[jira] [Commented] (HBASE-26105) Rectify the expired TODO comment in CombinedBC

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

    [ https://issues.apache.org/jira/browse/HBASE-26105?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17385274#comment-17385274 ] 

Duo Zhang commented on HBASE-26105:
-----------------------------------

Why not just call getBlock on l1Cache and check if it is null?

> Rectify the expired TODO comment in CombinedBC
> ----------------------------------------------
>
>                 Key: HBASE-26105
>                 URL: https://issues.apache.org/jira/browse/HBASE-26105
>             Project: HBase
>          Issue Type: Improvement
>          Components: BlockCache
>            Reporter: Yutong Xiao
>            Assignee: Yutong Xiao
>            Priority: Trivial
>
> In the method getBlock in CombinedBC, there is a TODO comment as follows:
> {code:java}
> @Override
>   public Cacheable getBlock(BlockCacheKey cacheKey, boolean caching,
>       boolean repeat, boolean updateCacheMetrics) {
>     // TODO: is there a hole here, or just awkwardness since in the lruCache getBlock
>     // we end up calling l2Cache.getBlock.
>     // We are not in a position to exactly look at LRU cache or BC as BlockType may not be getting
>     // passed always.
>     boolean existInL1 = l1Cache.containsBlock(cacheKey);
>     if (!existInL1 && updateCacheMetrics && !repeat) {
>       // If the block does not exist in L1, the containsBlock should be counted as one miss.
>       l1Cache.getStats().miss(caching, cacheKey.isPrimary(), cacheKey.getBlockType());
>     }
>     return existInL1 ?
>         l1Cache.getBlock(cacheKey, caching, repeat, updateCacheMetrics):
>         l2Cache.getBlock(cacheKey, caching, repeat, updateCacheMetrics);
>   }
> {code}
> The TODO comment is expired. While in CombinedBC, L2 is not the victim handler of L1.



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