NIFI-4208: Fixed bug in SchemaRepositoryRecordSerde that would return…

[markap14]

… null from deserializeEdit if there was no data; the interface documents that null cannot be returned from this method, as it is called only when data is expected to exist. As a result, if there is no data, we should throw EOFException instead, and the write-ahead log will handle that appropriately

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[alopresto]

Reviewing...

[alopresto]

I verified the new unit test passed successfully. I then started the app normally, ran a heavy flow, and debugged at the checkpoint() method to ensure I captured a valid snapshot file. I modified this by truncating the file after a transaction ID, yielding an incomplete record. I stopped the application, moved the modified snapshot into place, and restarted the app. On loading, NiFi stopped with the following expected error in the nifi-app.log:

org.apache.nifi.web.NiFiCoreException: Unable to start Flow Controller.
	at org.apache.nifi.web.contextlistener.ApplicationStartupContextListener.contextInitialized(ApplicationStartupContextListener.java:88)
	at org.eclipse.jetty.server.handler.ContextHandler.callContextInitialized(ContextHandler.java:876)
	at org.eclipse.jetty.servlet.ServletContextHandler.callContextInitialized(ServletContextHandler.java:532)
	at org.eclipse.jetty.server.handler.ContextHandler.startContext(ContextHandler.java:839)
	at org.eclipse.jetty.servlet.ServletContextHandler.startContext(ServletContextHandler.java:344)
	at org.eclipse.jetty.webapp.WebAppContext.startWebapp(WebAppContext.java:1480)
	at org.eclipse.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1442)
	at org.eclipse.jetty.server.handler.ContextHandler.doStart(ContextHandler.java:799)
	at org.eclipse.jetty.servlet.ServletContextHandler.doStart(ServletContextHandler.java:261)
	at org.eclipse.jetty.webapp.WebAppContext.doStart(WebAppContext.java:540)
	at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68)
	at org.eclipse.jetty.util.component.ContainerLifeCycle.start(ContainerLifeCycle.java:131)
	at org.eclipse.jetty.util.component.ContainerLifeCycle.doStart(ContainerLifeCycle.java:113)
	at org.eclipse.jetty.server.handler.AbstractHandler.doStart(AbstractHandler.java:113)
	at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68)
	at org.eclipse.jetty.util.component.ContainerLifeCycle.start(ContainerLifeCycle.java:131)
	at org.eclipse.jetty.util.component.ContainerLifeCycle.doStart(ContainerLifeCycle.java:105)
	at org.eclipse.jetty.server.handler.AbstractHandler.doStart(AbstractHandler.java:113)
	at org.eclipse.jetty.server.handler.gzip.GzipHandler.doStart(GzipHandler.java:290)
	at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68)
	at org.eclipse.jetty.util.component.ContainerLifeCycle.start(ContainerLifeCycle.java:131)
	at org.eclipse.jetty.server.Server.start(Server.java:452)
	at org.eclipse.jetty.util.component.ContainerLifeCycle.doStart(ContainerLifeCycle.java:105)
	at org.eclipse.jetty.server.handler.AbstractHandler.doStart(AbstractHandler.java:113)
	at org.eclipse.jetty.server.Server.doStart(Server.java:419)
	at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68)
	at org.apache.nifi.web.server.JettyServer.start(JettyServer.java:707)
	at org.apache.nifi.NiFi.<init>(NiFi.java:160)
	at org.apache.nifi.NiFi.main(NiFi.java:268)
Caused by: java.io.EOFException: Failed to read field 'Repository Record Update'
	at org.apache.nifi.repository.schema.SchemaRecordReader.readField(SchemaRecordReader.java:115)
	at org.apache.nifi.repository.schema.SchemaRecordReader.readRecord(SchemaRecordReader.java:72)
	at org.apache.nifi.controller.repository.SchemaRepositoryRecordSerde.deserializeRecord(SchemaRepositoryRecordSerde.java:124)
	at org.apache.nifi.controller.repository.SchemaRepositoryRecordSerde.deserializeRecord(SchemaRepositoryRecordSerde.java:46)
	at org.wali.MinimalLockingWriteAheadLog.recoverFromSnapshot(MinimalLockingWriteAheadLog.java:380)
	at org.wali.MinimalLockingWriteAheadLog.recoverRecords(MinimalLockingWriteAheadLog.java:300)
	at org.apache.nifi.controller.repository.WriteAheadFlowFileRepository.loadFlowFiles(WriteAheadFlowFileRepository.java:381)
	at org.apache.nifi.controller.FlowController.initializeFlow(FlowController.java:723)
	at org.apache.nifi.controller.StandardFlowService.initializeController(StandardFlowService.java:956)
	at org.apache.nifi.controller.StandardFlowService.load(StandardFlowService.java:535)
	at org.apache.nifi.web.contextlistener.ApplicationStartupContextListener.contextInitialized(ApplicationStartupContextListener.java:72)
	... 28 common frames omitted
	Suppressed: java.io.EOFException: Failed to read field 'Create or Update'
		at org.apache.nifi.repository.schema.SchemaRecordReader.readField(SchemaRecordReader.java:115)
		at org.apache.nifi.repository.schema.SchemaRecordReader.readFieldValue(SchemaRecordReader.java:186)
		at org.apache.nifi.repository.schema.SchemaRecordReader.readField(SchemaRecordReader.java:113)
		... 38 common frames omitted
		Suppressed: java.io.EOFException: Unexpected End-of-File when attempting to read Repetition value for field 'Swap Location'
			at org.apache.nifi.repository.schema.SchemaRecordReader.readField(SchemaRecordReader.java:101)
			at org.apache.nifi.repository.schema.SchemaRecordReader.readFieldValue(SchemaRecordReader.java:171)
			at org.apache.nifi.repository.schema.SchemaRecordReader.readField(SchemaRecordReader.java:113)
			... 40 common frames omitted

Ran contrib-check and all tests pass. +1, merging.