fix compression in replicator

[PikaZ76]

What changed? Why?

fix ZSTD compression in replicator

How did you test the change?

• unit test
• integration test
• functional test
• adhoc test (described below)

[gemini-code-assist]

Summary of Changes

Hello @PikaZ76, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses and rectifies issues related to data compression within the replicator component. It introduces a more flexible and robust mechanism for handling various compression types, with a specific focus on ensuring proper processing of ZSTD compressed data. The changes streamline the data flow by correctly decompressing incoming data and recompressing it to the required format.

Highlights

• Refactored Compression Logic: The pull request refactors the data compression and decompression logic within the replicator, moving from a switch statement based on blockFile.Compression to a more generalized approach that handles different source and target compression types.
• ZSTD Compression Support: Explicitly adds support for ZSTD compression in the replicator's data processing, ensuring that ZSTD compressed block data is correctly handled and assigned.
• Improved Robustness: The new logic ensures that block data is correctly decompressed from its source format and then recompressed to the desired target format, improving the overall robustness of the compression pipeline.

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[gemini-code-assist]

Code Review

This pull request aims to add support for ZSTD compression in the replicator. The changes correctly add ZSTD to the supported compression types and refactor the compression handling logic. However, the new logic for converting between compression formats has a potential issue where it might call compression/decompression utilities with api.Compression_NONE, which could lead to runtime errors. I've provided a suggestion to make this logic more robust by adding explicit checks. The rest of the changes look good.