`CachedCodecLookup` wrongly assumes uniqueness of `hashCode()`

[mar-v-in]

Bug Report

I got the following error on one of my machines repeatedly, when the same code worked fine on others:

class java.util.UUID cannot be cast to class java.net.InetAddress (java.util.UUID and java.net.InetAddress are in module java.base of loader 'bootstrap')
at io.r2dbc.postgresql.codec.InetAddressCodec.doEncode(InetAddressCodec.java:35)

It took me some time to debug this (also because running the JVM with debugger enabled would change the behavior), but I finally found the culprit.

It seems that it can happen that java.util.UUID.class.hashCode() == java.net.InetAddress.class.hashCode() and the CachedCodecLookup implementation does not handle that case. I don't know why this happens and would assume that the JVM makes best effort to not let this happen, but it does happen for me and for as far as I can tell, the JVM and Java documentation do not guarantee that it can't happen.

Versions

• Driver: 0.8.11
• Database: 13.5
• Java: 11.0.15
• OS: Linux 5.10

[mp911de]

That's fixed now. Care to restest against the latest snapshots?

[mar-v-in]

Mind backporting this to 0.8.x? The codebase where I see this issue is using Spring Boot 2.6.x, making tests with r2dbc-postgresql 0.9.x unfeasible.

[mp911de]

That's backported to 0.8.x now.

[mar-v-in]

Thanks. Can confirm it works fine on the system where it failed before using 0.8.13.BUILD-SNAPSHOT.

[edeesis]

We ran into this on 0.9.1.RELEASE, and had trouble finding the issue in the search.

For those looking for a fix to ClassCastException when using r2dbc postgres, upgrading to 0.9.2.RELEASE fixed it for us.