/**
* 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.mahout.cf.taste.impl.model;
import org.apache.mahout.cf.taste.impl.common.FastByIDMap;
import org.apache.mahout.cf.taste.model.UpdatableIDMigrator;
/**
* Implementation which stores the reverse long-to-String mapping in memory.
*/
public final class MemoryIDMigrator extends AbstractIDMigrator implements UpdatableIDMigrator {
private final FastByIDMap<String> longToString;
public MemoryIDMigrator() {
this.longToString = new FastByIDMap<String>(100);
}
@Override
public void storeMapping(long longID, String stringID) {
synchronized (longToString) {
longToString.put(longID, stringID);
}
}
@Override
public String toStringID(long longID) {
synchronized (longToString) {
return longToString.get(longID);
}
}
@Override
public void initialize(Iterable<String> stringIDs) {
for (String stringID : stringIDs) {
storeMapping(toLongID(stringID), stringID);
}
}
}