/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch licenses this file to you 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 org.elasticsearch.client;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.http.Header;
import org.apache.http.HttpEntity;
import org.apache.http.HttpHost;
import org.apache.http.HttpRequest;
import org.apache.http.HttpResponse;
import org.apache.http.client.AuthCache;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.HttpEntityEnclosingRequestBase;
import org.apache.http.client.methods.HttpHead;
import org.apache.http.client.methods.HttpOptions;
import org.apache.http.client.methods.HttpPatch;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.methods.HttpPut;
import org.apache.http.client.methods.HttpRequestBase;
import org.apache.http.client.methods.HttpTrace;
import org.apache.http.client.protocol.HttpClientContext;
import org.apache.http.client.utils.URIBuilder;
import org.apache.http.concurrent.FutureCallback;
import org.apache.http.impl.auth.BasicScheme;
import org.apache.http.impl.client.BasicAuthCache;
import org.apache.http.impl.nio.client.CloseableHttpAsyncClient;
import org.apache.http.nio.client.methods.HttpAsyncMethods;
import org.apache.http.nio.protocol.HttpAsyncRequestProducer;
import org.apache.http.nio.protocol.HttpAsyncResponseConsumer;
import java.io.Closeable;
import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Objects;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicReference;
/**
* Client that connects to an Elasticsearch cluster through HTTP.
* <p>
* Must be created using {@link RestClientBuilder}, which allows to set all the different options or just rely on defaults.
* The hosts that are part of the cluster need to be provided at creation time, but can also be replaced later
* by calling {@link #setHosts(HttpHost...)}.
* <p>
* The method {@link #performRequest(String, String, Map, HttpEntity, Header...)} allows to send a request to the cluster. When
* sending a request, a host gets selected out of the provided ones in a round-robin fashion. Failing hosts are marked dead and
* retried after a certain amount of time (minimum 1 minute, maximum 30 minutes), depending on how many times they previously
* failed (the more failures, the later they will be retried). In case of failures all of the alive nodes (or dead nodes that
* deserve a retry) are retried until one responds or none of them does, in which case an {@link IOException} will be thrown.
* <p>
* Requests can be either synchronous or asynchronous. The asynchronous variants all end with {@code Async}.
* <p>
* Requests can be traced by enabling trace logging for "tracer". The trace logger outputs requests and responses in curl format.
*/
public class RestClient implements Closeable {
private static final Log logger = LogFactory.getLog(RestClient.class);
private final CloseableHttpAsyncClient client;
//we don't rely on default headers supported by HttpAsyncClient as those cannot be replaced
private final Header[] defaultHeaders;
private final long maxRetryTimeoutMillis;
private final String pathPrefix;
private final AtomicInteger lastHostIndex = new AtomicInteger(0);
private volatile HostTuple<Set<HttpHost>> hostTuple;
private final ConcurrentMap<HttpHost, DeadHostState> blacklist = new ConcurrentHashMap<>();
private final FailureListener failureListener;
RestClient(CloseableHttpAsyncClient client, long maxRetryTimeoutMillis, Header[] defaultHeaders,
HttpHost[] hosts, String pathPrefix, FailureListener failureListener) {
this.client = client;
this.maxRetryTimeoutMillis = maxRetryTimeoutMillis;
this.defaultHeaders = defaultHeaders;
this.failureListener = failureListener;
this.pathPrefix = pathPrefix;
setHosts(hosts);
}
/**
* Returns a new {@link RestClientBuilder} to help with {@link RestClient} creation.
*/
public static RestClientBuilder builder(HttpHost... hosts) {
return new RestClientBuilder(hosts);
}
/**
* Replaces the hosts that the client communicates with.
