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Efficient reliable UDP unicast, UDP multicast, and IPC transport protocol.
/*
* Copyright 2014-2021 Real Logic Limited.
*
* 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.cluster.tutorial;
import io.aeron.ExclusivePublication;
import io.aeron.Image;
import io.aeron.cluster.codecs.CloseReason;
import io.aeron.cluster.service.ClientSession;
import io.aeron.cluster.service.Cluster;
import io.aeron.cluster.service.ClusteredService;
import io.aeron.logbuffer.Header;
import org.agrona.*;
import org.agrona.collections.MutableBoolean;
import org.agrona.concurrent.IdleStrategy;
import java.util.Objects;
/**
* Auction service implementing the business logic.
*/
// tag::new_service[]
public class BasicAuctionClusteredService implements ClusteredService
// end::new_service[]
{
public static final int CORRELATION_ID_OFFSET = 0;
public static final int CUSTOMER_ID_OFFSET = CORRELATION_ID_OFFSET + BitUtil.SIZE_OF_LONG;
public static final int PRICE_OFFSET = CUSTOMER_ID_OFFSET + BitUtil.SIZE_OF_LONG;
public static final int BID_MESSAGE_LENGTH = PRICE_OFFSET + BitUtil.SIZE_OF_LONG;
public static final int BID_SUCCEEDED_OFFSET = BID_MESSAGE_LENGTH;
public static final int EGRESS_MESSAGE_LENGTH = BID_SUCCEEDED_OFFSET + BitUtil.SIZE_OF_BYTE;
public static final int SNAPSHOT_CUSTOMER_ID_OFFSET = 0;
public static final int SNAPSHOT_PRICE_OFFSET = SNAPSHOT_CUSTOMER_ID_OFFSET + BitUtil.SIZE_OF_LONG;
public static final int SNAPSHOT_MESSAGE_LENGTH = SNAPSHOT_PRICE_OFFSET + BitUtil.SIZE_OF_LONG;
private final MutableDirectBuffer egressMessageBuffer = new ExpandableArrayBuffer();
private final MutableDirectBuffer snapshotBuffer = new ExpandableArrayBuffer();
// tag::state[]
private final Auction auction = new Auction();
// end::state[]
private Cluster cluster;
private IdleStrategy idleStrategy;
/**
* {@inheritDoc}
*/
// tag::start[]
public void onStart(final Cluster cluster, final Image snapshotImage)
{
this.cluster = cluster; // <1>
this.idleStrategy = cluster.idleStrategy(); // <2>
if (null != snapshotImage) // <3>
{
loadSnapshot(cluster, snapshotImage);
}
}
// end::start[]
/**
* {@inheritDoc}
*/
// tag::message[]
public void onSessionMessage(
final ClientSession session,
final long timestamp,
final DirectBuffer buffer,
final int offset,
final int length,
final Header header)
{
final long correlationId = buffer.getLong(offset + CORRELATION_ID_OFFSET); // <1>
final long customerId = buffer.getLong(offset + CUSTOMER_ID_OFFSET);
final long price = buffer.getLong(offset + PRICE_OFFSET);
final boolean bidSucceeded = auction.attemptBid(price, customerId); // <2>
if (null != session) // <3>
{
egressMessageBuffer.putLong(CORRELATION_ID_OFFSET, correlationId); // <4>
egressMessageBuffer.putLong(CUSTOMER_ID_OFFSET, auction.getCurrentWinningCustomerId());
egressMessageBuffer.putLong(PRICE_OFFSET, auction.getBestPrice());
egressMessageBuffer.putByte(BID_SUCCEEDED_OFFSET, bidSucceeded ? (byte)1 : (byte)0);
idleStrategy.reset();
while (session.offer(egressMessageBuffer, 0, EGRESS_MESSAGE_LENGTH) < 0) // <5>
{
idleStrategy.idle(); // <6>
}
}
}
// end::message[]
/**
* {@inheritDoc}
*/
// tag::takeSnapshot[]
public void onTakeSnapshot(final ExclusivePublication snapshotPublication)
{
snapshotBuffer.putLong(SNAPSHOT_CUSTOMER_ID_OFFSET, auction.getCurrentWinningCustomerId()); // <1>
