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https://issues.apache.org/jira/browse/HADOOP-14971?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16221673#comment-16221673
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ASF GitHub Bot commented on HADOOP-14971:
-----------------------------------------
Github user ajfabbri commented on a diff in the pull request:
https://github.com/apache/hadoop/pull/282#discussion_r147317939
--- Diff:
hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/Invoker.java ---
@@ -0,0 +1,446 @@
+/*
+ * 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.s3a;
+
+import java.io.IOException;
+import java.io.InterruptedIOException;
+import java.util.Optional;
+
+import com.amazonaws.AmazonClientException;
+import com.amazonaws.SdkBaseException;
+import com.google.common.base.Preconditions;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import org.apache.commons.lang3.StringUtils;
+import org.apache.hadoop.io.retry.RetryPolicy;
+
+/**
+ * Class to provide lambda expression invocation of AWS operations.
+ *
+ * The core retry logic is in
+ * {@link #retryUntranslated(String, boolean, Retried, Operation)};
+ * the other {@code retry() and retryUntranslated()} calls are wrappers.
+ *
+ * The static {@link #once(String, String, Operation)} and
+ * {@link #once(String, String, VoidOperation)} calls take an operation and
+ * return it with AWS exceptions translated to IOEs of some form.
+ *
+ * The retry logic on a failure is defined by the retry policy passed in
+ * the constructor; the standard retry policy is {@link S3ARetryPolicy},
+ * though others may be used.
+ *
+ * The constructor also takes two {@link Retried} callbacks.
+ * The {@code caughtCallback} is called whenever an exception (IOE or AWS)
+ * is caught, before the retry processing looks at it.
+ * The {@code retryCallback} is invoked after a retry is scheduled
+ * but before the sleep.
+ * These callbacks can be used for reporting and incrementing statistics.
+ *
+ * The static {@link #quietly(String, String, VoidOperation)} and
+ * {@link #quietlyEval(String, String, Operation)} calls exist to take any
+ * operation and quietly catch & log at debug. The return value of
+ * {@link #quietlyEval(String, String, Operation)} is a java 8 optional,
+ * which can then be used in java8-expressions.
+ */
+public class Invoker {
+ private static final Logger LOG = LoggerFactory.getLogger(Invoker.class);
+
+ /**
+ * Retry policy to use.
+ */
+ private final RetryPolicy retryPolicy;
+
+ /**
+ * Default retry handler.
+ */
+ private final Retried retryCallback;
+
+ /**
+ * Instantiate.
+ * @param retryPolicy retry policy for all operations.
+ * @param retryCallback standard retry policy
+ */
+ public Invoker(
+ RetryPolicy retryPolicy,
+ Retried retryCallback) {
+ this.retryPolicy = retryPolicy;
+ this.retryCallback = retryCallback;
+ }
+
+ public RetryPolicy getRetryPolicy() {
+ return retryPolicy;
+ }
+
+ public Retried getRetryCallback() {
+ return retryCallback;
+ }
+
+ /**
+ * Execute a function, translating any exception into an IOException.
+ * @param action action to execute (used in error messages)
+ * @param path path of work (used in error messages)
+ * @param operation operation to execute
+ * @param <T> type of return value
+ * @return the result of the function call
+ * @throws IOException any IOE raised, or translated exception
+ */
+ @Retries.OnceTranslated
+ public static <T> T once(String action, String path, Operation<T>
operation)
+ throws IOException {
+ try {
+ return operation.execute();
+ } catch (AmazonClientException e) {
+ throw S3AUtils.translateException(action, path, e);
+ }
+ }
+
+ /**
+ * Execute an operation with no result.
+ * @param action action to execute (used in error messages)
+ * @param path path of work (used in error messages)
+ * @param operation operation to execute
+ * @throws IOException any IOE raised, or translated exception
+ */
+ @Retries.OnceTranslated
+ public static void once(String action, String path, VoidOperation
operation)
+ throws IOException {
+ once(action, path,
+ () -> {
+ operation.execute();
+ return null;
+ });
+ }
+
+ /**
+ * Execute a void operation with retry processing.
+ * @param action action to execute (used in error messages)
+ * @param path path of work (used in error messages)
+ * @param idempotent does the operation have semantics
+ * which mean that it can be retried even if was already executed?
+ * @param retrying callback on retries
+ * @param operation operation to execute
+ * @throws IOException any IOE raised, or translated exception
+ */
+ @Retries.RetryTranslated
+ public void retry(String action,
+ String path,
+ boolean idempotent,
+ Retried retrying,
+ VoidOperation operation)
+ throws IOException {
+ retry(action, path, idempotent, retrying,
+ () -> {
+ operation.execute();
+ return null;
+ }
+ );
+ }
+
+ /**
+ * Execute a void operation with the default retry callback invoked.
