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Convert RestGetMappingAction to chunked encoding #89906

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merged 5 commits into from
Sep 9, 2022
Merged

Convert RestGetMappingAction to chunked encoding #89906

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ebddfc1
Convert RestGetMappingAction to chunked encoding
original-brownbear Sep 8, 2022
8d2225b
Merge remote-tracking branch 'elastic/main' into chunked-encoding-get…
original-brownbear Sep 9, 2022
f40e16d
remove needlessly complicated test
original-brownbear Sep 9, 2022
e115afd
Merge remote-tracking branch 'elastic/main' into chunked-encoding-get…
original-brownbear Sep 9, 2022
b6517df
assert chunk count
original-brownbear Sep 9, 2022
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73 changes: 73 additions & 0 deletions qa/smoke-test-http/src/javaRestTest/java/org/elasticsearch/http/RestGetMappingsIT.java
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Original file line number Diff line number Diff line change
@@ -0,0 +1,73 @@
/*
* 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.http;

import org.apache.http.client.methods.HttpGet;
import org.apache.lucene.tests.util.LuceneTestCase;
import org.elasticsearch.action.ActionListener;
import org.elasticsearch.action.admin.indices.create.CreateIndexResponse;
import org.elasticsearch.action.support.GroupedActionListener;
import org.elasticsearch.action.support.PlainActionFuture;
import org.elasticsearch.client.Request;
import org.elasticsearch.index.mapper.MapperService;
import org.elasticsearch.snapshots.AbstractSnapshotIntegTestCase;
import org.elasticsearch.xcontent.XContentBuilder;
import org.elasticsearch.xcontent.XContentParser;
import org.elasticsearch.xcontent.XContentParserConfiguration;
import org.elasticsearch.xcontent.json.JsonXContent;
import org.hamcrest.Matchers;

import java.io.InputStream;
import java.util.List;
import java.util.Map;

import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertAcked;
import static org.hamcrest.Matchers.aMapWithSize;

@LuceneTestCase.SuppressFileSystems(value = "HandleLimitFS") // we sometimes have >2048 open files
public class RestGetMappingsIT extends HttpSmokeTestCase {

public void testGetLargeMappingsResponse() throws Exception {
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Hmm I think if we approach testing chunked encoding like this across all APIs we'll end up adding a lot of costly tests. Could we instead reduce the chunk size in these smoke tests to force chunking at a more reasonable scale?

Also I think this test passes even without the production code changes. Can we assert that the REST response really did arrive in multiple chunks?

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Hmm now that I think about it more, maybe this test is pointless. I really wanted to have a test that would actually cause a round of chunked encoding where the channel becomes not-writable at least once. But now that I think about it again, that's a really redundant test probably ... I'll just remove this and rely on the fact that this is tested by the existing REST tests (that will now see a chunked response) and our Netty specific tests around flushing messages. I think that's good enough here. Sorry for the noise

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Maybe I'm confused, but I was expecting that we'd send the response in chunks regardless of writability. I think it's worth checking that, but MAX_BYTES_PER_WRITE = 1 << 18 is just a bit big for a test.

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Yea the response is always chunked but the fact that it serializes fine is already tested elsewhere. Adding a test that verifies that we actually get chunked bytes back seems quite redundant doesn't it, I mean unless someone wilfully changes the code to revert back to a normal response (which I'll make very hard shortly, PR incoming :)) this doesn't guard against anything does it?

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Ehh maybe I'm paranoid but I could imagine some future refactoring which accidentally puts all the objects into a single chunk, quietly destroying the memory-efficiency of this API.

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That makes sense :) How about b6517df to make sure that won't happen?

