software.amazon.awssdk.enhanced.dynamodb.internal.operations.DatabaseOperation Maven / Gradle / Ivy

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/*
 * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License").
 * You may not use this file except in compliance with the License.
 * A copy of the License is located at
 *
 *  http://aws.amazon.com/apache2.0
 *
 * or in the "license" file accompanying this file. 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 software.amazon.awssdk.enhanced.dynamodb.internal.operations;

import java.util.concurrent.CompletableFuture;
import java.util.function.Function;
import software.amazon.awssdk.annotations.SdkInternalApi;
import software.amazon.awssdk.enhanced.dynamodb.DynamoDbEnhancedClientExtension;
import software.amazon.awssdk.services.dynamodb.DynamoDbAsyncClient;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;

/**
 * Interface for a single operation that can be executed against a mapped database. These operations do not operate
 * on a specific table or index, and may reference multiple tables and indexes (eg: batch operations). Conceptually an
 * operation maps 1:1 with an actual DynamoDb call.
 *
 * @param   The type of the request object for the DynamoDb call in the low level {@link DynamoDbClient}.
 * @param  The type of the response object for the DynamoDb call in the low level {@link DynamoDbClient}.
 * @param  The type of the mapped result object that will be returned by the execution of this operation.
 */
@SdkInternalApi
public interface DatabaseOperation {
    /**
     * This method generates the request that needs to be sent to a low level {@link DynamoDbClient}.
     * @param extension A {@link DynamoDbEnhancedClientExtension} that may modify the request of this operation. A null
     *                  value here will result in no modifications.
     * @return A request that can be used as an argument to a {@link DynamoDbClient} call to perform the operation.
     */
    RequestT generateRequest(DynamoDbEnhancedClientExtension extension);

    /**
     * Provides a function for making the low level synchronous SDK call to DynamoDb.
     * @param dynamoDbClient A low level {@link DynamoDbClient} to make the call against.
     * @return A function that calls DynamoDb with a provided request object and returns the response object.
     */
    Function serviceCall(DynamoDbClient dynamoDbClient);

    /**
     * Provides a function for making the low level non-blocking asynchronous SDK call to DynamoDb.
     * @param dynamoDbAsyncClient A low level {@link DynamoDbAsyncClient} to make the call against.
     * @return A function that calls DynamoDb with a provided request object and returns a {@link CompletableFuture}
     * for the response object.
     */
    Function> asyncServiceCall(DynamoDbAsyncClient dynamoDbAsyncClient);

    /**
     * Takes the response object returned by the actual DynamoDb call and maps it into a higher level abstracted
     * result object.
     * @param response The response object returned by the DynamoDb call for this operation.
     * @param extension A {@link DynamoDbEnhancedClientExtension} that may modify the result of this operation. A null
     *                  value here will result in no modifications.
     * @return A high level result object as specified by the implementation of this operation.
     */
    ResultT transformResponse(ResponseT response, DynamoDbEnhancedClientExtension extension);

    /**
     * Default implementation of a complete synchronous execution of this operation. It performs three steps:
     * 1) Call generateRequest() to get the request object.
     * 2) Call getServiceCall() and call it using the request object generated in the previous step.
     * 3) Call transformResponse() to convert the response object returned in the previous step to a high level result.
     *
     * @param dynamoDbClient A {@link DynamoDbClient} to make the call against.
     * @param extension A {@link DynamoDbEnhancedClientExtension} that may modify the request or result of this
     *                  operation. A null value here will result in no modifications.
     * @return A high level result object as specified by the implementation of this operation.
     */
    default ResultT execute(DynamoDbClient dynamoDbClient, DynamoDbEnhancedClientExtension extension) {
        RequestT request = generateRequest(extension);
        ResponseT response = serviceCall(dynamoDbClient).apply(request);
        return transformResponse(response, extension);
    }

    /**
     * Default implementation of a complete non-blocking asynchronous execution of this operation. It performs three
     * steps:
     * 1) Call generateRequest() to get the request object.
     * 2) Call getServiceCall() and call it using the request object generated in the previous step.
     * 3) Wraps the {@link CompletableFuture} returned by the SDK in a new one that calls transformResponse() to
     * convert the response object returned in the previous step to a high level result.
     *
     * @param dynamoDbAsyncClient A {@link DynamoDbAsyncClient} to make the call against.
     * @param extension A {@link DynamoDbEnhancedClientExtension} that may modify the request or result of this
     *                  operation. A null value here will result in no modifications.
     * @return A high level result object as specified by the implementation of this operation.
     */
    default CompletableFuture executeAsync(DynamoDbAsyncClient dynamoDbAsyncClient,
                                                    DynamoDbEnhancedClientExtension extension) {

        RequestT request = generateRequest(extension);
        CompletableFuture response = asyncServiceCall(dynamoDbAsyncClient).apply(request);
        return response.thenApply(r -> transformResponse(r, extension));
    }
}