[jira] [Created] (HBASE-30392) Exclude checksum bytes from cache-on-write HFile block data size

["huginn (Jira)" <ji...@apache.org>]

huginn created HBASE-30392:
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             Summary: Exclude checksum bytes from cache-on-write HFile block data size
                 Key: HBASE-30392
                 URL: https://issues.apache.org/jira/browse/HBASE-30392
             Project: HBase
          Issue Type: Bug
          Components: BlockCache
    Affects Versions: 2.4.11
            Reporter: huginn


h3. What happens

When an HFile block is cached on write, the cache buffer contains only the block header and on-disk data. The HFileBlock metadata field onDiskDataSizeWithHeader is nevertheless populated with a value that also includes trailing checksum bytes.

h3. When it happens

This occurs when cache-on-write creates a block through HFileBlock.Writer#getBlockForCaching, including compressed cache and index or inline blocks.

h3. Impact

The metadata and buffer length disagree. Subsequent cache block validation or unpacking can use an incorrect data length, causing cache equality failures or read or decompression errors.

h3. Root cause

HFileBlock.Writer#getBlockForCaching uses onDiskBlockBytesWithHeader.size() + onDiskChecksum.length even though cloneOnDiskBufferWithHeader() copies only the header and data, and the cache context has no checksum bytes. The invariant for onDiskDataSizeWithHeader is the header plus data length, excluding checksums.

h3. Proposed fix

Set onDiskDataSizeWithHeader to onDiskBlockBytesWithHeader.size(), while preserving onDiskSizeWithoutHeader, which continues to include checksum bytes for the physical file size.

h3. Reproduction / Testing

Add test evidence here.




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