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// Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.vespa.jaxrs.client;
import com.yahoo.vespa.applicationmodel.HostName;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.Objects;
import java.util.Random;
import java.util.Set;
/**
* The idea behind this class is twofold:
*
* <ol>
* <li>
* It can provide alternative strategies for communicating with a JAX-RS-based server API.
* </li>
* <li>
* It can make it simpler to work with hosts that serve multiple APIs. Example:
* <pre>{@code
* final JaxRsStrategyFactory apiFactory = new JaxRsStrategyFactory(hostNames, port, clientFactory);
* // No need to repeat the hostNames etc here:
* apiFactory.apiWithRetries(FooApi.class).apply(FooApi::fooMethod);
* apiFactory.apiWithRetries(BarApi.class).apply(BarApi::barMethod);
* apiFactory.apiWithRetries(BazongaApi.class).apply(BazongaApi::bazinga);
* }</pre>
* </li>
* </ol>
*
* @author bakksjo
*/
public class JaxRsStrategyFactory {
private final Set<HostName> hostNames;
private int port;
private final JaxRsClientFactory jaxRsClientFactory;
// TODO: We might need to support per-host port specification.
public JaxRsStrategyFactory(
final Set<HostName> hostNames,
final int port,
final JaxRsClientFactory jaxRsClientFactory) {
if (hostNames.isEmpty()) {
throw new IllegalArgumentException("hostNames argument must not be empty");
}
Objects.requireNonNull(jaxRsClientFactory, "jaxRsClientFactory argument may not be null");
this.hostNames = hostNames;
this.port = port;
this.jaxRsClientFactory = jaxRsClientFactory;
}
public <T> JaxRsStrategy<T> apiWithRetries(final Class<T> apiClass, final String pathPrefix) {
Objects.requireNonNull(apiClass, "apiClass argument may not be null");
Objects.requireNonNull(pathPrefix, "pathPrefix argument may not be null");
return new RetryingJaxRsStrategy<T>(hostNames, port, jaxRsClientFactory, apiClass, pathPrefix);
}
public <T> JaxRsStrategy<T> apiNoRetries(final Class<T> apiClass, final String pathPrefix) {
Objects.requireNonNull(apiClass, "apiClass argument may not be null");
Objects.requireNonNull(pathPrefix, "pathPrefix argument may not be null");
final HostName hostName = getRandom(hostNames);
return new NoRetryJaxRsStrategy<T>(hostName, port, jaxRsClientFactory, apiClass, pathPrefix);
}
private static final Random random = new Random();
private static <T> T getRandom(final Collection<? extends T> collection) {
int index = random.nextInt(collection.size());
return getIndex(collection, index);
}
private static <T> T getIndex(final Collection<? extends T> collection, final int index) {
if (index >= collection.size() || index < 0) {
throw new IndexOutOfBoundsException(
"Attempt to get element #" + index + " from collection with " + collection.size() + " elements");
}
if (collection instanceof List) {
final List<? extends T> list = (List<? extends T>) collection;
return list.get(index);
}
final Iterator<? extends T> iterator = collection.iterator();
for (int i = 0; i < index; i++) {
iterator.next();
}
return iterator.next();
}
}
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