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GC.Collect() in Dispose in simple class

I have inherited a kind of ancient website project in c#. It originates from 2003
This has all over the place simple classes defined that inherit from IDisposible and implement a Dispose() method where GC.Collect() is called as below:
public class ProjectAutostart : IDisposable
{
public void Dispose()
{
Dispose(true);
GC.Collect();
}
protected virtual void Dispose(bool disposing) { }
private Int32 _id;
private Int32 _stepid;
private Int64 _stepcounter;
public Int32 ID
{
set { _id = value; }
get { return _id; }
}
public Int32 StepID
{
set { _stepid = value; }
get { return _stepid; }
}
public Int64 StepCounter
{
set { _stepcounter = value; }
get { return _stepcounter; }
}
}
These classes are called like:
List<Projects.ProjectAutostart> ProjectList = DataLayer.Projects.getProjectAutoStart();
Which ends up in:
public static List<Projects.ProjectAutostart> getProjectAutoStart()
{
List<Projects.ProjectAutostart> Projects = new List<Projects.ProjectAutostart>();
DataTable DataTable = SQL.DataTable("getProjectAutoStart", null);
foreach (DataRow dt in DataTable.Rows)
{
Projects.Add(new ProjectAutostart { ID = Convert.ToInt32(dt["projectid"]), StepID = Convert.ToInt32(dt["stepid"]), StepCounter = Convert.ToInt32(e["autostartstepcounter"]) });
}
DataTable.Dispose();
return Projects;
}
I'm not experienced with this type of projects, I'm totally into the .net core restfull area so this code is strange to me.
Asides from the total weird way of implementing, These GC.Collect() and that Dispose() feel totally useless since it is managed code and it are simple class without any coding executing. Why would someone put that Dispose and GC.Collect() in there?
Should I just remove it?

As already noted in the comments, GC.Collect() in the Dispose method is completely superfluous here. Maybe they got the dispose pattern wrong in the first place.
The recommended implementation for the dispose pattern is as follows:
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this); // sic!
}
protected virtual void Dispose(bool disposing)
{
}
However, since your ProjectAutostart class is a pure DTO and does not have any disposable fields (and any derived classes probably don't, either), you don't even need to implement dispose here. Just remove both Dispose methods as well as the interface declaration. What you do need to dispose is the DataTable object, but that's properly done already.

Implementing C# IDisposable [duplicate]

This question already has answers here:
Proper use of the IDisposable interface
(20 answers)
Closed 3 years ago.
I am trying to work out exactly what I need to do to dispose of a property in C# when using IDisposable. I can see the template, but I am not sure about actually disposing of objects.
I am working with the example given on this site:
https://learn.microsoft.com/en-us/dotnet/standard/garbage-collection/implementing-dispose
I have added 3 properties:
privInt: Private value type. Would I dispose of this as it could be saved on the heap so may require GC? If I would then how, cannot set to null or call dispose? If not then I assume it has to be left to GC - but is it not the point of Dispose to free resources?
NonIDisClassInstance - Do I set to null? Is that enough
Can anyone comment on my implementation below and advise on what is correct/wrong.
IDisClass - Just call dispose
class BaseClass : IDisposable
{
// Flag: Has Dispose already been called?
bool disposed = false;
// Public implementation of Dispose pattern callable by consumers.
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
}
//Private value type
private int privInt;
//Private class that does not implement IDisposable
Private NonIDisClass NonIDisClassInstance;
//Private class that does implement IDisposable
Private IDisClass IDisClassInstance;
// Protected implementation of Dispose pattern.
protected virtual void Dispose(bool disposing)
{
if (disposed)
return;
if (disposing) {
// Free any other managed objects here.
//
}
// Free any unmanaged objects here.
DisposeOfThis = ????;
NonIDisClassInstance = null;
IDisClassInstance.Dispose();
disposed = true;
}
~BaseClass()
{
Dispose(false);
}
}

You only need GC.SuppressFinalize(this); and a destructor if you are working with unmanaged memory. If not you can safely omit this.
In your Dispose implementation call this.IDisClassInstance?.Dispose();, that is all you need.
Your code can be condensed down to this.
class BaseClass : System.IDisposable
{
public virtual void Dispose()
{
// never throw an exception from Dispose so prevent an NRE by using ?.
this.IDisClassInstance?.Dispose();
}
//Private class that does not implement IDisposable
private object NonIDisClassInstance;
//Private class that does implement IDisposable
private IDisposable IDisClassInstance;
}
Do keep in mind that using Dispose is not necessarily about freeing up memory, it is about cleaning up / freeing up unmanaged resources which might also include memory. Things like open file streams or database connections or network connections.
Note that your derived types can override Dispose but those overriden methods should include a call to base.Dispose(); so the managed resources of the base class are released.