* @see HttpHost
*/
public synchronized void setHosts(HttpHost... hosts) {
if (hosts == null || hosts.length == 0) {
throw new IllegalArgumentException("hosts must not be null nor empty");
}
Set<HttpHost> httpHosts = new HashSet<>();
AuthCache authCache = new BasicAuthCache();
for (HttpHost host : hosts) {
Objects.requireNonNull(host, "host cannot be null");
httpHosts.add(host);
authCache.put(host, new BasicScheme());
}
this.hostTuple = new HostTuple<>(Collections.unmodifiableSet(httpHosts), authCache);
this.blacklist.clear();
}
/**
* Sends a request to the Elasticsearch cluster that the client points to and waits for the corresponding response
* to be returned. Shortcut to {@link #performRequest(String, String, Map, HttpEntity, Header...)} but without parameters
* and request body.
*
* @param method the http method
* @param endpoint the path of the request (without host and port)
* @param headers the optional request headers
* @return the response returned by Elasticsearch
* @throws IOException in case of a problem or the connection was aborted
* @throws ClientProtocolException in case of an http protocol error
* @throws ResponseException in case Elasticsearch responded with a status code that indicated an error
*/
public Response performRequest(String method, String endpoint, Header... headers) throws IOException {
return performRequest(method, endpoint, Collections.<String, String>emptyMap(), null, headers);
}
/**
* Sends a request to the Elasticsearch cluster that the client points to and waits for the corresponding response
* to be returned. Shortcut to {@link #performRequest(String, String, Map, HttpEntity, Header...)} but without request body.
*
* @param method the http method
* @param endpoint the path of the request (without host and port)
* @param params the query_string parameters
* @param headers the optional request headers
* @return the response returned by Elasticsearch
* @throws IOException in case of a problem or the connection was aborted
* @throws ClientProtocolException in case of an http protocol error
* @throws ResponseException in case Elasticsearch responded with a status code that indicated an error
*/
public Response performRequest(String method, String endpoint, Map<String, String> params, Header... headers) throws IOException {
return performRequest(method, endpoint, params, (HttpEntity)null, headers);
}
/**
* Sends a request to the Elasticsearch cluster that the client points to and waits for the corresponding response
* to be returned. Shortcut to {@link #performRequest(String, String, Map, HttpEntity, HttpAsyncResponseConsumerFactory, Header...)}
* which doesn't require specifying an {@link HttpAsyncResponseConsumerFactory} instance,
* {@link HttpAsyncResponseConsumerFactory} will be used to create the needed instances of {@link HttpAsyncResponseConsumer}.
*
* @param method the http method
* @param endpoint the path of the request (without host and port)
* @param params the query_string parameters
* @param entity the body of the request, null if not applicable
* @param headers the optional request headers
* @return the response returned by Elasticsearch
* @throws IOException in case of a problem or the connection was aborted
* @throws ClientProtocolException in case of an http protocol error
* @throws ResponseException in case Elasticsearch responded with a status code that indicated an error
*/
public Response performRequest(String method, String endpoint, Map<String, String> params,
HttpEntity entity, Header... headers) throws IOException {
return performRequest(method, endpoint, params, entity, HttpAsyncResponseConsumerFactory.DEFAULT, headers);
}
/**
* Sends a request to the Elasticsearch cluster that the client points to. Blocks until the request is completed and returns
* its response or fails by throwing an exception. Selects a host out of the provided ones in a round-robin fashion. Failing hosts
* are marked dead and retried after a certain amount of time (minimum 1 minute, maximum 30 minutes), depending on how many times
* they previously failed (the more failures, the later they will be retried). In case of failures all of the alive nodes (or dead
* nodes that deserve a retry) are retried until one responds or none of them does, in which case an {@link IOException} will be thrown.
*
* @param method the http method
* @param endpoint the path of the request (without host and port)
* @param params the query_string parameters
* @param entity the body of the request, null if not applicable
* @param httpAsyncResponseConsumerFactory the {@link HttpAsyncResponseConsumerFactory} used to create one
* {@link HttpAsyncResponseConsumer} callback per retry. Controls how the response body gets streamed from a non-blocking HTTP
* connection on the client side.
