io.grpc.ManagedChannelRegistry Maven / Gradle / Ivy
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/*
* Copyright 2020 The gRPC Authors
*
* 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.grpc;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Preconditions;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.annotation.concurrent.GuardedBy;
import javax.annotation.concurrent.ThreadSafe;
/**
* Registry of {@link ManagedChannelProvider}s. The {@link #getDefaultRegistry default instance}
* loads providers at runtime through the Java service provider mechanism.
*
* @since 1.32.0
*/
@Internal
@ThreadSafe
public final class ManagedChannelRegistry {
private static final Logger logger = Logger.getLogger(ManagedChannelRegistry.class.getName());
private static ManagedChannelRegistry instance;
@GuardedBy("this")
private final LinkedHashSet allProviders = new LinkedHashSet<>();
/** Immutable, sorted version of {@code allProviders}. Is replaced instead of mutating. */
@GuardedBy("this")
private List effectiveProviders = Collections.emptyList();
/**
* Register a provider.
*
* If the provider's {@link ManagedChannelProvider#isAvailable isAvailable()} returns
* {@code false}, this method will throw {@link IllegalArgumentException}.
*
*
Providers will be used in priority order. In case of ties, providers are used in
* registration order.
*/
public synchronized void register(ManagedChannelProvider provider) {
addProvider(provider);
refreshProviders();
}
private synchronized void addProvider(ManagedChannelProvider provider) {
Preconditions.checkArgument(provider.isAvailable(), "isAvailable() returned false");
allProviders.add(provider);
}
/**
* Deregisters a provider. No-op if the provider is not in the registry.
*
* @param provider the provider that was added to the register via {@link #register}.
*/
public synchronized void deregister(ManagedChannelProvider provider) {
allProviders.remove(provider);
refreshProviders();
}
private synchronized void refreshProviders() {
List providers = new ArrayList<>(allProviders);
// Sort descending based on priority.
// sort() must be stable, as we prefer first-registered providers
Collections.sort(providers, Collections.reverseOrder(new Comparator() {
@Override
public int compare(ManagedChannelProvider o1, ManagedChannelProvider o2) {
return o1.priority() - o2.priority();
}
}));
effectiveProviders = Collections.unmodifiableList(providers);
}
/**
* Returns the default registry that loads providers via the Java service loader mechanism.
*/
public static synchronized ManagedChannelRegistry getDefaultRegistry() {
if (instance == null) {
List providerList = ServiceProviders.loadAll(
ManagedChannelProvider.class,
getHardCodedClasses(),
ManagedChannelProvider.class.getClassLoader(),
new ManagedChannelPriorityAccessor());
instance = new ManagedChannelRegistry();
for (ManagedChannelProvider provider : providerList) {
logger.fine("Service loader found " + provider);
if (provider.isAvailable()) {
instance.addProvider(provider);
}
}
instance.refreshProviders();
}
return instance;
}
/**
* Returns effective providers, in priority order.
*/
@VisibleForTesting
synchronized List providers() {
return effectiveProviders;
}
// For emulating ManagedChannelProvider.provider()
ManagedChannelProvider provider() {
List providers = providers();
return providers.isEmpty() ? null : providers.get(0);
}
@VisibleForTesting
static List> getHardCodedClasses() {
// Class.forName(String) is used to remove the need for ProGuard configuration. Note that
// ProGuard does not detect usages of Class.forName(String, boolean, ClassLoader):
// https://sourceforge.net/p/proguard/bugs/418/
List> list = new ArrayList<>();
try {
list.add(Class.forName("io.grpc.okhttp.OkHttpChannelProvider"));
} catch (ClassNotFoundException e) {
logger.log(Level.FINE, "Unable to find OkHttpChannelProvider", e);
}
try {
list.add(Class.forName("io.grpc.netty.NettyChannelProvider"));
} catch (ClassNotFoundException e) {
logger.log(Level.FINE, "Unable to find NettyChannelProvider", e);
}
return Collections.unmodifiableList(list);
}
ManagedChannelBuilder newChannelBuilder(String target, ChannelCredentials creds) {
List providers = providers();
if (providers.isEmpty()) {
throw new ProviderNotFoundException("No functional channel service provider found. "
+ "Try adding a dependency on the grpc-okhttp, grpc-netty, or grpc-netty-shaded "
+ "artifact");
}
StringBuilder error = new StringBuilder();
for (ManagedChannelProvider provider : providers()) {
ManagedChannelProvider.NewChannelBuilderResult result
= provider.newChannelBuilder(target, creds);
if (result.getChannelBuilder() != null) {
return result.getChannelBuilder();
}
error.append("; ");
error.append(provider.getClass().getName());
error.append(": ");
error.append(result.getError());
}
throw new ProviderNotFoundException(error.substring(2));
}
private static final class ManagedChannelPriorityAccessor
implements ServiceProviders.PriorityAccessor {
@Override
public boolean isAvailable(ManagedChannelProvider provider) {
return provider.isAvailable();
}
@Override
public int getPriority(ManagedChannelProvider provider) {
return provider.priority();
}
}
/** Thrown when no suitable {@link ManagedChannelProvider} objects can be found. */
public static final class ProviderNotFoundException extends RuntimeException {
private static final long serialVersionUID = 1;
public ProviderNotFoundException(String msg) {
super(msg);
}
}
}