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Connector module providing infrastructure components that connect to AxonServer.
/*
* Copyright (c) 2020-2021. AxonIQ
*
* 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 io.axoniq.axonserver.connector.impl;
import io.axoniq.axonserver.grpc.control.ClientIdentification;
import io.axoniq.axonserver.grpc.control.NodeInfo;
import io.axoniq.axonserver.grpc.control.PlatformInfo;
import io.axoniq.axonserver.grpc.control.PlatformServiceGrpc;
import io.grpc.CallOptions;
import io.grpc.ClientCall;
import io.grpc.ConnectivityState;
import io.grpc.ManagedChannel;
import io.grpc.Metadata;
import io.grpc.MethodDescriptor;
import io.grpc.Status;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.ArrayList;
import java.util.List;
import java.util.Queue;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.RejectedExecutionException;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.atomic.AtomicReference;
import java.util.function.BiFunction;
import static io.axoniq.axonserver.connector.impl.ObjectUtils.doIfNotNull;
/**
* AxonServer specific {@link ManagedChannel} implementation providing AxonServer specific connection logic.
*/
public class AxonServerManagedChannel extends ManagedChannel {
private static final Logger logger = LoggerFactory.getLogger(AxonServerManagedChannel.class);
private final List routingServers;
private final long reconnectInterval;
private final String context;
private final ClientIdentification clientIdentification;
private final ScheduledExecutorService executor;
private final boolean forcePlatformReconnect;
private final BiFunction connectionFactory;
private final long connectTimeout;
private final AtomicReference activeChannel = new AtomicReference<>();
private final AtomicBoolean shutdown = new AtomicBoolean();
private final AtomicBoolean suppressErrors = new AtomicBoolean();
private final Queue connectListeners = new LinkedBlockingQueue<>();
private final AtomicLong nextAttemptTime = new AtomicLong();
private final AtomicLong connectionDeadline = new AtomicLong();
private final AtomicReference lastConnectException = new AtomicReference<>();
private final AtomicBoolean scheduleGate = new AtomicBoolean();
/**
* Constructs a {@link AxonServerManagedChannel}.
*
* @param routingServers {@link List} of {@link ServerAddress}' denoting the instances to connect with
* @param reconnectConfiguration configuration holder defining how this {@link ManagedChannel} implementation should
* reconnect
* @param context the context this {@link ManagedChannel} operates in
* @param clientIdentification the information identifying the client application which is connecting. This
* information is used to form the connection with a client
* @param executor {@link ScheduledExecutorService} used to schedule operations to ensure the
* connection is maintained
* @param connectionFactory factory method able of creating new {@link ManagedChannel} instances based on a
* given {@link ServerAddress} and context
*/
public AxonServerManagedChannel(List routingServers,
ReconnectConfiguration reconnectConfiguration,
String context,
ClientIdentification clientIdentification,
ScheduledExecutorService executor,
BiFunction connectionFactory) {
this.routingServers = new ArrayList<>(routingServers);
this.reconnectInterval = reconnectConfiguration.getTimeUnit()
.toMillis(reconnectConfiguration.getReconnectInterval());
this.context = context;
this.clientIdentification = clientIdentification;
this.executor = executor;
this.forcePlatformReconnect = reconnectConfiguration.isForcePlatformReconnect();
this.connectionFactory = connectionFactory;
this.connectTimeout = reconnectConfiguration.getTimeUnit().toMillis(reconnectConfiguration.getConnectTimeout());
}
private ManagedChannel connectChannel() {
ManagedChannel connection = null;
for (ServerAddress nodeInfo : routingServers) {
ManagedChannel candidate = null;
try {
candidate = connectionFactory.apply(nodeInfo, context);
PlatformServiceGrpc.PlatformServiceBlockingStub stub =
PlatformServiceGrpc.newBlockingStub(candidate)
.withDeadlineAfter(connectTimeout, TimeUnit.MILLISECONDS);
logger.info("Requesting connection details from {}:{}",
nodeInfo.getHostName(), nodeInfo.getGrpcPort());
PlatformInfo clusterInfo = stub.getPlatformServer(clientIdentification);
NodeInfo primaryClusterInfo = clusterInfo.getPrimary();
logger.debug("Received PlatformInfo suggesting [{}] ({}:{}), {}",
primaryClusterInfo.getNodeName(),
primaryClusterInfo.getHostName(),
primaryClusterInfo.getGrpcPort(),
clusterInfo.getSameConnection()
? "allowing use of existing connection"
: "requiring new connection");
if (clusterInfo.getSameConnection()
|| (primaryClusterInfo.getGrpcPort() == nodeInfo.getGrpcPort()
