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SDK for the development of HiveMQ extensions

There is a newer version: 4.35.0

/*
 * Copyright 2018-present HiveMQ GmbH
 *
 * 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.hivemq.extension.sdk.api.async;

import com.hivemq.extension.sdk.api.annotations.DoNotImplement;
import com.hivemq.extension.sdk.api.annotations.NotNull;

import java.time.Duration;

/**
 * Enables an output object to be processed in a non-blocking way.
 *
 * @author Christoph Schäbel
 * @since 4.0.0, CE 2019.1
 */
@DoNotImplement
public interface AsyncOutput extends SimpleAsyncOutput {

    /**
     * If the timeout is expired before {@link Async#resume()} is called then the outcome is handled either as failed or
     * successful, depending on the specified fallback.
     * 
     * Do not call this method more than once. If an async method is called multiple times an exception is thrown.
     *
     * @param timeout  Timeout that HiveMQ waits for the result of the async operation.
     * @param fallback Fallback behaviour if a timeout occurs. The outcome of the output for the fallback
     *                 {@link TimeoutFallback#SUCCESS} or {@link TimeoutFallback#FAILURE} is specified in the
     *                 implementation.
     * @return An {@link Async} object, usually containing the output object.
     * @throws UnsupportedOperationException If async is called more than once.
     * @since 4.0.0, CE 2019.1
     */
    @NotNull Async async(@NotNull Duration timeout, @NotNull TimeoutFallback fallback);
}