java.lang.IllegalAccessError when invoking protected method from another class in the same package path but different jar.

[bbarani <bb...@gmail.com>]

Hi,

I am overriding the query component and creating a custom component. I am
using _responseDocs from org.apache.solr.handler.component.ResponseBuilder
to get the values. I have my component in same package
(org.apache.solr.handler.component) to access the _responseDocs value.

Everything works fine when I run the test for this component but I am
getting the below error when I package the custom component in a jar and
place it in lib directory (inside solr/lib - using basic jetty
configuration).

I assume this is due to the fact that different class loaders load different
class at runtime. Is there a way to resolve this?

<str name="msg">java.lang.IllegalAccessError: tried to access field
org.apache.solr.handler.component.ResponseBuilder._responseDocs from class
org.apache.solr.handler.component.WPFastDistributedQueryComponent</str><str
name="trace">java.lang.RuntimeException: java.lang.IllegalAccessError: tried
to access field
org.apache.solr.handler.component.ResponseBuilder._responseDocs from class
org.apache.solr.handler.component.CustomComponent
	at
org.apache.solr.servlet.SolrDispatchFilter.sendError(SolrDispatchFilter.java:670)
	at
org.apache.solr.servlet.SolrDispatchFilter.doFilter(SolrDispatchFilter.java:380)
	at
org.apache.solr.servlet.SolrDispatchFilter.doFilter(SolrDispatchFilter.java:155)
	at
org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1307)
	at
org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:453)
	at
org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:137)
	at
org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:560)
	at
org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:231)
	at
org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1072)
	at
org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:382)
	at
org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:193)
	at
org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1006)
	at
org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:135)
	at
org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:255)
	at
org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:154)
	at
org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:116)
	at org.eclipse.jetty.server.Server.handle(Server.java:365)
	at
org.eclipse.jetty.server.AbstractHttpConnection.handleRequest(AbstractHttpConnection.java:485)
	at
org.eclipse.jetty.server.BlockingHttpConnection.handleRequest(BlockingHttpConnection.java:53)
	at
org.eclipse.jetty.server.AbstractHttpConnection.headerComplete(AbstractHttpConnection.java:926)
	at
org.eclipse.jetty.server.AbstractHttpConnection$RequestHandler.headerComplete(AbstractHttpConnection.java:988)
	at org.eclipse.jetty.http.HttpParser.parseNext(HttpParser.java:635)
	at org.eclipse.jetty.http.HttpParser.parseAvailable(HttpParser.java:235)
	at
org.eclipse.jetty.server.BlockingHttpConnection.handle(BlockingHttpConnection.java:72)
	at
org.eclipse.jetty.server.bio.SocketConnector$ConnectorEndPoint.run(SocketConnector.java:264)
	at
org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:608)
	at
org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:543)
	at java.lang.Thread.run(Thread.java:722)
Caused by: java.lang.IllegalAccessError: tried to access field
org.apache.solr.handler.component.ResponseBuilder._responseDocs from class
org.apache.solr.handler.component.WPFastDistributedQueryComponent
	at
org.apache.solr.handler.component.WPFastDistributedQueryComponent.handleResponses(WPFastDistributedQueryComponent.java:131)
	at
org.apache.solr.handler.component.SearchHandler.handleRequestBody(SearchHandler.java:311)
	at
org.apache.solr.handler.RequestHandlerBase.handleRequest(RequestHandlerBase.java:135)
	at org.apache.solr.core.SolrCore.execute(SolrCore.java:1816)
	at
org.apache.solr.servlet.SolrDispatchFilter.execute(SolrDispatchFilter.java:656)
	at
org.apache.solr.servlet.SolrDispatchFilter.doFilter(SolrDispatchFilter.java:359)
	... 26 more




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Re: java.lang.IllegalAccessError when invoking protected method from another class in the same package path but different jar.

[bbarani <bb...@gmail.com>]

Hoss, thanks a lot for the explanation.

We override most of the methods of query
component(prepare,handleResponses,finishStage etc..)  to incorporate custom
logic and we set the _responseDocs values based on custom logic (after
filtering out few data) and then we call the parent(super) method(query
component) with the modified responsedocs. Thats the main reason we are
using the _responsedocs variable as is..



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Re: java.lang.IllegalAccessError when invoking protected method from another class in the same package path but different jar.

[Chris Hostetter <ho...@fucit.org>]

: Subject: java.lang.IllegalAccessError when invoking protected method from
:     another class in the same package path but different jar.
	...
: I am overriding the query component and creating a custom component. I am
: using _responseDocs from org.apache.solr.handler.component.ResponseBuilder
: to get the values. I have my component in same package

_responseDocs is not "protected" it is "package-private" which is why you 
can't access it from a subclass in another *runtime* pacakge.  Even if 
you put your custom component in the same org.apache.solr... package 
namespace, the runtime package is determined by the ClassLoader combined 
with the source package...

http://www.cooljeff.co.uk/2009/05/03/the-subtleties-of-overriding-package-private-methods/

...this is helpful to ensure plugins don't attempt to do tihngs they 
shouldn't.

In general, the ResponseBuilder class internals aren't very friendly in 
terms of allowing custom components to interact with the intermediate 
results of other built in components -- it's primarily designed arround 
letting other internal Solr components share data with eachother in 
(hopefully) well tested ways.  Note that there is even a specific comment 
one line directly above the declaration of _responseDocs that alludes to 
it and several other variables being deliberately package-private...

  /* private... components that don't own these shouldn't use them */
  SolrDocumentList _responseDocs;
  StatsInfo _statsInfo;
  TermsComponent.TermsHelper _termsHelper;
  SimpleOrderedMap<List<NamedList<Object>>> _pivots;

If you want access to the SolrDocumentList containing the query results, 
the only safe way/time to do that is by fetching it out of the response 
(ResponseBuilder.rsp) after the QueryComponent has put it there in it's 
finishStage -- untill then ResponseBuilder._responseDocs may not be 
correct (ie: distribute search, grouped search, etc...)

-Hoss

Re: java.lang.IllegalAccessError when invoking protected method from another class in the same package path but different jar.

[bbarani <bb...@gmail.com>]

My assumptions were right :)!!!!

I was able to fix this error by copying all my custom jar inside
webapp/web-inf/lib directory and everything started working !!!!



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