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Date: Thu, 28 Jun 2012 21:59:44 +0000 (UTC)
From: "Jonathan Ellis (JIRA)" <jira@apache.org>
To: commits@cassandra.apache.org
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Subject: [jira] [Commented] (CASSANDRA-3881) reduce computational complexity
 of processing topology changes
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    [ https://issues.apache.org/jira/browse/CASSANDRA-3881?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13403507#comment-13403507 ] 

Jonathan Ellis commented on CASSANDRA-3881:
-------------------------------------------

bq. the places where tokenMetadata needs to be cloned look arbitrary and it's much less obvious what the convention is for other people looking at this

What if we just added an assert ({{assert tokenMetadata != StorageService.tokenMetadata}}) to enforce this requirement?

Granted that we are choosing lesser evils here, but I like that better than trying to reason about synchronized(Topology) mixed with locks mixed with synchronized(bootstrapTokens).
                
> reduce computational complexity of processing topology changes
> --------------------------------------------------------------
>
>                 Key: CASSANDRA-3881
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-3881
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>            Reporter: Peter Schuller
>            Assignee: Sam Overton
>              Labels: vnodes
>
> This constitutes follow-up work from CASSANDRA-3831 where a partial improvement was committed, but the fundamental issue was not fixed. The maximum "practical" cluster size was significantly improved, but further work is expected to be necessary as cluster sizes grow.
> _Edit0: Appended patch information._
> h3. Patches
> ||Compare||Raw diff||Description||
> |[00_snitch_topology|https://github.com/acunu/cassandra/compare/refs/top-bases/p/3881/00_snitch_topology...p/3881/00_snitch_topology]|[00_snitch_topology.patch|https://github.com/acunu/cassandra/compare/refs/top-bases/p/3881/00_snitch_topology...p/3881/00_snitch_topology.diff]|Adds some functionality to TokenMetadata to track which endpoints and racks exist in a DC.|
> |[01_calc_natural_endpoints|https://github.com/acunu/cassandra/compare/refs/top-bases/p/3881/01_calc_natural_endpoints...p/3881/01_calc_natural_endpoints]|[01_calc_natural_endpoints.patch|https://github.com/acunu/cassandra/compare/refs/top-bases/p/3881/01_calc_natural_endpoints...p/3881/01_calc_natural_endpoints.diff]|Rewritten O(logN) implementation of calculateNaturalEndpoints using the topology information from the tokenMetadata.|
> ----
> _Note: These are branches managed with TopGit. If you are applying the patch output manually, you will either need to filter the TopGit metadata files (i.e. {{wget -O - <url> | filterdiff -x*.topdeps -x*.topmsg | patch -p1}}), or remove them afterward ({{rm .topmsg .topdeps}})._

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