/*
* Copyright 2011-2014 Amazon Technologies, 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://aws.amazon.com/apache2.0
*
* This file 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.amazonaws.services.dynamodbv2.datamodeling;
import java.util.EnumMap;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import com.amazonaws.auth.AWSCredentials;
import com.amazonaws.regions.Regions;
import com.amazonaws.services.s3.AmazonS3Client;
import com.amazonaws.services.s3.model.Region;
import com.amazonaws.services.s3.transfer.TransferManager;
/**
* A smart Map for {@link AmazonS3Client} objects. {@link S3ClientCache} keeps the
* clients organized by region, and if provided {@link AWSCredentials} will
* create clients on the fly. Otherwise it just return clients given to it with
* {@link #useClient(AmazonS3Client)}.
*/
public class S3ClientCache {
private final ConcurrentMap<Region, AmazonS3Client> clientsByRegion = new ConcurrentHashMap<Region, AmazonS3Client>();
private final Map<Region, TransferManager> transferManagersByRegion = new EnumMap<Region, TransferManager>(Region.class);
private final AWSCredentials credentials;
/**
* Create a client cache with a set of credentials. If
* {@link #getClient(Regions)} or {@link #getTransferManager(Regions)} is
* called and a client has not been provided for the region, the cache will
* instantiate one from the provided {@link AWSCredentials}.
*
* @param credentials
* The credentials to use when creating new
* {@link AmazonS3Client}.
*/
S3ClientCache(AWSCredentials credentials) {
this.credentials = credentials;
}
/**
* Force the client cache to provide a certain client for the region which
* that client is configured. This can be useful to provide clients with
* different {@link com.amazonaws.services.s3.S3ClientOptions} or use a
* {@link com.amazonaws.services.s3.AmazonS3EncryptionClient} in place of a
* regular client.
*
* Using a new client will also forcibly shut down any
* {@link TransferManager} that has been instantiated with that client, with
* the {@link TransferManager#shutdownNow()} method.
*
* @param client
* An {@link AmazonS3Client} to use in the cache. Its region will
* be detected automatically.
*/
public void useClient(AmazonS3Client client) {
Region s3region = client.getRegion();
synchronized (transferManagersByRegion) {
TransferManager tm = transferManagersByRegion.remove(s3region);
if (tm != null) {
tm.shutdownNow();
}
clientsByRegion.put(s3region, client);
}
}
/**
* Returns a client for the requested region, or throws an exception when
* unable.
*
* @param s3region
* The region the returned {@link AmazonS3Client} will be
* configured to use.
* @return A client for the given region from the cache, either instantiated
* automatically from the provided {@link AWSCredentials} or
* provided with {@link #useClient(AmazonS3Client)}.
* @throws IllegalArgumentException
* When a region is requested that has not been provided to the
* cache with {@link #useClient(AmazonS3Client)}, and the cache
* has no {@link AWSCredentials} with which a client may be
* instantiated.
*/
public AmazonS3Client getClient(Region s3region) {
if ( s3region == null ) {
throw new IllegalArgumentException("S3 region must be specified");
}
AmazonS3Client client = clientsByRegion.get(s3region);
if (client != null) {
return client;
}
if (credentials == null) {
throw new IllegalArgumentException("No client provided for S3 region: " + s3region);
}
client = new AmazonS3Client(credentials);
client.setRegion(s3region.toAWSRegion());
AmazonS3Client prev = clientsByRegion.putIfAbsent(s3region, client);
return prev == null ? client : prev;
}
/**
* Returns a {@link TransferManager} for the given region, or throws an
* exception when unable. The returned {@link TransferManager} will always
* be instantiated from whatever {@link AmazonS3Client} is in the cache,
* whether provided with {@link #useClient(AmazonS3Client)} or instantiated
* automatically from {@link AWSCredentials}.
*
* Any {@link TransferManager} returned could be shut down if a new
* underlying {@link AmazonS3Client} is provided with
* {@link #useClient(AmazonS3Client)}.
*
* @param region
* The region the returned {@link TransferManager} will be
* configured to use.
* @return A transfer manager for the given region from the cache, or one
* instantiated automatically from any existing
* {@link AmazonS3Client},
*/
public TransferManager getTransferManager(Region region) {
synchronized (transferManagersByRegion) {
TransferManager tm = transferManagersByRegion.get(region);
if (tm == null) {
tm = new TransferManager(getClient(region));
transferManagersByRegion.put(region, tm);
}
return tm;
}
}
}