8b6b6aeb1a
Summary: Added a few classes in the same class hierarchy to remove code duplication and refactor the logic of reading and processing MANIFEST files. New classes are as follows. ``` class VersionEditHandlerBase; class ListColumnFamiliesHandler : VersionEditHandlerBase; class FileChecksumRetriever : VersionEditHandlerBase; class DumpManifestHandler : VersionEditHandler; ``` Classes that already existed before this PR are as follows. ``` class VersionEditHandler : VersionEditHandlerBase; ``` With these classes, refactored functions: `VersionSet::Recover()`, `VersionSet::ListColumnFamilies()`, `VersionSet::DumpManifest()`, `GetFileChecksumFromManifest()`. Test Plan (devserver): ``` make check COMPILE_WITH_ASAN=1 make check ``` These refactored code, especially recovery-related logic, will be tested intensively by all existing unit tests and stress tests. For example, run ``` make crash_test ``` Verified 3 successful runs on devserver. Pull Request resolved: https://github.com/facebook/rocksdb/pull/6581 Reviewed By: ajkr Differential Revision: D20616217 Pulled By: riversand963 fbshipit-source-id: 048c7743aa4be2623ccd0cc3e61c0027e604e78b