X-Git-Url: https://gerrit.simantics.org/r/gitweb?a=blobdiff_plain;f=bundles%2Forg.simantics.db.impl%2Fsrc%2Forg%2Fsimantics%2Fdb%2Fimpl%2Fquery%2FPendingTaskSupport.java;fp=bundles%2Forg.simantics.db.impl%2Fsrc%2Forg%2Fsimantics%2Fdb%2Fimpl%2Fquery%2FPendingTaskSupport.java;h=f63bad581695656ff9b367de74129981b1c0311c;hb=26b755c7e98b7bb3d9038abba139bef0e71f6607;hp=0000000000000000000000000000000000000000;hpb=501ad95ad5ca980ef4c6e65af1451a0d7b63cddc;p=simantics%2Fplatform.git

diff --git a/bundles/org.simantics.db.impl/src/org/simantics/db/impl/query/PendingTaskSupport.java b/bundles/org.simantics.db.impl/src/org/simantics/db/impl/query/PendingTaskSupport.java
new file mode 100644
index 000000000..f63bad581
--- /dev/null
+++ b/bundles/org.simantics.db.impl/src/org/simantics/db/impl/query/PendingTaskSupport.java
@@ -0,0 +1,45 @@
+package org.simantics.db.impl.query;
+
+import java.util.ArrayList;
+import java.util.Collection;
+
+import org.simantics.db.impl.query.QueryProcessor.SessionTask;
+
+/*
+ * Support class for queuing pending tasks to be executed when result gets ready
+ */
+public class PendingTaskSupport {
+
+    private ArrayList<SessionTask> pendingTasks;
+    private IPending pending;
+    
+    public PendingTaskSupport(IPending pending) {
+        this.pending = pending;
+    }
+    
+    /*
+     * We assume here that the associated IPending performs this atomically
+     * The caller is responsible for execution of the returned task after the critical section
+     */
+    public boolean executeWhenResultIsAvailable(SessionTask task) {
+        if(pending.isPending()) {
+            if(pendingTasks == null)
+                pendingTasks = new ArrayList<SessionTask>();
+            pendingTasks.add(task);
+            return false;
+        } else {
+            return true;
+        }
+    }
+
+    /*
+     * We assume here that the associated IPending performs this atomically after changing the pending result
+     * The caller is responsible for execution of the returned task after the critical section
+     */
+    public Collection<SessionTask> executePending() {
+        ArrayList<SessionTask> ret = pendingTasks;
+        pendingTasks = null;
+        return ret;
+    }
+
+}