[infinispan-issues] [JBoss JIRA] Commented: (ISPN-1132) Locking optimization: reorder lock acquisition to avoid deadlocks

[ https://issues.jboss.org/browse/ISPN-1132?page=com.atlassian.jira.plugin.... ] Mircea Markus commented on ISPN-1132: ------------------------------------- Suggested design. This feature is only available if *lockAtPrepareTime*, as defined within ISPN-1131, is enabled. It should be possible to control weather lock-reordering is enabled or not: e.g. there might be application where locks are being acquired in a ordered sequence already, so this optimization would not bring any benefit. The attribute that controls lock reordering is *reorderLockAcquisition*: {code:xml} <locking lockAtPrepareTime="true" reorderLockAcquisition="true" /> {code} Having *lockAtPrepareTime* disabled and *reorderLockAcquisition* would make the system output a warning stating that lock reordering is not active. In order to support this feature {{TxInterceptor.visitPrepareCommand}}is modified as follows: * it would first invoke {{invokeNextInterceptor(ctx, command)}} and only then {code:java} if (!ctx.isOriginLocal()) { // replay modifications for (VisitableCommand modification : command.getModifications()) { VisitableCommand toReplay = getCommandToReplay(modification); if (toReplay != null) { invokeNextInterceptor(ctx, toReplay); } } } {code} * this is needed in order to have {{LockInterceptor.visitPrepareCommand}} acquire locks at once for all keys involved in the transaction Also {{PrepareTimeLockingInterceptor.visitPrepareCommand}} is enhanced as follows: * {code:java} for (WriteCommand wc : command.getModifications()) { acquireLock(wc); } {code:java} is replaced with {code:java} for (WriteCommand wc : reorder(command.getModifications())) { acquireLock(wc); } {code:java} * {{reorder(WriteCommand[] commandsToReorder)}} works as follows: ** if *reorderLockAcquisition* is disabled returns {{commandsToReorder}} ** if {{commandsToReorder}} contrains a {{ClearCommand}} it returns {{commandsToReorder}} (unmodified) ** breaks {{PutMapCommand}} in individual {{PutKeyValue}} commands ** after the step above we have a sequence of {{DataCommands}} - based on the original {{commandsToReorder}} sequence, with {{PutMapCommand}} "expanded" ** -- This message is automatically generated by JIRA. For more information on JIRA, see: http://www.atlassian.com/software/jira