Scott Wegner created BEAM-308:
---------------------------------
Summary: 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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