org.apache.flink.runtime.io.disk.iomanager.BlockChannelReader Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 org.apache.flink.runtime.io.disk.iomanager;
import java.io.IOException;
import java.util.concurrent.LinkedBlockingQueue;
/**
* A reader that reads data in blocks from a file channel. The reader reads the blocks into a
* {@link org.apache.flink.core.memory.MemorySegment}. To support asynchronous implementations,
* the read method does not immediately return the full memory segment, but rather adds it to
* a blocking queue of finished read operations.
*/
public interface BlockChannelReader extends FileIOChannel {
/**
* Issues a read request, which will fill the given segment with the next block in the
* underlying file channel. Once the read request is fulfilled, the segment will be added to this reader's
* return queue.
*
* @param segment The segment to read the block into.
* @throws IOException Thrown, when the reader encounters an I/O error.
*/
void readBlock(T segment) throws IOException;
void seekToPosition(long position) throws IOException;
/**
* Gets the next memory segment that has been filled with data by the reader. This method blocks until
* such a segment is available, or until an error occurs in the reader, or the reader is closed.
*
* WARNING: If this method is invoked without any segment ever returning (for example, because the
* {@link #readBlock} method has not been invoked appropriately), the method may block
* forever.
*
* @return The next memory segment from the reader's return queue.
* @throws IOException Thrown, if an I/O error occurs in the reader while waiting for the request to return.
*/
public T getNextReturnedBlock() throws IOException;
/**
* Gets the queue in which the full memory segments are queued after the read is complete.
*
* @return The queue with the full memory segments.
*/
LinkedBlockingQueue getReturnQueue();
}