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https://issues.apache.org/jira/browse/WAVE-175?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Ali Lown updated WAVE-175:
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Component/s: Server
> Simultaneous first-time reading of the same conversation by the same user has
> race conditions
> ---------------------------------------------------------------------------------------------
>
> Key: WAVE-175
> URL: https://issues.apache.org/jira/browse/WAVE-175
> Project: Wave
> Issue Type: Bug
> Components: Server
> Priority: Minor
>
> <b>What steps will reproduce the problem?</b>
> [Theoretical, never done in practice]
> 1. Create a wave with several blips, add participant X.
> 2. User X logs in to two clients, then goes offline (e.g. disconnect network).
> 3. X opens the wave on both clients, reads some blips in one client, reads
> other blips in the other client.
> 4. X goes back online on both clients.
> <b>What is the expected output? What do you see instead?</b>
> Expected output (ideally) is that the reading actions merge concurrently.
> e.g. any blip read on either client becomes read on both clients. Each
> client should display this resolution live, without either client needing to
> re-open or refresh. Additionally, re-open or refresh should be a no-op after
> this resolution: all read-state should be the same.
> Instead, theoretically, both clients will have no change on reconnection, but
> when re-opening that wave, the reading actions from only one of the two
> clients will be preserved.
> The bug is simple: the embedding of WaveletReadState objects in the m/read
> documetn does not resolve multiple <wavelet> elements with the same id.
> A fix for this must preserve the cleanup-on-write property. i.e., active
> resolution of the XML, by merging the data in the XML as soon as duplicates
> are observed, is not acceptable. This makes a fix not completely trivial.
> Since the data types embedded inside each per-wavelet read-state object
> element are monotonic and superimposable, one solution is for
> WaveletBasedSupplement to collect all WaveletReadState objects that exist for
> the same id, and wrap them in a composite WaveletReadState object, that
> distributes all queries over each component read state object. On any write
> subsequent action, for any wavelet with multiple <wavelet> elements, a
> new <wavelet> object can be added that contains the sum information of
> all the others, and then all the original <wavelet> elements can be
> deleted.
> Doing this completely correctly, with respect to composition, intermediate
> transitive states, left-to-right broadcast of document events, and a sensible
> resolution of multiple WaveletReadState objects, may or may not be difficult.
> ---
> Issue imported from
> http://code.google.com/p/wave-protocol/issues/detail?id=174
> Label: Type-Defect
> Label: Priority-Medium
> Stars: 1
> State: open
> Status: New
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