* @param headers the optional request headers
* @return the response returned by Elasticsearch
* @throws IOException in case of a problem or the connection was aborted
* @throws ClientProtocolException in case of an http protocol error
* @throws ResponseException in case Elasticsearch responded with a status code that indicated an error
*/
public Response performRequest(String method, String endpoint, Map<String, String> params,
HttpEntity entity, HttpAsyncResponseConsumerFactory httpAsyncResponseConsumerFactory,
Header... headers) throws IOException {
SyncResponseListener listener = new SyncResponseListener(maxRetryTimeoutMillis);
performRequestAsync(method, endpoint, params, entity, httpAsyncResponseConsumerFactory, listener, headers);
return listener.get();
}
/**
* Sends a request to the Elasticsearch cluster that the client points to. Doesn't wait for the response, instead
* the provided {@link ResponseListener} will be notified upon completion or failure. Shortcut to
* {@link #performRequestAsync(String, String, Map, HttpEntity, ResponseListener, Header...)} but without parameters and request body.
*
* @param method the http method
* @param endpoint the path of the request (without host and port)
* @param responseListener the {@link ResponseListener} to notify when the request is completed or fails
* @param headers the optional request headers
*/
public void performRequestAsync(String method, String endpoint, ResponseListener responseListener, Header... headers) {
performRequestAsync(method, endpoint, Collections.<String, String>emptyMap(), null, responseListener, headers);
}
/**
* Sends a request to the Elasticsearch cluster that the client points to. Doesn't wait for the response, instead
* the provided {@link ResponseListener} will be notified upon completion or failure. Shortcut to
* {@link #performRequestAsync(String, String, Map, HttpEntity, ResponseListener, Header...)} but without request body.
*
* @param method the http method
* @param endpoint the path of the request (without host and port)
* @param params the query_string parameters
* @param responseListener the {@link ResponseListener} to notify when the request is completed or fails
* @param headers the optional request headers
*/
public void performRequestAsync(String method, String endpoint, Map<String, String> params,
ResponseListener responseListener, Header... headers) {
performRequestAsync(method, endpoint, params, null, responseListener, headers);
}
/**
* Sends a request to the Elasticsearch cluster that the client points to. Doesn't wait for the response, instead
* the provided {@link ResponseListener} will be notified upon completion or failure.
* Shortcut to {@link #performRequestAsync(String, String, Map, HttpEntity, HttpAsyncResponseConsumerFactory, ResponseListener,
* Header...)} which doesn't require specifying an {@link HttpAsyncResponseConsumerFactory} instance,
* {@link HttpAsyncResponseConsumerFactory} will be used to create the needed instances of {@link HttpAsyncResponseConsumer}.
*
* @param method the http method
* @param endpoint the path of the request (without host and port)
* @param params the query_string parameters
* @param entity the body of the request, null if not applicable
* @param responseListener the {@link ResponseListener} to notify when the request is completed or fails
* @param headers the optional request headers
*/
public void performRequestAsync(String method, String endpoint, Map<String, String> params,
HttpEntity entity, ResponseListener responseListener, Header... headers) {
performRequestAsync(method, endpoint, params, entity, HttpAsyncResponseConsumerFactory.DEFAULT, responseListener, headers);
}
/**
* Sends a request to the Elasticsearch cluster that the client points to. The request is executed asynchronously
* and the provided {@link ResponseListener} gets notified upon request completion or failure.
* Selects a host out of the provided ones in a round-robin fashion. Failing hosts are marked dead and retried after a certain
* amount of time (minimum 1 minute, maximum 30 minutes), depending on how many times they previously failed (the more failures,
* the later they will be retried). In case of failures all of the alive nodes (or dead nodes that deserve a retry) are retried
* until one responds or none of them does, in which case an {@link IOException} will be thrown.
