LevelDB native support #1839

[JiriOndrusek]

fixes #1839

There are several "topics" where I'd appreciate opinion of others.

1. Preferred implementation of LevelDb is in C++, implementation in Java is much slower (see https://github.com/dain/leveldb#leveldb-in-java). Current PR uses only Java implementation in native. I'd like to investigate possible usage of C++ library in native, but I see it more like an enhancement, because current PR works.

2. Component levelDb uses serialization of DefaultExchangeHolder. I've used workaround with Jackson serialization instead. (see https://github.com/apache/camel-quarkus/compare/master...JiriOndrusek:1839-leveldb-native?expand=1#diff-5fbe79b4f16469a82d30051dc3cf564aR46)

3. Java implementation of LevelDB uses methodHandle which is not supported by GraalVM. I used previous version of ByteBufferSupport and applied it via substitutions until issue Implement method handle support for GraalVM Native Image oracle/graal#2761 is fixed. See more information here: https://github.com/apache/camel-quarkus/compare/master...JiriOndrusek:1839-leveldb-native?expand=1#diff-799b2f59808725c0c8b95feacb5b4c8aR25

From my POV this PR could be merged. I'm currently starting to investigate support of C++ levelDB. If this approach will work, I'd enhance this extension (which is working as is)

What do you think, @ppalaga ?

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[ppalaga]

1. Preferred implementation of LevelDb is in C++, implementation in Java is much slower (see https://github.com/dain/leveldb#leveldb-in-java). Current PR uses only Java implementation in native. I'd like to investigate possible usage of C++ library in native, but I see it more like an enhancement, because current PR works.

+1. If the LevelDB Java port works well in the native, it is a good state to start with. We can file an issue to track how much interest is there to support also the C++ implementation and consider revisiting it if enough people ask for it.

2. Component levelDb uses serialization of DefaultExchangeHolder. I've used workaround with Jackson serialization instead. (see https://github.com/apache/camel-quarkus/compare/master...JiriOndrusek:1839-leveldb-native?expand=1#diff-5fbe79b4f16469a82d30051dc3cf564aR46)

Commented inline

3. Java implementation of LevelDB uses methodHandle which is not supported by GraalVM. I used previous version of ByteBufferSupport and applied it via substitutions until issue oracle/graal#2761 is fixed. See more information here: https://github.com/apache/camel-quarkus/compare/master...JiriOndrusek:1839-leveldb-native?expand=1#diff-799b2f59808725c0c8b95feacb5b4c8aR25

Commented inline

From my POV this PR could be merged. I'm currently starting to investigate support of C++ levelDB. If this approach will work, I'd enhance this extension (which is working as is)

Let me review properly. so far I looked only at the areas you asked about.

[ppalaga]

Great work, thanks @JiriOndrusek ! Some minor suggestions and comments inline.

[JiriOndrusek]

Do not merge, please!

It seems, that current implementation has another limoitation (see https://issues.apache.org/jira/browse/CAMEL-15679?focusedCommentId=17213151&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-17213151) This implementation will work only for text based payloads.

I'll try to formulate limitations.adoc and try to add some validations.

[JiriOndrusek]

I've added into limitation.adoc new limitation. Binary payloads are not supported in native mode. This will be possible once camel-leveldb component is refactored (https://issues.apache.org/jira/browse/CAMEL-15679)
New test for binary payload is added, test in native mode expects failure.

Can be merged.

[ppalaga]

I rebased on top of the current master. Let's merge if the CI passes.