03a781a90c
Summary: This PR adds support for pipelined & parallel compression optimization for `BlockBasedTableBuilder`. This optimization makes block building, block compression and block appending a pipeline, and uses multiple threads to accelerate block compression. Users can set `CompressionOptions::parallel_threads` greater than 1 to enable compression parallelism. Pull Request resolved: https://github.com/facebook/rocksdb/pull/6262 Reviewed By: ajkr Differential Revision: D20651306 fbshipit-source-id: 62125590a9c15b6d9071def9dc72589c1696a4cb