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From "Keith Wall (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (QPID-5787) Management can observe a child object before its constructor has completed
Date Mon, 26 May 2014 16:11:02 GMT

    [ https://issues.apache.org/jira/browse/QPID-5787?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14008935#comment-14008935
] 

Keith Wall commented on QPID-5787:
----------------------------------

Hi Rob,

I have two ideas to solve this problem:

# We change the automatically generated CO factories so they have responsibility for calling
#registerChild, and/or
# We impose a rule that objects cannot be observed before they are open.

I think my preference is for the first - owing to its simplify.   It does mean that ACO#registerChild
will have to become public.




> Management can observe a child object before its constructor has completed
> --------------------------------------------------------------------------
>
>                 Key: QPID-5787
>                 URL: https://issues.apache.org/jira/browse/QPID-5787
>             Project: Qpid
>          Issue Type: Bug
>          Components: Java Broker
>    Affects Versions: 0.29
>            Reporter: Keith Wall
>            Assignee: Rob Godfrey
>
> Currently new ConfiguredObjects register themselves within their parent within the constructor
(ACO constructor's invocation of registerChild - line 243).
> This allows *this* to escape before the object has completed its constructor.  A client
calling parent.getChildren is able to see partly constructed children (DEFECT).
> This problem is revealed by a sporadic test failure - BDBHAVirtualHostNodeRestTest. 
The REST API tries to query virtual host node whose child is still undergoing construction.
 This leads to a NPE in the Broker logs and a 500 back to the http agent. 
> In this case, the VH's statistics fields are final and initialised once during AVH's
constructor.
> {noformat}
> Broker-Configuration-Thread 2014-05-26 11:04:05,038 INFO [qpid.server.stats.StatisticsCounter]
Resetting statistics for counter: bytes-received-BDBHAVirtualHostNodeRestTest.testNewMasterElectedWhenVirtualHostIsStopped-28
> qtp1754689051-872 2014-05-26 11:04:05,039 WARN [eclipse.jetty.servlet.ServletHandler]
/api/latest/virtualhostnode/node3
> java.lang.NullPointerException
>         at org.apache.qpid.server.virtualhost.AbstractVirtualHost.getBytesIn(AbstractVirtualHost.java:1175)
>         at sun.reflect.GeneratedMethodAccessor46.invoke(Unknown Source)
>         at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
>         at java.lang.reflect.Method.invoke(Method.java:606)
>         at org.apache.qpid.server.model.ConfiguredObjectAttributeOrStatistic.getValue(ConfiguredObjectAttributeOrStatistic.java:138)
>         at org.apache.qpid.server.model.AbstractConfiguredObject.getStatistics(AbstractConfiguredObject.java:1296)
>         at org.apache.qpid.server.management.plugin.servlet.rest.ConfiguredObjectToMapConverter.incorporateStatisticsIntoMap(ConfiguredObjectToMapConverter.java:89)
>         at org.apache.qpid.server.management.plugin.servlet.rest.ConfiguredObjectToMapConverter.convertObjectToMap(ConfiguredObjectToMapConverter.java:42)
>         at org.apache.qpid.server.management.plugin.servlet.rest.ConfiguredObjectToMapConverter.incorporateChildrenIntoMap(ConfiguredObjectToMapConverter.java:112)
>         at org.apache.qpid.server.management.plugin.servlet.rest.ConfiguredObjectToMapConverter.convertObjectToMap(ConfiguredObjectToMapConverter.java:46)
>         at org.apache.qpid.server.management.plugin.servlet.rest.RestServlet.doGetWithSubjectAndActor(RestServlet.java:318)
>         at org.apache.qpid.server.management.plugin.servlet.rest.AbstractServlet$1.run(AbstractServlet.java:76)
>         at org.apache.qpid.server.management.plugin.servlet.rest.AbstractServlet$1.run(AbstractServlet.java:72)
>         at java.security.AccessController.doPrivileged(Native Method)
>         at javax.security.auth.Subject.doAs(Subject.java:415)
>         at org.apache.qpid.server.management.plugin.servlet.rest.AbstractServlet.doWithSubjectAndActor(AbstractServlet.java:195)
>         at org.apache.qpid.server.management.plugin.servlet.rest.AbstractServlet.doGet(AbstractServlet.java:70)
>         at javax.servlet.http.HttpServlet.service(HttpServlet.java:575)
>         at javax.servlet.http.HttpServlet.service(HttpServlet.java:668)
>         at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:684)
>         at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1496)
>         at org.apache.qpid.server.management.plugin.filter.ForbiddingAuthorisationFilter.doFilter(ForbiddingAuthorisationFilter.java:90)
>         at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1467)
>         at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:499)
>         at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:229)
>         at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1086)
>         at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:428)
>         at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:193)
>         at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1020)
>         at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:135)
>         at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:116)
>         at org.eclipse.jetty.server.Server.handle(Server.java:370)
>         at org.eclipse.jetty.server.AbstractHttpConnection.handleRequest(AbstractHttpConnection.java:494)
>         at org.eclipse.jetty.server.AbstractHttpConnection.headerComplete(AbstractHttpConnection.java:971)
>         at org.eclipse.jetty.server.AbstractHttpConnection$RequestHandler.headerComplete(AbstractHttpConnection.java:1033)
>         at org.eclipse.jetty.http.HttpParser.parseNext(HttpParser.java:644)
>         at org.eclipse.jetty.http.HttpParser.parseAvailable(HttpParser.java:235)
>         at org.eclipse.jetty.server.AsyncHttpConnection.handle(AsyncHttpConnection.java:82)
>         at org.eclipse.jetty.io.nio.SelectChannelEndPoint.handle(SelectChannelEndPoint.java:667)
>         at org.eclipse.jetty.io.nio.SelectChannelEndPoint$1.run(SelectChannelEndPoint.java:52)
>         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:744)
>  
> {noformat}



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