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The Apache Cassandra Project develops a highly scalable second-generation distributed database, bringing together Dynamo's fully distributed design and Bigtable's ColumnFamily-based data model.
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/*
* 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.cassandra.net;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.TimeoutException;
import javax.annotation.Nullable;
import com.google.common.annotations.VisibleForTesting;
import org.apache.cassandra.concurrent.ScheduledExecutorPlus;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.cassandra.config.DatabaseDescriptor;
import org.apache.cassandra.exceptions.RequestFailureReason;
import org.apache.cassandra.locator.InetAddressAndPort;
import org.apache.cassandra.locator.Replica;
import org.apache.cassandra.metrics.InternodeOutboundMetrics;
import org.apache.cassandra.service.AbstractWriteResponseHandler;
import static java.lang.String.format;
import static java.util.concurrent.TimeUnit.MILLISECONDS;
import static java.util.concurrent.TimeUnit.NANOSECONDS;
import static org.apache.cassandra.concurrent.ExecutorFactory.Global.executorFactory;
import static org.apache.cassandra.concurrent.ExecutorFactory.SimulatorSemantics.DISCARD;
import static org.apache.cassandra.concurrent.Stage.INTERNAL_RESPONSE;
import static org.apache.cassandra.utils.Clock.Global.nanoTime;
import static org.apache.cassandra.utils.MonotonicClock.Global.preciseTime;
/**
* An expiring map of request callbacks.
*
* Used to match response (id, peer) pairs to corresponding {@link RequestCallback}s, or, if said responses
* don't arrive in a timely manner (within verb's timeout), to expire the callbacks.
*
* Since we reuse the same request id for multiple messages now, the map is keyed by (id, peer) tuples
* rather than just id as it used to before 4.0.
*/
public class RequestCallbacks implements OutboundMessageCallbacks
{
private static final Logger logger = LoggerFactory.getLogger(RequestCallbacks.class);
private final MessagingService messagingService;
private final ScheduledExecutorPlus executor = executorFactory().scheduled("Callback-Map-Reaper", DISCARD);
private final ConcurrentMap callbacks = new ConcurrentHashMap<>();
RequestCallbacks(MessagingService messagingService)
{
this.messagingService = messagingService;
long expirationInterval = defaultExpirationInterval();
executor.scheduleWithFixedDelay(this::expire, expirationInterval, expirationInterval, NANOSECONDS);
}
/**
* @return the registered {@link CallbackInfo} for this id and peer, or {@code null} if unset or expired.
*/
@Nullable
CallbackInfo get(long id, InetAddressAndPort peer)
{
return callbacks.get(key(id, peer));
}
/**
* Remove and return the {@link CallbackInfo} associated with given id and peer, if known.
*/
@Nullable
@VisibleForTesting
public CallbackInfo remove(long id, InetAddressAndPort peer)
{
return callbacks.remove(key(id, peer));
}
/**
* Register the provided {@link RequestCallback}, inferring expiry and id from the provided {@link Message}.
*/
public void addWithExpiration(RequestCallback cb, Message message, InetAddressAndPort to)
{
// mutations need to call the overload
assert message.verb() != Verb.MUTATION_REQ && message.verb() != Verb.COUNTER_MUTATION_REQ;
CallbackInfo previous = callbacks.put(key(message.id(), to), new CallbackInfo(message, to, cb));
assert previous == null : format("Callback already exists for id %d/%s! (%s)", message.id(), to, previous);
}
public void addWithExpiration(AbstractWriteResponseHandler cb, Message message, Replica to)
{
assert message.verb() == Verb.MUTATION_REQ || message.verb() == Verb.COUNTER_MUTATION_REQ || message.verb() == Verb.PAXOS_COMMIT_REQ;
CallbackInfo previous = callbacks.put(key(message.id(), to.endpoint()), new CallbackInfo(message, to.endpoint(), cb));
assert previous == null : format("Callback already exists for id %d/%s! (%s)", message.id(), to.endpoint(), previous);
}
@VisibleForTesting
