Passing class pointer to native could improve performance.

[hideki]

• Accessing from native to java code is more expensive.
• To obtain class pointer from native requires one additional JNI call.
  http://www.ibm.com/developerworks/java/library/j-jni/#reaching

Passing class pointer to native could improve performance.

[pasin]

Will this also help collator calling back to java for unicode comparison?

[hideki]

@pasin No. Article suggested to less call from native to java code by passing all values in one JNI call from java to native.

If collator can consolidate the calls from native to java or reduce the number of calls, it will improve the performance. We need to review collator codes.

[snej]

Can you give examples of how we could optimize particular calls?

[hideki]

Java_com_couchbase_cbforest_QueryIterator_next() calls getEnum(env, self) to obtain the pointer of C4QueryEnumerator. In side the getEnum(env, self), it calls env->GetLongField(self, kHandleField); which is JNI call from native to Java code. By passing class pointer from Java to native, we could avoid this JNI call. In case of iterating 100 or 1K docs, we could same number of JNI calls.
https://github.com/couchbaselabs/cbforest/blob/master/Java/jni/native_queryIterator.cc#L35