org.elasticsearch.rest.BaseRestHandler Maven / Gradle / Ivy
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/*
* Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
* or more contributor license agreements. Licensed under the Elastic License
* 2.0 and the Server Side Public License, v 1; you may not use this file except
* in compliance with, at your election, the Elastic License 2.0 or the Server
* Side Public License, v 1.
*/
package org.elasticsearch.rest;
import org.apache.lucene.search.spell.LevenshteinDistance;
import org.apache.lucene.util.CollectionUtil;
import org.elasticsearch.client.internal.node.NodeClient;
import org.elasticsearch.common.settings.Setting;
import org.elasticsearch.common.settings.Setting.Property;
import org.elasticsearch.core.CheckedConsumer;
import org.elasticsearch.core.RestApiVersion;
import org.elasticsearch.core.Tuple;
import org.elasticsearch.plugins.ActionPlugin;
import org.elasticsearch.rest.action.admin.cluster.RestNodesUsageAction;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Locale;
import java.util.Set;
import java.util.SortedSet;
import java.util.TreeSet;
import java.util.concurrent.atomic.LongAdder;
import java.util.stream.Collectors;
/**
* Base handler for REST requests.
*
* This handler makes sure that the headers & context of the handled {@link RestRequest requests} are copied over to
* the transport requests executed by the associated client. While the context is fully copied over, not all the headers
* are copied, but a selected few. It is possible to control what headers are copied over by returning them in
* {@link ActionPlugin#getRestHeaders()}.
*/
public abstract class BaseRestHandler implements RestHandler {
/**
* Parameter that controls whether certain REST apis should include type names in their requests or responses.
* Note: This parameter is only available through compatible rest api for {@link RestApiVersion#V_7}.
*/
public static final String INCLUDE_TYPE_NAME_PARAMETER = "include_type_name";
public static final boolean DEFAULT_INCLUDE_TYPE_NAME_POLICY = false;
public static final Setting MULTI_ALLOW_EXPLICIT_INDEX = Setting.boolSetting(
"rest.action.multi.allow_explicit_index",
true,
Property.NodeScope
);
private final LongAdder usageCount = new LongAdder();
public final long getUsageCount() {
return usageCount.sum();
}
/**
* @return the name of this handler. The name should be human readable and
* should describe the action that will performed when this API is
* called. This name is used in the response to the
* {@link RestNodesUsageAction}.
*/
public abstract String getName();
/**
* {@inheritDoc}
*/
@Override
public abstract List routes();
@Override
public final void handleRequest(RestRequest request, RestChannel channel, NodeClient client) throws Exception {
// prepare the request for execution; has the side effect of touching the request parameters
final RestChannelConsumer action = prepareRequest(request, client);
// validate unconsumed params, but we must exclude params used to format the response
// use a sorted set so the unconsumed parameters appear in a reliable sorted order
final SortedSet unconsumedParams = request.unconsumedParams()
.stream()
.filter(p -> responseParams(request.getRestApiVersion()).contains(p) == false)
.collect(Collectors.toCollection(TreeSet::new));
// validate the non-response params
if (unconsumedParams.isEmpty() == false) {
final Set candidateParams = new HashSet<>();
candidateParams.addAll(request.consumedParams());
candidateParams.addAll(responseParams(request.getRestApiVersion()));
throw new IllegalArgumentException(unrecognized(request, unconsumedParams, candidateParams, "parameter"));
}
if (request.hasContent() && request.isContentConsumed() == false) {
throw new IllegalArgumentException("request [" + request.method() + " " + request.path() + "] does not support having a body");
}
usageCount.increment();
// execute the action
action.accept(channel);
}
@Override
public boolean mediaTypesValid(RestRequest request) {
return request.getXContentType() != null;
}
protected final String unrecognized(
final RestRequest request,
final Set invalids,
final Set candidates,
final String detail
) {
StringBuilder message = new StringBuilder(
String.format(Locale.ROOT, "request [%s] contains unrecognized %s%s: ", request.path(), detail, invalids.size() > 1 ? "s" : "")
);
boolean first = true;
for (final String invalid : invalids) {
final LevenshteinDistance ld = new LevenshteinDistance();
final List> scoredParams = new ArrayList<>();
for (final String candidate : candidates) {
final float distance = ld.getDistance(invalid, candidate);
if (distance > 0.5f) {
scoredParams.add(new Tuple<>(distance, candidate));
}
}
CollectionUtil.timSort(scoredParams, (a, b) -> {
// sort by distance in reverse order, then parameter name for equal distances
int compare = a.v1().compareTo(b.v1());
if (compare != 0) return -compare;
else return a.v2().compareTo(b.v2());
});
if (first == false) {
message.append(", ");
}
message.append("[").append(invalid).append("]");
final List keys = scoredParams.stream().map(Tuple::v2).collect(Collectors.toList());
if (keys.isEmpty() == false) {
message.append(" -> did you mean ");
if (keys.size() == 1) {
message.append("[").append(keys.get(0)).append("]");
} else {
message.append("any of ").append(keys.toString());
}
message.append("?");
}
first = false;
}
return message.toString();
}
/**
* REST requests are handled by preparing a channel consumer that represents the execution of
* the request against a channel.
*/
@FunctionalInterface
protected interface RestChannelConsumer extends CheckedConsumer {}
/**
* Prepare the request for execution. Implementations should consume all request params before
* returning the runnable for actual execution. Unconsumed params will immediately terminate
* execution of the request. However, some params are only used in processing the response;
* implementations can override {@link BaseRestHandler#responseParams()} to indicate such
* params.
*
* @param request the request to execute
* @param client client for executing actions on the local node
* @return the action to execute
* @throws IOException if an I/O exception occurred parsing the request and preparing for
* execution
*/
protected abstract RestChannelConsumer prepareRequest(RestRequest request, NodeClient client) throws IOException;
/**
* Parameters used for controlling the response and thus might not be consumed during
* preparation of the request execution in
* {@link BaseRestHandler#prepareRequest(RestRequest, NodeClient)}.
*
* @return a set of parameters used to control the response and thus should not trip strict
* URL parameter checks.
*/
protected Set responseParams() {
return Collections.emptySet();
}
/**
* Parameters used for controlling the response and thus might not be consumed during
* preparation of the request execution. The value depends on the RestApiVersion provided
* by a user on a request.
* Used in RestHandlers with Compatible Rest Api
* @param restApiVersion - a version provided by a user on a request
* @return a set of parameters used to control the response, depending on a restApiVersion
*/
protected Set responseParams(RestApiVersion restApiVersion) {
return responseParams();
}
public static class Wrapper extends BaseRestHandler {
protected final BaseRestHandler delegate;
public Wrapper(BaseRestHandler delegate) {
this.delegate = delegate;
}
@Override
public String getName() {
return delegate.getName();
}
@Override
public List routes() {
return delegate.routes();
}
@Override
protected RestChannelConsumer prepareRequest(RestRequest request, NodeClient client) throws IOException {
return delegate.prepareRequest(request, client);
}
@Override
protected Set responseParams() {
return delegate.responseParams();
}
@Override
protected Set responseParams(RestApiVersion restApiVersion) {
return delegate.responseParams(restApiVersion);
}
@Override
public boolean canTripCircuitBreaker() {
return delegate.canTripCircuitBreaker();
}
@Override
public boolean supportsContentStream() {
return delegate.supportsContentStream();
}
@Override
public boolean allowsUnsafeBuffers() {
return delegate.allowsUnsafeBuffers();
}
@Override
public boolean mediaTypesValid(RestRequest request) {
return delegate.mediaTypesValid(request);
}
}
}