*
* @param method the http method
* @param endpoint the path of the request (without host and port)
* @param params the query_string parameters
* @param entity the body of the request, null if not applicable
* @param httpAsyncResponseConsumerFactory the {@link HttpAsyncResponseConsumerFactory} used to create one
* {@link HttpAsyncResponseConsumer} callback per retry. Controls how the response body gets streamed from a non-blocking HTTP
* connection on the client side.
* @param responseListener the {@link ResponseListener} to notify when the request is completed or fails
* @param headers the optional request headers
*/
public void performRequestAsync(String method, String endpoint, Map<String, String> params,
HttpEntity entity, HttpAsyncResponseConsumerFactory httpAsyncResponseConsumerFactory,
ResponseListener responseListener, Header... headers) {
try {
Objects.requireNonNull(params, "params must not be null");
Map<String, String> requestParams = new HashMap<>(params);
//ignore is a special parameter supported by the clients, shouldn't be sent to es
String ignoreString = requestParams.remove("ignore");
Set<Integer> ignoreErrorCodes;
if (ignoreString == null) {
if (HttpHead.METHOD_NAME.equals(method)) {
//404 never causes error if returned for a HEAD request
ignoreErrorCodes = Collections.singleton(404);
} else {
ignoreErrorCodes = Collections.emptySet();
}
} else {
String[] ignoresArray = ignoreString.split(",");
ignoreErrorCodes = new HashSet<>();
if (HttpHead.METHOD_NAME.equals(method)) {
//404 never causes error if returned for a HEAD request
ignoreErrorCodes.add(404);
}
for (String ignoreCode : ignoresArray) {
try {
ignoreErrorCodes.add(Integer.valueOf(ignoreCode));
} catch (NumberFormatException e) {
throw new IllegalArgumentException("ignore value should be a number, found [" + ignoreString + "] instead", e);
}
}
}
URI uri = buildUri(pathPrefix, endpoint, requestParams);
HttpRequestBase request = createHttpRequest(method, uri, entity);
setHeaders(request, headers);
FailureTrackingResponseListener failureTrackingResponseListener = new FailureTrackingResponseListener(responseListener);
long startTime = System.nanoTime();
performRequestAsync(startTime, nextHost(), request, ignoreErrorCodes, httpAsyncResponseConsumerFactory,
failureTrackingResponseListener);
} catch (Exception e) {
responseListener.onFailure(e);
}
}
private void performRequestAsync(final long startTime, final HostTuple<Iterator<HttpHost>> hostTuple, final HttpRequestBase request,
final Set<Integer> ignoreErrorCodes,
final HttpAsyncResponseConsumerFactory httpAsyncResponseConsumerFactory,
final FailureTrackingResponseListener listener) {
final HttpHost host = hostTuple.hosts.next();
//we stream the request body if the entity allows for it
final HttpAsyncRequestProducer requestProducer = HttpAsyncMethods.create(host, request);
final HttpAsyncResponseConsumer<HttpResponse> asyncResponseConsumer =
httpAsyncResponseConsumerFactory.createHttpAsyncResponseConsumer();
final HttpClientContext context = HttpClientContext.create();
context.setAuthCache(hostTuple.authCache);
client.execute(requestProducer, asyncResponseConsumer, context, new FutureCallback<HttpResponse>() {
@Override
public void completed(HttpResponse httpResponse) {
try {
RequestLogger.logResponse(logger, request, host, httpResponse);
int statusCode = httpResponse.getStatusLine().getStatusCode();
Response response = new Response(request.getRequestLine(), host, httpResponse);
if (isSuccessfulResponse(statusCode) || ignoreErrorCodes.contains(response.getStatusLine().getStatusCode())) {
onResponse(host);
listener.onSuccess(response);
} else {
ResponseException responseException = new ResponseException(response);
if (isRetryStatus(statusCode)) {
//mark host dead and retry against next one
onFailure(host);
retryIfPossible(responseException);
} else {
//mark host alive and don't retry, as the error should be a request problem
onResponse(host);
