<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><br><div><div>On 8 Mar 2010, at 14:05, Manik Surtani wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><br><div><div>On 4 Mar 2010, at 10:12, Mircea Markus wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Hi,<div><br></div><div>This is a discussion Galder and I started on the irc.</div><div>We son't currently have a well defined policy for what happens when fetchPersistentState="true" and the node that receives state already has some data in it, that might overlap with remotely received data.</div><div>Most of the loaders right now do a clear() now, before integrating any data. This is not done by all the loaders: JdbmCacheStore, BdbjeCacheStore override this.</div><div>So some of the loaders do a mirror of the data(first they empty the store), some do an override. </div></div></blockquote><div><br></div><div>Correct behaviour should be:</div><div><br></div><div>1. Shared stores do not fetch persistent state at all.</div><div>2. Non-shared cache stores clear() and then apply retrieved persistent state.</div><div><br></div><div>Any impls that do not follow this pattern should be considered buggy and a JIRA should be created accordingly. Perhaps this functionality could be in the AbstractCacheStore.</div><br><blockquote type="cite"><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div>Mirror might make sense in <span class="Apple-style-span" style="font-family: 'Lucida Grande'; ">at least one scenario: you have a cluster running, each node having it's own local store. One node goes down and, after a while you re-start it. This new node will integrate the persistent state of the others, and entries might have been deleted in between (while the node was down). now, if these deleted entries are in new joiner's store, this would mean data inconsistency.</span></div></div></blockquote><div><br></div><div>This is why a clear() needs to happen before state is applied.</div><br><blockquote type="cite"><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><span class="Apple-style-span" style="font-family: 'Lucida Grande'; ">So I think we should:</span></div><div><font class="Apple-style-span" face="'Lucida Grande'">- clearly define what happens with the existing data in the cache store during fetchPersistentState</font></div><div><font class="Apple-style-span" face="'Lucida Grande'">- if we decide to clear it before fetchPersistentState, we should call store.clear() from StateTransferManager and not from particular cache store implementation, as this is error prone</font></div></div></blockquote><div><br></div><div>+1.</div></div></div></blockquote>I've created <a href="https://jira.jboss.org/jira/browse/ISPN-370">https://jira.jboss.org/jira/browse/ISPN-370</a> for this.<br><blockquote type="cite"><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><br><blockquote type="cite"><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><font class="Apple-style-span" face="'Lucida Grande'">- we can even use a configurable strategy, e.g. fetchPersistentState="none" fetchPersistentState="override" fetchPersistentState="mirror"</font></div></div></blockquote><div><br></div><div>I don't see the purpose of this "mirror" option?</div><br><blockquote type="cite"><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><font class="Apple-style-span" face="'Lucida Grande'"><br></font></div><div><font class="Apple-style-span" face="'Lucida Grande'">Cheers,</font></div><div><font class="Apple-style-span" face="'Lucida Grande'">Mircea</font></div></div>_______________________________________________<br>infinispan-dev mailing list<br><a href="mailto:infinispan-dev@lists.jboss.org">infinispan-dev@lists.jboss.org</a><br><a href="https://lists.jboss.org/mailman/listinfo/infinispan-dev">https://lists.jboss.org/mailman/listinfo/infinispan-dev</a></blockquote></div><br><div>
<span class="Apple-style-span" style="border-collapse: separate; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><span class="Apple-style-span" style="border-collapse: separate; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div>--</div><div>Manik Surtani</div><div><a href="mailto:manik@jboss.org">manik@jboss.org</a></div><div>Lead, Infinispan</div><div>Lead, JBoss Cache</div><div><a href="http://www.infinispan.org/">http://www.infinispan.org</a></div><div><a href="http://www.jbosscache.org/">http://www.jbosscache.org</a></div><div><br></div></div></span><br class="Apple-interchange-newline"></span><br class="Apple-interchange-newline">
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