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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.container.di;
import com.google.common.collect.Sets;
import com.yahoo.config.ConfigInstance;
import com.yahoo.container.di.componentgraph.core.Keys;
import com.yahoo.container.di.config.Subscriber;
import com.yahoo.container.di.config.SubscriberFactory;
import com.yahoo.vespa.config.ConfigKey;
import java.util.Collections;
import java.util.HashSet;
import java.util.Map;
import java.util.Optional;
import java.util.Set;
import java.util.function.Function;
import java.util.logging.Level;
import java.util.logging.Logger;
import static java.util.logging.Level.FINE;
/**
* @author Tony Vaagenes
* @author gjoranv
* @author ollivir
*/
public final class ConfigRetriever {
private static final Logger log = Logger.getLogger(ConfigRetriever.class.getName());
private final Set<ConfigKey<? extends ConfigInstance>> bootstrapKeys;
private Set<ConfigKey<? extends ConfigInstance>> componentSubscriberKeys;
private final SubscriberFactory subscriberFactory;
private final Subscriber bootstrapSubscriber;
private Subscriber componentSubscriber;
private int componentSubscriberIndex;
public ConfigRetriever(Set<ConfigKey<? extends ConfigInstance>> bootstrapKeys, SubscriberFactory subscriberFactory) {
this.bootstrapKeys = bootstrapKeys;
this.componentSubscriberKeys = new HashSet<>();
this.subscriberFactory = subscriberFactory;
if (bootstrapKeys.isEmpty()) {
throw new IllegalArgumentException("Bootstrap key set is empty");
}
this.bootstrapSubscriber = this.subscriberFactory.getSubscriber(bootstrapKeys, "bootstrap");
this.componentSubscriber = this.subscriberFactory.getSubscriber(componentSubscriberKeys, "component_" + ++componentSubscriberIndex);
}
public ConfigSnapshot getConfigs(Set<ConfigKey<? extends ConfigInstance>> componentConfigKeys,
long leastGeneration, boolean isInitializing) {
// Loop until we get config.
while (true) {
Optional<ConfigSnapshot> maybeSnapshot = getConfigsOnce(componentConfigKeys, leastGeneration, isInitializing);
if (maybeSnapshot.isPresent()) {
var configSnapshot = maybeSnapshot.get();
resetComponentSubscriberIfBootstrap(configSnapshot);
return configSnapshot;
}
}
}
private Optional<ConfigSnapshot> getConfigsOnce(Set<ConfigKey<? extends ConfigInstance>> componentConfigKeys,
long leastGeneration, boolean isInitializing) {
if (!Sets.intersection(componentConfigKeys, bootstrapKeys).isEmpty()) {
throw new IllegalArgumentException(
"Component config keys [" + componentConfigKeys + "] overlaps with bootstrap config keys [" + bootstrapKeys + "]");
}
Set<ConfigKey<? extends ConfigInstance>> allKeys = new HashSet<>(componentConfigKeys);
allKeys.addAll(bootstrapKeys);
setupComponentSubscriber(allKeys);
if (componentSubscriber.generation() < bootstrapSubscriber.generation()) {
return getComponentsSnapshot(leastGeneration, isInitializing);
}
long newestBootstrapGeneration = bootstrapSubscriber.waitNextGeneration(isInitializing);
log.log(FINE, () -> "getConfigsOptional: new bootstrap generation: " + newestBootstrapGeneration);
// leastGeneration is used to ensure newer generation (than the latest bootstrap or component gen)
// when the previous generation was invalidated due to an exception upon creating the component graph.
if (newestBootstrapGeneration < leastGeneration) {
return Optional.empty();
}
return bootstrapConfigIfChanged()
// At this point, we normally assume that the bootstrap subscriber is one generation ahead
// of the component subscriber, but this is not always the case in practice.
.or(this::componentsSnapshotReceivedBeforeBootstrap);
}
private Optional<ConfigSnapshot> componentsSnapshotReceivedBeforeBootstrap() {
if (componentSubscriber.generation() == bootstrapSubscriber.generation()) {
// The component subscriber originally had a newer config generation than the bootstrap subscriber.
