X-Git-Url: https://gerrit.simantics.org/r/gitweb?a=blobdiff_plain;f=bundles%2Forg.simantics.db.layer0%2Fsrc%2Forg%2Fsimantics%2Fdb%2Flayer0%2Fgenericrelation%2FExternalRequest.java;h=8cf5652ce0367f31baeca31e72c0f70425657c0c;hb=ccb253462b54a0e036f0906ec8ac11a9021a968c;hp=77520aa6e66ce2ed324ec91b8868955698a4759a;hpb=969bd23cab98a79ca9101af33334000879fb60c5;p=simantics%2Fplatform.git

diff --git a/bundles/org.simantics.db.layer0/src/org/simantics/db/layer0/genericrelation/ExternalRequest.java b/bundles/org.simantics.db.layer0/src/org/simantics/db/layer0/genericrelation/ExternalRequest.java
index 77520aa6e..8cf5652ce 100644
--- a/bundles/org.simantics.db.layer0/src/org/simantics/db/layer0/genericrelation/ExternalRequest.java
+++ b/bundles/org.simantics.db.layer0/src/org/simantics/db/layer0/genericrelation/ExternalRequest.java
@@ -1,45 +1,48 @@
-package org.simantics.db.layer0.genericrelation;
-
-import org.simantics.db.ReadGraph;
-import org.simantics.db.Resource;
-import org.simantics.db.Session;
-import org.simantics.db.common.request.ParametrizedPrimitiveRead;
-import org.simantics.db.layer0.adapter.GenericRelationIndex;
-import org.simantics.db.procedure.Listener;
-import org.simantics.utils.datastructures.Pair;
-
-class ExternalRequest extends ParametrizedPrimitiveRead<Pair<GenericRelationIndex,Resource>,Long> implements Runnable {
-
-    private static long value = 0;
-    private Session session;
-    private Listener<Long> procedure;
-
-    public ExternalRequest(GenericRelationIndex index, Resource model) {
-        super(Pair.make(index, model));
-    }
-
-    @Override
-    public void register(ReadGraph graph, Listener<Long> procedure) {
-        synchronized(getClass()) {
-            procedure.execute(value++);
-        }
-        if(procedure.isDisposed()) return;
-        assert(this.procedure == null);
-        this.session = graph.getSession();
-        this.procedure = procedure;
-        parameter.first.addListener(graph, parameter.second, this);
-    }
-    
-    @Override
-    public void unregistered() {
-        parameter.first.removeListener(session, parameter.second, this);
-    }
-    
-    @Override
-    public void run() {
-        synchronized(getClass()) {
-            procedure.execute(value++);
-        }
-    }
-    
+package org.simantics.db.layer0.genericrelation;
+
+import org.simantics.db.ReadGraph;
+import org.simantics.db.Resource;
+import org.simantics.db.Session;
+import org.simantics.db.common.request.ParametrizedPrimitiveRead;
+import org.simantics.db.layer0.adapter.GenericRelationIndex;
+import org.simantics.db.procedure.Listener;
+import org.simantics.utils.datastructures.Pair;
+
+class ExternalRequest extends ParametrizedPrimitiveRead<Pair<GenericRelationIndex,Resource>,Long> implements Runnable {
+
+    private static long value = 0;
+    private Session session;
+    private Listener<Long> procedure;
+
+    public ExternalRequest(GenericRelationIndex index, Resource model) {
+        super(Pair.make(index, model));
+    }
+
+    @Override
+    public void register(ReadGraph graph, Listener<Long> procedure) {
+        synchronized(getClass()) {
+            procedure.execute(value++);
+        }
+        if(procedure.isDisposed()) return;
+        assert(this.procedure == null);
+        this.session = graph.getSession();
+        this.procedure = procedure;
+        parameter.first.addListener(graph, parameter.second, this);
+    }
+
+    @Override
+    public void unregistered() {
+        // Session will be null if the listener was not added at all.
+        if (session != null) {
+            parameter.first.removeListener(session, parameter.second, this);
+        }
+    }
+
+    @Override
+    public void run() {
+        synchronized(getClass()) {
+            procedure.execute(value++);
+        }
+    }
+
 }
\ No newline at end of file