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From kahat...@apache.org
Subject svn commit: r614530 - /db/derby/code/branches/10.3/java/engine/org/apache/derby/impl/sql/GenericActivationHolder.java
Date Wed, 23 Jan 2008 13:22:08 GMT
Author: kahatlen
Date: Wed Jan 23 05:22:06 2008
New Revision: 614530

URL: http://svn.apache.org/viewvc?rev=614530&view=rev
Log:
DERBY-3260: NullPointerException caused by race condition in GenericActivationHolder

Merged fix from trunk (svn merge -c 613815 ../trunk)

Modified:
    db/derby/code/branches/10.3/java/engine/org/apache/derby/impl/sql/GenericActivationHolder.java

Modified: db/derby/code/branches/10.3/java/engine/org/apache/derby/impl/sql/GenericActivationHolder.java
URL: http://svn.apache.org/viewvc/db/derby/code/branches/10.3/java/engine/org/apache/derby/impl/sql/GenericActivationHolder.java?rev=614530&r1=614529&r2=614530&view=diff
==============================================================================
--- db/derby/code/branches/10.3/java/engine/org/apache/derby/impl/sql/GenericActivationHolder.java
(original)
+++ db/derby/code/branches/10.3/java/engine/org/apache/derby/impl/sql/GenericActivationHolder.java
Wed Jan 23 05:22:06 2008
@@ -255,9 +255,20 @@
 			if (gc != ps.getActivationClass())
 			{
 
+                GeneratedClass newGC;
+
 				// ensure the statement is valid by rePreparing it.
-				ps.rePrepare(getLanguageConnectionContext());
-				
+                // DERBY-3260: If someone else reprepares the statement at the
+                // same time as we do, there's a window between the calls to
+                // rePrepare() and getActivationClass() when the activation
+                // class can be set to null, leading to NullPointerException
+                // being thrown later. Therefore, synchronize on ps to close
+                // the window.
+                synchronized (ps) {
+                    ps.rePrepare(getLanguageConnectionContext());
+                    newGC = ps.getActivationClass();
+                }
+
 				/*
 				** If we get here, it means the PreparedStatement has been
 				** recompiled.  Get a new Activation and check whether the
@@ -265,8 +276,6 @@
 				** from the old Activation to the new one, and make that the
 				** current Activation.  If not, throw an exception.
 				*/
-				GeneratedClass		newGC = ps.getActivationClass();
-
 				BaseActivation		newAC = (BaseActivation) newGC.newInstance(lcc);
 
 				DataTypeDescriptor[]	newParamTypes = ps.getParameterTypes();



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