Github user jiajunwang commented on a diff in the pull request:
https://github.com/apache/helix/pull/145#discussion_r174326343
--- Diff:
helix-core/src/main/java/org/apache/helix/util/WeightAwareRebalanceUtil.java ---
@@ -0,0 +1,141 @@
+package org.apache.helix.util;
+
+import org.apache.helix.HelixException;
+import org.apache.helix.ZNRecord;
+import org.apache.helix.api.config.RebalanceConfig;
+import
org.apache.helix.api.rebalancer.constraint.AbstractRebalanceHardConstraint;
+import
org.apache.helix.api.rebalancer.constraint.AbstractRebalanceSoftConstraint;
+import org.apache.helix.controller.common.PartitionStateMap;
+import org.apache.helix.controller.common.ResourcesStateMap;
+import
org.apache.helix.controller.rebalancer.strategy.ConstraintRebalanceStrategy;
+import org.apache.helix.controller.stages.ClusterDataCache;
+import org.apache.helix.model.*;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * A rebalance tool that generate an resource partition assignment based
on the input.
+ * Note the assignment won't be automatically applied to the cluster.
Applications are supposed to
+ * apply the change.
+ */
+public class WeightAwareRebalanceUtil {
+ private final ClusterConfig _clusterConfig;
+ private final Map<String, InstanceConfig> _instanceConfigMap = new
HashMap<>();
+ // For the possible customized state models.
+ private final Map<String, StateModelDefinition> _stateModelDefs = new
HashMap<>();
+ private final ClusterDataCache _dataCache;
+
+ public enum RebalanceOption {
+ INIT,
+ REASSIGN
+ }
+
+ public WeightAwareRebalanceUtil(ClusterConfig clusterConfig,
+ List<InstanceConfig> instanceConfigs) {
+ for (InstanceConfig instanceConfig : instanceConfigs) {
+ _instanceConfigMap.put(instanceConfig.getInstanceName(),
instanceConfig);
+ }
+ _clusterConfig = clusterConfig;
+
+ _dataCache = new ClusterDataCache();
+ _dataCache.setInstanceConfigMap(_instanceConfigMap);
+ _dataCache.setClusterConfig(_clusterConfig);
+ List<LiveInstance> liveInstanceList = new ArrayList<>();
+ for (String instance : _instanceConfigMap.keySet()) {
+ LiveInstance liveInstance = new LiveInstance(instance);
+ liveInstanceList.add(liveInstance);
+ }
+ _dataCache.setLiveInstances(liveInstanceList);
+ }
+
+ /**
+ * The method to generate partition assignment mappings.
+ *
+ * @param resourceConfigs Config of all the resources that need to be
rebalanced.
+ * The tool throws Exception if any resource
has no IS or broken/uninitialized IS.
+ * The tool throws Exception if any resource
is in full-auto mode.
+ * @param existingAssignment The existing partition assignment of the
input resources.
+ * @param option INIT or REASSIGN
+ * INIT: Keep existing assignment. Only
generate new partition assignment.
--- End diff --
"Mode" is confusing while we already have "RebalanceMode".
About the option name, how about "incremental" rebalance & "full"
rebalance? I think those 2 names are much better.
I will add the comment about the resourceConfig, this is where users should
specify the partitions.
Also, as a standalone tool, most rebalance options won't work even
configured in the cluster config / instance config. I will add comments to
point it out.
---
