01013ae766
Summary: This is essentially a re-submission of #4251 with a few improvements: - Split `CompressionDict` into two separate classes: `CompressionDict` and `UncompressionDict` - Eliminated `Init` functions. Instead do all initialization work in constructors. - Added test case for parallel DB open, which is the scenario where #4251 failed under TSAN. Pull Request resolved: https://github.com/facebook/rocksdb/pull/4849 Differential Revision: D13606039 Pulled By: ajkr fbshipit-source-id: 08c236059798c710db9cbf545fce0f371232d447