Interconnecting Java and Native Code with the FFM API
summary
Shows how Java SE 22’s Foreign Function & Memory API models off‑heap buffers as a memory segment, enforces bounds and deterministic deallocation via arena lifetimes, and describes native functions with var handles and downcall handle descriptors so calling C is pure Java. Demonstrations include invoking getpid, passing C strings, qsort with a Java comparator via a callback, and using jextract to auto‑generate bindings for OpenGL TensorFlow and FFmpeg. Performance equals JNI for calls and often beats JNI for upcalls.
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chapters (10)
- 0:00Introduction to FFM
- 2:08JNI limitations
- 6:49Memory segments
- 10:21Memory safety with arenas
- 17:42Memory layouts
- 22:38Foreign function API
- 25:07Using jextract
- 27:57Live coding demonstration
- 36:42API evolution
- 40:23Summary and Q&A
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