Random sampling get stats

rest-api-spec/src/main/resources/rest-api-spec/api/indices.get_sample_stats.json

@@ -0,0 +1,31 @@
+{
+  "indices.get_sample_stats": {
+    "documentation": {
+      "url": "https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-indices-get-sample",
+      "description": "Get stats about a random sample of ingested data"
+    },
+    "stability": "experimental",
+    "visibility": "public",
+    "headers": {
+      "accept": [
+        "application/json"
+      ]
+    },
+    "url": {
+      "paths": [
+        {
+          "path": "/{index}/_sample/stats",
+          "methods": [
+            "GET"
+          ],
+          "parts": {
+            "index": {
+              "type": "string",
+              "description": "The name of a data stream or index"
+            }
+          }
+        }
+      ]
+    }
+  }
+}

rest-api-spec/src/yamlRestTest/resources/rest-api-spec/test/indices.get_sample_stats/10_basic.yml

@@ -0,0 +1,19 @@
+---
+"Test get sample stats for index with no sample config":
+  - requires:
+      cluster_features: [ "random_sampling" ]
+      reason: requires feature 'random_sampling' to get random samples
+
+  - do:
+      indices.get_sample_stats:
+        index: non_existent
+      catch: missing
+
+  - do:
+      indices.create:
+        index: no_config
+
+  - do:
+      indices.get_sample_stats:
+        index: no_config
+      catch: missing

server/src/internalClusterTest/java/org/elasticsearch/action/admin/indices/sampling/GetSampleActionIT.java

@@ -16,13 +16,15 @@
 import org.elasticsearch.cluster.metadata.ProjectMetadata;
 import org.elasticsearch.cluster.service.ClusterService;
 import org.elasticsearch.common.Priority;
+import org.elasticsearch.core.TimeValue;
 import org.elasticsearch.ingest.SamplingService;
 import org.elasticsearch.test.ESIntegTestCase;
 
 import java.util.List;
 import java.util.Map;
 
 import static org.hamcrest.Matchers.equalTo;
+import static org.hamcrest.Matchers.greaterThan;
 
 public class GetSampleActionIT extends ESIntegTestCase {
 
@@ -34,7 +36,8 @@ public void testGetSample() throws Exception {
         createIndex(indexName);
         // the index exists but there is no sampling configuration for it, so getting its sample will throw an exception:
         assertGetSampleThrowsResourceNotFoundException(indexName);
-        addSamplingConfig(indexName);
+        final int maxSamples = 30;
+        addSamplingConfig(indexName, maxSamples);
         // There is now a sampling configuration, but no data has been ingested:
         assertEmptySample(indexName);
         int docsToIndex = randomIntBetween(1, 20);
@@ -49,6 +52,29 @@ public void testGetSample() throws Exception {
         for (int i = 0; i < docsToIndex; i++) {
             assertRawDocument(sample.get(i), indexName);
         }
+
+        GetSampleStatsAction.Request statsRequest = new GetSampleStatsAction.Request(indexName);
+        GetSampleStatsAction.Response statsResponse = client().execute(GetSampleStatsAction.INSTANCE, statsRequest).actionGet();
+        SamplingService.SampleStats stats = statsResponse.getSampleStats();
+        assertThat(stats.getSamples(), equalTo((long) docsToIndex));
+        assertThat(stats.getPotentialSamples(), equalTo((long) docsToIndex));
+        assertThat(stats.getTimeSampling(), greaterThan(TimeValue.ZERO));
+        assertThat(stats.getSamplesRejectedForMaxSamplesExceeded(), equalTo(0L));
+        assertThat(stats.getSamplesRejectedForRate(), equalTo(0L));
+        assertThat(stats.getSamplesRejectedForCondition(), equalTo(0L));
+        assertThat(stats.getSamplesRejectedForCondition(), equalTo(0L));
+
+        final int samplesOverMax = randomIntBetween(1, 5);
+        for (int i = docsToIndex; i < maxSamples + samplesOverMax; i++) {
+            indexDoc(indexName, randomIdentifier(), randomAlphanumericOfLength(10), randomAlphanumericOfLength(10));
+        }
+        statsRequest = new GetSampleStatsAction.Request(indexName);
+        statsResponse = client().execute(GetSampleStatsAction.INSTANCE, statsRequest).actionGet();
+        stats = statsResponse.getSampleStats();
+        assertThat(stats.getSamples(), equalTo((long) maxSamples));
+        assertThat(stats.getPotentialSamples(), equalTo((long) maxSamples + samplesOverMax));
+        assertThat(stats.getSamplesRejectedForMaxSamplesExceeded(), equalTo((long) samplesOverMax));
+
     }
 
     private void assertRawDocument(SamplingService.RawDocument rawDocument, String indexName) {
@@ -68,7 +94,7 @@ private void assertGetSampleThrowsResourceNotFoundException(String indexName) {
     }
 
