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https://issues.apache.org/jira/browse/HADOOP-17271?focusedWorklogId=523876&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-523876
]
ASF GitHub Bot logged work on HADOOP-17271:
-------------------------------------------
Author: ASF GitHub Bot
Created on: 14/Dec/20 13:59
Start Date: 14/Dec/20 13:59
Worklog Time Spent: 10m
Work Description: steveloughran commented on a change in pull request
#2324:
URL: https://github.com/apache/hadoop/pull/2324#discussion_r542403956
##########
File path:
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/functional/RemoteIterators.java
##########
@@ -0,0 +1,698 @@
+/*
+ * 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.util.functional;
+
+import javax.annotation.Nullable;
+import java.io.Closeable;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Iterator;
+import java.util.List;
+import java.util.NoSuchElementException;
+import java.util.Objects;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.hadoop.fs.RemoteIterator;
+import org.apache.hadoop.fs.statistics.IOStatistics;
+import org.apache.hadoop.fs.statistics.IOStatisticsSource;
+import org.apache.hadoop.io.IOUtils;
+
+import static java.util.Objects.requireNonNull;
+import static
org.apache.hadoop.fs.statistics.IOStatisticsLogging.logIOStatisticsAtDebug;
+import static
org.apache.hadoop.fs.statistics.IOStatisticsSupport.retrieveIOStatistics;
+
+/**
+ * A set of remote iterators supporting transformation and filtering,
+ * with IOStatisticsSource passthrough, and of conversions of
+ * the iterators to lists/arrays and of performing actions
+ * on the values.
+ * <p></p>
+ * This aims to make it straightforward to use lambda-expressions to
+ * transform the results of an iterator, without losing the statistics
+ * in the process, and to chain the operations together.
+ * <p></p>
+ * The closeable operation will be passed through RemoteIterators which
+ * wrap other RemoteIterators. This is to support any iterator which
+ * can be closed to release held connections, file handles etc.
+ * Unless client code is written to assume that RemoteIterator instances
+ * may be closed, this is not likely to be broadly used. It is added
+ * to make it possible to adopt this feature in a managed way.
+ * <p></p>
+ * One notable feature is that the
+ * {@link #foreach(RemoteIterator, ConsumerRaisingIOE)} method will
+ * LOG at debug any IOStatistics provided by the iterator, if such
+ * statistics are provided. There's no attempt at retrieval and logging
+ * if the LOG is not set to debug, so it is a zero cost feature unless
+ * the logger {@code org.apache.hadoop.fs.functional.RemoteIterators}
+ * is at DEBUG.
+ * <p></p>
+ * Based on the S3A Listing code, and some some work on moving other code
+ * to using iterative listings so as to pick up the statistics.
+ */
[email protected]
[email protected]
+public final class RemoteIterators {
Review comment:
This is actually a class to work with RemoteIterator instances
* A set of chainable iterators to filter, transform and map from java
Iterable to remote Iterator. If you look at S3a's Listing class, we wrap
iterators this way. RemoteIterators makes this more generic
* And the iterators pass down IOStatistics all the way to the bottom. This
is needed so we can get the final IOStats through those FS listing APIs.
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Issue Time Tracking
-------------------
Worklog Id: (was: 523876)
Time Spent: 6h 40m (was: 6.5h)
> S3A statistics to support IOStatistics
> --------------------------------------
>
> Key: HADOOP-17271
> URL: https://issues.apache.org/jira/browse/HADOOP-17271
> Project: Hadoop Common
> Issue Type: Sub-task
> Components: fs/s3
> Affects Versions: 3.3.0
> Reporter: Steve Loughran
> Assignee: Steve Loughran
> Priority: Major
> Labels: pull-request-available
> Time Spent: 6h 40m
> Remaining Estimate: 0h
>
> S3A to rework statistics with
> * API + Implementation split of the interfaces used by subcomponents when
> reporting stats
> * S3A Instrumentation to implement all the interfaces
> * streams, etc to all implement IOStatisticsSources and serve to callers
> * Add some tracking of durations of remote requests
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