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/*
* Copyright 2014-2021 Real Logic Limited.
* Copyright 2015 Kaazing Corporation
*
* 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
*
* https://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.aeron.samples;
import io.aeron.Aeron;
import io.aeron.FragmentAssembler;
import io.aeron.Image;
import io.aeron.Subscription;
import io.aeron.logbuffer.FragmentHandler;
import org.agrona.concurrent.BackoffIdleStrategy;
import org.agrona.concurrent.IdleStrategy;
import org.agrona.concurrent.SigInt;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
/**
* A subscriber application with two subscriptions which can receive fragmented messages.
*
* Creates two subscriptions on a given channel subscribed to two different stream IDs.
* The default STREAM_ID and CHANNEL are configured in {@link SampleConfiguration}. The default
* channel and stream IDs can be changed by setting Java system properties at the command line, e.g.:
* {@code -Daeron.sample.channel=aeron:udp?endpoint=localhost:5555 -Daeron.sample.streamId=20}
*/
public class MultipleSubscribersWithFragmentAssembly
{
private static final int FRAGMENT_COUNT_LIMIT = SampleConfiguration.FRAGMENT_COUNT_LIMIT;
private static final int STREAM_ID_1 = SampleConfiguration.STREAM_ID;
private static final int STREAM_ID_2 = SampleConfiguration.STREAM_ID + 1;
private static final String CHANNEL = SampleConfiguration.CHANNEL;
/**
* Main method for launching the process.
*
* @param args passed to the process.
*/
public static void main(final String[] args)
{
System.out.format("Subscribing to %s on stream ID %d and stream ID %d%n",
CHANNEL, STREAM_ID_1, STREAM_ID_2);
final Aeron.Context ctx = new Aeron.Context()
.availableImageHandler(MultipleSubscribersWithFragmentAssembly::eventAvailableImage)
.unavailableImageHandler(MultipleSubscribersWithFragmentAssembly::eventUnavailableImage);
final FragmentAssembler assembler1 = new FragmentAssembler(reassembledMessage1(STREAM_ID_1));
final FragmentAssembler assembler2 = new FragmentAssembler(reassembledMessage2(STREAM_ID_2));
final AtomicBoolean running = new AtomicBoolean(true);
SigInt.register(() -> running.set(false));
try (Aeron aeron = Aeron.connect(ctx);
Subscription subscription1 = aeron.addSubscription(CHANNEL, STREAM_ID_1);
Subscription subscription2 = aeron.addSubscription(CHANNEL, STREAM_ID_2))
{
final IdleStrategy idleStrategy = new BackoffIdleStrategy(
100, 10, TimeUnit.MICROSECONDS.toNanos(1), TimeUnit.MICROSECONDS.toNanos(100));
int idleCount = 0;
while (running.get())
{
final int fragmentsRead1 = subscription1.poll(assembler1, FRAGMENT_COUNT_LIMIT);
final int fragmentsRead2 = subscription2.poll(assembler2, FRAGMENT_COUNT_LIMIT);
if ((fragmentsRead1 + fragmentsRead2) == 0)
{
idleStrategy.idle(idleCount++);
}
else
{
idleCount = 0;
}
}
System.out.println("Shutting down...");
}
}
/**
* Print the information for an available image to stdout.
*
* @param image that has been created.
*/
public static void eventAvailableImage(final Image image)
{
final Subscription subscription = image.subscription();
System.out.format(
"new image on %s streamId %x sessionId %x from %s%n",
subscription.channel(), subscription.streamId(), image.sessionId(), image.sourceIdentity());
}
/**
* This handler is called when image is unavailable.
*
* @param image that has gone inactive.
*/
public static void eventUnavailableImage(final Image image)
{
final Subscription subscription = image.subscription();
System.out.format(
"inactive image on %s streamId %d sessionId %x%n",
subscription.channel(), subscription.streamId(), image.sessionId());
}
/**
* Return a reusable, parameterized {@link FragmentHandler} that prints to stdout for the first stream(STREAM).
*
* @param streamId to show when printing.
* @return subscription data handler function that prints the message contents.
*/
public static FragmentHandler reassembledMessage1(final int streamId)
{
return (buffer, offset, length, header) ->
{
System.out.format(
"message to stream %d from session %x term id %x term offset %d (%d@%d)%n",
streamId, header.sessionId(), header.termId(), header.termOffset(), length, offset);
if (length != 10000)
{
System.out.format(
"Received message was not assembled properly;" +
" received length was %d, but was expecting 10000%n",
length);
}
};
}
/**
* A reusable, parameterised {@link FragmentHandler} that prints to stdout for the second stream (STREAM + 1).
*
* @param streamId to show when printing.
* @return subscription data handler function that prints the message contents.
*/
public static FragmentHandler reassembledMessage2(final int streamId)
{
return (buffer, offset, length, header) ->
{
System.out.format(
"message to stream %d from session %x term id %x term offset %d (%d@%d)%n",
streamId, header.sessionId(), header.termId(), header.termOffset(), length, offset);
if (length != 9000)
{
System.out.format(
"Received message was not assembled properly; received length was %d, but was expecting 9000%n",
length);
}
};
}
}