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DiscoveryClientResolverFactory.java
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DiscoveryClientResolverFactory.java
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/*
* Copyright (c) 2016-2021 Michael Zhang <yidongnan@gmail.com>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated
* documentation files (the "Software"), to deal in the Software without restriction, including without limitation the
* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
* WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
* OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
package net.devh.boot.grpc.client.nameresolver;
import static java.util.Objects.requireNonNull;
import java.net.URI;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import javax.annotation.Nullable;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.discovery.DiscoveryClient;
import org.springframework.cloud.client.discovery.event.HeartbeatEvent;
import org.springframework.cloud.client.discovery.event.HeartbeatMonitor;
import org.springframework.context.event.EventListener;
import io.grpc.Attributes.Key;
import io.grpc.NameResolver;
import io.grpc.NameResolverProvider;
import io.grpc.internal.GrpcUtil;
import jakarta.annotation.PreDestroy;
/**
* A name resolver factory that will create a {@link DiscoveryClientNameResolver} based on the target uri.
*
* @author Michael (yidongnan@gmail.com)
*/
// Do not add this to the NameResolverProvider service loader list
public class DiscoveryClientResolverFactory extends NameResolverProvider {
/**
* The constant containing the scheme that will be used by this factory.
*/
public static final String DISCOVERY_SCHEME = "discovery";
/**
* A key for the service name used to related {@link ServiceInstance}s from the {@link DiscoveryClient}.
*/
public static final Key<String> DISCOVERY_SERVICE_NAME_KEY = Key.create("serviceName");
/**
* A key for the {@link ServiceInstance#getInstanceId() instance id}.
*/
public static final Key<String> DISCOVERY_INSTANCE_ID_KEY = Key.create("instanceId");
private final Set<DiscoveryClientNameResolver> discoveryClientNameResolvers = ConcurrentHashMap.newKeySet();
private final HeartbeatMonitor monitor = new HeartbeatMonitor();
private final DiscoveryClient client;
/**
* Creates a new discovery client based name resolver factory.
*
* @param client The client to use for the address discovery.
*/
public DiscoveryClientResolverFactory(final DiscoveryClient client) {
this.client = requireNonNull(client, "client");
}
@Nullable
@Override
public NameResolver newNameResolver(final URI targetUri, final NameResolver.Args args) {
if (DISCOVERY_SCHEME.equals(targetUri.getScheme())) {
final String serviceName = targetUri.getPath();
if (serviceName == null || serviceName.length() <= 1 || !serviceName.startsWith("/")) {
throw new IllegalArgumentException("Incorrectly formatted target uri; "
+ "expected: '" + DISCOVERY_SCHEME + ":[//]/<service-name>'; "
+ "but was '" + targetUri.toString() + "'");
}
final DiscoveryClientNameResolver nameResolver = newNameResolver(serviceName.substring(1), args);
this.discoveryClientNameResolvers.add(nameResolver);
return nameResolver;
}
return null;
}
/**
* Factory method to create the resolver for the given service name.
*
* @param serviceName The service name to create it for.
* @param args The NameResolver arguments to use.
* @return A newly created DiscoveryClientNameResolver.
*/
protected DiscoveryClientNameResolver newNameResolver(final String serviceName, final NameResolver.Args args) {
return new DiscoveryClientNameResolver(serviceName, this.client, args,
GrpcUtil.SHARED_CHANNEL_EXECUTOR, this.discoveryClientNameResolvers::remove);
}
@Override
public String getDefaultScheme() {
return DISCOVERY_SCHEME;
}
@Override
protected boolean isAvailable() {
return true;
}
@Override
protected int priority() {
return 6; // More important than DNS
}
/**
* Triggers a refresh of the registered name resolvers.
*
* @param event The event that triggered the update.
*/
@EventListener(HeartbeatEvent.class)
public void heartbeat(final HeartbeatEvent event) {
if (this.monitor.update(event.getValue())) {
for (final DiscoveryClientNameResolver discoveryClientNameResolver : this.discoveryClientNameResolvers) {
discoveryClientNameResolver.refreshFromExternal();
}
}
}
/**
* Cleans up the name resolvers.
*/
@PreDestroy
public void destroy() {
this.discoveryClientNameResolvers.clear();
}
@Override
public String toString() {
return "DiscoveryClientResolverFactory [scheme=" + getDefaultScheme() +
", discoveryClient=" + this.client + "]";
}
}