/*
* Copyright 2008-2016 MongoDB, Inc.
*
* 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
*
* 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 com.mongodb.connection;
import com.mongodb.MongoClientException;
import com.mongodb.MongoIncompatibleDriverException;
import com.mongodb.MongoInterruptedException;
import com.mongodb.MongoTimeoutException;
import com.mongodb.MongoWaitQueueFullException;
import com.mongodb.ServerAddress;
import com.mongodb.async.SingleResultCallback;
import com.mongodb.diagnostics.logging.Logger;
import com.mongodb.diagnostics.logging.Loggers;
import com.mongodb.event.ClusterClosedEvent;
import com.mongodb.event.ClusterDescriptionChangedEvent;
import com.mongodb.event.ClusterEventMulticaster;
import com.mongodb.event.ClusterListener;
import com.mongodb.event.ClusterOpeningEvent;
import com.mongodb.event.ServerListener;
import com.mongodb.internal.connection.ConcurrentLinkedDeque;
import com.mongodb.selector.CompositeServerSelector;
import com.mongodb.selector.ServerSelector;
import java.util.ArrayList;
import java.util.Deque;
import java.util.Iterator;
import java.util.List;
import java.util.Random;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicReference;
import static com.mongodb.assertions.Assertions.isTrue;
import static com.mongodb.assertions.Assertions.notNull;
import static java.lang.String.format;
import static java.util.Arrays.asList;
import static java.util.concurrent.TimeUnit.MILLISECONDS;
import static java.util.concurrent.TimeUnit.NANOSECONDS;
abstract class BaseCluster implements Cluster {
private static final Logger LOGGER = Loggers.getLogger("cluster");
private final AtomicReference<CountDownLatch> phase = new AtomicReference<CountDownLatch>(new CountDownLatch(1));
private final ClusterableServerFactory serverFactory;
private final ThreadLocal<Random> random = new ThreadLocal<Random>();
private final ClusterId clusterId;
private final ClusterSettings settings;
private final ClusterListener clusterListener;
private final Deque<ServerSelectionRequest> waitQueue = new ConcurrentLinkedDeque<ServerSelectionRequest>();
private final AtomicInteger waitQueueSize = new AtomicInteger(0);
private Thread waitQueueHandler;
private volatile boolean isClosed;
private volatile ClusterDescription description;
BaseCluster(final ClusterId clusterId, final ClusterSettings settings, final ClusterableServerFactory serverFactory) {
this.clusterId = notNull("clusterId", clusterId);
this.settings = notNull("settings", settings);
this.serverFactory = notNull("serverFactory", serverFactory);
this.clusterListener = settings.getClusterListeners().isEmpty()
? new NoOpClusterListener() : new ClusterEventMulticaster(settings.getClusterListeners());
clusterListener.clusterOpening(new ClusterOpeningEvent(clusterId));
}
@Override
public Server selectServer(final ServerSelector serverSelector) {
isTrue("open", !isClosed());
try {
CountDownLatch currentPhase = phase.get();
ClusterDescription curDescription = description;
ServerSelector compositeServerSelector = getCompositeServerSelector(serverSelector);
Server server = selectRandomServer(compositeServerSelector, curDescription);
boolean selectionFailureLogged = false;
long startTimeNanos = System.nanoTime();
long curTimeNanos = startTimeNanos;
long maxWaitTimeNanos = getMaxWaitTimeNanos();
while (true) {
throwIfIncompatible(curDescription);
if (server != null) {
return server;
}
