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XdsNameResolver.java
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XdsNameResolver.java
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/*
* Copyright 2019 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.xds;
import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.collect.Sets;
import com.google.gson.Gson;
import io.grpc.Attributes;
import io.grpc.CallOptions;
import io.grpc.Channel;
import io.grpc.ClientCall;
import io.grpc.ClientInterceptor;
import io.grpc.ForwardingClientCall.SimpleForwardingClientCall;
import io.grpc.ForwardingClientCallListener.SimpleForwardingClientCallListener;
import io.grpc.InternalConfigSelector;
import io.grpc.InternalLogId;
import io.grpc.LoadBalancer.PickSubchannelArgs;
import io.grpc.Metadata;
import io.grpc.MethodDescriptor;
import io.grpc.NameResolver;
import io.grpc.Status;
import io.grpc.SynchronizationContext;
import io.grpc.internal.GrpcUtil;
import io.grpc.internal.ObjectPool;
import io.grpc.xds.EnvoyProtoData.ClusterWeight;
import io.grpc.xds.EnvoyProtoData.Route;
import io.grpc.xds.EnvoyProtoData.RouteAction;
import io.grpc.xds.EnvoyProtoData.VirtualHost;
import io.grpc.xds.ThreadSafeRandom.ThreadSafeRandomImpl;
import io.grpc.xds.XdsClient.LdsResourceWatcher;
import io.grpc.xds.XdsClient.LdsUpdate;
import io.grpc.xds.XdsClient.RdsResourceWatcher;
import io.grpc.xds.XdsClient.RdsUpdate;
import io.grpc.xds.XdsLogger.XdsLogLevel;
import io.grpc.xds.XdsNameResolverProvider.CallCounterProvider;
import io.grpc.xds.XdsNameResolverProvider.XdsClientPoolFactory;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.atomic.AtomicInteger;
import javax.annotation.Nullable;
/**
* A {@link NameResolver} for resolving gRPC target names with "xds:" scheme.
*
* <p>Resolving a gRPC target involves contacting the control plane management server via xDS
* protocol to retrieve service information and produce a service config to the caller.
*
* @see XdsNameResolverProvider
*/
final class XdsNameResolver extends NameResolver {
static final CallOptions.Key<String> CLUSTER_SELECTION_KEY =
CallOptions.Key.create("io.grpc.xds.CLUSTER_SELECTION_KEY");
@VisibleForTesting
static boolean enableTimeout =
Boolean.parseBoolean(System.getenv("GRPC_XDS_EXPERIMENTAL_ENABLE_TIMEOUT"));
private final XdsLogger logger;
private final String authority;
private final ServiceConfigParser serviceConfigParser;
private final SynchronizationContext syncContext;
private final XdsClientPoolFactory xdsClientPoolFactory;
private final ThreadSafeRandom random;
private final ConcurrentMap<String, AtomicInteger> clusterRefs = new ConcurrentHashMap<>();
private final ConfigSelector configSelector = new ConfigSelector();
private volatile RoutingConfig routingConfig = RoutingConfig.empty;
private Listener2 listener;
private ObjectPool<XdsClient> xdsClientPool;
private XdsClient xdsClient;
private CallCounterProvider callCounterProvider;
private ResolveState resolveState;
XdsNameResolver(String name, ServiceConfigParser serviceConfigParser,
SynchronizationContext syncContext) {
this(name, serviceConfigParser, syncContext, SharedXdsClientPoolProvider.getDefaultProvider(),
ThreadSafeRandomImpl.instance);
}
@VisibleForTesting
XdsNameResolver(String name, ServiceConfigParser serviceConfigParser,
SynchronizationContext syncContext, XdsClientPoolFactory xdsClientPoolFactory,
ThreadSafeRandom random) {
authority = GrpcUtil.checkAuthority(checkNotNull(name, "name"));
this.serviceConfigParser = checkNotNull(serviceConfigParser, "serviceConfigParser");
this.syncContext = checkNotNull(syncContext, "syncContext");
this.xdsClientPoolFactory = checkNotNull(xdsClientPoolFactory, "xdsClientPoolFactory");
this.random = checkNotNull(random, "random");
logger = XdsLogger.withLogId(InternalLogId.allocate("xds-resolver", name));
logger.log(XdsLogLevel.INFO, "Created resolver for {0}", name);
}
@Override
public String getServiceAuthority() {
return authority;
}
@Override
public void start(Listener2 listener) {
this.listener = checkNotNull(listener, "listener");