// Ensure that this generation is applied if it contains changed configs.
// The root cause is probably that the component subscriber skipped a generation and got
// one ahead of the bootstrap subscriber.
return componentsConfigIfChanged();
}
return Optional.empty();
}
private Optional<ConfigSnapshot> getComponentsSnapshot(long leastGeneration, boolean isInitializing) {
long newestBootstrapGeneration = bootstrapSubscriber.generation();
long newestComponentGeneration = componentSubscriber.waitNextGeneration(isInitializing);
if (newestComponentGeneration < leastGeneration) {
log.log(FINE, () -> "Component generation too old: " + componentSubscriber.generation() + " < " + leastGeneration);
return Optional.empty();
}
if (newestComponentGeneration == newestBootstrapGeneration) {
log.log(FINE, () -> "getConfigsOptional: new component generation: " + componentSubscriber.generation());
return componentsConfigIfChanged();
} else {
// Should not be a normal case, and hence a warning to allow investigation.
log.warning("Did not get same generation for bootstrap (" + newestBootstrapGeneration +
") and components configs (" + newestComponentGeneration + ").");
return Optional.empty();
}
}
private Optional<ConfigSnapshot> bootstrapConfigIfChanged() {
return configIfChanged(bootstrapSubscriber, BootstrapConfigs::new);
}
private Optional<ConfigSnapshot> componentsConfigIfChanged() {
return configIfChanged(componentSubscriber, ComponentsConfigs::new);
}
private Optional<ConfigSnapshot> configIfChanged(Subscriber subscriber,
Function<Map<ConfigKey<? extends ConfigInstance>, ConfigInstance>, ConfigSnapshot> constructor) {
if (subscriber.configChanged()) {
return Optional.of(constructor.apply(Keys.covariantCopy(subscriber.config())));
} else {
return Optional.empty();
}
}
private void resetComponentSubscriberIfBootstrap(ConfigSnapshot configSnapshot) {
if (configSnapshot instanceof BootstrapConfigs) {
setupComponentSubscriber(Collections.emptySet());
}
}
private void setupComponentSubscriber(Set<ConfigKey<? extends ConfigInstance>> keys) {
if (! componentSubscriberKeys.equals(keys)) {
componentSubscriber.close();
log.log(FINE, () -> "Closed " + componentSubscriber);
componentSubscriberKeys = keys;
try {
componentSubscriber = subscriberFactory.getSubscriber(keys, "component_" + ++componentSubscriberIndex);
log.log(FINE, () -> "Set up new subscriber " + componentSubscriber + " for keys: " + keys);
} catch (Throwable e) {
log.log(Level.WARNING, "Failed setting up subscriptions for component configs: " + e.getMessage());
log.log(Level.WARNING, "Config keys: " + keys);
throw e;
}
}
}
public void shutdown() {
bootstrapSubscriber.close();
componentSubscriber.close();
}
//TODO: check if these are really needed
public long getBootstrapGeneration() {
return bootstrapSubscriber.generation();
}
public long getComponentsGeneration() {
return componentSubscriber.generation();
}
public static class ConfigSnapshot {
private final Map<ConfigKey<? extends ConfigInstance>, ConfigInstance> configs;
ConfigSnapshot(Map<ConfigKey<? extends ConfigInstance>, ConfigInstance> configs) {
this.configs = configs;
}
public Map<ConfigKey<? extends ConfigInstance>, ConfigInstance> configs() {
return configs;
}
public int size() {
return configs.size();
}
}
public static class BootstrapConfigs extends ConfigSnapshot {
BootstrapConfigs(Map<ConfigKey<? extends ConfigInstance>, ConfigInstance> configs) {
super(configs);
}
}
public static class ComponentsConfigs extends ConfigSnapshot {
ComponentsConfigs(Map<ConfigKey<? extends ConfigInstance>, ConfigInstance> configs) {
super(configs);
}
}
}
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