listener.onDefinitiveFailure(responseException);
}
}
} catch(Exception e) {
listener.onDefinitiveFailure(e);
}
}
@Override
public void failed(Exception failure) {
try {
RequestLogger.logFailedRequest(logger, request, host, failure);
onFailure(host);
retryIfPossible(failure);
} catch(Exception e) {
listener.onDefinitiveFailure(e);
}
}
private void retryIfPossible(Exception exception) {
if (hostTuple.hosts.hasNext()) {
//in case we are retrying, check whether maxRetryTimeout has been reached
long timeElapsedMillis = TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - startTime);
long timeout = maxRetryTimeoutMillis - timeElapsedMillis;
if (timeout <= 0) {
IOException retryTimeoutException = new IOException(
"request retries exceeded max retry timeout [" + maxRetryTimeoutMillis + "]");
listener.onDefinitiveFailure(retryTimeoutException);
} else {
listener.trackFailure(exception);
request.reset();
performRequestAsync(startTime, hostTuple, request, ignoreErrorCodes, httpAsyncResponseConsumerFactory, listener);
}
} else {
listener.onDefinitiveFailure(exception);
}
}
@Override
public void cancelled() {
listener.onDefinitiveFailure(new ExecutionException("request was cancelled", null));
}
});
}
private void setHeaders(HttpRequest httpRequest, Header[] requestHeaders) {
Objects.requireNonNull(requestHeaders, "request headers must not be null");
// request headers override default headers, so we don't add default headers if they exist as request headers
final Set<String> requestNames = new HashSet<>(requestHeaders.length);
for (Header requestHeader : requestHeaders) {
Objects.requireNonNull(requestHeader, "request header must not be null");
httpRequest.addHeader(requestHeader);
requestNames.add(requestHeader.getName());
}
for (Header defaultHeader : defaultHeaders) {
if (requestNames.contains(defaultHeader.getName()) == false) {
httpRequest.addHeader(defaultHeader);
}
}
}
/**
* Returns an {@link Iterable} of hosts to be used for a request call.
* Ideally, the first host is retrieved from the iterable and used successfully for the request.
* Otherwise, after each failure the next host has to be retrieved from the iterator so that the request can be retried until
* there are no more hosts available to retry against. The maximum total of attempts is equal to the number of hosts in the iterable.
* The iterator returned will never be empty. In case there are no healthy hosts available, or dead ones to be be retried,
* one dead host gets returned so that it can be retried.
*/
private HostTuple<Iterator<HttpHost>> nextHost() {
final HostTuple<Set<HttpHost>> hostTuple = this.hostTuple;
Collection<HttpHost> nextHosts = Collections.emptySet();
do {
Set<HttpHost> filteredHosts = new HashSet<>(hostTuple.hosts);
for (Map.Entry<HttpHost, DeadHostState> entry : blacklist.entrySet()) {
if (System.nanoTime() - entry.getValue().getDeadUntilNanos() < 0) {
filteredHosts.remove(entry.getKey());
}
}
if (filteredHosts.isEmpty()) {
//last resort: if there are no good host to use, return a single dead one, the one that's closest to being retried
List<Map.Entry<HttpHost, DeadHostState>> sortedHosts = new ArrayList<>(blacklist.entrySet());
if (sortedHosts.size() > 0) {
Collections.sort(sortedHosts, new Comparator<Map.Entry<HttpHost, DeadHostState>>() {
@Override
public int compare(Map.Entry<HttpHost, DeadHostState> o1, Map.Entry<HttpHost, DeadHostState> o2) {
return Long.compare(o1.getValue().getDeadUntilNanos(), o2.getValue().getDeadUntilNanos());
}
});
HttpHost deadHost = sortedHosts.get(0).getKey();
logger.trace("resurrecting host [" + deadHost + "]");
nextHosts = Collections.singleton(deadHost);
}
} else {
List<HttpHost> rotatedHosts = new ArrayList<>(filteredHosts);
Collections.rotate(rotatedHosts, rotatedHosts.size() - lastHostIndex.getAndIncrement());
nextHosts = rotatedHosts;
}
} while(nextHosts.isEmpty());
return new HostTuple<>(nextHosts.iterator(), hostTuple.authCache);
}
/**
* Called after each successful request call.