try {
xdsClientPool = xdsClientPoolFactory.getXdsClientPool();
} catch (Exception e) {
listener.onError(
Status.UNAVAILABLE.withDescription("Failed to initialize xDS").withCause(e));
return;
}
xdsClient = xdsClientPool.getObject();
callCounterProvider = SharedCallCounterMap.getInstance();
resolveState = new ResolveState();
resolveState.start();
}
@Override
public void shutdown() {
logger.log(XdsLogLevel.INFO, "Shutdown");
if (resolveState != null) {
resolveState.stop();
}
if (xdsClient != null) {
xdsClient = xdsClientPool.returnObject(xdsClient);
}
}
@VisibleForTesting
static Map<String, ?> generateServiceConfigWithMethodTimeoutConfig(long timeoutNano) {
String timeout = timeoutNano / 1_000_000_000.0 + "s";
Map<String, Object> methodConfig = new HashMap<>();
methodConfig.put(
"name", Collections.singletonList(Collections.emptyMap()));
methodConfig.put("timeout", timeout);
return Collections.singletonMap(
"methodConfig", Collections.singletonList(Collections.unmodifiableMap(methodConfig)));
}
@VisibleForTesting
static Map<String, ?> generateServiceConfigWithLoadBalancingConfig(Collection<String> clusters) {
Map<String, Object> childPolicy = new HashMap<>();
for (String cluster : clusters) {
List<Map<String, Map<String, String>>> lbPolicy =
Collections.singletonList(
Collections.singletonMap(
"cds_experimental", Collections.singletonMap("cluster", cluster)));
childPolicy.put(cluster, Collections.singletonMap("lbPolicy", lbPolicy));
}
return Collections.singletonMap("loadBalancingConfig",
Collections.singletonList(
Collections.singletonMap(
"cluster_manager_experimental", Collections.singletonMap(
"childPolicy", Collections.unmodifiableMap(childPolicy)))));
}
@VisibleForTesting
XdsClient getXdsClient() {
return xdsClient;
}
private void updateResolutionResult() {
Map<String, ?> rawServiceConfig =
generateServiceConfigWithLoadBalancingConfig(clusterRefs.keySet());
if (logger.isLoggable(XdsLogLevel.INFO)) {
logger.log(
XdsLogLevel.INFO, "Generated service config:\n{0}", new Gson().toJson(rawServiceConfig));
}
ConfigOrError parsedServiceConfig = serviceConfigParser.parseServiceConfig(rawServiceConfig);
Attributes attrs =
Attributes.newBuilder()
.set(InternalXdsAttributes.XDS_CLIENT_POOL, xdsClientPool)
.set(InternalXdsAttributes.CALL_COUNTER_PROVIDER, callCounterProvider)
.set(InternalConfigSelector.KEY, configSelector)
.build();
ResolutionResult result =
ResolutionResult.newBuilder()
.setAttributes(attrs)
.setServiceConfig(parsedServiceConfig)
.build();
listener.onResult(result);
}
@VisibleForTesting
@Nullable
static VirtualHost findVirtualHostForHostName(List<VirtualHost> virtualHosts, String hostName) {
// Domain search order:
// 1. Exact domain names: ``www.foo.com``.
// 2. Suffix domain wildcards: ``*.foo.com`` or ``*-bar.foo.com``.
// 3. Prefix domain wildcards: ``foo.*`` or ``foo-*``.
// 4. Special wildcard ``*`` matching any domain.
//
// The longest wildcards match first.
// Assuming only a single virtual host in the entire route configuration can match
// on ``*`` and a domain must be unique across all virtual hosts.
int matchingLen = -1; // longest length of wildcard pattern that matches host name
boolean exactMatchFound = false; // true if a virtual host with exactly matched domain found
VirtualHost targetVirtualHost = null; // target VirtualHost with longest matched domain
for (VirtualHost vHost : virtualHosts) {
for (String domain : vHost.getDomains()) {
boolean selected = false;
if (matchHostName(hostName, domain)) { // matching
if (!domain.contains("*")) { // exact matching
exactMatchFound = true;
targetVirtualHost = vHost;
break;
} else if (domain.length() > matchingLen) { // longer matching pattern
selected = true;
} else if (domain.length() == matchingLen && domain.startsWith("*")) { // suffix matching
selected = true;
}
}
if (selected) {
matchingLen = domain.length();
targetVirtualHost = vHost;
}
}
if (exactMatchFound) {
break;
}
}
return targetVirtualHost;
}
/**
* Returns {@code true} iff {@code hostName} matches the domain name {@code pattern} with
* case-insensitive.