     @SuppressWarnings("deprecation")
-    private void addSamplingConfig(String indexName) throws Exception {
+    private void addSamplingConfig(String indexName, int maxSamples) throws Exception {
         /*
          * Note: The following code writes a sampling config directly to the cluster state. It can be replaced with a call to the action
          * that does this once that action exists.
@@ -81,7 +107,7 @@ public ClusterState execute(ClusterState currentState) throws Exception {
                     currentState.metadata().getProject(ProjectId.DEFAULT)
                 );
                 SamplingMetadata samplingMetadata = new SamplingMetadata(
-                    Map.of(indexName, new SamplingConfiguration(1.0d, 100, null, null, null))
+                    Map.of(indexName, new SamplingConfiguration(1.0d, maxSamples, null, null, null))
                 );
                 projectMetadataBuilder.putCustom(SamplingMetadata.TYPE, samplingMetadata);
                 ClusterState newState = new ClusterState.Builder(currentState).putProjectMetadata(projectMetadataBuilder).build();

server/src/main/java/org/elasticsearch/action/ActionModule.java

@@ -130,8 +130,11 @@
 import org.elasticsearch.action.admin.indices.rollover.RolloverAction;
 import org.elasticsearch.action.admin.indices.rollover.TransportRolloverAction;
 import org.elasticsearch.action.admin.indices.sampling.GetSampleAction;
+import org.elasticsearch.action.admin.indices.sampling.GetSampleStatsAction;
 import org.elasticsearch.action.admin.indices.sampling.RestGetSampleAction;
+import org.elasticsearch.action.admin.indices.sampling.RestGetSampleStatsAction;
 import org.elasticsearch.action.admin.indices.sampling.TransportGetSampleAction;
+import org.elasticsearch.action.admin.indices.sampling.TransportGetSampleStatsAction;
 import org.elasticsearch.action.admin.indices.segments.IndicesSegmentsAction;
 import org.elasticsearch.action.admin.indices.segments.TransportIndicesSegmentsAction;
 import org.elasticsearch.action.admin.indices.settings.get.GetSettingsAction;
@@ -821,6 +824,7 @@ public <Request extends ActionRequest, Response extends ActionResponse> void reg
 
         if (RANDOM_SAMPLING_FEATURE_FLAG) {
             actions.register(GetSampleAction.INSTANCE, TransportGetSampleAction.class);
+            actions.register(GetSampleStatsAction.INSTANCE, TransportGetSampleStatsAction.class);
         }
 
         return unmodifiableMap(actions.getRegistry());
@@ -1053,6 +1057,7 @@ public void initRestHandlers(Supplier<DiscoveryNodes> nodesInCluster, Predicate<
 
         if (RANDOM_SAMPLING_FEATURE_FLAG) {
             registerHandler.accept(new RestGetSampleAction());
+            registerHandler.accept(new RestGetSampleStatsAction());
         }
     }
 

server/src/main/java/org/elasticsearch/action/admin/indices/sampling/GetSampleStatsAction.java

