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From "Gopal V (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HADOOP-10047) Allow Compressor/Decompressor APIs to expose a Direct ByteBuffer API
Date Thu, 24 Oct 2013 14:04:03 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-10047?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13804209#comment-13804209
] 

Gopal V commented on HADOOP-10047:
----------------------------------

[~cmccabe]: oh, hell no! It was just a way to test-drive the API (as you said, you wanted
to see the API used before it was baked in).

With that example, I think I have finally figure out a way to not write more native code (I'd
use the phrase "attack surface", considering my security work).

All it needs is for a relatively safe protected exposure of inflateDirect() (and friends),
which does the appropriate buffer swaps there.

That franken-zlib there clearly illustrates how I only need new interfaces to expose existing
code for record compression case (i.e no loop around decompress(), in particular for SNAPPY).

> Allow Compressor/Decompressor APIs to expose a Direct ByteBuffer API
> --------------------------------------------------------------------
>
>                 Key: HADOOP-10047
>                 URL: https://issues.apache.org/jira/browse/HADOOP-10047
>             Project: Hadoop Common
>          Issue Type: New Feature
>          Components: io
>            Reporter: Gopal V
>            Assignee: Gopal V
>              Labels: compression
>         Attachments: DirectCompressor.html, DirectDecompressor.html, HADOOP-10047-WIP.patch,
HADOOP-10047-with-tests.patch
>
>
> With the Zero-Copy reads in HDFS (HDFS-5260), it becomes important to perform all I/O
operations without copying data into byte[] buffers or other buffers which wrap over them.
> This is a proposal for adding new DirectCompressor and DirectDecompressor interfaces
to the io.compress, to indicate codecs which want to surface the direct buffer layer upwards.
> The implementation may or may not copy the buffers passed in, but should work with direct
heap/mmap buffers and cannot assume .array() availability.



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