CASSANDRA-16703 Exception thrown by custom QueryHandler constructor i…

[zoltanersek]

…s ignored

https://issues.apache.org/jira/browse/CASSANDRA-16703

[chicobento]

Thanks for working on this issue. I just added some minor comments.

[chicobento]

In our case, the exception thrown by the QueryHandler is a cassandra ConfigurationException, which has nested exception that gives valuable information to the user.
In that sense, I'd recommend to pass the whole exception to the logger rather than just the message, like:
logger.error("Cannot use class {} as query handler ({})", customHandlerClass, e);

[zersek]

done

[chicobento]

Since the contextualized exception is already being logged above and the root cause is well known, I think quiet parameter could be true, otherwise it will print the stackTrace to System.err and to the logger.error "JVM state determined to be unstable. Exiting forcefully due to:" which is not really necessary in this case.

Overall, this is how Im currently handling this situation in my custom query handler:

MyQueryHandler() {
   try {
     configure();
   } catch (ConfigurationException e) {
     log.error("Error registering MyQueryHandler", e);
     JVMStabilityInspector.killCurrentJVM(e, true);
   }
}

[zersek]

done
this is the output I get:

ERROR [main] 2021-07-01 16:16:33,552 ClientState.java:103 - Cannot use class org.apache.cassandra.cql3.CustomPayloadMirroringQueryHandler2 as query handler
org.apache.cassandra.exceptions.ConfigurationException: Unable to find QueryHandler class 'org.apache.cassandra.cql3.CustomPayloadMirroringQueryHandler2'
	at org.apache.cassandra.utils.FBUtilities.classForName(FBUtilities.java:720)
	at org.apache.cassandra.utils.FBUtilities.construct(FBUtilities.java:753)
	at org.apache.cassandra.service.ClientState.<clinit>(ClientState.java:98)
	at org.apache.cassandra.cql3.QueryProcessor$InternalStateInstance.<init>(QueryProcessor.java:129)
	at org.apache.cassandra.cql3.QueryProcessor$InternalStateInstance.<clinit>(QueryProcessor.java:123)
	at org.apache.cassandra.cql3.QueryProcessor.internalQueryState(QueryProcessor.java:174)
	at org.apache.cassandra.cql3.QueryProcessor.prepareInternal(QueryProcessor.java:312)
	at org.apache.cassandra.cql3.QueryProcessor.executeInternal(QueryProcessor.java:322)
	at org.apache.cassandra.db.SystemKeyspace.checkHealth(SystemKeyspace.java:973)
	at org.apache.cassandra.service.StartupChecks$10.execute(StartupChecks.java:442)
	at org.apache.cassandra.service.StartupChecks.verify(StartupChecks.java:132)
	at org.apache.cassandra.service.CassandraDaemon.runStartupChecks(CassandraDaemon.java:487)
	at org.apache.cassandra.service.CassandraDaemon.setup(CassandraDaemon.java:262)
	at org.apache.cassandra.service.CassandraDaemon.activate(CassandraDaemon.java:763)
	at org.apache.cassandra.service.CassandraDaemon.main(CassandraDaemon.java:887)
Caused by: java.lang.ClassNotFoundException: org.apache.cassandra.cql3.CustomPayloadMirroringQueryHandler2
	at java.net.URLClassLoader.findClass(URLClassLoader.java:382)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:418)
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:352)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:351)
	at java.lang.Class.forName0(Native Method)
	at java.lang.Class.forName(Class.java:264)
	at org.apache.cassandra.utils.FBUtilities.classForName(FBUtilities.java:716)
	... 14 common frames omitted

Process finished with exit code 100

[chicobento]

LGTM, thanks a lot for fixing this issue.
Would love to see it backported to 3.x if possible.

[zoltanersek]

Committed into cassandra-3.0 at eadb171 and merged into cassandra-3.11, cassandra-4.0 and trunk

[chicobento]

Great! Thanks a lot for taking your time to work on this issue.