hadoop EmptyPrefetchingStatistics 源码
haddop EmptyPrefetchingStatistics 代码
文件路径：/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/impl/prefetch/EmptyPrefetchingStatistics.java
/*
* 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.fs.impl.prefetch;
import java.time.Duration;
import org.apache.hadoop.fs.statistics.DurationTracker;
import static org.apache.hadoop.fs.statistics.IOStatisticsSupport.stubDurationTracker;
/**
* Empty implementation of the prefetching statistics interface.
*/
public final class EmptyPrefetchingStatistics
implements PrefetchingStatistics {
private static final EmptyPrefetchingStatistics
EMPTY_PREFETCHING_STATISTICS =
new EmptyPrefetchingStatistics();
private EmptyPrefetchingStatistics() {
}
public static EmptyPrefetchingStatistics getInstance() {
return EMPTY_PREFETCHING_STATISTICS;
}
@Override
public DurationTracker prefetchOperationStarted() {
return stubDurationTracker();
}
@Override
public void blockAddedToFileCache() {
}
@Override
public void blockRemovedFromFileCache() {
}
@Override
public void prefetchOperationCompleted() {
}
@Override
public void executorAcquired(Duration timeInQueue) {
}
@Override
public void memoryAllocated(int size) {
}
@Override
public void memoryFreed(int size) {
}
}
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