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Code Issues Wiki Activity

Bug 500988: better handle race condition in SourceContainer

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Instead of an indiscriminate NPE at termination of a launch, handle it
more cleanly with a friendly error message.

Change-Id: Ie37e675c3f5e4883c0b160bfe86c4848f1983fa7
This commit is contained in:
Jonah Graham 2017-11-15 10:45:54 +00:00
parent b721d6a424
commit 2173d1dd52
1 changed files with 31 additions and 1 deletions
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32
dsf-gdb/org.eclipse.cdt.dsf.gdb/src/org/eclipse/cdt/dsf/gdb/launching/GdbSourceLookupDirector.java
View file

@ -10,6 +10,7 @@
*******************************************************************************/
package org.eclipse.cdt.dsf.gdb.launching;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
@ -17,11 +18,14 @@ import org.eclipse.cdt.debug.core.sourcelookup.IMappingSourceContainer;
import org.eclipse.cdt.debug.core.sourcelookup.MappingSourceContainer;
import org.eclipse.cdt.debug.internal.core.sourcelookup.MapEntrySourceContainer;
import org.eclipse.cdt.dsf.debug.sourcelookup.DsfSourceLookupDirector;
import org.eclipse.cdt.dsf.gdb.internal.GdbPlugin;
import org.eclipse.cdt.dsf.gdb.service.IGDBSourceLookup;
import org.eclipse.cdt.dsf.service.DsfSession;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IPath;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Path;
import org.eclipse.core.runtime.Status;
import org.eclipse.debug.core.sourcelookup.ISourceContainer;
import org.eclipse.debug.core.sourcelookup.ISourceLookupParticipant;
import org.eclipse.debug.core.sourcelookup.containers.DefaultSourceContainer;
@ -61,7 +65,33 @@ public class GdbSourceLookupDirector extends DsfSourceLookupDirector {
*/
public Map<String, String> getSubstitutionsPaths() {
Map<String, String> entries = new HashMap<>();
collectSubstitutionsPaths(getSourceContainers(), entries);
try {
collectSubstitutionsPaths(getSourceContainers(), entries);
} catch (NullPointerException npe) {
/*
* Bug 500988: getting source containers from composite containers has a race
* condition around termination. This can lead to a NPE being thrown from within
* the above code.
*
* The reason for the NPE is that termination of a launch can cause the launch
* configuration to be updated (e.g. with memory settings memento). This update
* causes the source lookups to be recalculated, however that recalculation is
* happening while the launch is terminating. The termination causes the source
* containers to be disposed in another thread and as the dispose method is not
* thread safe, we get NPEs. See CompositeSourceContainer.dispose() where the
* race condition is. Unfortunately synchronizing it leads to potential
* deadlocks.
*
* Catching all NPEs and silently discarding them makes it very hard to track
* down bugs, so in case the NPE is caused for another reason we are logging it.
*/
GdbPlugin.log(new Status(IStatus.ERROR, GdbPlugin.getUniqueIdentifier(), IStatus.ERROR,
"NullPointerException while trying to calculated source lookup path. " //$NON-NLS-1$
+ "This can be ignored if it occurs while terminating a debug session. " //$NON-NLS-1$
+ "See Bug 500988.", //$NON-NLS-1$
npe));
entries = Collections.emptyMap();
}
return entries;
}