for an
instance. Therefore, I've created the following sample code below to
illustrate the step necessary in disposing unmanaged resources.

I believe that to dispose unmanaged resources, we'll need to call the
Destructor of the COM object. However, I don't know what's the right
syntax. I'm looking for advice and input on the piece of code below.
Thanks!

using System;
using System.Runtime.InteropServices;

      namespace iopmb
      {

          [DllImport("user32.dll", EntryPoint="MessageBoxW",
CharSet=CharSet.Auto, ExactSpelling=true)]
          public static extern bool COMDbConnection (string connectionString,
bool useTrustedConnection, string, userName, string password);

          COMDbConnection myConnection = new
COMDbConnection("Provider=sqloledb;Data Source=DataWarehouse;Initial
Catalog=Pace;", true, "sa",  "password") ;

          try
          {
                // do something with myConnection
          }
          catch
          {
          finally
          {
                myConnection.Dispose() ;
          }

      }

      class COMDbConnection
      {
        protected override void Dispose(bool disposing)
        {
            if (disposing)
            {
                // Call distructor of the COM object. I know this is not right to
clean memory this way.
                // But if anyone points out the right way,I'd appreciate it!
                this.~COMDbConnection();
            }
            // This should be skipped
            //base.Dispose(disposing);
        }
      }
Click to expand...

Hi,

I think you should use Marshal.ReleaseComObject method

HTH,
Sergey
 
Curious said:
We all know that in .NET, we don't need to worry about memory leak
becaseu GC does a nice job to collect it.

The only time we need to worry about memory leak is when we use
unmanaged resources, such as COM-based objects written in C++, for an
instance. Therefore, I've created the following sample code below to
illustrate the step necessary in disposing unmanaged resources.

I believe that to dispose unmanaged resources, we'll need to call the
Destructor of the COM object. However, I don't know what's the right
syntax. I'm looking for advice and input on the piece of code below.
Thanks!

using System;
using System.Runtime.InteropServices;

namespace iopmb
{


[DllImport("user32.dll", EntryPoint="MessageBoxW",
CharSet=CharSet.Auto, ExactSpelling=true)]
public static extern bool COMDbConnection (string connectionString,
bool useTrustedConnection, string, userName, string password);

COMDbConnection myConnection = new
COMDbConnection("Provider=sqloledb;Data Source=DataWarehouse;Initial
Catalog=Pace;", true, "sa", "password") ;

try
{
// do something with myConnection
}
catch
{
finally
{
myConnection.Dispose() ;
}

}


class COMDbConnection
{
protected override void Dispose(bool disposing)
{
if (disposing)
{
// Call distructor of the COM object. I know this is not right to
clean memory this way.
// But if anyone points out the right way, I'd appreciate it!
this.~COMDbConnection();
}
// This should be skipped
//base.Dispose(disposing);
}
}
Click to expand...


According to Dispose pattern, you must call overload Dispose() method in
destructor but you called destructor in Dispose() method.
 
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