cc.redberry.pipe.OutputPort.kt Maven / Gradle / Ivy

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Java library for implementation of concurrent pipelines.

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/*
 * Copyright (c) 2022 MiLaboratories 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 cc.redberry.pipe

/**
 * Base interface for passive object producer.
 *
 * @param  type of produced objects
 * @author Bolotin Dmitriy ([email protected])
 */
interface OutputPort : AutoCloseable {
    /**
     * Returns next element from this output port, or `null` if port is closed.
     *
     * @return next element from this output port, or `null` if port is closed
     */
    fun take(): T?

    /**
     * Close current output port and frees all resources used by it (threads, file streams, etc...).
     *
     *
     * Contract for implementation:
     *
     *  * The implementation of this method must not throw an exceptions if port is already closed.
     *
     *
     *
     *
     * If the implementation of this method does not fulfill this contract, than methods [ ][cc.redberry.pipe.blocks.Merger.close], [cc.redberry.pipe.blocks.ParallelProcessor.close], etc... will
     * have an unpredictable behavior.
     */
    override fun close() {}
}