/** | |
* 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. | |
*/ | |
package org.apache.hadoop.contrib.index.mapred; | |
/** | |
* A distribution policy decides, given a document with a document id, which | |
* one shard the request should be sent to if the request is an insert, and | |
* which shard(s) the request should be sent to if the request is a delete. | |
*/ | |
public interface IDistributionPolicy { | |
/** | |
* Initialization. It must be called before any chooseShard() is called. | |
* @param shards | |
*/ | |
void init(Shard[] shards); | |
/** | |
* Choose a shard to send an insert request. | |
* @param key | |
* @return the index of the chosen shard | |
*/ | |
int chooseShardForInsert(DocumentID key); | |
/** | |
* Choose a shard or all shards to send a delete request. E.g. a round-robin | |
* distribution policy would send a delete request to all the shards. | |
* -1 represents all the shards. | |
* @param key | |
* @return the index of the chosen shard, -1 if all the shards are chosen | |
*/ | |
int chooseShardForDelete(DocumentID key); | |
} |