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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.ClassicHttpRequest;
import org.apache.hc.core5.http.ClassicHttpResponse;
import org.apache.hc.core5.http.ContentType;
import org.apache.hc.core5.http.HttpEntity;
import org.apache.hc.core5.http.HttpStatus;
import org.apache.hc.core5.http.Method;
import org.apache.hc.core5.http.io.entity.EntityUtils;
import org.apache.hc.core5.util.Timeout;
import java.io.Closeable;
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.BiFunction;
import java.util.function.Consumer;
import java.util.function.Function;
import java.util.stream.IntStream;
import static java.nio.charset.StandardCharsets.UTF_8;
import static java.util.Objects.requireNonNull;
import static java.util.stream.Collectors.toUnmodifiableList;
/**
* @author jonmv
*/
public interface ConfigServerClient extends Closeable {
RequestConfig defaultRequestConfig = RequestConfig.custom()
.setConnectionRequestTimeout(Timeout.ofSeconds(5))
.setConnectTimeout(Timeout.ofSeconds(5))
.setRedirectsEnabled(false)
.build();
/** Wraps with a {@link RetryException} and rethrows. */
Consumer<IOException> retryAll = (e) -> {
throw new RetryException(e);
};
/** Throws a a {@link RetryException} if {@code statusCode == 503}, or a {@link ResponseException} unless {@code 200 <= statusCode < 300}. */
ResponseVerifier throwOnError = new DefaultResponseVerifier() { };
/** Reads the response body, throwing an {@link UncheckedIOException} if this fails, or {@code null} if there is none. */
static byte[] getBytes(ClassicHttpResponse response) {
try {
return response.getEntity() == null ? null : EntityUtils.toByteArray(response.getEntity());
}
catch (IOException e) {
throw new UncheckedIOException(e);
}
}
/** 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 {
/** Appends to the request path. */
default RequestBuilder at(String... pathSegments) { return at(List.of(pathSegments)); }
/** Appends to 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 the catch clause for {@link IOException}s during execution of this.
* The default is to wrap the IOException in a {@link RetryException} and rethrow this;
* this makes the client retry the request, as long as there are remaining entries in the {@link HostStrategy}.
* If the catcher returns normally, the {@link IOException} is unchecked and thrown instead.
*/
RequestBuilder catching(Consumer<IOException> catcher);
/**
* Sets the (error) response handler for this request. The default is {@link #throwOnError}.
* When the handler returns normally, the response is treated as a success, and passed on to a response mapper.
*/
RequestBuilder throwing(ResponseVerifier handler);
/** Reads the response as a {@link String}, or throws if unsuccessful. */
String read();
/** Reads and maps the response, or throws if unsuccessful. */
<T> T read(Function<byte[], T> mapper);
/** Discards the response, but throws if unsuccessful. */
void discard();
/** Returns the raw response input stream, or throws if unsuccessful. The caller must close the returned stream. */
HttpInputStream stream();
/** Uses the response and request, if successful, to generate a mapped response. */
<T> T handle(ResponseHandler<T> handler);
}
class HttpInputStream extends ForwardingInputStream {
private final ClassicHttpResponse response;
protected HttpInputStream(ClassicHttpResponse response) throws IOException {
super(response.getEntity() != null ? response.getEntity().getContent()
: InputStream.nullInputStream());
this.response = response;
}
public int statusCode() { return response.getCode(); }
public String contentType() { return response.getEntity().getContentType(); }
@Override
public void close() throws IOException {
super.close();
response.close();
}
}
/** Reads a successful response and request to compute a result. */
@FunctionalInterface
interface ResponseHandler<T> {
/** Called with successful responses, as per {@link ResponseVerifier}. The caller must close the response. */
T handle(ClassicHttpResponse response, ClassicHttpRequest request) throws IOException;
}
/** Verifies a response, throwing on error responses, possibly indicating retries. */
@FunctionalInterface
interface ResponseVerifier {
/** Whether this status code means the response is an error response. */
default boolean isError(int statusCode) {
return statusCode < HttpStatus.SC_OK || HttpStatus.SC_REDIRECTION <= statusCode;
}
/** Whether this status code means we should retry. Has no effect if this is not also an error. */
default boolean shouldRetry(int statusCode) {
return statusCode == HttpStatus.SC_SERVICE_UNAVAILABLE;
}
/** Verifies the given response, consuming it and throwing if it is an error; or leaving it otherwise. */
default void verify(ClassicHttpResponse response, ClassicHttpRequest request) throws IOException {
if (isError(response.getCode())) {
try (response) {
byte[] body = response.getEntity() == null ? new byte[0] : EntityUtils.toByteArray(response.getEntity());
RuntimeException exception = toException(response.getCode(), body, request);
throw shouldRetry(response.getCode()) ? new RetryException(exception) : exception;
}
}
}
/** Throws the appropriate exception, for the given status code and body. */
RuntimeException toException(int statusCode, byte[] body, ClassicHttpRequest request);
}
interface DefaultResponseVerifier extends ResponseVerifier {
@Override
default RuntimeException toException(int statusCode, byte[] body, ClassicHttpRequest request) {
return new ResponseException(request + " failed with status " + statusCode + " and body '" + new String(body, UTF_8) + "'");
}
}
/** 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()));
}
}
/** 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));
}
}
/** An exception due to server error, a bad request, or similar, which resulted in a non-OK HTTP response. */
class ResponseException extends RuntimeException {
public ResponseException(String message) {
super(message);
}
}
}
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