narendly commented on a change in pull request #381: Implement the POC work
greedy constraint based algorithm
URL: https://github.com/apache/helix/pull/381#discussion_r311729802
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File path:
helix-core/src/main/java/org/apache/helix/controller/rebalancer/waged/algorithm/ConstraintBasedAlgorithm.java
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@@ -0,0 +1,109 @@
+package org.apache.helix.controller.rebalancer.waged.algorithm;
+
+import org.apache.helix.controller.rebalancer.waged.constraints.HardConstraint;
+import org.apache.helix.controller.rebalancer.waged.constraints.SoftConstraint;
+import org.apache.helix.controller.rebalancer.waged.model.AssignableNode;
+import org.apache.helix.controller.rebalancer.waged.model.AssignableReplica;
+import org.apache.helix.controller.rebalancer.waged.model.ClusterContext;
+import org.apache.helix.controller.rebalancer.waged.model.ClusterModel;
+import org.apache.helix.controller.rebalancer.waged.model.OptimalAssignment;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
+
+/**
+ * The algorithm is based on a given set of constraints
+ * - HardConstraint: Approve or deny the assignment given its condition, any
assignment cannot bypass any "hard constraint"
+ * - SoftConstraint: Evaluate the assignment by points/rewards/scores, a
higher point means a better assignment
+ * <p>
+ * The goal is to avoid all "hard constraints" while accumulating the most
points(rewards) from "soft constraints"
+ */
+public class ConstraintBasedAlgorithm implements RebalanceAlgorithm {
+ private static final Logger LOG =
LoggerFactory.getLogger(ConstraintBasedAlgorithm.class);
+ private final List<HardConstraint> _hardConstraints;
+ private final List<SoftConstraint> _softConstraints;
+
+ public ConstraintBasedAlgorithm(List<HardConstraint> hardConstraints,
List<SoftConstraint> softConstraints) {
+ _hardConstraints = hardConstraints;
+ _softConstraints = softConstraints;
+ }
+
+ @Override
+ public OptimalAssignment calculate(ClusterModel clusterModel) {
+ OptimalAssignment currentAssignment = new OptimalAssignment();
+ Map<String, Set<AssignableReplica>> replicasByResource =
clusterModel.getAssignableReplicaMap();
+ List<AssignableNode> nodes = new
ArrayList<>(clusterModel.getAssignableNodes().values());
+ ClusterContext clusterContext = clusterModel.getContext();
+
+
Review comment:
Extra space?
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