snapshotBuffer.putLong(SNAPSHOT_PRICE_OFFSET, auction.getBestPrice());
idleStrategy.reset();
while (snapshotPublication.offer(snapshotBuffer, 0, SNAPSHOT_MESSAGE_LENGTH) < 0) // <2>
{
idleStrategy.idle();
}
}
// end::takeSnapshot[]
// tag::loadSnapshot[]
private void loadSnapshot(final Cluster cluster, final Image snapshotImage)
{
final MutableBoolean allDataLoaded = new MutableBoolean(false);
while (!snapshotImage.isEndOfStream()) // <1>
{
final int fragmentsPolled = snapshotImage.poll(
(buffer, offset, length, header) -> // <2>
{
assert length >= SNAPSHOT_MESSAGE_LENGTH; // <3>
final long customerId = buffer.getLong(offset + SNAPSHOT_CUSTOMER_ID_OFFSET);
final long price = buffer.getLong(offset + SNAPSHOT_PRICE_OFFSET);
auction.loadInitialState(price, customerId); // <4>
allDataLoaded.set(true);
},
1);
if (allDataLoaded.value) // <5>
{
break;
}
idleStrategy.idle(fragmentsPolled); // <6>
}
assert snapshotImage.isEndOfStream(); // <7>
assert allDataLoaded.value;
}
// end::loadSnapshot[]
/**
* {@inheritDoc}
*/
public void onRoleChange(final Cluster.Role newRole)
{
}
/**
* {@inheritDoc}
*/
public void onTerminate(final Cluster cluster)
{
}
/**
* {@inheritDoc}
*/
public void onSessionOpen(final ClientSession session, final long timestamp)
{
System.out.println("onSessionOpen(" + session + ")");
}
/**
* {@inheritDoc}
*/
public void onSessionClose(final ClientSession session, final long timestamp, final CloseReason closeReason)
{
System.out.println("onSessionClose(" + session + ")");
}
/**
* {@inheritDoc}
*/
public void onTimerEvent(final long correlationId, final long timestamp)
{
}
static class Auction
{
private long bestPrice = 0;
private long currentWinningCustomerId = -1;
void loadInitialState(final long price, final long customerId)
{
bestPrice = price;
currentWinningCustomerId = customerId;
}
boolean attemptBid(final long price, final long customerId)
{
System.out.println("attemptBid(this=" + this + ", price=" + price + ",customerId=" + customerId + ")");
if (price <= bestPrice)
{
return false;
}
bestPrice = price;
currentWinningCustomerId = customerId;
return true;
}
long getBestPrice()
{
return bestPrice;
}
long getCurrentWinningCustomerId()
{
return currentWinningCustomerId;
}
/**
* {@inheritDoc}
*/
public boolean equals(final Object o)
{
if (this == o)
{
return true;
}
if (o == null || getClass() != o.getClass())
{
return false;
}
final Auction auction = (Auction)o;
return bestPrice == auction.bestPrice && currentWinningCustomerId == auction.currentWinningCustomerId;
}
/**
* {@inheritDoc}
*/
public int hashCode()
{
return Objects.hash(bestPrice, currentWinningCustomerId);
}
/**
* {@inheritDoc}
*/
public String toString()
{
return "Auction{" +
"bestPrice=" + bestPrice +
", currentWinningCustomerId=" + currentWinningCustomerId +
'}';
}
}
/**
* {@inheritDoc}
*/
public boolean equals(final Object o)
{
if (this == o)
{
return true;
}
if (o == null || getClass() != o.getClass())
{
return false;
}
final BasicAuctionClusteredService that = (BasicAuctionClusteredService)o;
return auction.equals(that.auction);
}
/**
* {@inheritDoc}
*/
public int hashCode()
{
return Objects.hash(auction);
}
/**
* {@inheritDoc}
*/
public String toString()
{
return "BasicAuctionClusteredService{" +
"auction=" + auction +
'}';
}
}