[OAK-6294] The "missing" node cache value breaks the DocumentNodeStore#applyChanges

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.4.10
• Fix Version/s: 1.7.2, 1.8.0, 1.4.22, 1.6.13
• Component/s: documentmk
• Assignee: Tomek Rękawek
• Reporter: Tomek Rękawek
• Created: 02/Jun/17 09:27
• Updated: 31/May/18 18:24
• Resolved: 15/Jun/17 13:19

Description

In the DocumentNodeStore#nodeCache, the special object missing is being used to mark the node entries that don't exists in the repository.

This object should be unwrapped to null every time we call nodeCache#getIfPresent() method. It's not the case in the applyChanges() method - as a result, we may get a NPE (since the missing.getLastRev() == null):

Caused by: java.lang.NullPointerException: null
	at com.google.common.base.Preconditions.checkNotNull(Preconditions.java:192)
	at org.apache.jackrabbit.oak.plugins.document.PathRev.<init>(PathRev.java:40)
	at org.apache.jackrabbit.oak.plugins.document.DocumentNodeStore.applyChanges(DocumentNodeStore.java:1171)
	at org.apache.jackrabbit.oak.plugins.document.Commit.applyToCache(Commit.java:667)
	at org.apache.jackrabbit.oak.plugins.document.DocumentNodeStore$3.headOfQueue(DocumentNodeStore.java:674)
	at org.apache.jackrabbit.oak.plugins.document.CommitQueue.waitUntilHeadOfQueue(CommitQueue.java:240)
	at org.apache.jackrabbit.oak.plugins.document.CommitQueue.done(CommitQueue.java:92)
	at org.apache.jackrabbit.oak.plugins.document.DocumentNodeStore.done(DocumentNodeStore.java:668)

(taken from the production instance running the Oak 1.4.10).

//cc: Chetan Mehrotra, Marcel Reutegger, Vikas Saurabh

Issue Links

• is related to: OAK-6351 Invalidate cache entries when getChildNodes() is aborted