TSDB: Add dimensions and timestamp to parse errors

server/src/main/java/org/elasticsearch/index/mapper/DocumentParserContext.java

@@ -220,7 +220,7 @@ public final void seqID(SeqNoFieldMapper.SequenceIDFields seqID) {
      */
     public final String documentDescription() {
         IdFieldMapper idMapper = (IdFieldMapper) getMetadataMapper(IdFieldMapper.NAME);
-        return idMapper.documentDescription(sourceToParse);
+        return idMapper.documentDescription(this);
     }
 
     /**

server/src/main/java/org/elasticsearch/index/mapper/IdFieldMapper.java

@@ -35,7 +35,7 @@ protected final String contentType() {
      * Description on the document being parsed used in error messages. Not
      * called unless there is an error.
      */
-    public abstract String documentDescription(SourceToParse source);
+    public abstract String documentDescription(DocumentParserContext context);
 
     /**
      * Create a {@link Field} to store the provided {@code _id} that "stores"

server/src/main/java/org/elasticsearch/index/mapper/ProvidedIdFieldMapper.java

@@ -271,7 +271,7 @@ public void preParse(DocumentParserContext context) {
     }
 
     @Override
-    public String documentDescription(SourceToParse source) {
-        return "document with id '" + source.id() + "'";
+    public String documentDescription(DocumentParserContext context) {
+        return "document with id '" + context.sourceToParse().id() + "'";
     }
 }

server/src/main/java/org/elasticsearch/index/mapper/TsidExtractingIdFieldMapper.java

@@ -37,6 +37,11 @@
  */
 public class TsidExtractingIdFieldMapper extends IdFieldMapper {
     private static final FieldType FIELD_TYPE = new FieldType();
+    /**
+     * Maximum length of the {@code _tsid} in the {@link #documentDescription}.
+     */
+    static final int DESCRIPTION_TSID_LIMIT = 1000;
+
     static {
         FIELD_TYPE.setTokenized(false);
         FIELD_TYPE.setIndexOptions(IndexOptions.DOCS);
@@ -156,13 +161,28 @@ public void createField(DocumentParserContext context, BytesRef tsid) {
     }
 
     @Override
-    public String documentDescription(SourceToParse source) {
+    public String documentDescription(DocumentParserContext context) {
         /*
          * We don't yet have an _id because it'd be generated by the document
-         * parsing process. And the _id isn't all that useful anyway - what
-         * folks really want to to see is the dimensions and timestamp. And
-         * those too aren't available until after we've parsed the document.
+         * parsing process. But we *might* have something more useful - the
+         * time series dimensions and the timestamp! If we have those, then
+         * include them in the description. If not, all we know is
+         * "a time series document".
          */
-        return "a time series document";
+        StringBuilder description = new StringBuilder("a time series document");
+        IndexableField tsidField = context.doc().getField(TimeSeriesIdFieldMapper.NAME);
+        if (tsidField != null) {
+            String tsid = TimeSeriesIdFieldMapper.decodeTsid(tsidField.binaryValue()).toString();
+            if (tsid.length() > DESCRIPTION_TSID_LIMIT) {
+                tsid = tsid.substring(0, DESCRIPTION_TSID_LIMIT) + "...}";
+            }
+            description.append(" with dimensions ").append(tsid);
+        }
+        IndexableField timestampField = context.doc().getField(DataStreamTimestampFieldMapper.DEFAULT_PATH);
+        if (timestampField != null) {
+            String timestamp = DateFieldMapper.DEFAULT_DATE_TIME_FORMATTER.formatMillis(timestampField.numericValue().longValue());
+            description.append(" at [").append(timestamp).append(']');
+        }
+        return description.toString();
     }
 }

server/src/test/java/org/elasticsearch/index/mapper/DocumentParserTests.java

@@ -2049,7 +2049,23 @@ public void testDocumentDescriptionInTsdb() throws IOException {
                 MapperException.class,
                 () -> mapper.parse(source(null, b -> b.field("foo", true), null))
             );
-            assertThat(exception.getMessage(), containsString("failed to parse field [foo] of type [long] in a time series document"));
+            assertThat(
+                exception.getMessage(),
+                equalTo("failed to parse field [foo] of type [long] in a time series document. Preview of field's value: 'true'")
+            );
+        }
+        {
+            MapperException exception = expectThrows(
+                MapperException.class,
+                () -> mapper.parse(source(null, b -> b.field("@timestamp", "2021-04-28T00:01:00Z").field("foo", true), null))
+            );
+            assertThat(
+                exception.getMessage(),
+                equalTo(
+                    "failed to parse field [foo] of type [long] in a time series document at "
+                        + "2021-04-28T00:01:00.000Z. Preview of field's value: 'true'"
+                )
+            );
         }
     }
 

server/src/test/java/org/elasticsearch/index/mapper/ProvidedIdFieldMapperTests.java

@@ -12,6 +12,8 @@
 import org.apache.lucene.index.IndexableField;
 import org.apache.lucene.index.LeafReaderContext;
 import org.apache.lucene.search.IndexSearcher;
+import org.elasticsearch.Version;
+import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.index.query.SearchExecutionContext;
 import org.elasticsearch.indices.IndicesService;
 import org.elasticsearch.search.lookup.SearchLookup;
@@ -89,7 +91,15 @@ public void testFetchIdFieldValue() throws IOException {
     public void testDescription() throws IOException {
         String id = randomAlphaOfLength(4);
         assertThat(
-            ProvidedIdFieldMapper.NO_FIELD_DATA.documentDescription(source(id, b -> {}, randomAlphaOfLength(2))),
+            ProvidedIdFieldMapper.NO_FIELD_DATA.documentDescription(
+                new TestDocumentParserContext(
+                    MappingLookup.EMPTY,
+                    MapperTestCase.createIndexSettings(Version.CURRENT, Settings.EMPTY),
+                    null,
+                    null,
+                    source(id, b -> {}, randomAlphaOfLength(2))
+                )
+            ),
             equalTo("document with id '" + id + "'")
         );
     }