Summary:
closes https://github.com/facebook/rocksdb/issues/8039
Unnecessary use of multiple local JNI references at the same time, 1 per key, was limiting the size of the key array. The local references don't need to be held simultaneously, so if we rearrange the code we can make it work for bigger key arrays.
Incidentally, make errors throw helpful exception messages rather than returning a null pointer.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/9012
Reviewed By: mrambacher
Differential Revision: D31580862
Pulled By: jay-zhuang
fbshipit-source-id: ce05831d52ede332e1b20e74d2dc621d219b9616