*
* <p>Wildcard pattern rules:
* <ol>
* <li>A single asterisk (*) matches any domain.</li>
* <li>Asterisk (*) is only permitted in the left-most or the right-most part of the pattern,
* but not both.</li>
* </ol>
*/
@VisibleForTesting
static boolean matchHostName(String hostName, String pattern) {
checkArgument(hostName.length() != 0 && !hostName.startsWith(".") && !hostName.endsWith("."),
"Invalid host name");
checkArgument(pattern.length() != 0 && !pattern.startsWith(".") && !pattern.endsWith("."),
"Invalid pattern/domain name");
hostName = hostName.toLowerCase(Locale.US);
pattern = pattern.toLowerCase(Locale.US);
// hostName and pattern are now in lower case -- domain names are case-insensitive.
if (!pattern.contains("*")) {
// Not a wildcard pattern -- hostName and pattern must match exactly.
return hostName.equals(pattern);
}
// Wildcard pattern
if (pattern.length() == 1) {
return true;
}
int index = pattern.indexOf('*');
// At most one asterisk (*) is allowed.
if (pattern.indexOf('*', index + 1) != -1) {
return false;
}
// Asterisk can only match prefix or suffix.
if (index != 0 && index != pattern.length() - 1) {
return false;
}
// HostName must be at least as long as the pattern because asterisk has to
// match one or more characters.
if (hostName.length() < pattern.length()) {
return false;
}
if (index == 0 && hostName.endsWith(pattern.substring(1))) {
// Prefix matching fails.
return true;
}
// Pattern matches hostname if suffix matching succeeds.
return index == pattern.length() - 1
&& hostName.startsWith(pattern.substring(0, pattern.length() - 1));
}
private final class ConfigSelector extends InternalConfigSelector {
@Override
public Result selectConfig(PickSubchannelArgs args) {
// Index ASCII headers by keys.
Map<String, Iterable<String>> asciiHeaders = new HashMap<>();
Metadata headers = args.getHeaders();
for (String headerName : headers.keys()) {
if (headerName.endsWith(Metadata.BINARY_HEADER_SUFFIX)) {
continue;
}
Metadata.Key<String> key = Metadata.Key.of(headerName, Metadata.ASCII_STRING_MARSHALLER);
asciiHeaders.put(headerName, headers.getAll(key));
}
String cluster = null;
Route selectedRoute = null;
do {
for (Route route : routingConfig.routes) {
if (route.getRouteMatch().matches(
"/" + args.getMethodDescriptor().getFullMethodName(), asciiHeaders)) {
selectedRoute = route;
break;
}
}
if (selectedRoute == null) {
return Result.forError(
Status.UNAVAILABLE.withDescription("Could not find xDS route matching RPC"));
}
RouteAction action = selectedRoute.getRouteAction();
if (action.getCluster() != null) {
cluster = action.getCluster();
} else if (action.getWeightedCluster() != null) {
int totalWeight = 0;
for (ClusterWeight weightedCluster : action.getWeightedCluster()) {
totalWeight += weightedCluster.getWeight();
}
int select = random.nextInt(totalWeight);
int accumulator = 0;
for (ClusterWeight weightedCluster : action.getWeightedCluster()) {
accumulator += weightedCluster.getWeight();
if (select < accumulator) {
cluster = weightedCluster.getName();
break;
}
}
}
} while (!retainCluster(cluster));
// TODO(chengyuanzhang): avoid service config generation and parsing for each call.
