[jira] [Commented] (BEAM-308) PipelineOptions throws when using package-private PipelineOptions interfaces from multiple packages

["Scott Wegner (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/BEAM-308?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15300563#comment-15300563 ] 

Scott Wegner commented on BEAM-308:
-----------------------------------

PR with failing test cases: https://github.com/apache/incubator-beam/pull/389/files

/cc [~bchambers] [~lcwik]

> PipelineOptions throws when using package-private PipelineOptions interfaces from multiple packages
> ---------------------------------------------------------------------------------------------------
>
>                 Key: BEAM-308
>                 URL: https://issues.apache.org/jira/browse/BEAM-308
>             Project: Beam
>          Issue Type: Bug
>          Components: sdk-java-core
>            Reporter: Scott Wegner
>            Assignee: Scott Wegner
>            Priority: Minor
>
> If a PipelineOptions instance is used as multiple PipelineOptions package-private interfaces from different packages, {{PipelineOptions.as}} will throw an exception:
> {quote}
> java.lang.IllegalArgumentException: non-public interfaces from different packages
> 	at java.lang.reflect.Proxy$ProxyClassFactory.apply(Proxy.java:652)
> 	at java.lang.reflect.Proxy$ProxyClassFactory.apply(Proxy.java:592)
> 	at java.lang.reflect.WeakCache$Factory.get(WeakCache.java:244)
> 	at java.lang.reflect.WeakCache.get(WeakCache.java:141)
> 	at java.lang.reflect.Proxy.getProxyClass0(Proxy.java:455)
> 	at java.lang.reflect.Proxy.getProxyClass(Proxy.java:405)
> 	at org.apache.beam.sdk.options.PipelineOptionsFactory.validateWellFormed(PipelineOptionsFactory.java:620)
> 	at org.apache.beam.sdk.options.ProxyInvocationHandler.as(ProxyInvocationHandler.java:209)
> 	at org.apache.beam.sdk.options.ProxyInvocationHandler.invoke(ProxyInvocationHandler.java:135)
> 	at com.sun.proxy.$Proxy6.as(Unknown Source)
> {quote}
> This fails because ProxyInvocationHandler attempts to create a Java Proxy object implementing the full set of interfaces, which has the [restriction|https://docs.oracle.com/javase/7/docs/api/java/lang/reflect/Proxy.html#getProxyClass(java.lang.ClassLoader,%20java.lang.Class...)]: 
> bq. All non-public interfaces must be in the same package; otherwise, it would not be possible for the proxy class to implement all of the interfaces, regardless of what package it is defined in.
> This can be triggered in a couple edge-case scenarios:
> # {{PipelineOptions.as}} is called on the same PipelineOptions instance with multiple package-private interfaces.
> # {{PipelineOptionsFactory.register}} is called with a package-private interface, and then {{PipelineOptions.as}} is called with a different package-private instance.
> We hit the second scenario in [DataflowSDK unit tests|https://github.com/GoogleCloudPlatform/DataflowJavaSDK/pull/286#issuecomment-221438063]. It's hard to trigger, but possible.
> ----
> I propose we make the behavior for package-private options explicit:
> # Give a better exception message if we hit this issue in {{PipelineOptions.as}} listing the non-public interfaces and what packages they're in.
> # Explicitly reject non-public interfaces from {{PipelineOptionsFactory.register}}, since this state is global and is easier to cause issues.



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