* Receives as an argument the host that was used for the successful request.
*/
private void onResponse(HttpHost host) {
DeadHostState removedHost = this.blacklist.remove(host);
if (logger.isDebugEnabled() && removedHost != null) {
logger.debug("removed host [" + host + "] from blacklist");
}
}
/**
* Called after each failed attempt.
* Receives as an argument the host that was used for the failed attempt.
*/
private void onFailure(HttpHost host) throws IOException {
while(true) {
DeadHostState previousDeadHostState = blacklist.putIfAbsent(host, DeadHostState.INITIAL_DEAD_STATE);
if (previousDeadHostState == null) {
logger.debug("added host [" + host + "] to blacklist");
break;
}
if (blacklist.replace(host, previousDeadHostState, new DeadHostState(previousDeadHostState))) {
logger.debug("updated host [" + host + "] already in blacklist");
break;
}
}
failureListener.onFailure(host);
}
@Override
public void close() throws IOException {
client.close();
}
private static boolean isSuccessfulResponse(int statusCode) {
return statusCode < 300;
}
private static boolean isRetryStatus(int statusCode) {
switch(statusCode) {
case 502:
case 503:
case 504:
return true;
}
return false;
}
private static Exception addSuppressedException(Exception suppressedException, Exception currentException) {
if (suppressedException != null) {
currentException.addSuppressed(suppressedException);
}
return currentException;
}
private static HttpRequestBase createHttpRequest(String method, URI uri, HttpEntity entity) {
switch(method.toUpperCase(Locale.ROOT)) {
case HttpDeleteWithEntity.METHOD_NAME:
return addRequestBody(new HttpDeleteWithEntity(uri), entity);
case HttpGetWithEntity.METHOD_NAME:
return addRequestBody(new HttpGetWithEntity(uri), entity);
case HttpHead.METHOD_NAME:
return addRequestBody(new HttpHead(uri), entity);
case HttpOptions.METHOD_NAME:
return addRequestBody(new HttpOptions(uri), entity);
case HttpPatch.METHOD_NAME:
return addRequestBody(new HttpPatch(uri), entity);
case HttpPost.METHOD_NAME:
HttpPost httpPost = new HttpPost(uri);
addRequestBody(httpPost, entity);
return httpPost;
case HttpPut.METHOD_NAME:
return addRequestBody(new HttpPut(uri), entity);
case HttpTrace.METHOD_NAME:
return addRequestBody(new HttpTrace(uri), entity);
default:
throw new UnsupportedOperationException("http method not supported: " + method);
}
}
private static HttpRequestBase addRequestBody(HttpRequestBase httpRequest, HttpEntity entity) {
if (entity != null) {
if (httpRequest instanceof HttpEntityEnclosingRequestBase) {
((HttpEntityEnclosingRequestBase)httpRequest).setEntity(entity);
} else {
throw new UnsupportedOperationException(httpRequest.getMethod() + " with body is not supported");
}
}
return httpRequest;
}
private static URI buildUri(String pathPrefix, String path, Map<String, String> params) {
Objects.requireNonNull(path, "path must not be null");
try {
String fullPath;
if (pathPrefix != null) {
if (path.startsWith("/")) {
fullPath = pathPrefix + path;
} else {
fullPath = pathPrefix + "/" + path;
}
} else {
fullPath = path;
}
URIBuilder uriBuilder = new URIBuilder(fullPath);
for (Map.Entry<String, String> param : params.entrySet()) {
uriBuilder.addParameter(param.getKey(), param.getValue());
}
return uriBuilder.build();
} catch(URISyntaxException e) {
throw new IllegalArgumentException(e.getMessage(), e);
}
}
/**
* Listener used in any async call to wrap the provided user listener (or SyncResponseListener in sync calls).
