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duckdb / duckdb-java

DuckDB JDBC Driver
https://duckdb.org/docs/api/java.html
MIT License
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Expose db memory address and path to libduckdb_java.so #87

Open Jens-H opened 2 months ago

Jens-H commented 2 months ago

This PR adds two methods to the DuckDBConnection object to:

  1. Get the memory address of the DuckDB pointer from JNI
  2. Get the path and name of the loaded libduckdb_java.so

With these two pieces of information, it should be possible to create db connections with another driver like e.g. https://github.com/techascent/tmducken for Clojure in parallel. (By the way: this driver is not yet mentioned on the homepage as third-party driver.)

Jens-H commented 2 months ago

No idea why the format check failed - locally it runs without errors. Maybe the non-ASCII chars ...

@Mause Any idea? Or may we ignore it?

Mause commented 2 months ago

Looks like it might be an encoding thing yeah.

As far as the change goes, why return the memory address as a string?

And I'd like to see some kind of javadoc on the memory method at least mentioning the unsafety

Jens-H commented 2 months ago

Sadly a string seems to be the simplest and secure way without having pointers and unsigned 64 bit integers in Java/JNI return types.

You're right, some kind of warning seems appropriate. I'll add that.

Mause commented 1 month ago

Can you expand on why returning a pointer cast to an integer via jni is unsafe?

Jens-H commented 1 month ago

Well, basically I'm not sure if casting the memory address like this will work everywhere (Linux-AMD64 seems ok): return (jlong)conn_ref->db.get();

Maybe you can confirm that this should be fine. Then I'm happy to change the PR accordingly.