if (curTimeNanos - startTimeNanos > maxWaitTimeNanos) {
throw createTimeoutException(serverSelector, curDescription);
}
if (!selectionFailureLogged) {
logServerSelectionFailure(serverSelector, curDescription);
selectionFailureLogged = true;
}
connect();
currentPhase.await(Math.min(maxWaitTimeNanos - (curTimeNanos - startTimeNanos), getMinWaitTimeNanos()), NANOSECONDS);
curTimeNanos = System.nanoTime();
currentPhase = phase.get();
curDescription = description;
server = selectRandomServer(compositeServerSelector, curDescription);
}
} catch (InterruptedException e) {
throw new MongoInterruptedException(format("Interrupted while waiting for a server that matches %s", serverSelector), e);
}
}
@Override
public void selectServerAsync(final ServerSelector serverSelector, final SingleResultCallback<Server> callback) {
isTrue("open", !isClosed());
if (LOGGER.isTraceEnabled()) {
LOGGER.trace(String.format("Asynchronously selecting server with selector %s", serverSelector));
}
ServerSelectionRequest request = new ServerSelectionRequest(serverSelector, getCompositeServerSelector(serverSelector),
getMaxWaitTimeNanos(), callback);
CountDownLatch currentPhase = phase.get();
ClusterDescription currentDescription = description;
if (!handleServerSelectionRequest(request, currentPhase, currentDescription)) {
notifyWaitQueueHandler(request);
}
}
@Override
public ClusterDescription getDescription() {
isTrue("open", !isClosed());
try {
CountDownLatch currentPhase = phase.get();
ClusterDescription curDescription = description;
boolean selectionFailureLogged = false;
long startTimeNanos = System.nanoTime();
long curTimeNanos = startTimeNanos;
long maxWaitTimeNanos = getMaxWaitTimeNanos();
while (curDescription.getType() == ClusterType.UNKNOWN) {
if (curTimeNanos - startTimeNanos > maxWaitTimeNanos) {
throw new MongoTimeoutException(format("Timed out after %d ms while waiting to connect. Client view of cluster state "
+ "is %s",
settings.getServerSelectionTimeout(MILLISECONDS),
curDescription.getShortDescription()));
}
if (!selectionFailureLogged) {
if (LOGGER.isInfoEnabled()) {
if (settings.getServerSelectionTimeout(MILLISECONDS) < 0) {
LOGGER.info(format("Cluster description not yet available. Waiting indefinitely."));
} else {
LOGGER.info(format("Cluster description not yet available. Waiting for %d ms before timing out",
settings.getServerSelectionTimeout(MILLISECONDS)));
}
}
selectionFailureLogged = true;
}
connect();
currentPhase.await(Math.min(maxWaitTimeNanos - (curTimeNanos - startTimeNanos), getMinWaitTimeNanos()), NANOSECONDS);
curTimeNanos = System.nanoTime();
currentPhase = phase.get();
curDescription = description;
}
return curDescription;
} catch (InterruptedException e) {
throw new MongoInterruptedException(format("Interrupted while waiting to connect"), e);
}
}
protected ClusterId getClusterId() {
return clusterId;
}
public ClusterSettings getSettings() {
return settings;
}
public ClusterableServerFactory getServerFactory() {
return serverFactory;
}
protected abstract void connect();
@Override
public void close() {
if (!isClosed()) {
isClosed = true;
phase.get().countDown();
clusterListener.clusterClosed(new ClusterClosedEvent(clusterId));
stopWaitQueueHandler();
}
}
@Override
public boolean isClosed() {
return isClosed;
}
/**
* Return the server at the given address.
*
* @param serverAddress the address
* @return the server, or null if the cluster no longer contains a server at this address.