+ * @param action action to execute (used in error messages)
+ * @param path path of work (used in error messages)
+ * @param idempotent does the operation have semantics
+ * which mean that it can be retried even if was already executed?
+ * @param operation operation to execute
+ * @throws IOException any IOE raised, or translated exception
+ */
+ @Retries.RetryTranslated
+ public void retry(String action,
+ String path,
+ boolean idempotent,
+ VoidOperation operation)
+ throws IOException {
+ retry(action, path, idempotent, retryCallback, operation);
+ }
+
+ /**
+ * Execute a function with the default retry callback invoked.
+ * @param action action to execute (used in error messages)
+ * @param path path of work (used in error messages)
+ * @param idempotent does the operation have semantics
+ * which mean that it can be retried even if was already executed?
+ * @param operation operation to execute
+ * @param <T> type of return value
+ * @return the result of the call
+ * @throws IOException any IOE raised, or translated exception
+ */
+ @Retries.RetryTranslated
+ public <T> T retry(String action,
+ String path,
+ boolean idempotent,
+ Operation<T> operation)
+ throws IOException {
+
+ return retry(action, path, idempotent, retryCallback, operation);
+ }
+
+ /**
+ * Execute a function with retry processing.
+ * Uses {@link #once(String, String, Operation)} as the inner
+ * invocation mechanism before retry logic is performed.
+ * @param <T> type of return value
+ * @param action action to execute (used in error messages)
+ * @param path path of work (used in error messages)
+ * @param idempotent does the operation have semantics
+ * which mean that it can be retried even if was already executed?
+ * @param retrying callback on retries
+ * @param operation operation to execute
+ * @return the result of the call
+ * @throws IOException any IOE raised, or translated exception
+ */
+ @Retries.RetryTranslated
+ public <T> T retry(
+ String action,
+ String path,
+ boolean idempotent,
+ Retried retrying,
+ Operation<T> operation)
+ throws IOException {
+ return retryUntranslated(
+ toDescription(action, path),
+ idempotent,
+ retrying,
+ () -> once(action, path, operation));
+ }
+
+ /**
+ * Execute a function with retry processing and no translation.
+ * and the default retry callback.
+ * @param text description for the catching callback
+ * @param idempotent does the operation have semantics
+ * which mean that it can be retried even if was already executed?
+ * @param operation operation to execute
+ * @param <T> type of return value
+ * @return the result of the call
+ * @throws IOException any IOE raised
+ * @throws RuntimeException any Runtime exception raised
+ */
+ @Retries.RetryRaw
+ public <T> T retryUntranslated(
+ String text,
+ boolean idempotent,
+ Operation<T> operation) throws IOException {
+ return retryUntranslated(text, idempotent,
+ retryCallback, operation);
+ }
+
+ /**
+ * Execute a function with retry processing: AWS SDK Exceptions
+ * are <i>not</i> translated.
+ * This is method which the others eventually invoke.
+ * @param <T> type of return value
+ * @param text text to include in messages
+ * @param idempotent does the operation have semantics
+ * which mean that it can be retried even if was already executed?
+ * @param retrying callback on retries
+ * @param operation operation to execute
+ * @return the result of the call
+ * @throws IOException any IOE raised
+ * @throws SdkBaseException any AWS exception raised
+ */
+ @Retries.RetryRaw
+ public <T> T retryUntranslated(
+ String text,
+ boolean idempotent,
+ Retried retrying,
+ Operation<T> operation) throws IOException {
+
+ Preconditions.checkArgument(retrying != null, "null retrying
argument");
+ int retryCount = 0;
+ Exception caught;
+ RetryPolicy.RetryAction retryAction;
+ boolean shouldRetry;
+ do {
+ try {
+ // execute the operation, returning if successful
+ return operation.execute();
+ } catch (IOException | SdkBaseException e) {
+ caught = e;
+ }
--- End diff --
Commented on this section before.. may have had it wrong then, but to be
clear: you want to propagate things like NullPointerException thrown from
operation.execute()? I suppose unexpected exceptions are always non-retryable
but I'm surprised we don't want to make it an IOE here.
> Merge S3A committers into trunk
> -------------------------------
>
> Key: HADOOP-14971
> URL: https://issues.apache.org/jira/browse/HADOOP-14971
> Project: Hadoop Common
> Issue Type: Sub-task
> Components: fs/s3
> Affects Versions: 3.0.0
> Reporter: Steve Loughran
> Assignee: Steve Loughran
>
> Merge the HADOOP-13786 committer into trunk. This branch is being set up as a
> github PR for review there & to keep it out the mailboxes of the watchers on
> the main JIRA
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