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https://issues.apache.org/jira/browse/HDDS-1496?focusedWorklogId=239831&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-239831
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ASF GitHub Bot logged work on HDDS-1496:
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Author: ASF GitHub Bot
Created on: 09/May/19 17:43
Start Date: 09/May/19 17:43
Worklog Time Spent: 10m
Work Description: hanishakoneru commented on issue #804: HDDS-1496.
Support partial chunk reads and checksum verification
URL: https://github.com/apache/hadoop/pull/804#issuecomment-490999735
This patch requires more changes (after HDDS-1491 which fixes seek
operation).
1. In BlockInputStream#seek(), it is not sufficient to just check if the
required chunkIndex matches with current buffers chunk index and that the
buffer has data remaining. Since the buffer might have only a partial chunk, it
is possible that it does not cover the position seeked.
2. In BlockInputStream#readChunkFromContainer(), we should not blindly
increment the chunkIndex. The last read might have read only a part of the
chunk and the next read may be required to read from the same chunk again.
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Issue Time Tracking
-------------------
Worklog Id: (was: 239831)
Time Spent: 0.5h (was: 20m)
> Support partial chunk reads and checksum verification
> -----------------------------------------------------
>
> Key: HDDS-1496
> URL: https://issues.apache.org/jira/browse/HDDS-1496
> Project: Hadoop Distributed Data Store
> Issue Type: Improvement
> Reporter: Hanisha Koneru
> Assignee: Hanisha Koneru
> Priority: Major
> Labels: pull-request-available
> Time Spent: 0.5h
> Remaining Estimate: 0h
>
> BlockInputStream#readChunkFromContainer() reads the whole chunk from disk
> even if we need to read only a part of the chunk.
> This Jira aims to improve readChunkFromContainer so that only that part of
> the chunk file is read which is needed by client plus the part of chunk file
> which is required to verify the checksum.
> For example, lets say the client is reading from index 120 to 450 in the
> chunk. And let's say checksum is stored for every 100 bytes in the chunk i.e.
> the first checksum is for bytes from index 0 to 99, the next for bytes from
> index 100 to 199 and so on. To verify bytes from 120 to 450, we would need to
> read from bytes 100 to 499 so that checksum verification can be done.
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