public void removeAndRespond(long id, InetAddressAndPort peer, Message message)
{
CallbackInfo ci = remove(id, peer);
if (null != ci) ci.callback.onResponse(message);
}
private void removeAndExpire(long id, InetAddressAndPort peer)
{
CallbackInfo ci = remove(id, peer);
if (null != ci) onExpired(ci);
}
private void expire()
{
long start = preciseTime.now();
int n = 0;
for (Map.Entry entry : callbacks.entrySet())
{
if (entry.getValue().isReadyToDieAt(start))
{
if (callbacks.remove(entry.getKey(), entry.getValue()))
{
n++;
onExpired(entry.getValue());
}
}
}
logger.trace("Expired {} entries", n);
}
private void forceExpire()
{
for (Map.Entry entry : callbacks.entrySet())
if (callbacks.remove(entry.getKey(), entry.getValue()))
onExpired(entry.getValue());
}
private void onExpired(CallbackInfo info)
{
messagingService.latencySubscribers.maybeAdd(info.callback, info.peer, info.timeout(), NANOSECONDS);
InternodeOutboundMetrics.totalExpiredCallbacks.mark();
messagingService.markExpiredCallback(info.peer);
if (info.invokeOnFailure())
INTERNAL_RESPONSE.submit(() -> info.callback.onFailure(info.peer, RequestFailureReason.TIMEOUT));
}
void shutdownNow(boolean expireCallbacks)
{
executor.shutdownNow();
if (expireCallbacks)
forceExpire();
}
void shutdownGracefully()
{
expire();
if (!callbacks.isEmpty())
executor.schedule(this::shutdownGracefully, 100L, MILLISECONDS);
else
executor.shutdownNow();
}
void awaitTerminationUntil(long deadlineNanos) throws TimeoutException, InterruptedException
{
if (!executor.isTerminated())
{
long wait = deadlineNanos - nanoTime();
if (wait <= 0 || !executor.awaitTermination(wait, NANOSECONDS))
throw new TimeoutException();
}
}
@VisibleForTesting
public void unsafeClear()
{
callbacks.clear();
}
private static CallbackKey key(long id, InetAddressAndPort peer)
{
return new CallbackKey(id, peer);
}
private static class CallbackKey
{
final long id;
final InetAddressAndPort peer;
CallbackKey(long id, InetAddressAndPort peer)
{
this.id = id;
this.peer = peer;
}
@Override
public boolean equals(Object o)
{
if (!(o instanceof CallbackKey))
return false;
CallbackKey that = (CallbackKey) o;
return this.id == that.id && this.peer.equals(that.peer);
}
@Override
public int hashCode()
{
return Long.hashCode(id) + 31 * peer.hashCode();
}
@Override
public String toString()
{
return "{id:" + id + ", peer:" + peer + '}';
}
}
@VisibleForTesting
public static class CallbackInfo
{
final long createdAtNanos;
final long expiresAtNanos;
final InetAddressAndPort peer;
public final RequestCallback callback;
private CallbackInfo(Message message, InetAddressAndPort peer, RequestCallback callback)
{
this.createdAtNanos = message.createdAtNanos();
this.expiresAtNanos = message.expiresAtNanos();
this.peer = peer;
this.callback = callback;
}
public long timeout()
{
return expiresAtNanos - createdAtNanos;
}
boolean isReadyToDieAt(long atNano)
{
return atNano > expiresAtNanos;
}
boolean invokeOnFailure()
{
return callback.invokeOnFailure();
}
public String toString()
{
return "{peer:" + peer + ", callback:" + callback + ", invokeOnFailure:" + invokeOnFailure() + '}';
}
}
@Override
public void onOverloaded(Message message, InetAddressAndPort peer)
{
removeAndExpire(message, peer);
}
@Override
public void onExpired(Message message, InetAddressAndPort peer)
{
removeAndExpire(message, peer);
}
@Override
public void onFailedSerialize(Message message, InetAddressAndPort peer, int messagingVersion, int bytesWrittenToNetwork, Throwable failure)
{
removeAndExpire(message, peer);
}
@Override
public void onDiscardOnClose(Message message, InetAddressAndPort peer)
{
removeAndExpire(message, peer);
}
private void removeAndExpire(Message message, InetAddressAndPort peer)
{
removeAndExpire(message.id(), peer);
/* in case of a write sent to a different DC, also expire all forwarding targets */
ForwardingInfo forwardTo = message.forwardTo();
if (null != forwardTo)
forwardTo.forEach(this::removeAndExpire);
}
public static long defaultExpirationInterval()
{
return DatabaseDescriptor.getMinRpcTimeout(NANOSECONDS) / 2;
}
}