Will using destroy data if return will be inside [duplicate]

This question already has answers here:
What happens if i return before the end of using statement? Will the dispose be called?
(5 answers)
Closed 4 years ago.
While working on my project, I was wondering, will using auto-destruct data if return will be inside of a using.
Example block of code:
using(ManagedObject obj = new ManagedObject())
{
int usualNumber = 0;
// some magic stuff
...
// magic stuff ends
return usualNumber; // return goes inside of 'using' brackets
}
And here is the question, will our ManagedObject which implements IDisposable be disposed by 'using' statement?

using statement can be seen as try and finally combination.
Your code is equivalent to:
ManagedObject obj = new ManagedObject();
try
{
int usualNumber = 0;
// some magic stuff
...
// magic stuff ends
return usualNumber;
}
finally
{
if (obj != null)
((IDisposable)obj ).Dispose();
}
I assume, that the answer to your question can be seen thanks to this code sample.

using is a Syntactic sugar, it need to contain an object which implements IDisposable interface when you leave the using scope .net will call the IDisposable.Dispose method Automatically.
Here is a sample c# online
when the program leave Test method. .net will call IDisposable.Dispose method Automatically

Yes, It will call the Dispose() function implemented by the IDisposable interface
class Program
{
static void Main(string[] args)
{
new Test().TestIt();
Console.Read();
}
}
class Test
{
public int TestIt()
{
using (ManagedObject obj = new ManagedObject())
{
int usualNumber = 0;
return usualNumber;
}
}
}
internal class ManagedObject : IDisposable
{
public void Dispose()
{
Console.WriteLine("Disposed");
}
}

Yes, even if you return from inside the using block, it will still call Dispose on obj.
Note that returning the usualNumber is perfectly fine, but if you were to return obj, that could be a problem because you would be returning a "disposed" object.
(Technically, objects could be usable after calling Dispose. For example, you could implement a Dispose that does nothing. But generally, most Dispose implementations would put the object in an unusable state).

Should I always implement the dispose pattern if my class defines a field in which the field’s type implements the dispose pattern? c# [duplicate]

This question already has answers here:
Who Disposes of an IDisposable public property?
(10 answers)
Closed 6 years ago.
I recently read this in "CLR via C#" by Jeffery Richter;
Important If a class defines a field in which the field’s type
implements the dispose pattern, the class itself should also implement
the dispose pattern. The Dispose method should dispose of the object
referred to by the field. This allows someone using the class to call
Dispose on it, which in turn releases the resources used by the object
itself.
Would this be true in the following example?
public class SomeClass
{
private readonly StreamReader _reader; //a disposable class
public SomeClass(StreamReader reader)
{
_reader = reader;
}
}
Although StreamReader is a disposable class its intance has been passed in via the constructor, it will therefore probably be referenced somewhere else and so implementing IDisposable on SomeClass so that _reader can be disposed seems like a bad idea. Is the point that Jeffery Richter is trying to make only applicable to classes where the instances of disposable classes are instantiated within that class?

Although StreamReader is a disposable class its instance has been
passed in via the constructor, it will therefore probably be
referenced somewhere else and so implementing IDisposable on SomeClass
That really depends. Generally, it is a good rule of thumb to implement IDisposable when you're holding disposable resources. But, if you know for a fact that someone else is going to hold a reference to the said resource, you can create an overload in your class constructor which explicitly asks the caller if he wants you to dispose:
public class SomeClass : IDisposable
{
private readonly StreamReader _reader; //a disposable class
private bool shouldDispose;
public SomeClass(StreamReader reader) : this(reader, true)
{
}
public SomeClass(StreamReader reader, bool shouldDispose)
{
_reader = reader;
this.shouldDispose = shouldDispose;
}
public void Dispose()
{
if (shouldDispose)
{
Dispose(true);
}
}
protected void Dispose(bool isDisposing)
{
if (isDisposing)
{
_reader.Dispose();
}
}
}

