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// Copyright Verizon Media. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package ai.vespa.hosted.client;
import org.apache.hc.client5.http.config.RequestConfig;
import org.apache.hc.core5.http.ClassicHttpResponse;
import org.apache.hc.core5.http.HttpEntity;
import org.apache.hc.core5.http.Method;
import java.io.IOException;
import java.io.InputStream;
import java.io.UncheckedIOException;
import java.net.URI;
import java.time.Duration;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.function.Function;
import java.util.stream.IntStream;
import static java.util.Objects.requireNonNull;
import static java.util.stream.Collectors.toUnmodifiableList;
/**
* @author jonmv
*/
public interface ConfigServerClient extends AutoCloseable {
/** Creates a builder for sending the given method, using the specified host strategy. */
RequestBuilder send(HostStrategy hosts, Method method);
/** Builder for a request against a given set of hosts, using this config server client. */
interface RequestBuilder {
/** Sets the request path. */
default RequestBuilder at(String... pathSegments) { return at(List.of(pathSegments)); }
/** Sets the request path. */
RequestBuilder at(List<String> pathSegments);
/** Sets the request body as UTF-8 application/json. */
RequestBuilder body(byte[] json);
/** Sets the request body. */
RequestBuilder body(HttpEntity entity);
/** Sets the parameter key/values for the request. Number of arguments must be even. */
default RequestBuilder parameters(String... pairs) {
return parameters(Arrays.asList(pairs));
}
/** Sets the parameter key/values for the request. Number of arguments must be even. */
RequestBuilder parameters(List<String> pairs);
/** Overrides the default socket read timeout of the request. {@code Duration.ZERO} gives infinite timeout. */
RequestBuilder timeout(Duration timeout);
/** Overrides the default request config of the request. */
RequestBuilder config(RequestConfig config);
/**
* Sets custom retry/failure logic for this.
* <p>
* Exactly one of the callbacks will be invoked, with a non-null argument.
* Return a value to have that returned to the caller;
* throw a {@link RetryException} to have the request retried; or
* throw any other unchecked exception to have this propagate out to the caller.
* The caller must close the provided response, if any.
*/
<T> T handle(Function<ClassicHttpResponse, T> handler, Function<IOException, T> catcher) throws UncheckedIOException;
/** Sets the response body mapper for this, for successful requests. */
<T> T read(Function<byte[], T> mapper) throws UncheckedIOException, ResponseException;
/** Discards the response, but throws if the response is unsuccessful. */
void discard() throws UncheckedIOException, ResponseException;
/** Returns the raw input stream of the response, if successful. The caller must close the returned stream. */
InputStream stream() throws UncheckedIOException, ResponseException;
}
/** Exception wrapper that signals retries should be attempted. */
final class RetryException extends RuntimeException {
public RetryException(IOException cause) {
super(requireNonNull(cause));
}
public RetryException(RuntimeException cause) {
super(requireNonNull(cause));
}
}
/** What host(s) to try for a request, in what order. A host may be specified multiple times, for retries. */
@FunctionalInterface
interface HostStrategy extends Iterable<URI> {
/** Attempts each request once against each listed host. */
static HostStrategy ordered(List<URI> hosts) {
return List.copyOf(hosts)::iterator;
}
/** Attempts each request once against each listed host, in random order. */
static HostStrategy shuffling(List<URI> hosts) {
return () -> {
List<URI> copy = new ArrayList<>(hosts);
Collections.shuffle(copy);
return copy.iterator();
};
}
/** Attempts each request against the host the specified number of times. */
static HostStrategy repeating(URI host, int count) {
return ordered(IntStream.range(0, count).mapToObj(__ -> host).collect(toUnmodifiableList()));
}
}
/** An exception due to server error, a bad request, or similar, which resulted in a non-OK HTTP response. */
class ResponseException extends RuntimeException {
private final int code;
private final String body;
public ResponseException(int code, String body, String context) {
super(context + ": " + body);
this.code = code;
this.body = body;
}
public int code() { return code; }
public String body() { return body; }
}
}
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