Do not expand stacktraces when completion exception is rethrown multiple times

[pakrym]

Fixes #31388

Because of incorrect usage of ExceptionDispatchInfo exception stack trace is expanded every time it's rethrown https://github.com/dotnet/corefx/issues/31371

[ahsonkhan]

Remove s_completedNoException now that it is no longer used.
https://github.com/dotnet/corefx/pull/31375/files#diff-ff9ac9c14f9484dcfcaa2332b6353541L16

[pakrym]

Done

[halter73]

Nit: The IsCompleted check now redundant since _exception can't be non-null if not completed.

[halter73]

Nit _exceptionInfo

[benaadams]

Do you also want a test that if the same source exception is passed into multiple pipes it only returns a single entry? aspnet/KestrelHttpServer#2730 (comment)

[pakrym]

But we can't guarantee that. Different instances of EDI would still mutate the same exception object.

[benaadams]

void Main()
{
    Exception exception;
    try
    {
        throw new Exception();
    }
    catch (Exception ex)
    {
        exception = ex;
    }

    var edi1 = ExceptionDispatchInfo.Capture(exception);
    var edi2 = ExceptionDispatchInfo.Capture(exception);

    try
    {
        edi1.Throw();
    }
    catch (Exception ex)
    {
        Console.WriteLine("***");
        Console.WriteLine(ex.ToString());
    }
    try
    {
        edi1.Throw();
    }
    catch (Exception ex)
    {
        Console.WriteLine("***");
        Console.WriteLine(ex.ToString());
    }

    try
    {
        edi2.Throw();
    }
    catch (Exception ex)
    {
        Console.WriteLine("***");
        Console.WriteLine(ex.ToString());
    }
    try
    {
        edi2.Throw();
    }
    catch (Exception ex)
    {
        Console.WriteLine("***");
        Console.WriteLine(ex.ToString());
    }
}

Doesn't seem to?

***
System.Exception: Exception of type 'System.Exception' was thrown.
   at UserQuery.Main() in C:\Users\thund\AppData\Local\Temp\LINQPad5\_jffesacy\query_ibgjui.cs:line 36
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at UserQuery.Main() in C:\Users\thund\AppData\Local\Temp\LINQPad5\_jffesacy\query_ibgjui.cs:line 48
***
System.Exception: Exception of type 'System.Exception' was thrown.
   at UserQuery.Main() in C:\Users\thund\AppData\Local\Temp\LINQPad5\_jffesacy\query_ibgjui.cs:line 36
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at UserQuery.Main() in C:\Users\thund\AppData\Local\Temp\LINQPad5\_jffesacy\query_ibgjui.cs:line 57
***
System.Exception: Exception of type 'System.Exception' was thrown.
   at UserQuery.Main() in C:\Users\thund\AppData\Local\Temp\LINQPad5\_jffesacy\query_ibgjui.cs:line 36
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at UserQuery.Main() in C:\Users\thund\AppData\Local\Temp\LINQPad5\_jffesacy\query_ibgjui.cs:line 67
***
System.Exception: Exception of type 'System.Exception' was thrown.
   at UserQuery.Main() in C:\Users\thund\AppData\Local\Temp\LINQPad5\_jffesacy\query_ibgjui.cs:line 36
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at UserQuery.Main() in C:\Users\thund\AppData\Local\Temp\LINQPad5\_jffesacy\query_ibgjui.cs:line 76

[pakrym]

{
    Exception exception;
    try
    {
        throw new Exception();
    }
    catch (Exception ex)
    {
        exception = ex;
    }

    var edi1 = ExceptionDispatchInfo.Capture(exception);

    try
    {
        edi1.Throw();
    }
    catch (Exception ex)
    {
        Console.WriteLine("***");
        Console.WriteLine(ex.ToString());
    }

    var edi2 = ExceptionDispatchInfo.Capture(exception);
    try
    {
        edi2.Throw();
    }
    catch (Exception ex)
    {
        Console.WriteLine("***");
        Console.WriteLine(ex.ToString());
    }
}

Yes it does:

***
System.Exception: Exception of type 'System.Exception' was thrown.
   at UserQuery.RunUserAuthoredQuery() in C:\Users\pakrymet\AppData\Local\Temp\LINQPad5\_clqswnhi\query_ztirrw.cs:line 39
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at UserQuery.RunUserAuthoredQuery() in C:\Users\pakrymet\AppData\Local\Temp\LINQPad5\_clqswnhi\query_ztirrw.cs:line 50
***
System.Exception: Exception of type 'System.Exception' was thrown.
   at UserQuery.RunUserAuthoredQuery() in C:\Users\pakrymet\AppData\Local\Temp\LINQPad5\_clqswnhi\query_ztirrw.cs:line 39
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at UserQuery.RunUserAuthoredQuery() in C:\Users\pakrymet\AppData\Local\Temp\LINQPad5\_clqswnhi\query_ztirrw.cs:line 50
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at UserQuery.RunUserAuthoredQuery() in C:\Users\pakrymet\AppData\Local\Temp\LINQPad5\_clqswnhi\query_ztirrw.cs:line 61

[benaadams]

So Throw isn't threadsafe as it uses the same exception object

Exception exception;
Exception exception1 = null;
Exception exception2 = null;
try
{
    throw new Exception();
}
catch (Exception ex)
{
    exception = ex;
}

var edi1 = ExceptionDispatchInfo.Capture(exception);

try
{
    edi1.Throw();
}
catch (Exception ex)
{
    Console.WriteLine("***");
    exception1 = ex;
    Console.WriteLine(ex.ToString());
}

var edi2 = ExceptionDispatchInfo.Capture(exception);
try
{
    edi2.Throw();
}
catch (Exception ex)
{
    Console.WriteLine("***");
    exception2 = ex;
    Console.WriteLine(ex.ToString());
}

Console.WriteLine("***");
Console.WriteLine(ReferenceEquals(exception, exception1));
Console.WriteLine(ReferenceEquals(exception, exception2));

***
System.Exception: Exception of type 'System.Exception' was thrown.
   at UserQuery.Main() in C:\Users\thund\AppData\Local\Temp\LINQPad5\_jffesacy\query_tugyst.cs:line 38
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at UserQuery.Main() in C:\Users\thund\AppData\Local\Temp\LINQPad5\_jffesacy\query_tugyst.cs:line 49
***
System.Exception: Exception of type 'System.Exception' was thrown.
   at UserQuery.Main() in C:\Users\thund\AppData\Local\Temp\LINQPad5\_jffesacy\query_tugyst.cs:line 38
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at UserQuery.Main() in C:\Users\thund\AppData\Local\Temp\LINQPad5\_jffesacy\query_tugyst.cs:line 49
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at UserQuery.Main() in C:\Users\thund\AppData\Local\Temp\LINQPad5\_jffesacy\query_tugyst.cs:line 61
***
True
True

So it looks like its equivalent to throw ex; but it keeps the StackTrace at capture and appends from there; whereas throw ex would completely overwrite.

[pakrym]

@ahsonkhan ping