*/
protected abstract ClusterableServer getServer(ServerAddress serverAddress);
protected synchronized void updateDescription(final ClusterDescription newDescription) {
if (LOGGER.isDebugEnabled()) {
LOGGER.debug(format("Updating cluster description to %s", newDescription.getShortDescription()));
}
description = newDescription;
phase.getAndSet(new CountDownLatch(1)).countDown();
}
protected void fireChangeEvent(final ClusterDescriptionChangedEvent event) {
clusterListener.clusterDescriptionChanged(event);
}
ClusterDescription getCurrentDescription() {
return description;
}
private long getMaxWaitTimeNanos() {
if (settings.getServerSelectionTimeout(NANOSECONDS) < 0) {
return Long.MAX_VALUE;
}
return settings.getServerSelectionTimeout(NANOSECONDS);
}
private long getMinWaitTimeNanos() {
return serverFactory.getSettings().getMinHeartbeatFrequency(NANOSECONDS);
}
private boolean handleServerSelectionRequest(final ServerSelectionRequest request, final CountDownLatch currentPhase,
final ClusterDescription description) {
try {
if (currentPhase != request.phase) {
CountDownLatch prevPhase = request.phase;
request.phase = currentPhase;
if (!description.isCompatibleWithDriver()) {
if (LOGGER.isTraceEnabled()) {
LOGGER.trace(String.format("Asynchronously failed server selection due to driver incompatibility with server"));
}
request.onResult(null, createIncompatibleException(description));
return true;
}
Server server = selectRandomServer(request.compositeSelector, description);
if (server != null) {
if (LOGGER.isTraceEnabled()) {
LOGGER.trace(String.format("Asynchronously selected server %s", server.getDescription().getAddress()));
}
request.onResult(server, null);
return true;
}
if (prevPhase == null) {
logServerSelectionFailure(request.originalSelector, description);
}
}
if (request.timedOut()) {
if (LOGGER.isTraceEnabled()) {
LOGGER.trace(String.format("Asynchronously failed server selection after timeout"));
}
request.onResult(null, createTimeoutException(request.originalSelector, description));
return true;
}
return false;
} catch (Exception e) {
request.onResult(null, e);
return true;
}
}
private void logServerSelectionFailure(final ServerSelector serverSelector, final ClusterDescription curDescription) {
if (LOGGER.isInfoEnabled()) {
if (settings.getServerSelectionTimeout(MILLISECONDS) < 0) {
LOGGER.info(format("No server chosen by %s from cluster description %s. Waiting indefinitely.",
serverSelector, curDescription));
} else {
LOGGER.info(format("No server chosen by %s from cluster description %s. Waiting for %d ms before timing out",
serverSelector, curDescription, settings.getServerSelectionTimeout(MILLISECONDS)));
}
}
}
private Server selectRandomServer(final ServerSelector serverSelector, final ClusterDescription clusterDescription) {
List<ServerDescription> serverDescriptions = serverSelector.select(clusterDescription);
if (!serverDescriptions.isEmpty()) {
return getRandomServer(new ArrayList<ServerDescription>(serverDescriptions));
} else {
return null;
}
}
private ServerSelector getCompositeServerSelector(final ServerSelector serverSelector) {
if (settings.getServerSelector() == null) {
return serverSelector;
} else {
return new CompositeServerSelector(asList(serverSelector, settings.getServerSelector()));
}
}
// gets a random server that still exists in the cluster. Returns null if there are none.
private ClusterableServer getRandomServer(final List<ServerDescription> serverDescriptions) {
while (!serverDescriptions.isEmpty()) {
int serverPos = getRandom().nextInt(serverDescriptions.size());
ClusterableServer server = getServer(serverDescriptions.get(serverPos).getAddress());
if (server != null) {
return server;
} else {
serverDescriptions.remove(serverPos);
}
}
return null;
}
// it's important that Random instances are created in this way instead of via subclassing ThreadLocal and overriding the
// initialValue() method.
