JSR356 Encoder#init is not called when created on demand

[fbuecklers]

I have created a BaseMessage class and 3 sub classes wich can be converted by one generic Encoder<BaseMessage> encoder.

Jetty correctly creates encoders for my subclasses but the init methods of the created Encoders are not called.

The reason seems to be in EncoderFactory#getWrapperFor implementation where the on demand wrapper creation doesn't call the Encoder#init method after creation.

Testet with Jetty 9.3.14.v20161028

[joakime]

Cannot replicate this.

Do you have a sample project that can replicate this?

[joakime]

Unable to Replicate. Feel free to reopen if you have a reproduction case.

[ericljiang]

I'm encountering this in 9.4.18.v20190429. It seems very similar to #425. Jetty constructs and initializes (calls init()) an encoder instance upon connection but never uses it. Instead it creates a new instance upon calling session.getBasicRemote().sendObject(event) and never calls init() on the new instance. Debugging shows that the second instance is created by the same code @fbuecklers referenced:
https://github.com/eclipse/jetty.project/blob/jetty-9.4.x/jetty-websocket/javax-websocket-client-impl/src/main/java/org/eclipse/jetty/websocket/jsr356/EncoderFactory.java#L139-L147

Working on providing a sample project soon.

[joakime]

@ericljiang interesting discovery. reopened.

[joakime]

@lachlan-roberts do you recall any changes on jetty-9.4.x related to this?

I cannot seem to replicate this.

[lachlan-roberts]

@joakime not that I can recall, I don't think I've touched encoders in 9.4.
I'll take a closer look and see if I can replicate the issue.

[lachlan-roberts]

@joakime I was able to reproduce this and have proposed a fix in PR #4987.

[lachlan-roberts]

The fix for this has been merged into 9.4.x with PR #4987 and will be available in a 9.4.31 release.