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| private GetResult innerGet(String id, String[] gFields, boolean realtime, long version, VersionType versionType,
long ifSeqNo, long ifPrimaryTerm, FetchSourceContext fetchSourceContext) {
fetchSourceContext = normalizeFetchSourceContent(fetchSourceContext, gFields);
// 调用Engine获取数据
Engine.GetResult get = indexShard.get(new Engine.Get(realtime, realtime, id)
.version(version).versionType(versionType).setIfSeqNo(ifSeqNo).setIfPrimaryTerm(ifPrimaryTerm));
assert get.isFromTranslog() == false || realtime : "should only read from translog if realtime enabled";
if (get.exists() == false) {
get.close();
}
if (get == null || get.exists() == false) {
return new GetResult(shardId.getIndexName(), id, UNASSIGNED_SEQ_NO, UNASSIGNED_PRIMARY_TERM, -1, false, null, null, null);
}
try {
// 获取返回结果
// break between having loaded it from translog (so we only have _source), and having a document to load
return innerGetLoadFromStoredFields(id, gFields, fetchSourceContext, get, mapperService);
} finally {
get.close();
}
}
//对指定的field、source进行过滤(source过滤只支持对字段)，
//把结果存于GetResult对象中
private GetResult innerGetLoadFromStoredFields(String id, String[] storedFields, FetchSourceContext fetchSourceContext,
Engine.GetResult get, MapperService mapperService) {
assert get.exists() : "method should only be called if document could be retrieved";
// check first if stored fields to be loaded don't contain an object field
DocumentMapper docMapper = mapperService.documentMapper();
if (storedFields != null) {
for (String field : storedFields) {
Mapper fieldMapper = docMapper.mappers().getMapper(field);
if (fieldMapper == null) {
if (docMapper.mappers().objectMappers().get(field) != null) {
// Only fail if we know it is a object field, missing paths / fields shouldn't fail.
throw new IllegalArgumentException("field [" + field + "] isn't a leaf field");
}
}
}
}
Map<String, DocumentField> documentFields = null;
Map<String, DocumentField> metadataFields = null;
BytesReference source = null;
DocIdAndVersion docIdAndVersion = get.docIdAndVersion();
// force fetching source if we read from translog and need to recreate stored fields
boolean forceSourceForComputingTranslogStoredFields = get.isFromTranslog() && storedFields != null &&
Stream.of(storedFields).anyMatch(f -> TranslogLeafReader.ALL_FIELD_NAMES.contains(f) == false);
FieldsVisitor fieldVisitor = buildFieldsVisitors(storedFields,
forceSourceForComputingTranslogStoredFields ? FetchSourceContext.FETCH_SOURCE : fetchSourceContext);
if (fieldVisitor != null) {
try {
docIdAndVersion.reader.document(docIdAndVersion.docId, fieldVisitor);
} catch (IOException e) {
throw new ElasticsearchException("Failed to get id [" + id + "]", e);
}
source = fieldVisitor.source();
// in case we read from translog, some extra steps are needed to make _source consistent and to load stored fields
if (get.isFromTranslog()) {
// Fast path: if only asked for the source or stored fields that have been already provided by TranslogLeafReader,
// just make source consistent by reapplying source filters from mapping (possibly also nulling the source)
if (forceSourceForComputingTranslogStoredFields == false) {
try {
source = indexShard.mapperService().documentMapper().sourceMapper().applyFilters(source, null);
} catch (IOException e) {
throw new ElasticsearchException("Failed to reapply filters for [" + id + "] after reading from translog", e);
}
} else {
// Slow path: recreate stored fields from original source
assert source != null : "original source in translog must exist";
SourceToParse sourceToParse = new SourceToParse(shardId.getIndexName(), id, source, XContentHelper.xContentType(source),
fieldVisitor.routing());
ParsedDocument doc = indexShard.mapperService().documentMapper().parse(sourceToParse);
assert doc.dynamicMappingsUpdate() == null : "mapping updates should not be required on already-indexed doc";
// update special fields
doc.updateSeqID(docIdAndVersion.seqNo, docIdAndVersion.primaryTerm);
doc.version().setLongValue(docIdAndVersion.version);
// retrieve stored fields from parsed doc
fieldVisitor = buildFieldsVisitors(storedFields, fetchSourceContext);
for (IndexableField indexableField : doc.rootDoc().getFields()) {
IndexableFieldType fieldType = indexableField.fieldType();
if (fieldType.stored()) {
FieldInfo fieldInfo = new FieldInfo(indexableField.name(), 0, false, false, false, IndexOptions.NONE,
DocValuesType.NONE, -1, Collections.emptyMap(), 0, 0, 0, false);
StoredFieldVisitor.Status status = fieldVisitor.needsField(fieldInfo);
if (status == StoredFieldVisitor.Status.YES) {
if (indexableField.numericValue() != null) {
fieldVisitor.objectField(fieldInfo, indexableField.numericValue());
} else if (indexableField.binaryValue() != null) {
fieldVisitor.binaryField(fieldInfo, indexableField.binaryValue());
} else if (indexableField.stringValue() != null) {
fieldVisitor.objectField(fieldInfo, indexableField.stringValue());
}
} else if (status == StoredFieldVisitor.Status.STOP) {
break;
}
}
}
// retrieve source (with possible transformations, e.g. source filters
source = fieldVisitor.source();
}
}
// put stored fields into result objects
if (!fieldVisitor.fields().isEmpty()) {
fieldVisitor.postProcess(mapperService::fieldType);
documentFields = new HashMap<>();
metadataFields = new HashMap<>();
for (Map.Entry<String, List<Object>> entry : fieldVisitor.fields().entrySet()) {
if (mapperService.isMetadataField(entry.getKey())) {
metadataFields.put(entry.getKey(), new DocumentField(entry.getKey(), entry.getValue()));
} else {
documentFields.put(entry.getKey(), new DocumentField(entry.getKey(), entry.getValue()));
}
}
}
}
if (source != null) {
// apply request-level source filtering
if (fetchSourceContext.fetchSource() == false) {
source = null;
} else if (fetchSourceContext.includes().length > 0 || fetchSourceContext.excludes().length > 0) {
Map<String, Object> sourceAsMap;
// TODO: The source might be parsed and available in the sourceLookup but that one uses unordered maps so different.
// Do we care?
Tuple<XContentType, Map<String, Object>> typeMapTuple = XContentHelper.convertToMap(source, true);
XContentType sourceContentType = typeMapTuple.v1();
sourceAsMap = typeMapTuple.v2();
sourceAsMap = XContentMapValues.filter(sourceAsMap, fetchSourceContext.includes(), fetchSourceContext.excludes());
try {
source = BytesReference.bytes(XContentFactory.contentBuilder(sourceContentType).map(sourceAsMap));
} catch (IOException e) {
throw new ElasticsearchException("Failed to get id [" + id + "] with includes/excludes set", e);
}
}
}
return new GetResult(shardId.getIndexName(), id, get.docIdAndVersion().seqNo, get.docIdAndVersion().primaryTerm,
get.version(), get.exists(), source, documentFields, metadataFields);
}
|