&& primaryClusterInfo.getHostName().equals(nodeInfo.getHostName()))) {
logger.debug("Reusing existing channel");
connection = candidate;
} else {
candidate.shutdown();
logger.info("Connecting to [{}] ({}:{})",
primaryClusterInfo.getNodeName(),
primaryClusterInfo.getHostName(),
primaryClusterInfo.getGrpcPort());
ServerAddress serverAddress =
new ServerAddress(primaryClusterInfo.getHostName(), primaryClusterInfo.getGrpcPort());
connection = connectionFactory.apply(serverAddress, context);
}
suppressErrors.set(false);
lastConnectException.set(null);
break;
} catch (Exception e) {
lastConnectException.set(e);
doIfNotNull(candidate, this::shutdownNow);
if (!suppressErrors.getAndSet(true)) {
logger.warn("Connecting to AxonServer node [{}] failed.", nodeInfo, e);
} else {
logger.warn("Connecting to AxonServer node [{}] failed: {}", nodeInfo, e.getMessage());
}
}
}
return connection;
}
private void shutdownNow(ManagedChannel managedChannel) {
try {
managedChannel.shutdownNow().awaitTermination(1, TimeUnit.SECONDS);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
logger.debug("Interrupted during shutdown");
}
}
@Override
public ManagedChannel shutdown() {
shutdown.set(true);
doIfNotNull(activeChannel.get(), ManagedChannel::shutdown);
return this;
}
@Override
public boolean isShutdown() {
return shutdown.get();
}
@Override
public boolean isTerminated() {
if (!shutdown.get()) {
return false;
}
ManagedChannel current = this.activeChannel.get();
return current == null || current.isTerminated();
}
@Override
public ManagedChannel shutdownNow() {
shutdown.set(true);
doIfNotNull(activeChannel.get(), ManagedChannel::shutdownNow);
return this;
}
@Override
public boolean awaitTermination(long timeout, TimeUnit unit) throws InterruptedException {
ManagedChannel current = activeChannel.get();
if (current != null) {
current.awaitTermination(timeout, unit);
}
return true;
}
@Override
public ClientCall newCall(MethodDescriptor methodDescriptor,
CallOptions callOptions) {
ManagedChannel current = activeChannel.get();
if (current == null || current.getState(false) != ConnectivityState.READY) {
ensureConnected();
current = activeChannel.get();
}
if (current == null) {
return new FailingCall<>();
}
return current.newCall(methodDescriptor, callOptions);
}
@Override
public String authority() {
return routingServers.get(0).toString();
}
@Override
public ConnectivityState getState(boolean requestConnection) {
if (shutdown.get()) {
return ConnectivityState.SHUTDOWN;
}
if (requestConnection) {
ensureConnected();
}
ManagedChannel current = activeChannel.get();
if (current == null) {
if (lastConnectException.get() == null) {
return ConnectivityState.IDLE;
} else {
return ConnectivityState.TRANSIENT_FAILURE;
}
}
ConnectivityState state = current.getState(requestConnection);
return state == ConnectivityState.SHUTDOWN ? ConnectivityState.TRANSIENT_FAILURE : state;
}
@Override
public void notifyWhenStateChanged(ConnectivityState source, Runnable callback) {
ManagedChannel current = activeChannel.get();
logger.debug("Registering state change listener for {} on channel {}", source, current);
switch (source) {
case SHUTDOWN:
case READY:
case IDLE:
case CONNECTING:
if (current != null) {
current.notifyWhenStateChanged(source, callback);
} else {
callback.run();
}
break;
case TRANSIENT_FAILURE:
if (current == null) {
connectListeners.add(callback);
} else {
callback.run();
}
break;
}
}
@Override
public void resetConnectBackoff() {
doIfNotNull(activeChannel.get(), ManagedChannel::resetConnectBackoff);
}
@Override
public void enterIdle() {
doIfNotNull(activeChannel.get(), ManagedChannel::enterIdle);
}
private synchronized void ensureConnected() {
if (shutdown.get()) {
return;
}
logger.debug("Checking connection state");
ManagedChannel current = activeChannel.get();
ConnectivityState state = current == null ? ConnectivityState.SHUTDOWN : current.getState(true);
long now = System.currentTimeMillis();
switch (state) {
case TRANSIENT_FAILURE:
case SHUTDOWN:
long deadline = nextAttemptTime.getAndUpdate(d -> d > now ? d : now + reconnectInterval);
if (deadline > now) {
long timeLeft = Math.min(500, deadline - now);
logger.debug("Reconnect timeout still enforced. Scheduling a new connection check in {}ms", timeLeft);
scheduleConnectionCheck(timeLeft);
return;
}
if (current != null) {
logger.info("Connection to AxonServer lost. Attempting to reconnect...");
}
createConnection(current);
break;
case CONNECTING:
long connectDeadline = connectionDeadline.getAndUpdate(d -> d > now ? d : now + connectTimeout);
// if connectDeadline == 0, then this is the first time we're in CONNECTING state. We should give that
// connection a chance. If it's not 0, then a deadline has been set.
