Exception logging in XML-RPC and JSON-RPC is different

[Karl]

Exceptions raised in the XML-RPC component are logged in the send_rpc_error() method. The corresponding method in the JSON-RPC method does not include any logging.

This means that tracebacks are shown to the user, but don't exist in the logs, which is an issue for debugging.

I've attached a patch which simply adds a log.exception call to the JSON-RPC send_rpc_error method.

[Olemis Lang]

It'd be nice to have a generic solution for this i.e. log.exception always called from a single location no matter what RPC protocol handler is involved .

[osimons]

A few comments:

1. Having each handler log errors as it wants is fine by me. Somehow doing this in a shared location will just add complicated scaffolding with entangled code that will just come back and bite us later. I'm fine with the approach suggested in the patch.
2. I don't think log.exception() is available for all the versions of Trac the plugin supports, and just for this purpose I added tracrpc.util.exception_to_unicode() compat handling to ensure we have a way that works for all. Grep the code to see examples of its use.
3. I actually don't think you can do logging as the last line if send_rpc_error(). Does that really work? _send_response() will actually raise RequestDone which in turn should abort any further execution. Move the exception logging one line up to log before sending the response.

Care to update the patch?