final XContentBuilder builder = JsonXContent.contentBuilder()
.startObject()
.startObject(MapperService.SINGLE_MAPPING_NAME)
.startObject("properties");
final int fields = randomIntBetween(500, 1000);
for (int i = 0; i < fields; i++) {
builder.startObject("loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong-named-field-" + i)
.field("type", "text")
.field("store", true)
.endObject();
}
builder.endObject().endObject().endObject();
assertAcked(admin().indices().preparePutTemplate("large-mapping").setPatterns(List.of("test-idx-*")).setMapping(builder).get());
final int indexCount = randomIntBetween(50, 150);
final PlainActionFuture<Void> f = PlainActionFuture.newFuture();
final ActionListener<CreateIndexResponse> listener = new GroupedActionListener<>(f.map(l -> null), indexCount);
for (int i = 0; i < indexCount; i++) {
admin().indices()
.prepareCreate("test-idx-" + i)
.setSettings(AbstractSnapshotIntegTestCase.SINGLE_SHARD_NO_REPLICA)
.execute(listener);
}
f.get();
final var response = getRestClient().performRequest(new Request(HttpGet.METHOD_NAME, "/_mappings"));
try (
InputStream input = response.getEntity().getContent();
XContentParser parser = JsonXContent.jsonXContent.createParser(XContentParserConfiguration.EMPTY, input)
) {
final Map<String, Object> mappings = parser.map();
assertThat(mappings, Matchers.aMapWithSize(indexCount));
final Object idx0 = mappings.get("test-idx-0");
@SuppressWarnings("unchecked")
var properties = ((Map<String, Map<String, Object>>) idx0).get("mappings").get("properties");
assertThat((Map<?, ?>) properties, aMapWithSize(fields));
mappings.forEach((key, value) -> assertEquals(key, idx0, value));
}
}
}
2 changes: 1 addition & 1 deletion server/src/main/java/org/elasticsearch/action/ActionModule.java
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Original file line number Diff line number Diff line change
Expand Up @@ -791,7 +791,7 @@ public void initRestHandlers(Supplier<DiscoveryNodes> nodesInCluster) {
registerHandler.accept(new RestSimulateTemplateAction());

registerHandler.accept(new RestPutMappingAction());
registerHandler.accept(new RestGetMappingAction(threadPool));
registerHandler.accept(new RestGetMappingAction());
registerHandler.accept(new RestGetFieldMappingAction());

registerHandler.accept(new RestRefreshAction());
Expand Down
14 changes: 8 additions & 6 deletions ...src/main/java/org/elasticsearch/action/admin/indices/mapping/get/GetMappingsResponse.java
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Expand Up @@ -14,19 +14,21 @@
import org.elasticsearch.common.Strings;
import org.elasticsearch.common.io.stream.StreamInput;
import org.elasticsearch.common.io.stream.StreamOutput;
import org.elasticsearch.common.xcontent.ChunkedToXContent;
import org.elasticsearch.core.RestApiVersion;
import org.elasticsearch.index.mapper.MapperService;
import org.elasticsearch.xcontent.ParseField;
import org.elasticsearch.xcontent.ToXContent;
import org.elasticsearch.xcontent.ToXContentFragment;
import org.elasticsearch.xcontent.XContentBuilder;

import java.io.IOException;
import java.util.Iterator;
import java.util.Map;

import static org.elasticsearch.rest.BaseRestHandler.DEFAULT_INCLUDE_TYPE_NAME_POLICY;
import static org.elasticsearch.rest.BaseRestHandler.INCLUDE_TYPE_NAME_PARAMETER;

public class GetMappingsResponse extends ActionResponse implements ToXContentFragment {
public class GetMappingsResponse extends ActionResponse implements ToXContentFragment, ChunkedToXContent {

private static final ParseField MAPPINGS = new ParseField("mappings");

Expand Down Expand Up @@ -65,8 +67,8 @@ public void writeTo(StreamOutput out) throws IOException {
}

@Override
public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
for (final Map.Entry<String, MappingMetadata> indexEntry : getMappings().entrySet()) {
public Iterator<ToXContent> toXContentChunked() {
return getMappings().entrySet().stream().map(indexEntry -> (ToXContent) (builder, params) -> {
builder.startObject(indexEntry.getKey());
boolean includeTypeName = params.paramAsBoolean(INCLUDE_TYPE_NAME_PARAMETER, DEFAULT_INCLUDE_TYPE_NAME_POLICY);
if (builder.getRestApiVersion() == RestApiVersion.V_7 && includeTypeName && indexEntry.getValue() != null) {
Expand All @@ -83,8 +85,8 @@ public XContentBuilder toXContent(XContentBuilder builder, Params params) throws
builder.startObject(MAPPINGS.getPreferredName()).endObject();
}
builder.endObject();
}
return builder;
return builder;
}).iterator();
}

