[jira] [Commented] (CASSANDRA-2731) Impelement in-house file caching.

["Jonathan Ellis (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-2731?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13048613#comment-13048613 ] 

Jonathan Ellis commented on CASSANDRA-2731:
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So the idea is we store disk blocks in the radix tree?  Why a radix tree?  What do we do for Windows? Would it make sense to store sstable blocks directly instead if we move to a block-based format like CASSANDRA-674?

> Impelement in-house file caching.
> ---------------------------------
>
>                 Key: CASSANDRA-2731
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-2731
>             Project: Cassandra
>          Issue Type: New Feature
>          Components: Core
>    Affects Versions: 1.0
>            Reporter: Pavel Yaskevich
>            Assignee: Pavel Yaskevich
>
> Implement FileCache, CachedRandomAccessFile (to replace BufferedRandomAccessFile) and RadixTree (to play role of the backend cache storage) classes.
> FileCache class with be responsible for storing/retrieving data from Radix Tree and also flushing of the dirty pages to the disk, page management such as adding new pages, utilizing old/unused pages.
> CRAF Linux only features (via JNI):
> 1). O_DIRECT for both read/write operations.
> 2). AIO's lio_listio write operation batching.
> Provide possibility to migrate hot data directly from Memtable to CRAF cache to keep live-reads data always hot in memory. To minimise compaction effects CRAF should provide a way to by-pass a caching data if it does not already exists. 
> Provide a way to make pointers in the cache which will be useful to minimize impact on performance when a single column is distributed among multiple SSTable files (except counter columns).
> Use jemalloc (http://www.canonware.com/jemalloc/) for cache memory management.

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