private Random getRandom() {
Random result = random.get();
if (result == null) {
result = new Random();
random.set(result);
}
return result;
}
protected ClusterableServer createServer(final ServerAddress serverAddress,
final ServerListener serverListener) {
ClusterableServer server = serverFactory.create(serverAddress, serverListener);
return server;
}
private void throwIfIncompatible(final ClusterDescription curDescription) {
if (!curDescription.isCompatibleWithDriver()) {
throw createIncompatibleException(curDescription);
}
}
private MongoIncompatibleDriverException createIncompatibleException(final ClusterDescription curDescription) {
return new MongoIncompatibleDriverException(format("This version of the driver is not compatible with one or more of "
+ "the servers to which it is connected: %s", curDescription),
curDescription);
}
private MongoTimeoutException createTimeoutException(final ServerSelector serverSelector, final ClusterDescription curDescription) {
return new MongoTimeoutException(format("Timed out after %d ms while waiting for a server that matches %s. "
+ "Client view of cluster state is %s",
settings.getServerSelectionTimeout(MILLISECONDS), serverSelector,
curDescription.getShortDescription()));
}
private MongoWaitQueueFullException createWaitQueueFullException() {
return new MongoWaitQueueFullException(format("Too many operations are already waiting for a server. "
+ "Max number of operations (maxWaitQueueSize) of %d has "
+ "been exceeded.",
settings.getMaxWaitQueueSize()));
}
private static final class ServerSelectionRequest {
private final ServerSelector originalSelector;
private final ServerSelector compositeSelector;
private final long maxWaitTimeNanos;
private final SingleResultCallback<Server> callback;
private final long startTimeNanos = System.nanoTime();
private CountDownLatch phase;
ServerSelectionRequest(final ServerSelector serverSelector, final ServerSelector compositeSelector,
final long maxWaitTimeNanos,
final SingleResultCallback<Server> callback) {
this.originalSelector = serverSelector;
this.compositeSelector = compositeSelector;
this.maxWaitTimeNanos = maxWaitTimeNanos;
this.callback = callback;
}
void onResult(final Server server, final Throwable t) {
try {
callback.onResult(server, t);
} catch (Throwable tr) {
// ignore
}
}
boolean timedOut() {
return System.nanoTime() - startTimeNanos > maxWaitTimeNanos;
}
long getRemainingTime() {
return startTimeNanos + maxWaitTimeNanos - System.nanoTime();
}
}
private synchronized void notifyWaitQueueHandler(final ServerSelectionRequest request) {
if (isClosed) {
return;
}
if (waitQueueSize.incrementAndGet() > settings.getMaxWaitQueueSize()) {
waitQueueSize.decrementAndGet();
request.onResult(null, createWaitQueueFullException());
} else {
waitQueue.add(request);
if (waitQueueHandler == null) {
waitQueueHandler = new Thread(new WaitQueueHandler(), "cluster-" + clusterId.getValue());
waitQueueHandler.setDaemon(true);
waitQueueHandler.start();
}
}
}
private synchronized void stopWaitQueueHandler() {
if (waitQueueHandler != null) {
waitQueueHandler.interrupt();
}
}
private final class WaitQueueHandler implements Runnable {
public void run() {
while (!isClosed) {
CountDownLatch currentPhase = phase.get();
ClusterDescription curDescription = description;
long waitTimeNanos = Long.MAX_VALUE;
for (Iterator<ServerSelectionRequest> iter = waitQueue.iterator(); iter.hasNext();) {
ServerSelectionRequest nextRequest = iter.next();
if (handleServerSelectionRequest(nextRequest, currentPhase, curDescription)) {
iter.remove();
waitQueueSize.decrementAndGet();
} else {
waitTimeNanos = Math.min(nextRequest.getRemainingTime(), Math.min(getMinWaitTimeNanos(), waitTimeNanos));
}
}
// if there are any waiters that were not satisfied, connect
if (waitTimeNanos < Long.MAX_VALUE) {
connect();
}
try {
currentPhase.await(waitTimeNanos, NANOSECONDS);
} catch (InterruptedException e) {
// The cluster has been closed and the while loop will exit.
}
}
// Notify all remaining waiters that a shutdown is in progress
for (Iterator<ServerSelectionRequest> iter = waitQueue.iterator(); iter.hasNext();) {
iter.next().onResult(null, new MongoClientException("Shutdown in progress"));
iter.remove();
}
}
}
}