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https://issues.apache.org/jira/browse/HELIX-674?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16409890#comment-16409890
]
ASF GitHub Bot commented on HELIX-674:
--------------------------------------
Github user mcvsubbu commented on a diff in the pull request:
https://github.com/apache/helix/pull/145#discussion_r176490613
--- Diff:
helix-core/src/main/java/org/apache/helix/api/rebalancer/constraint/dataprovider/CapacityProvider.java
---
@@ -0,0 +1,48 @@
+package org.apache.helix.api.rebalancer.constraint.dataprovider;
+
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+/**
+ * An interface for getting participant capacity information.
+ * The return value will be used to estimate available capacity, as well
as utilization in percentage for prioritizing participants.
+ *
+ * Note that all return values of the provider are supposed to be in the
same unit.
+ * For example, if the provider is for memory capacity of a host (total
memory size is 8G, current usage is 512MB),
+ * the return values could be {@link
org.apache.helix.api.rebalancer.constraint.dataprovider.CapacityProvider#getParticipantCapacity(String)}
= 8192, and {@link
org.apache.helix.api.rebalancer.constraint.dataprovider.CapacityProvider#getParticipantUsage(String)}
= 512.
+ * Another example, if the provider is for partition count capacity (max
count 1000 partitions, currently no partition assigned),
+ * the return values should be {@link
org.apache.helix.api.rebalancer.constraint.dataprovider.CapacityProvider#getParticipantCapacity(String)}
= 1000, and {@link
org.apache.helix.api.rebalancer.constraint.dataprovider.CapacityProvider#getParticipantUsage(String)}
= 0.
+ *
+ * Moreover, while this provider is used together with a {@link
org.apache.helix.api.rebalancer.constraint.dataprovider.PartitionWeightProvider
PartitionWeightProvider},
+ * both providers are supposed to return values in the same unit so they
can be used to estimate the resource usage of an proposed assignment.
+ */
+public interface CapacityProvider {
+
+ /**
+ * @param participant
+ * @return The total participant capacity.
+ */
+ int getParticipantCapacity(String participant);
+
+ /**
+ * @param participant
+ * @return The participant usage (provisioned capacity).
--- End diff --
The comment "(provisioned capacity)" is confusing. Can we remove it?
> Constraint Based Resource Rebalancer
> ------------------------------------
>
> Key: HELIX-674
> URL: https://issues.apache.org/jira/browse/HELIX-674
> Project: Apache Helix
> Issue Type: New Feature
> Reporter: Jiajun Wang
> Assignee: Jiajun Wang
> Priority: Major
> Fix For: 0.8.x
>
> Attachments: Constraint-BasedResourceRebalancing-080318-2226-240.pdf
>
>
> Helix rebalancer assigns resources according to different strategies.
> Recently, we optimize the strategy for evenness and minimize movement.
> However, the evenness here only applies to partition numbers. Moreover, we've
> got more requests for customizable rebalancer from our users.
> Take partition weight as an example:
> In reality, partition replicas have different size. We use "partition weight"
> as an abstraction of the partition size. It can be network traffic usage,
> disk usage, or any other combined factors.
> Given each partition may have different weights, Helix should be able to
> assign partition accordingly. So that the distribution would be even
> regarding the weight.
> In this project, we are planning new rebalancer mechanism that generates
> resource partition assignment according to a list of "constraints". Current
> rebalance strategy can be regarded as one kind of constraint. Moving forward,
> Helix users would be able to extend the constraint interface using their own
> logic.
> Some init discussions are in progress and we will have a proposal posted here
> soon.
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