org.apache.flink.runtime.io.network.api.writer.RecordWriter Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
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* 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,
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* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.flink.runtime.io.network.api.writer;
import org.apache.flink.core.io.IOReadableWritable;
import org.apache.flink.runtime.metrics.groups.IOMetricGroup;
import org.apache.flink.runtime.accumulators.AccumulatorRegistry;
import org.apache.flink.runtime.event.AbstractEvent;
import org.apache.flink.runtime.io.network.api.serialization.RecordSerializer;
import org.apache.flink.runtime.io.network.api.serialization.SpanningRecordSerializer;
import org.apache.flink.runtime.io.network.buffer.Buffer;
import java.io.IOException;
import static org.apache.flink.runtime.io.network.api.serialization.RecordSerializer.SerializationResult;
/**
* A record-oriented runtime result writer.
*
* The RecordWriter wraps the runtime's {@link ResultPartitionWriter} and takes care of
* serializing records into buffers.
*
* Important: it is necessary to call {@link #flush()} after
* all records have been written with {@link #emit(IOReadableWritable)}. This
* ensures that all produced records are written to the output stream (incl.
* partially filled ones).
*
* @param the type of the record that can be emitted with this record writer
*/
public class RecordWriter {
protected final ResultPartitionWriter writer;
private final ChannelSelector channelSelector;
private final int numChannels;
/** {@link RecordSerializer} per outgoing channel */
private final RecordSerializer[] serializers;
public RecordWriter(ResultPartitionWriter writer) {
this(writer, new RoundRobinChannelSelector());
}
@SuppressWarnings("unchecked")
public RecordWriter(ResultPartitionWriter writer, ChannelSelector channelSelector) {
this.writer = writer;
this.channelSelector = channelSelector;
this.numChannels = writer.getNumberOfOutputChannels();
/**
* The runtime exposes a channel abstraction for the produced results
* (see {@link ChannelSelector}). Every channel has an independent
* serializer.
*/
this.serializers = new SpanningRecordSerializer[numChannels];
for (int i = 0; i < numChannels; i++) {
serializers[i] = new SpanningRecordSerializer();
}
}
public void emit(T record) throws IOException, InterruptedException {
for (int targetChannel : channelSelector.selectChannels(record, numChannels)) {
// serialize with corresponding serializer and send full buffer
RecordSerializer serializer = serializers[targetChannel];
synchronized (serializer) {
SerializationResult result = serializer.addRecord(record);
while (result.isFullBuffer()) {
Buffer buffer = serializer.getCurrentBuffer();
if (buffer != null) {
writeBuffer(buffer, targetChannel, serializer);
}
buffer = writer.getBufferProvider().requestBufferBlocking();
result = serializer.setNextBuffer(buffer);
}
}
}
}
/**
* This is used to broadcast Streaming Watermarks in-band with records. This ignores
* the {@link ChannelSelector}.
*/
public void broadcastEmit(T record) throws IOException, InterruptedException {
for (int targetChannel = 0; targetChannel < numChannels; targetChannel++) {
// serialize with corresponding serializer and send full buffer
RecordSerializer serializer = serializers[targetChannel];
synchronized (serializer) {
SerializationResult result = serializer.addRecord(record);
while (result.isFullBuffer()) {
Buffer buffer = serializer.getCurrentBuffer();
if (buffer != null) {
writeBuffer(buffer, targetChannel, serializer);
}
buffer = writer.getBufferProvider().requestBufferBlocking();
result = serializer.setNextBuffer(buffer);
}
}
}
}
public void broadcastEvent(AbstractEvent event) throws IOException, InterruptedException {
for (int targetChannel = 0; targetChannel < numChannels; targetChannel++) {
RecordSerializer serializer = serializers[targetChannel];
synchronized (serializer) {
if (serializer.hasData()) {
Buffer buffer = serializer.getCurrentBuffer();
if (buffer == null) {
throw new IllegalStateException("Serializer has data but no buffer.");
}
writeBuffer(buffer, targetChannel, serializer);
writer.writeEvent(event, targetChannel);
buffer = writer.getBufferProvider().requestBufferBlocking();
serializer.setNextBuffer(buffer);
}
else {
writer.writeEvent(event, targetChannel);
}
}
}
}
public void sendEndOfSuperstep() throws IOException, InterruptedException {
for (int targetChannel = 0; targetChannel < numChannels; targetChannel++) {
RecordSerializer serializer = serializers[targetChannel];
synchronized (serializer) {
Buffer buffer = serializer.getCurrentBuffer();
if (buffer != null) {
writeBuffer(buffer, targetChannel, serializer);
buffer = writer.getBufferProvider().requestBufferBlocking();
serializer.setNextBuffer(buffer);
}
}
}
writer.writeEndOfSuperstep();
}
public void flush() throws IOException {
for (int targetChannel = 0; targetChannel < numChannels; targetChannel++) {
RecordSerializer serializer = serializers[targetChannel];
synchronized (serializer) {
try {
Buffer buffer = serializer.getCurrentBuffer();
if (buffer != null) {
writeBuffer(buffer, targetChannel, serializer);
}
} finally {
serializer.clear();
}
}
}
}
public void clearBuffers() {
for (RecordSerializer serializer : serializers) {
synchronized (serializer) {
try {
Buffer buffer = serializer.getCurrentBuffer();
if (buffer != null) {
buffer.recycle();
}
}
finally {
serializer.clear();
}
}
}
}
/**
* Counter for the number of records emitted and the records processed.
*/
public void setReporter(AccumulatorRegistry.Reporter reporter) {
for(RecordSerializer serializer : serializers) {
serializer.setReporter(reporter);
}
}
/**
* Sets the metric group for this RecordWriter.
* @param metrics
*/
public void setMetricGroup(IOMetricGroup metrics) {
for(RecordSerializer serializer : serializers) {
serializer.instantiateMetrics(metrics);
}
}
/**
* Writes the buffer to the {@link ResultPartitionWriter}.
*
* The buffer is cleared from the serializer state after a call to this method.
*/
private void writeBuffer(
Buffer buffer,
int targetChannel,
RecordSerializer serializer) throws IOException {
try {
writer.writeBuffer(buffer, targetChannel);
}
finally {
serializer.clearCurrentBuffer();
}
}
}