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/*
 * Copyright © 2017 camunda services GmbH ([email protected])
 *
 * 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 io.zeebe.logstreams.spi;

import java.nio.ByteBuffer;

/**
 * Represents an processor, which process the given byte buffer and the read result.
 * The read result corresponds to the bytes which was read before.
 *
 * Is used in the {@link LogStorage#read(ByteBuffer, long, ReadResultProcessor)} method to process
 * the bytes, which are read and return the count of the appropriated bytes which should be only been read.
 * Can for example be used to throw away bytes,
 * because they belong to another fragment which was not read completely into the buffer.
 *
 * @author Christopher Zell 
 */
public interface ReadResultProcessor
{
    /**
     * Process the given buffer and use the readResult to return the right count of bytes, which should been read.
     * If some bytes are part of another fragment, which is not completely read into the buffer, the buffer can be
     * cleaned up and the returned count can be for example ${readResult - fragmentBytes}.
     *
     * @param buffer the buffer, which should been processed
     * @param readResult the count of bytes,which are read before
     * @return the count of bytes, which should only been read
     */
    int process(ByteBuffer buffer, int readResult);
}