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From "abdullah alamoudi (Code Review)" <>
Subject Change in asterixdb[master]: Enable Component rollback in LSM Indexes
Date Wed, 07 Jun 2017 15:29:44 GMT
abdullah alamoudi has posted comments on this change.

Change subject: Enable Component rollback in LSM Indexes

Patch Set 9:


1. we already use the code in exitComponents to get rid of the files.
2. the clear is needed in case of rollback while new component is being created through flush
or merge.

It is needed because the rollback doesn't see the new component being created. if we don't
clear, then we will write a valid new component to disk instead of writing an invalid component
in case of failure.
File asterixdb/asterix-app/src/test/java/org/apache/asterix/test/dataflow/

PS9, Line 83: ComponentRollbackTest
> Fix all Thread.sleep(...) according to the sonar cube suggestion?
File asterixdb/asterix-common/src/main/java/org/apache/asterix/common/context/

PS9, Line 280: || immutableComponents.get(i).getState() == ComponentState.DECOMMISSIONING
> why decommissioning implies isMergeOngoing==true?
yes. decommissioning on memory component means flush is finishing but still ongoing. decommissioning
on disk component means merge is finishing but still ongoing
File hyracks-fullstack/hyracks/hyracks-control/hyracks-control-nc/src/main/java/org/apache/hyracks/control/nc/utils/

PS9, Line 19:
> move this to hyracks-util?
Done. can maximumly put it in hyracks-api. since it needs to see the ErrorCode.
File hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/

PS9, Line 121: IllegalStateException
> Error code?
This is illegal state which should never happen according to the code. you can see that the
one in the middle where writerCount > 0 can happen and so I created an error code for it.
but for those, I think illegalstate is the right type of exception.
File hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/

PS9, Line 138: immutableComponents.get(i).getState() == ComponentState.DECOMMISSIONING
> The code reads weird:
File hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/

PS9, Line 217: failedOperation
> pull if(failedOperation) out to reduce nested levels.

PS9, Line 261:   if (opType == LSMOperationType.ROLLBACK) {
> Move the if branch to be CASE in side the next switch(opType)?

PS9, Line 262: lsmIndex.getDiskComponents().remove(c);
> Do that inside lsmIndex so that readers can easily track which component(s)

PS9, Line 496: if (newComponent != null)
> reverse the if condition to reduce nesting levels.

PS9, Line 690: rollback
> change the method name to logRollback()?

PS9, Line 686: try {
             :                 for (ILSMComponent c : ctx.getComponentHolder()) {
             :                     if (c.getType() == LSMComponentType.DISK) {
             :                         // persist rollback in case of crash
             :                         ((ILSMDiskComponent) c).rollback();
             :                     }
             :                 }
             :             }
> Creating a shadow file does not need to be within synchronized(opTracker).
all the rollback should be within the synchronized block since the enterComponent doesn't
do anything but increment the number or readers.

we can't allow a flush/merge/modify/search to enter while we're rolling back.

All the actual work (beside logging the operation) happens in exitComponent()

we just can't start doing anything in enter component since we don't know if we will be able
to enter all components.

PS9, Line 693: finally {
             :                 exitComponents(ctx, LSMOperationType.ROLLBACK, null, false);
             :             }
> exitComponents(...) shouldn't under the umbrella of synchronized(opTracker)
See above comment!

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Gerrit-MessageType: comment
Gerrit-Change-Id: I5fe10965734b60776100580c9568a0f954d6cb58
Gerrit-PatchSet: 9
Gerrit-Project: asterixdb
Gerrit-Branch: master
Gerrit-Owner: abdullah alamoudi <>
Gerrit-Reviewer: Ian Maxon <>
Gerrit-Reviewer: Jenkins <>
Gerrit-Reviewer: Luo Chen <>
Gerrit-Reviewer: Murtadha Hubail <>
Gerrit-Reviewer: Till Westmann <>
Gerrit-Reviewer: Yingyi Bu <>
Gerrit-Reviewer: abdullah alamoudi <>
Gerrit-HasComments: Yes

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