@@ -0,0 +1,239 @@
+/*
+ * 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", the "GNU Affero General Public License v3.0 only", 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", the "GNU Affero General Public
+ * License v3.0 only", or the "Server Side Public License, v 1".
+ */
+
+package org.elasticsearch.action.admin.indices.sampling;
+
+import org.elasticsearch.action.ActionRequestValidationException;
+import org.elasticsearch.action.ActionType;
+import org.elasticsearch.action.FailedNodeException;
+import org.elasticsearch.action.IndicesRequest;
+import org.elasticsearch.action.support.IndicesOptions;
+import org.elasticsearch.action.support.nodes.BaseNodeResponse;
+import org.elasticsearch.action.support.nodes.BaseNodesRequest;
+import org.elasticsearch.action.support.nodes.BaseNodesResponse;
+import org.elasticsearch.cluster.ClusterName;
+import org.elasticsearch.cluster.node.DiscoveryNode;
+import org.elasticsearch.common.io.stream.StreamInput;
+import org.elasticsearch.common.io.stream.StreamOutput;
+import org.elasticsearch.common.io.stream.Writeable;
+import org.elasticsearch.common.xcontent.ChunkedToXContent;
+import org.elasticsearch.ingest.SamplingService;
+import org.elasticsearch.tasks.CancellableTask;
+import org.elasticsearch.tasks.Task;
+import org.elasticsearch.tasks.TaskId;
+import org.elasticsearch.transport.AbstractTransportRequest;
+import org.elasticsearch.xcontent.ToXContent;
+
+import java.io.IOException;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+
+import static org.elasticsearch.common.xcontent.ChunkedToXContentHelper.chunk;
+
+public class GetSampleStatsAction extends ActionType<GetSampleStatsAction.Response> {
+
+    public static final GetSampleStatsAction INSTANCE = new GetSampleStatsAction();
+    public static final String NAME = "indices:admin/sample/stats";
+
+    private GetSampleStatsAction() {
+        super(NAME);
+    }
+
+    public static class Request extends BaseNodesRequest implements IndicesRequest.Replaceable {
+        private String indexName;
+
+        public Request(String indexName) {
+            super((String[]) null);
+            this.indexName = indexName;
+        }
+
+        @Override
+        public Task createTask(long id, String type, String action, TaskId parentTaskId, Map<String, String> headers) {
+            return new CancellableTask(id, type, action, "get sample stats", parentTaskId, headers);
+        }
+
+        @Override
+        public ActionRequestValidationException validate() {
+            if (this.indexName.contains("*")) {
+                return (ActionRequestValidationException) new ActionRequestValidationException().addValidationError(
+                    "Wildcards are not supported, but found [" + indexName + "]"
+                );
+            }
+            return null;
+        }
+
+        @Override
+        public IndicesRequest indices(String... indices) {
+            assert indices.length == 1 : "GetSampleStatsAction only supports a single index name";
+            this.indexName = indices[0];
+            return this;
+        }
+
+        @Override
+        public String[] indices() {
+            return new String[] { indexName };
+        }
+
+        @Override
+        public IndicesOptions indicesOptions() {
+            return IndicesOptions.STRICT_SINGLE_INDEX_NO_EXPAND_FORBID_CLOSED_ALLOW_SELECTORS;
+        }
+    }
+
+    public static class NodeRequest extends AbstractTransportRequest implements IndicesRequest {
+        private final String indexName;
+
+        public NodeRequest(String indexName) {
+            this.indexName = indexName;
+        }
+
+        public NodeRequest(StreamInput in) throws IOException {
+            super(in);
+            this.indexName = in.readString();
+        }
+
+        @Override
+        public void writeTo(StreamOutput out) throws IOException {
+            super.writeTo(out);
+            out.writeString(indexName);
+        }
+
+        public String getIndexName() {
+            return indexName;
+        }
+
+        @Override
+        public String[] indices() {
+            return new String[] { indexName };
+        }
+
+        @Override
+        public IndicesOptions indicesOptions() {
+            return IndicesOptions.STRICT_SINGLE_INDEX_NO_EXPAND_FORBID_CLOSED_ALLOW_SELECTORS;
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) return true;
+            if (o == null || getClass() != o.getClass()) return false;
+            NodeRequest other = (NodeRequest) o;
+            return Objects.equals(indexName, other.indexName);
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(indexName);
+        }
+    }
+
+    public static class Response extends BaseNodesResponse<GetSampleStatsAction.NodeResponse> implements Writeable, ChunkedToXContent {
+        final int maxSize;
+
+        public Response(StreamInput in) throws IOException {
+            super(in);
+            maxSize = in.readInt();
+        }
+
+        public Response(
+            ClusterName clusterName,
+            List<GetSampleStatsAction.NodeResponse> nodes,
+            List<FailedNodeException> failures,
+            int maxSize
+        ) {
+            super(clusterName, nodes, failures);
+            this.maxSize = maxSize;
+        }
+
+        @Override
+        public void writeTo(StreamOutput out) throws IOException {
+            super.writeTo(out);
+            out.writeInt(maxSize);
+        }
+
+        public SamplingService.SampleStats getSampleStats() {
+            SamplingService.SampleStats rawStats = getRawSampleStats();
+            return rawStats.adjustForMaxSize(maxSize);
+        }
+
+        private SamplingService.SampleStats getRawSampleStats() {
+            return getNodes().stream()
+                .map(NodeResponse::getSampleStats)
+                .filter(Objects::nonNull)
+                .reduce(SamplingService.SampleStats::combine)
+                .orElse(new SamplingService.SampleStats());
+        }
+
+        @Override
+        protected List<GetSampleStatsAction.NodeResponse> readNodesFrom(StreamInput in) throws IOException {
+            return in.readCollectionAsList(GetSampleStatsAction.NodeResponse::new);
+        }
+
+        @Override
+        protected void writeNodesTo(StreamOutput out, List<GetSampleStatsAction.NodeResponse> nodes) throws IOException {
+            out.writeCollection(nodes);
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) return true;
+            if (o == null || getClass() != o.getClass()) return false;
+            Response other = (Response) o;
+            return Objects.equals(getNodes(), other.getNodes()) && maxSize == other.maxSize;
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(getNodes(), maxSize);
+        }
+
+        @Override
+        public Iterator<? extends ToXContent> toXContentChunked(ToXContent.Params params) {
+            return chunk(getSampleStats());
+        }
+    }
+
+    public static class NodeResponse extends BaseNodeResponse {
+        private final SamplingService.SampleStats sampleStats;
+
+        protected NodeResponse(StreamInput in) throws IOException {
+            super(in);
+            sampleStats = new SamplingService.SampleStats(in);
+        }
+
+        protected NodeResponse(DiscoveryNode node, SamplingService.SampleStats sampleStats) {
+            super(node);
+            this.sampleStats = sampleStats;
+        }
+
+        public SamplingService.SampleStats getSampleStats() {
+            return sampleStats;
+        }
+
+        @Override
+        public void writeTo(StreamOutput out) throws IOException {
+            super.writeTo(out);
+            sampleStats.writeTo(out);
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) return true;
+            if (o == null || getClass() != o.getClass()) return false;
+            GetSampleStatsAction.NodeResponse other = (GetSampleStatsAction.NodeResponse) o;
+            return getNode().equals(other.getNode()) && sampleStats.equals(other.sampleStats);
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(getNode(), sampleStats);
+        }
+    }
+}