There is almost never a scenario where the term "always" is appropriate. There are a lot of scenarios where this can be both true and not true. Here's the following example
public class DbSomething : IDisposable
{
private SqlConnection _connection;
public DbSomething (SqlConnection connection){
_connection = connection;
}
~DbSomething() {
Dispose(true);
}
bool disposed = false;
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
}
protected virtual void Dispose(bool disposing)
{
if (disposed)
return;
if (disposing)
{
_connection.Dispose();
}
disposed = true;
}
}
Now if this class implements IDisposable and disposes the connection, what happens if this connection is going to be used somewhere else? This class is modifying the state of an object that doesn't belong to it.
Consequently,
public class DbSomething : IDisposable
{
private SqlConnection _connection;
public DbSomething (){
_connection = new SqlConnection();
}
//same dispose
}
This class has control over the SqlConnection object. It created it and it should dispose of it. So what happens if you make the SqlConnection public for other things to consume?
public class DbSomething
{
public SqlConnection Connection;
public DbSomething (){
Connection = new SqlConnection();
}
//same dispose
}
Now I would still default to, that object created it, that object should get rid of it, but depending on the code, that might not be possible. It might be just a factory to create a long lived object which eventually needs to be disposed, and the creation object is no longer necessary after that. In this case case having the creation object dispose of it becomes a problem, so even though the first two scenarios seem like good ideas, deviating from them is the appropriate choice.
The method could also be something like this, where it doesn't even hold an instance to the object to dispose:
public class DbSomething
{
public SqlConnection CreateSqlConnection () => return new SqlConnection();
}

Implementing IDisposable correctly

In my classes I implement IDisposable as follows:
public class User : IDisposable
{
public int id { get; protected set; }
public string name { get; protected set; }
public string pass { get; protected set; }
public User(int UserID)
{
id = UserID;
}
public User(string Username, string Password)
{
name = Username;
pass = Password;
}
// Other functions go here...
public void Dispose()
{
// Clear all property values that maybe have been set
// when the class was instantiated
id = 0;
name = String.Empty;
pass = String.Empty;
}
}
In VS2012, my Code Analysis says to implement IDisposable correctly, but I'm not sure what I've done wrong here.
The exact text is as follows:
CA1063 Implement IDisposable correctly Provide an overridable implementation of Dispose(bool) on 'User' or mark the type as sealed. A call to Dispose(false) should only clean up native resources. A call to Dispose(true) should clean up both managed and native resources. stman User.cs 10
For reference: CA1063: Implement IDisposable correctly
I've read through this page, but I'm afraid I don't really understand what needs to be done here.
If anyone can explain in more layman's terms what the problem is and/or how IDisposable should be implemented, that will really help!

This would be the correct implementation, although I don't see anything you need to dispose in the code you posted. You only need to implement IDisposable when:
You have unmanaged resources
You're holding on to references of things that are themselves disposable.
Nothing in the code you posted needs to be disposed.
public class User : IDisposable
{
public int id { get; protected set; }
public string name { get; protected set; }
public string pass { get; protected set; }
public User(int userID)
{
id = userID;
}
public User(string Username, string Password)
{
name = Username;
pass = Password;
}
// Other functions go here...
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
}
protected virtual void Dispose(bool disposing)
{
if (disposing)
{
// free managed resources
}
// free native resources if there are any.
}
}

First of all, you don't need to "clean up" strings and ints - they will be taken care of automatically by the garbage collector. The only thing that needs to be cleaned up in Dispose are unmanaged resources or managed recources that implement IDisposable.
However, assuming this is just a learning exercise, the recommended way to implement IDisposable is to add a "safety catch" to ensure that any resources aren't disposed of twice:
public void Dispose()
{
Dispose(true);
// Use SupressFinalize in case a subclass
// of this type implements a finalizer.
GC.SuppressFinalize(this);
}
protected virtual void Dispose(bool disposing)
{
if (!_disposed)
{
if (disposing)
{
// Clear all property values that maybe have been set
// when the class was instantiated
id = 0;
name = String.Empty;
pass = String.Empty;
}
// Indicate that the instance has been disposed.
_disposed = true;
}
}