Map<String, ?> rawServiceConfig = Collections.emptyMap();
if (enableTimeout) {
Long timeoutNano = selectedRoute.getRouteAction().getTimeoutNano();
if (timeoutNano == null) {
timeoutNano = routingConfig.fallbackTimeoutNano;
}
if (timeoutNano > 0) {
rawServiceConfig = generateServiceConfigWithMethodTimeoutConfig(timeoutNano);
}
}
ConfigOrError parsedServiceConfig = serviceConfigParser.parseServiceConfig(rawServiceConfig);
Object config = parsedServiceConfig.getConfig();
if (config == null) {
releaseCluster(cluster);
return Result.forError(
parsedServiceConfig.getError().augmentDescription(
"Failed to parse service config (method config)"));
}
final String finalCluster = cluster;
class ClusterSelectionInterceptor implements ClientInterceptor {
@Override
public <ReqT, RespT> ClientCall<ReqT, RespT> interceptCall(
MethodDescriptor<ReqT, RespT> method, CallOptions callOptions, Channel next) {
CallOptions callOptionsForCluster =
callOptions.withOption(CLUSTER_SELECTION_KEY, finalCluster);
return new SimpleForwardingClientCall<ReqT, RespT>(
next.newCall(method, callOptionsForCluster)) {
@Override
public void start(Listener<RespT> listener, Metadata headers) {
listener = new SimpleForwardingClientCallListener<RespT>(listener) {
boolean committed;
@Override
public void onHeaders(Metadata headers) {
committed = true;
releaseCluster(finalCluster);
delegate().onHeaders(headers);
}
@Override
public void onClose(Status status, Metadata trailers) {
if (!committed) {
releaseCluster(finalCluster);
}
delegate().onClose(status, trailers);
}
};
delegate().start(listener, headers);
}
};
}
}
return
Result.newBuilder()
.setConfig(config)
.setInterceptor(new ClusterSelectionInterceptor())
.build();
}
private boolean retainCluster(String cluster) {
AtomicInteger refCount = clusterRefs.get(cluster);
if (refCount == null) {
return false;
}
int count;
do {
count = refCount.get();
if (count == 0) {
return false;
}
} while (!refCount.compareAndSet(count, count + 1));
return true;
}
private void releaseCluster(final String cluster) {
int count = clusterRefs.get(cluster).decrementAndGet();
if (count == 0) {
syncContext.execute(new Runnable() {
@Override
public void run() {
if (clusterRefs.get(cluster).get() == 0) {
clusterRefs.remove(cluster);
updateResolutionResult();
}
}
});
}
}
}
private class ResolveState implements LdsResourceWatcher {
private final ConfigOrError emptyServiceConfig =
serviceConfigParser.parseServiceConfig(Collections.<String, Object>emptyMap());
private final ResolutionResult emptyResult =
ResolutionResult.newBuilder()
.setServiceConfig(emptyServiceConfig)
// let channel take action for no config selector
.build();
private boolean stopped;
private Set<String> existingClusters;
@Nullable
private String rdsResource;
@Nullable
private RdsResourceWatcher rdsWatcher;
private long httpMaxStreamDurationNano;
@Override
public void onChanged(final LdsUpdate update) {
syncContext.execute(new Runnable() {
@Override
public void run() {
if (stopped) {
return;
}
logger.log(XdsLogLevel.INFO, "Receive LDS resource update: {0}", update);
httpMaxStreamDurationNano = update.httpMaxStreamDurationNano;
List<VirtualHost> virtualHosts = update.virtualHosts;
String rdsName = update.rdsName;
if (rdsName != null && rdsName.equals(rdsResource)) {
return;
}
cleanUpRdsWatcher();
if (virtualHosts != null) {
updateRoutes(virtualHosts);
} else {
rdsResource = rdsName;
rdsWatcher = new RdsResourceWatcherImpl();
logger.log(XdsLogLevel.INFO, "Start watching RDS resource {0}", rdsResource);
xdsClient.watchRdsResource(rdsResource, rdsWatcher);
}
}
});
}
@Override
public void onError(final Status error) {
syncContext.execute(new Runnable() {
@Override
public void run() {
if (stopped) {
return;
}
logger.log(
XdsLogLevel.WARNING,
"Received error from xDS client {0}: {1}", xdsClient, error.getDescription());
listener.onError(error);
}
});
}
@Override
public void onResourceDoesNotExist(final String resourceName) {
