com.proofpoint.event.collector.combiner.S3ObjectListing.java Source code

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Here is the source code for com.proofpoint.event.collector.combiner.S3ObjectListing.java

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/*
 * Copyright 2011-2014 Proofpoint, Inc.
 *
 * Licensed 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 com.proofpoint.event.collector.combiner;

import com.amazonaws.services.s3.AmazonS3;
import com.amazonaws.services.s3.model.ListObjectsRequest;
import com.amazonaws.services.s3.model.ObjectListing;
import com.amazonaws.services.s3.model.S3ObjectSummary;
import com.google.common.base.Function;
import com.google.common.collect.AbstractSequentialIterator;
import com.google.common.collect.Iterators;

import java.util.Iterator;

class S3ObjectListing implements Iterable<S3ObjectSummary> {
    private final AmazonS3 s3Client;
    private final ListObjectsRequest listObjectsRequest;

    public S3ObjectListing(AmazonS3 s3Client, ListObjectsRequest listObjectsRequest) {
        this.s3Client = s3Client;
        this.listObjectsRequest = listObjectsRequest;
    }

    @Override
    public Iterator<S3ObjectSummary> iterator() {
        Iterator<ObjectListing> objectListings = new AbstractSequentialIterator<ObjectListing>(
                s3Client.listObjects(listObjectsRequest)) {
            @Override
            protected ObjectListing computeNext(ObjectListing previous) {
                if (!previous.isTruncated()) {
                    return null;
                }
                return s3Client.listNextBatchOfObjects(previous);
            }
        };

        return Iterators.concat(
                Iterators.transform(objectListings, new Function<ObjectListing, Iterator<S3ObjectSummary>>() {
                    @Override
                    public Iterator<S3ObjectSummary> apply(ObjectListing input) {
                        return input.getObjectSummaries().iterator();
                    }
                }));
    }
}