if (connectDeadline != 0 && connectDeadline < now) {
logger.info("Unable to recover current connection to AxonServer. Attempting to reconnect...");
createConnection(current);
} else {
scheduleConnectionCheck(Math.min(500, connectDeadline - now));
}
break;
case READY:
if (forcePlatformReconnect) {
// by forcing a non-0 value, it will reconnect automatically when the connection switches to
// CONNECTING state from here. When forcePlatformReconnect is enabled, we want this more aggressive
// reconnection
connectionDeadline.set(1);
}
logger.debug("Connection is {}", state);
break;
case IDLE:
default:
logger.debug("Connection is {}, checking again in 50ms", state);
scheduleConnectionCheck(50);
break;
}
}
private void createConnection(ManagedChannel current) {
if (forcePlatformReconnect && current != null && !current.isShutdown()) {
logger.debug("Shut down current connection");
current.shutdown();
}
ManagedChannel newConnection = connectChannel();
if (newConnection != null) {
if (!activeChannel.compareAndSet(current, newConnection)) {
// concurrency. We need to abandon the given connection
logger.debug("A successful Connection was concurrently set up. Closing this one.");
newConnection.shutdown();
return;
}
doIfNotNull(current, ManagedChannel::shutdown);
if (logger.isInfoEnabled()) {
logger.info("Successfully connected to {}", newConnection.authority());
}
// a new connection, so deadlines should be reset
connectionDeadline.set(0);
nextAttemptTime.set(0);
logger.debug("Registering state change handler");
newConnection.notifyWhenStateChanged(ConnectivityState.READY, () -> verifyConnectionStateChange(newConnection));
Runnable listener;
while ((listener = connectListeners.poll()) != null) {
listener.run();
}
} else {
logger.info("Failed to get connection to AxonServer. Scheduling a reconnect in {}ms", reconnectInterval);
scheduleConnectionCheck(reconnectInterval);
}
}
private void verifyConnectionStateChange(ManagedChannel channel) {
ConnectivityState currentState = channel.getState(false);
logger.debug("Connection state changed to {} scheduling connection check.", currentState);
if (currentState != ConnectivityState.SHUTDOWN) {
logger.debug("Registering new state change handler");
channel.notifyWhenStateChanged(currentState, () -> verifyConnectionStateChange(channel));
}
scheduleConnectionCheck(10);
}
private void scheduleConnectionCheck(long interval) {
try {
if (scheduleGate.compareAndSet(false, true)) {
executor.schedule(() -> {
scheduleGate.set(false);
ensureConnected();
}, interval, TimeUnit.MILLISECONDS);
}
} catch (RejectedExecutionException e) {
scheduleGate.set(false);
logger.debug("Did not schedule reconnect attempt. Connector is shut down");
}
}
/**
* Requests a dedicated reconnect of this {@link ManagedChannel} implementation.
*/
public void requestReconnect() {
doIfNotNull(this.activeChannel.getAndSet(null), currentChannel -> {
logger.info("Reconnect for context {} requested. Closing current connection.", context);
nextAttemptTime.set(0);
currentChannel.shutdown();
executor.schedule(currentChannel::shutdownNow, 5, TimeUnit.SECONDS);
});
}
/**
* Indicates whether the channel is READY, meaning is is connected to an Axon Server instance,
* and ready to accept calls.
*
* @return {@code true} if the connection is ready to accept calls, otherwise {@code false}
*/
public boolean isReady() {
return getState(false) == ConnectivityState.READY;
}
private static class FailingCall extends ClientCall {
@Override
public void start(Listener responseListener, Metadata headers) {
responseListener.onClose(Status.UNAVAILABLE, null);
}
@Override
public void request(int numMessages) {
// ignore
}
@Override
public void cancel(String message, Throwable cause) {
// great
}
@Override
public void halfClose() {
// great
}
@Override
public void sendMessage(REQ message) {
// ignore these messages. The returning stream has already given an error
}
}
}
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