| /** |
| * 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; |
| |
| import java.util.Iterator; |
| import java.util.Map.Entry; |
| import java.util.NavigableMap; |
| import java.util.NoSuchElementException; |
| import java.util.TreeMap; |
| |
| import com.google.common.base.Preconditions; |
| import org.apache.hadoop.classification.InterfaceAudience; |
| |
| /** |
| * Stores global storage statistics objects. |
| */ |
| @InterfaceAudience.Public |
| public enum GlobalStorageStatistics { |
| /** |
| * The GlobalStorageStatistics singleton. |
| */ |
| INSTANCE; |
| |
| /** |
| * A map of all global StorageStatistics objects, indexed by name. |
| */ |
| private final NavigableMap<String, StorageStatistics> map = new TreeMap<>(); |
| |
| /** |
| * A callback API for creating new StorageStatistics instances. |
| */ |
| public interface StorageStatisticsProvider { |
| StorageStatistics provide(); |
| } |
| |
| /** |
| * Get the StorageStatistics object with the given name. |
| * |
| * @param name The storage statistics object name. |
| * @return The StorageStatistics object with the given name, or |
| * null if there is none. |
| */ |
| public synchronized StorageStatistics get(String name) { |
| return name == null ? null : map.get(name); |
| } |
| |
| /** |
| * Create or return the StorageStatistics object with the given name. |
| * |
| * @param name The storage statistics object name. |
| * @param provider An object which can create a new StorageStatistics |
| * object if needed. |
| * @return The StorageStatistics object with the given name. |
| * @throws RuntimeException If the StorageStatisticsProvider provides a null |
| * object or a new StorageStatistics object with the |
| * wrong name. |
| */ |
| public synchronized StorageStatistics put(String name, |
| StorageStatisticsProvider provider) { |
| Preconditions.checkNotNull(name, |
| "Storage statistics can not have a null name!"); |
| StorageStatistics stats = map.get(name); |
| if (stats != null) { |
| return stats; |
| } |
| stats = provider.provide(); |
| if (stats == null) { |
| throw new RuntimeException("StorageStatisticsProvider for " + name + |
| " should not provide a null StorageStatistics object."); |
| } |
| if (!stats.getName().equals(name)) { |
| throw new RuntimeException("StorageStatisticsProvider for " + name + |
| " provided a StorageStatistics object for " + stats.getName() + |
| " instead."); |
| } |
| map.put(name, stats); |
| return stats; |
| } |
| |
| /** |
| * Reset all global storage statistics. |
| */ |
| public synchronized void reset() { |
| for (StorageStatistics statistics : map.values()) { |
| statistics.reset(); |
| } |
| } |
| |
| /** |
| * Get an iterator that we can use to iterate throw all the global storage |
| * statistics objects. |
| */ |
| synchronized public Iterator<StorageStatistics> iterator() { |
| Entry<String, StorageStatistics> first = map.firstEntry(); |
| return new StorageIterator((first == null) ? null : first.getValue()); |
| } |
| |
| private class StorageIterator implements Iterator<StorageStatistics> { |
| private StorageStatistics next = null; |
| |
| StorageIterator(StorageStatistics first) { |
| this.next = first; |
| } |
| |
| @Override |
| public boolean hasNext() { |
| return (next != null); |
| } |
| |
| @Override |
| public StorageStatistics next() { |
| if (next == null) { |
| throw new NoSuchElementException(); |
| } |
| synchronized (GlobalStorageStatistics.this) { |
| StorageStatistics cur = next; |
| Entry<String, StorageStatistics> nextEntry = |
| map.higherEntry(cur.getName()); |
| next = (nextEntry == null) ? null : nextEntry.getValue(); |
| return cur; |
| } |
| } |
| |
| @Override |
| public void remove() { |
| throw new UnsupportedOperationException(); |
| } |
| } |
| } |