CSHARP-5572: Implement new KnownSerializerFinder

[rstam]

No description provided.

[Szmiglo]

hi @rstam, what's the status of this effort?

[rstam]

hi @rstam, what's the status of this effort?

It is progressing well, but it is a large effort. I work on this whenever I'm not working on some smaller higher priority task.

[adelinowona]

I think we should move the duplicate check to the beginning of the AddSerializer method to implement fail-fast behavior. This would avoid unnecessary serializer transformation work when a serializer already exists for the node.

However, I notice the current implementation places this check at the end, likely to preserve information about the conflicting serializer for the exception. While this debugging information could be helpful, I question just how useful it is. Knowing where a duplicate attempt happened seems more useful knowing what the conflicting serializer would have been.

I lean toward the fail-fast approach since the conflicting serializer details seem like a "nice-to-have" rather than essential debugging information.

[rstam]

If we move the error check further up then we have to remove information about the redundant serializer from the error message.

Also, I don't think we need to worry about failing fast because we actually never expect to hit this error. This check is here to help us find bugs. In the absence of bugs this exception will never be thrown.

[adelinowona]

Seems like this is never used?

[rstam]

Removed.

[adelinowona]

Could we maybe make use of a state enum as such:

private enum DiscoveryPhase
{
    InferringFromContext,      // Not using defaults
    UsingDefaultSerializers,   // Last attempt with defaults
    Complete                    // No more progress possible
}

to replace the use of all these booleans used in keeping track of the state of the visitor?

[rstam]

It's somewhat reasonable, but I think the booleans work better here.

There are only 2 booleans.

One issue is that if we ever had more states the order of the enum values could get very confusing and maybe even no order is possible.