Add an option to disable duplicate path mapping detection

[trustin]

As proposed by @anuraaga at #529 (comment)

[anuraaga]

Also I was thinking this is probably cleanest as adding serviceIfAbsent methods. It would be too much to add all the convenience method versions but just two for PathMapping and ServiceWithPathMapping should be complete and enough since it's just an advanced usage.

[trustin]

Duplicate detection can never be perfect, so serviceIfAbsent() would not work as expected - it may be added even if there is actually a duplicate mapping. 😭

[anuraaga]

Ah yeah that's true. Actually I guess it means on the flip side it could only have the one version that takes an exact path String since it's the only duplicate we detect right now IIUC

[trustin]

Actually I guess it means on the flip side it could only have the one version that takes an exact path String since it's the only duplicate we detect right now IIUC.

We also check duplicates for all trie-based path mappings. Regex-based mappings complicate the matter.

I see a few options here:

• Add an option that disables duplicate mapping detection.
  • We may also want to add a method the checks if there's duplicate mapping.
• Do not perform duplicate mapping detection at all, i.e. revert the PR.
  • .. because it's imperfect and a user will notice eventually? /cc @imasahiro
• Allow a user to specify the callback for duplicate services.
  • The default callback would be to raise an exception or log a warning message.
  • A user could choose to do nothing in the callback.

Thoughts?

[minwoox]

I think we need to catch the duplicate paths as much as possible although it cannot be perfect.
So the user would notice when he/she start the server.
I like the way that allow a user to specify the callback and the default callback is raising an exception.

[hyangtack]

I agree with @minwoox 's comment. Option 1 or 3 sounds good to me.

[anuraaga]

Yeah the callback sounds good too. Maybe it can be something on the exception itself, something like DuplicatePathException#applyAnyways(), and users just catch the exception if they care about applying anyways.

[trustin]

Let me schedule this for the release after the next release since we are releasing soon.