@Override
Expand Down
69 changes: 26 additions & 43 deletions server/src/main/java/org/elasticsearch/rest/action/admin/indices/RestGetMappingAction.java
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Original file line number Diff line number Diff line change
Expand Up @@ -8,27 +8,26 @@

package org.elasticsearch.rest.action.admin.indices;

import org.elasticsearch.ElasticsearchTimeoutException;
import org.elasticsearch.action.admin.indices.mapping.get.GetMappingsRequest;
import org.elasticsearch.action.admin.indices.mapping.get.GetMappingsResponse;
import org.elasticsearch.action.support.IndicesOptions;
import org.elasticsearch.client.internal.node.NodeClient;
import org.elasticsearch.common.Strings;
import org.elasticsearch.common.collect.Iterators;
import org.elasticsearch.common.logging.DeprecationLogger;
import org.elasticsearch.core.RestApiVersion;
import org.elasticsearch.core.TimeValue;
import org.elasticsearch.http.HttpChannel;
import org.elasticsearch.rest.BaseRestHandler;
import org.elasticsearch.rest.ChunkedRestResponseBody;
import org.elasticsearch.rest.RestRequest;
import org.elasticsearch.rest.action.DispatchingRestToXContentListener;
import org.elasticsearch.rest.RestResponse;
import org.elasticsearch.rest.RestStatus;
import org.elasticsearch.rest.action.RestActionListener;
import org.elasticsearch.rest.action.RestCancellableNodeClient;
import org.elasticsearch.threadpool.ThreadPool;
import org.elasticsearch.xcontent.ToXContentObject;
import org.elasticsearch.xcontent.XContentBuilder;

import java.io.IOException;
import java.util.List;
import java.util.function.LongSupplier;

import static org.elasticsearch.rest.RestRequest.Method.GET;
import static org.elasticsearch.rest.RestRequest.Method.HEAD;
Expand All @@ -40,11 +39,7 @@ public class RestGetMappingAction extends BaseRestHandler {
public static final String TYPES_DEPRECATION_MESSAGE = "[types removal] Specifying types in get mapping request is deprecated. "
+ "Use typeless api instead";

private final ThreadPool threadPool;

public RestGetMappingAction(ThreadPool threadPool) {
this.threadPool = threadPool;
}
public RestGetMappingAction() {}

@Override
public List<Route> routes() {
Expand Down Expand Up @@ -97,37 +92,25 @@ public RestChannelConsumer prepareRequest(final RestRequest request, final NodeC
final HttpChannel httpChannel = request.getHttpChannel();
return channel -> new RestCancellableNodeClient(client, httpChannel).admin()
.indices()
.getMappings(
getMappingsRequest,
new DispatchingRestToXContentListener<>(threadPool.executor(ThreadPool.Names.MANAGEMENT), channel, request).map(
getMappingsResponse -> new RestGetMappingsResponse(getMappingsResponse, threadPool::relativeTimeInMillis, timeout)
)
);
}

private static final class RestGetMappingsResponse implements ToXContentObject {
private final GetMappingsResponse response;
private final LongSupplier relativeTimeSupplierMillis;
private final TimeValue timeout;
private final long startTimeMs;

private RestGetMappingsResponse(GetMappingsResponse response, LongSupplier relativeTimeSupplierMillis, TimeValue timeout) {
this.response = response;
this.relativeTimeSupplierMillis = relativeTimeSupplierMillis;
this.timeout = timeout;
this.startTimeMs = relativeTimeSupplierMillis.getAsLong();
}

@Override
public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
if (relativeTimeSupplierMillis.getAsLong() - startTimeMs > timeout.millis()) {
throw new ElasticsearchTimeoutException("Timed out getting mappings");
}

builder.startObject();
response.toXContent(builder, params);
builder.endObject();
return builder;
}
.getMappings(getMappingsRequest, new RestActionListener<>(channel) {
@Override
protected void processResponse(GetMappingsResponse getMappingsResponse) throws Exception {
ensureOpen();
channel.sendResponse(
new RestResponse(
RestStatus.OK,
ChunkedRestResponseBody.fromXContent(
() -> Iterators.concat(
Iterators.single((b, p) -> b.startObject()),
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I'm not quite sure why the GetMappingsResponse is a fragment and we had the complicated wrapping here but didn't want to change it in this PR so I manually wrapped it for now.

getMappingsResponse.toXContentChunked(),
Iterators.single((b, p) -> b.endObject())
),
request,
channel
)
)
);
}
});
}
}