| /** |
| * 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.hdfs.protocol; |
| |
| import java.io.IOException; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| import org.apache.hadoop.fs.BatchedRemoteIterator; |
| import org.apache.hadoop.fs.InvalidRequestException; |
| import org.apache.hadoop.ipc.RemoteException; |
| |
| import com.google.common.base.Preconditions; |
| import org.apache.htrace.core.TraceScope; |
| import org.apache.htrace.core.Tracer; |
| |
| /** |
| * CacheDirectiveIterator is a remote iterator that iterates cache directives. |
| * It supports retrying in case of namenode failover. |
| */ |
| @InterfaceAudience.Private |
| @InterfaceStability.Evolving |
| public class CacheDirectiveIterator |
| extends BatchedRemoteIterator<Long, CacheDirectiveEntry> { |
| |
| private CacheDirectiveInfo filter; |
| private final ClientProtocol namenode; |
| private final Tracer tracer; |
| |
| public CacheDirectiveIterator(ClientProtocol namenode, |
| CacheDirectiveInfo filter, Tracer tracer) { |
| super(0L); |
| this.namenode = namenode; |
| this.filter = filter; |
| this.tracer = tracer; |
| } |
| |
| private static CacheDirectiveInfo removeIdFromFilter(CacheDirectiveInfo filter) { |
| CacheDirectiveInfo.Builder builder = new CacheDirectiveInfo.Builder(filter); |
| builder.setId(null); |
| return builder.build(); |
| } |
| |
| /** |
| * Used for compatibility when communicating with a server version that |
| * does not support filtering directives by ID. |
| */ |
| private static class SingleEntry implements |
| BatchedEntries<CacheDirectiveEntry> { |
| |
| private final CacheDirectiveEntry entry; |
| |
| public SingleEntry(final CacheDirectiveEntry entry) { |
| this.entry = entry; |
| } |
| |
| @Override |
| public CacheDirectiveEntry get(int i) { |
| if (i > 0) { |
| return null; |
| } |
| return entry; |
| } |
| |
| @Override |
| public int size() { |
| return 1; |
| } |
| |
| @Override |
| public boolean hasMore() { |
| return false; |
| } |
| } |
| |
| @Override |
| public BatchedEntries<CacheDirectiveEntry> makeRequest(Long prevKey) |
| throws IOException { |
| BatchedEntries<CacheDirectiveEntry> entries; |
| try (TraceScope ignored = tracer.newScope("listCacheDirectives")) { |
| entries = namenode.listCacheDirectives(prevKey, filter); |
| } catch (IOException e) { |
| if (e.getMessage().contains("Filtering by ID is unsupported")) { |
| // Retry case for old servers, do the filtering client-side |
| long id = filter.getId(); |
| filter = removeIdFromFilter(filter); |
| // Using id - 1 as prevId should get us a window containing the id |
| // This is somewhat brittle, since it depends on directives being |
| // returned in order of ascending ID. |
| entries = namenode.listCacheDirectives(id - 1, filter); |
| for (int i = 0; i < entries.size(); i++) { |
| CacheDirectiveEntry entry = entries.get(i); |
| if (entry.getInfo().getId().equals(id)) { |
| return new SingleEntry(entry); |
| } |
| } |
| throw new RemoteException(InvalidRequestException.class.getName(), |
| "Did not find requested id " + id); |
| } |
| throw e; |
| } |
| Preconditions.checkNotNull(entries); |
| return entries; |
| } |
| |
| @Override |
| public Long elementToPrevKey(CacheDirectiveEntry entry) { |
| return entry.getInfo().getId(); |
| } |
| } |