syncContext.execute(new Runnable() {
@Override
public void run() {
if (stopped) {
return;
}
logger.log(XdsLogLevel.INFO, "LDS resource {0} unavailable", resourceName);
cleanUpRdsWatcher();
listener.onResult(emptyResult);
}
});
}
private void start() {
logger.log(XdsLogLevel.INFO, "Start watching LDS resource {0}", authority);
xdsClient.watchLdsResource(authority, this);
}
private void stop() {
logger.log(XdsLogLevel.INFO, "Stop watching LDS resource {0}", authority);
stopped = true;
cleanUpRdsWatcher();
xdsClient.cancelLdsResourceWatch(authority, this);
}
private void updateRoutes(List<VirtualHost> virtualHosts) {
VirtualHost virtualHost = findVirtualHostForHostName(virtualHosts, authority);
if (virtualHost == null) {
logger.log(XdsLogLevel.WARNING,
"Failed to find virtual host matching hostname {0}", authority);
listener.onResult(emptyResult);
return;
}
List<Route> routes = virtualHost.getRoutes();
Set<String> clusters = new HashSet<>();
for (Route route : routes) {
RouteAction action = route.getRouteAction();
if (action.getCluster() != null) {
clusters.add(action.getCluster());
} else if (action.getWeightedCluster() != null) {
for (ClusterWeight weighedCluster : action.getWeightedCluster()) {
clusters.add(weighedCluster.getName());
}
}
}
Set<String> addedClusters =
existingClusters == null ? clusters : Sets.difference(clusters, existingClusters);
Set<String> deletedClusters =
existingClusters == null
? Collections.<String>emptySet() : Sets.difference(existingClusters, clusters);
existingClusters = clusters;
boolean shouldUpdateResult = false;
for (String cluster : addedClusters) {
if (clusterRefs.containsKey(cluster)) {
clusterRefs.get(cluster).incrementAndGet();
} else {
clusterRefs.put(cluster, new AtomicInteger(1));
shouldUpdateResult = true;
}
}
// Update service config to include newly added clusters.
if (shouldUpdateResult) {
updateResolutionResult();
}
// Make newly added clusters selectable by config selector and deleted clusters no longer
// selectable.
routingConfig = new RoutingConfig(httpMaxStreamDurationNano, routes);
shouldUpdateResult = false;
for (String cluster : deletedClusters) {
int count = clusterRefs.get(cluster).decrementAndGet();
if (count == 0) {
clusterRefs.remove(cluster);
shouldUpdateResult = true;
}
}
if (shouldUpdateResult) {
updateResolutionResult();
}
}
private void cleanUpRdsWatcher() {
if (rdsWatcher != null) {
logger.log(XdsLogLevel.INFO, "Stop watching RDS resource {0}", rdsResource);
xdsClient.cancelRdsResourceWatch(rdsResource, rdsWatcher);
rdsResource = null;
rdsWatcher = null;
}
}
private class RdsResourceWatcherImpl implements RdsResourceWatcher {
@Override
public void onChanged(final RdsUpdate update) {
syncContext.execute(new Runnable() {
@Override
public void run() {
if (RdsResourceWatcherImpl.this != rdsWatcher) {
return;
}
updateRoutes(update.virtualHosts);
}
});
}
@Override
public void onError(final Status error) {
syncContext.execute(new Runnable() {
@Override
public void run() {
if (RdsResourceWatcherImpl.this != rdsWatcher) {
return;
}
logger.log(
XdsLogLevel.WARNING,
"Received error from xDS client {0}: {1}", xdsClient, error.getDescription());
listener.onError(error);
}
});
}
@Override
public void onResourceDoesNotExist(final String resourceName) {
syncContext.execute(new Runnable() {
@Override
public void run() {
if (RdsResourceWatcherImpl.this != rdsWatcher) {
return;
}
logger.log(XdsLogLevel.INFO, "RDS resource {0} unavailable", resourceName);
listener.onResult(emptyResult);
}
});
}
}
}
/**
* Grouping of the list of usable routes and their corresponding fallback timeout value.
*/
private static class RoutingConfig {
private long fallbackTimeoutNano;
private List<Route> routes;
private static RoutingConfig empty = new RoutingConfig(0L, Collections.<Route>emptyList());
private RoutingConfig(long fallbackTimeoutNano, List<Route> routes) {
this.fallbackTimeoutNano = fallbackTimeoutNano;
this.routes = routes;
}
}
}