org.apache.flink.connector.base.source.reader.fetcher.SingleThreadFetcherManager Maven / Gradle / Ivy
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* to you under the Apache License, Version 2.0 (the
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*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
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package org.apache.flink.connector.base.source.reader.fetcher;
import org.apache.flink.annotation.VisibleForTesting;
import org.apache.flink.api.connector.source.SourceSplit;
import org.apache.flink.connector.base.source.reader.RecordsWithSplitIds;
import org.apache.flink.connector.base.source.reader.SourceReaderBase;
import org.apache.flink.connector.base.source.reader.splitreader.SplitReader;
import org.apache.flink.connector.base.source.reader.synchronization.FutureCompletingBlockingQueue;
import java.util.Collection;
import java.util.List;
import java.util.function.Consumer;
import java.util.function.Supplier;
/**
* A Fetcher Manager with a single fetching thread (I/O thread) that handles all splits
* concurrently.
*
* This pattern is, for example, useful for connectors like File Readers, Apache Kafka Readers,
* etc. In the example of Kafka, there is a single thread that reads all splits (topic partitions)
* via the same client. In the example of the file source, there is a single thread that reads the
* files after another.
*/
public class SingleThreadFetcherManager
extends SplitFetcherManager {
/**
* Creates a new SplitFetcherManager with a single I/O threads.
*
* @param elementsQueue The queue that is used to hand over data from the I/O thread (the
* fetchers) to the reader (which emits the records and book-keeps the state. This must be
* the same queue instance that is also passed to the {@link SourceReaderBase}.
* @param splitReaderSupplier The factory for the split reader that connects to the source
* system.
*/
public SingleThreadFetcherManager(
FutureCompletingBlockingQueue> elementsQueue,
Supplier> splitReaderSupplier) {
super(elementsQueue, splitReaderSupplier);
}
/**
* Creates a new SplitFetcherManager with a single I/O threads.
*
* @param elementsQueue The queue that is used to hand over data from the I/O thread (the
* fetchers) to the reader (which emits the records and book-keeps the state. This must be
* the same queue instance that is also passed to the {@link SourceReaderBase}.
* @param splitReaderSupplier The factory for the split reader that connects to the source
* system.
* @param splitFinishedHook Hook for handling finished splits in split fetchers
*/
@VisibleForTesting
public SingleThreadFetcherManager(
FutureCompletingBlockingQueue> elementsQueue,
Supplier> splitReaderSupplier,
Consumer> splitFinishedHook) {
super(elementsQueue, splitReaderSupplier, splitFinishedHook);
}
@Override
public void addSplits(List splitsToAdd) {
SplitFetcher fetcher = getRunningFetcher();
if (fetcher == null) {
fetcher = createSplitFetcher();
// Add the splits to the fetchers.
fetcher.addSplits(splitsToAdd);
startFetcher(fetcher);
} else {
fetcher.addSplits(splitsToAdd);
}
}
protected SplitFetcher getRunningFetcher() {
return fetchers.isEmpty() ? null : fetchers.values().iterator().next();
}
}