lihaosky commented on code in PR #14696:
URL: https://github.com/apache/kafka/pull/14696#discussion_r1382016189
##########
streams/src/main/java/org/apache/kafka/streams/processor/internals/assignment/Graph.java:
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@@ -200,13 +219,40 @@ public Graph<V> residualGraph() {
return residualGraph;
}
+ private void addDummySourceNode(final Graph<V> residualGraph) {
+ if (!residualGraph.isResidualGraph) {
+ throw new IllegalStateException("Graph should be residual graph to
add dummy source node");
+ }
+
+ // Add a dummy null node connected to every existing node with
residual flow 1 and cost 0
+ // Then try to find negative cylce starting using dummy node as source
node. Since there's no
+ // path from original nodes to null node, negative cycles must be
within original nodes.
+ final TreeMap<V, Edge> destMap = new TreeMap<>();
+ for (final V node : residualGraph.nodes) {
+ final Edge edge = new Edge(node, 1, 0, 1, 0);
+ destMap.put(node, edge);
+ }
+ residualGraph.adjList.put(null, destMap);
+ residualGraph.nodes.add(null);
+ }
+
+ private void removeDummySourceNode(final Graph<V> residualGraph) {
+ if (!residualGraph.isResidualGraph) {
+ throw new IllegalStateException("Graph should be residual graph to
add dummy source node");
Review Comment:
Good catch!
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