* Allows to track potential failures coming from the different retry attempts and returning to the original listener
* only when we got a response (successful or not to be retried) or there are no hosts to retry against.
*/
static class FailureTrackingResponseListener {
private final ResponseListener responseListener;
private volatile Exception exception;
FailureTrackingResponseListener(ResponseListener responseListener) {
this.responseListener = responseListener;
}
/**
* Notifies the caller of a response through the wrapped listener
*/
void onSuccess(Response response) {
responseListener.onSuccess(response);
}
/**
* Tracks one last definitive failure and returns to the caller by notifying the wrapped listener
*/
void onDefinitiveFailure(Exception exception) {
trackFailure(exception);
responseListener.onFailure(this.exception);
}
/**
* Tracks an exception, which caused a retry hence we should not return yet to the caller
*/
void trackFailure(Exception exception) {
this.exception = addSuppressedException(this.exception, exception);
}
}
/**
* Listener used in any sync performRequest calls, it waits for a response or an exception back up to a timeout
*/
static class SyncResponseListener implements ResponseListener {
private final CountDownLatch latch = new CountDownLatch(1);
private final AtomicReference<Response> response = new AtomicReference<>();
private final AtomicReference<Exception> exception = new AtomicReference<>();
private final long timeout;
SyncResponseListener(long timeout) {
assert timeout > 0;
this.timeout = timeout;
}
@Override
public void onSuccess(Response response) {
Objects.requireNonNull(response, "response must not be null");
boolean wasResponseNull = this.response.compareAndSet(null, response);
if (wasResponseNull == false) {
throw new IllegalStateException("response is already set");
}
latch.countDown();
}
@Override
public void onFailure(Exception exception) {
Objects.requireNonNull(exception, "exception must not be null");
boolean wasExceptionNull = this.exception.compareAndSet(null, exception);
if (wasExceptionNull == false) {
throw new IllegalStateException("exception is already set");
}
latch.countDown();
}
/**
* Waits (up to a timeout) for some result of the request: either a response, or an exception.
*/
Response get() throws IOException {
try {
//providing timeout is just a safety measure to prevent everlasting waits
//the different client timeouts should already do their jobs
if (latch.await(timeout, TimeUnit.MILLISECONDS) == false) {
throw new IOException("listener timeout after waiting for [" + timeout + "] ms");
}
} catch (InterruptedException e) {
throw new RuntimeException("thread waiting for the response was interrupted", e);
}
Exception exception = this.exception.get();
Response response = this.response.get();
if (exception != null) {
if (response != null) {
IllegalStateException e = new IllegalStateException("response and exception are unexpectedly set at the same time");
e.addSuppressed(exception);
throw e;
}
//try and leave the exception untouched as much as possible but we don't want to just add throws Exception clause everywhere
if (exception instanceof IOException) {
throw (IOException) exception;
}
if (exception instanceof RuntimeException){
throw (RuntimeException) exception;
}
throw new RuntimeException("error while performing request", exception);
}
if (response == null) {
throw new IllegalStateException("response not set and no exception caught either");
}
return response;
}
}
/**
* Listener that allows to be notified whenever a failure happens. Useful when sniffing is enabled, so that we can sniff on failure.
* The default implementation is a no-op.
*/
public static class FailureListener {
/**
* Notifies that the host provided as argument has just failed
*/
public void onFailure(HttpHost host) {
}
}
/**
* {@code HostTuple} enables the {@linkplain HttpHost}s and {@linkplain AuthCache} to be set together in a thread
* safe, volatile way.
*/
private static class HostTuple<T> {
public final T hosts;
public final AuthCache authCache;
HostTuple(final T hosts, final AuthCache authCache) {
this.hosts = hosts;
this.authCache = authCache;
}
}
}