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https://issues.apache.org/jira/browse/CASSANDRA-3866?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13202150#comment-13202150
]
Sylvain Lebresne commented on CASSANDRA-3866:
---------------------------------------------
Agreed on the principle. On the patch itself, I'd prefer having
SeedProviderDef.parameters defaulting to an empty map. Custom providers that
don't care about parameters could just ignore the map, but that avoids having
to create 2 constructor for each providers (in particular, SimpleSeedProvider
doesn't have a default constructor).
> Allow default constructor for seed providers
> --------------------------------------------
>
> Key: CASSANDRA-3866
> URL: https://issues.apache.org/jira/browse/CASSANDRA-3866
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Affects Versions: 1.0.7
> Reporter: Chris Lohfink
> Priority: Trivial
> Attachments: DnsSeedProvider.java, patch.txt
>
>
> Would be nice for cases where you do not have any parameters. ie if you have
> a simple custom seed provider. In that scenario you will not provide a
> parameters argument to the seed_provider (since using default constructor):
> {code}
> seed_provider:
> - class_name: foo.bar.DnsSeedProvider
> {code}
> This causes an exception
> {code:java}ERROR 11:57:06,744 Fatal configuration error error
> Can't construct a java object for
> tag:yaml.org,2002:org.apache.cassandra.config.Config; exception=Cannot create
> property=seed_provider for
> JavaBean=org.apache.cassandra.config.Config@3c50507;
> java.lang.reflect.InvocationTargetException
> in "<reader>", line 10, column 1:
> cluster_name: 'Test Cluster'
> ^
> at
> org.yaml.snakeyaml.constructor.Constructor$ConstructYamlObject.construct(Constructor.java:372)
>
> at
> org.yaml.snakeyaml.constructor.BaseConstructor.constructObject(BaseConstructor.java:177)
>
> at
> org.yaml.snakeyaml.constructor.BaseConstructor.constructDocument(BaseConstructor.java:136)
>
> at
> org.yaml.snakeyaml.constructor.BaseConstructor.getSingleData(BaseConstructor.java:122)
>
> at org.yaml.snakeyaml.Loader.load(Loader.java:52)
> at org.yaml.snakeyaml.Yaml.load(Yaml.java:166)
> at
> org.apache.cassandra.config.DatabaseDescriptor.<clinit>(DatabaseDescriptor.java:133)
>
> at
> org.apache.cassandra.service.AbstractCassandraDaemon.setup(AbstractCassandraDaemon.java:125)
>
> at com.datastax.bdp.server.DseDaemon.setup(DseDaemon.java:89)
> at
> org.apache.cassandra.service.AbstractCassandraDaemon.init(AbstractCassandraDaemon.java:238)
>
> at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
> at
> sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
> at
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
>
> at java.lang.reflect.Method.invoke(Method.java:597)
> at org.apache.commons.daemon.support.DaemonLoader.load(DaemonLoader.java:212)
> Caused by: org.yaml.snakeyaml.error.YAMLException: Cannot create
> property=seed_provider for
> JavaBean=org.apache.cassandra.config.Config@3c50507;
> java.lang.reflect.InvocationTargetException
> at
> org.yaml.snakeyaml.constructor.Constructor$ConstructMapping.constructJavaBean2ndStep(Constructor.java:305)
>
> at
> org.yaml.snakeyaml.constructor.Constructor$ConstructMapping.construct(Constructor.java:184)
>
> at
> org.yaml.snakeyaml.constructor.Constructor$ConstructYamlObject.construct(Constructor.java:370)
>
> ... 14 more
> Caused by: org.yaml.snakeyaml.error.YAMLException:
> java.lang.reflect.InvocationTargetException
> at
> org.yaml.snakeyaml.constructor.Constructor$ConstructSequence.construct(Constructor.java:589)
>
> at
> org.yaml.snakeyaml.constructor.BaseConstructor.constructObject(BaseConstructor.java:177)
>
> at
> org.yaml.snakeyaml.constructor.Constructor$ConstructMapping.constructJavaBean2ndStep(Constructor.java:298)
>
> ... 16 more
> Caused by: java.lang.reflect.InvocationTargetException
> at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
> at
> sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
>
> at
> sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
>
> at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
> at
> org.yaml.snakeyaml.constructor.Constructor$ConstructSequence.construct(Constructor.java:587)
>
> ... 18 more
> Caused by: java.lang.NullPointerException
> at
> org.apache.cassandra.config.SeedProviderDef.<init>(SeedProviderDef.java:34)
> ... 23 more
> {code}
> If you then add parameters you get a java.lang.NoSuchMethodException. The
> workaround being you create a constructor that takes a Map argument, set the
> parameters to anything and ignore them, which is fine but then has to be
> documented as they are options that do not mean anything. Would be nice to
> make the parameters optional. I attached a very simple example and a patch
> that I think would work.
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