The following example shows the general best practice to implement IDisposable interface. Reference
Keep in mind that you need a destructor(finalizer) only if you have unmanaged resources in your class. And if you add a destructor you should suppress Finalization in the Dispose, otherwise it will cause your objects resides in memory longer that it should (Note: Read how Finalization works). Below example elaborate all above.
public class DisposeExample
{
// A base class that implements IDisposable.
// By implementing IDisposable, you are announcing that
// instances of this type allocate scarce resources.
public class MyResource: IDisposable
{
// Pointer to an external unmanaged resource.
private IntPtr handle;
// Other managed resource this class uses.
private Component component = new Component();
// Track whether Dispose has been called.
private bool disposed = false;
// The class constructor.
public MyResource(IntPtr handle)
{
this.handle = handle;
}
// Implement IDisposable.
// Do not make this method virtual.
// A derived class should not be able to override this method.
public void Dispose()
{
Dispose(true);
// This object will be cleaned up by the Dispose method.
// Therefore, you should call GC.SupressFinalize to
// take this object off the finalization queue
// and prevent finalization code for this object
// from executing a second time.
GC.SuppressFinalize(this);
}
// Dispose(bool disposing) executes in two distinct scenarios.
// If disposing equals true, the method has been called directly
// or indirectly by a user's code. Managed and unmanaged resources
// can be disposed.
// If disposing equals false, the method has been called by the
// runtime from inside the finalizer and you should not reference
// other objects. Only unmanaged resources can be disposed.
protected virtual void Dispose(bool disposing)
{
// Check to see if Dispose has already been called.
if(!this.disposed)
{
// If disposing equals true, dispose all managed
// and unmanaged resources.
if(disposing)
{
// Dispose managed resources.
component.Dispose();
}
// Call the appropriate methods to clean up
// unmanaged resources here.
// If disposing is false,
// only the following code is executed.
CloseHandle(handle);
handle = IntPtr.Zero;
// Note disposing has been done.
disposed = true;
}
}
// Use interop to call the method necessary
// to clean up the unmanaged resource.
[System.Runtime.InteropServices.DllImport("Kernel32")]
private extern static Boolean CloseHandle(IntPtr handle);
// Use C# destructor syntax for finalization code.
// This destructor will run only if the Dispose method
// does not get called.
// It gives your base class the opportunity to finalize.
// Do not provide destructors in types derived from this class.
~MyResource()
{
// Do not re-create Dispose clean-up code here.
// Calling Dispose(false) is optimal in terms of
// readability and maintainability.
Dispose(false);
}
}
public static void Main()
{
// Insert code here to create
// and use the MyResource object.
}
}

IDisposable exists to provide a means for you to clean up unmanaged resources that won't be cleaned up automatically by the Garbage Collector.
All of the resources that you are "cleaning up" are managed resources, and as such your Dispose method is accomplishing nothing. Your class shouldn't implement IDisposable at all. The Garbage Collector will take care of all of those fields just fine on its own.

You need to use the Disposable Pattern like this:
private bool _disposed = false;
protected virtual void Dispose(bool disposing)
{
if (!_disposed)
{
if (disposing)
{
// Dispose any managed objects
// ...
}
// Now disposed of any unmanaged objects
// ...
_disposed = true;
}
}
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
}
// Destructor
~YourClassName()
{
Dispose(false);
}

You have no need to do your User class being IDisposable since the class doesn't acquire any non-managed resources (file, database connection, etc.). Usually, we mark classes as
IDisposable if they have at least one IDisposable field or/and property.
When implementing IDisposable, better put it according Microsoft typical scheme:
public class User: IDisposable {
...
protected virtual void Dispose(Boolean disposing) {
if (disposing) {
// There's no need to set zero empty values to fields
// id = 0;
// name = String.Empty;
// pass = String.Empty;
//TODO: free your true resources here (usually IDisposable fields)
}
}
public void Dispose() {
Dispose(true);
GC.SuppressFinalize(this);
}
}

Idisposable is implement whenever you want a deterministic (confirmed) garbage collection.
class Users : IDisposable
{
~Users()
{
Dispose(false);
}
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
// This method will remove current object from garbage collector's queue
// and stop calling finilize method twice
}
public void Dispose(bool disposer)
{
if (disposer)
{
// dispose the managed objects
}
// dispose the unmanaged objects
}
}
When creating and using the Users class use "using" block to avoid explicitly calling dispose method:
using (Users _user = new Users())
{
// do user related work
}
end of the using block created Users object will be disposed by implicit invoke of dispose method.

I see a lot of examples of the Microsoft Dispose pattern which is really an anti-pattern. As many have pointed out the code in the question does not require IDisposable at all. But if you where going to implement it please don't use the Microsoft pattern. Better answer would be following the suggestions in this article:
https://www.codeproject.com/Articles/29534/IDisposable-What-Your-Mother-Never-Told-You-About
The only other thing that would likely be helpful is suppressing that code analysis warning... https://learn.microsoft.com/en-us/visualstudio/code-quality/in-source-suppression-overview?view=vs-2017