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/*
* 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.util.Collection;
import java.util.List;
import java.util.Set;
import java.util.stream.Collectors;
import com.amazonaws.services.s3.model.ListObjectsV2Result;
import com.amazonaws.services.s3.model.ObjectListing;
import com.amazonaws.services.s3.model.S3ObjectSummary;
import org.slf4j.Logger;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.fs.s3a.impl.ContextAccessors;
/**
* API version-independent container for S3 List responses.
*/
public class S3ListResult {
private ObjectListing v1Result;
private ListObjectsV2Result v2Result;
protected S3ListResult(ObjectListing v1, ListObjectsV2Result v2) {
v1Result = v1;
v2Result = v2;
}
/**
* Restricted constructors to ensure v1 or v2, not both.
* @param result v1 result
* @return new list result container
*/
public static S3ListResult v1(ObjectListing result) {
return new S3ListResult(result, null);
}
/**
* Restricted constructors to ensure v1 or v2, not both.
* @param result v2 result
* @return new list result container
*/
public static S3ListResult v2(ListObjectsV2Result result) {
return new S3ListResult(null, result);
}
/**
* Is this a v1 API result or v2?
* @return true if v1, false if v2
*/
public boolean isV1() {
return v1Result != null;
}
public ObjectListing getV1() {
return v1Result;
}
public ListObjectsV2Result getV2() {
return v2Result;
}
public List getObjectSummaries() {
if (isV1()) {
return v1Result.getObjectSummaries();
} else {
return v2Result.getObjectSummaries();
}
}
public boolean isTruncated() {
if (isV1()) {
return v1Result.isTruncated();
} else {
return v2Result.isTruncated();
}
}
public List getCommonPrefixes() {
if (isV1()) {
return v1Result.getCommonPrefixes();
} else {
return v2Result.getCommonPrefixes();
}
}
/**
* Is the list of object summaries empty
* after accounting for tombstone markers (if provided)?
* @param accessors callback for key to path mapping.
* @param tombstones Set of tombstone markers, or null if not applicable.
* @return false if summaries contains objects not accounted for by
* tombstones.
*/
public boolean isEmptyOfObjects(
final ContextAccessors accessors,
final Set tombstones) {
if (tombstones == null) {
return getObjectSummaries().isEmpty();
}
return isEmptyOfKeys(accessors,
objectSummaryKeys(),
tombstones);
}
/**
* Get the list of keys in the object summary.
* @return a possibly empty list
*/
private List objectSummaryKeys() {
return getObjectSummaries().stream()
.map(S3ObjectSummary::getKey)
.collect(Collectors.toList());
}
/**
* Does this listing have prefixes or objects after entries with
* tombstones have been stripped?
* @param accessors callback for key to path mapping.
* @param tombstones Set of tombstone markers, or null if not applicable.
* @return true if the reconciled list is non-empty
*/
public boolean hasPrefixesOrObjects(
final ContextAccessors accessors,
final Set tombstones) {
return !isEmptyOfKeys(accessors, getCommonPrefixes(), tombstones)
|| !isEmptyOfObjects(accessors, tombstones);
}
/**
* Helper function to determine if a collection of keys is empty
* after accounting for tombstone markers (if provided).
* @param accessors callback for key to path mapping.
* @param keys Collection of path (prefixes / directories or keys).
* @param tombstones Set of tombstone markers, or null if not applicable.
* @return true if the list is considered empty.
*/
public boolean isEmptyOfKeys(
final ContextAccessors accessors,
final Collection keys,
final Set tombstones) {
if (tombstones == null) {
return keys.isEmpty();
}
for (String key : keys) {
Path qualified = accessors.keyToPath(key);
if (!tombstones.contains(qualified)) {
return false;
}
}
return true;
}
/**
* Does this listing represent an empty directory?
* @param contextAccessors callback for key to path mapping.
* @param dirKey directory key
* @param tombstones Set of tombstone markers, or null if not applicable.
* @return true if the list is considered empty.
*/
public boolean representsEmptyDirectory(
final ContextAccessors contextAccessors,
final String dirKey,
final Set tombstones) {
// If looking for an empty directory, the marker must exist but
// no children.
// So the listing must contain the marker entry only as an object,
// and prefixes is null
List keys = objectSummaryKeys();
return keys.size() == 1 && keys.contains(dirKey)
&& getCommonPrefixes().isEmpty();
}
/**
* Dmp the result at debug level.
* @param log log to use
*/
public void logAtDebug(Logger log) {
Collection prefixes = getCommonPrefixes();
Collection summaries = getObjectSummaries();
log.debug("Prefix count = {}; object count={}",
prefixes.size(), summaries.size());
for (S3ObjectSummary summary : summaries) {
log.debug("Summary: {} {}", summary.getKey(), summary.getSize());
}
for (String prefix : prefixes) {
log.debug("Prefix: {}", prefix);
}
}
}