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From: Jonathan Ellis <jbellis@gmail.com>
Date: Wed, 4 Nov 2009 20:30:59 -0600
Message-ID: <e06563880911041830p14b4b7e6nb30ea3d007b55d30@mail.gmail.com>
Subject: Re: gossip & partitioning
To: cassandra-dev@incubator.apache.org
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Yes, I was missing something.  EndPointState is maintained in its
entirety for each node in Gossiper, but onChange is called on EPS
containing only a single "delta" key.

On Wed, Nov 4, 2009 at 3:25 PM, Jonathan Ellis <jbellis@gmail.com> wrote:
> There's some code in StorageService.onChange that looks like this:
>
> =A0 =A0 =A0 =A0// if there is no token data in the endpointstate
> =A0 =A0 =A0 =A0 =A0 =A0/*
> =A0 =A0 =A0 =A0 =A0 =A0 * If we are here and if this node is UP and alrea=
dy has an entry
> =A0 =A0 =A0 =A0 =A0 =A0 * in the token map. It means that the node was be=
hind a
> network partition.
> =A0 =A0 =A0 =A0 =A0 =A0*/
> =A0 =A0 =A0 =A0 =A0 =A0if ( epState.isAlive() && tokenMetadata_.isKnownEn=
dPoint(endpoint) )
> =A0 =A0 =A0 =A0 =A0 =A0{
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0logger_.debug("EndPoint " + ep + " just re=
covered from
> a partition. Sending hinted data.");
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0// send hinted handoffs
> =A0 =A0 =A0 =A0 =A0 =A0}
>
> I don't see how you could actually have null token data. =A0Since token
> (NODE_ID) is the first thing a node gossips, and is required for an
> entry to be added to tokenMetadata, I don't see how that could
> disappear from EndPointState. =A0My understanding is that Gossiper never
> actually discards data from EndPointState, only updates it with
> more-current information (see applyApplicationStateLocally).
>
> Am I missing something, or can this part of onChange be safely removed?
>
> -Jonathan
>