创建索引需要创建索引并且更新集群index matedata，这一过程在MetaDataCreateIndexService的createIndex方法中完成。这里会提交一个高优先级，AckedClusterStateUpdateTask类型的task。索引创建需要即时得到反馈，异常这个task需要返回，会超时，而且这个任务的优先级也非常高。
下面具体看一下它的execute方法，这个方法会在master执行任务时调用，这个方法非常长，主要完成以下三个功能：更新合并request，template中的mapping和setting，调用indiceService创建索引，对创建后的索引添加mapping。这一系列功能完成后，合并完成后生成新的matedata，并更新集群状态，完成了索引的创建。具体的调用方法参考上一篇。
代码如下所示：
@Override
public ClusterState execute(ClusterState currentState) throws Exception {
boolean indexCreated = false;
String removalReason = null;
try {
//检查request的合法性，1.5版本主要检查index名字是否合法，如不能含有某些字符，另外就是集群节点版本
validate(request, currentState);
for (Alias alias : request.aliases()) {//检查别称是否合法
aliasValidator.validateAlias(alias, request.index(), currentState.metaData());
}
// 查找索引模板
List<IndexTemplateMetaData> templates = findTemplates(request, currentState, indexTemplateFilter);
Map<String, Custom> customs = Maps.newHashMap();
// add the request mapping
Map<String, Map<String, Object>> mappings = Maps.newHashMap();
Map<String, AliasMetaData> templatesAliases = Maps.newHashMap();
List<String> templateNames = Lists.newArrayList();
//取出request中的mapping配置，虽然mapping可以后面添加，多数情况创建索引的时候还是会附带着mapping，在request中mapping是一个map
for (Map.Entry<String, String> entry : request.mappings().entrySet()) {
mappings.put(entry.getKey(), parseMapping(entry.getValue()));
}
//一些预设如warm等
for (Map.Entry<String, Custom> entry : request.customs().entrySet()) {
customs.put(entry.getKey(), entry.getValue());
}
// 将找到的template和request中的mapping合并
for (IndexTemplateMetaData template : templates) {
templateNames.add(template.getName());
for (ObjectObjectCursor<String, CompressedString> cursor : template.mappings()) {
if (mappings.containsKey(cursor.key)) {
XContentHelper.mergeDefaults(mappings.get(cursor.key), parseMapping(cursor.value.string()));
} else {
mappings.put(cursor.key, parseMapping(cursor.value.string()));
}
}
// 合并custom
for (ObjectObjectCursor<String, Custom> cursor : template.customs()) {
String type = cursor.key;
IndexMetaData.Custom custom = cursor.value;
IndexMetaData.Custom existing = customs.get(type);
if (existing == null) {
customs.put(type, custom);
} else {
IndexMetaData.Custom merged = IndexMetaData.lookupFactorySafe(type).merge(existing, custom);
customs.put(type, merged);
}
}
//处理合并别名
for (ObjectObjectCursor<String, AliasMetaData> cursor : template.aliases()) {
AliasMetaData aliasMetaData = cursor.value;
//if an alias with same name came with the create index request itself,
// ignore this one taken from the index template
if (request.aliases().contains(new Alias(aliasMetaData.alias()))) {
continue;
}
//if an alias with same name was already processed, ignore this one
if (templatesAliases.containsKey(cursor.key)) {
continue;
}
//Allow templatesAliases to be templated by replacing a token with the name of the index that we are applying it to
if (aliasMetaData.alias().contains("{index}")) {
String templatedAlias = aliasMetaData.alias().replace("{index}", request.index());
aliasMetaData = AliasMetaData.newAliasMetaData(aliasMetaData, templatedAlias);
}
aliasValidator.validateAliasMetaData(aliasMetaData, request.index(), currentState.metaData());
templatesAliases.put(aliasMetaData.alias(), aliasMetaData);
}
}
// 合并完template和request，现在开始处理配置基本的mapping，合并逻辑跟之前相同，只是mapping来源不同
File mappingsDir = new File(environment.configFile(), "mappings");
if (mappingsDir.isDirectory()) {
// first index level
File indexMappingsDir = new File(mappingsDir, request.index());
if (indexMappingsDir.isDirectory()) {
addMappings(mappings, indexMappingsDir);
}
// second is the _default mapping
File defaultMappingsDir = new File(mappingsDir, "_default");
if (defaultMappingsDir.isDirectory()) {
addMappings(mappings, defaultMappingsDir);
}
}
//处理index的配置（setting）
ImmutableSettings.Builder indexSettingsBuilder = settingsBuilder();
//加入模板中的setting
for (int i = templates.size() - 1; i >= 0; i--) {
indexSettingsBuilder.put(templates.get(i).settings());
}
// 加入request中的mapping，request中设置会覆盖模板中的设置
indexSettingsBuilder.put(request.settings());
//处理shard，shard数量不能小于1，因此这里需要特殊处理，如果没有则要使用默认值
if (request.index().equals(ScriptService.SCRIPT_INDEX)) {
indexSettingsBuilder.put(SETTING_NUMBER_OF_SHARDS, settings.getAsInt(SETTING_NUMBER_OF_SHARDS, 1));
} else {
if (indexSettingsBuilder.get(SETTING_NUMBER_OF_SHARDS) == null) {
if (request.index().equals(riverIndexName)) {
indexSettingsBuilder.put(SETTING_NUMBER_OF_SHARDS, settings.getAsInt(SETTING_NUMBER_OF_SHARDS, 1));
} else {
indexSettingsBuilder.put(SETTING_NUMBER_OF_SHARDS, settings.getAsInt(SETTING_NUMBER_OF_SHARDS, 5));
}
}
}
if (request.index().equals(ScriptService.SCRIPT_INDEX)) {
indexSettingsBuilder.put(SETTING_NUMBER_OF_REPLICAS, settings.getAsInt(SETTING_NUMBER_OF_REPLICAS, 0));
indexSettingsBuilder.put(SETTING_AUTO_EXPAND_REPLICAS, "0-all");
}
else {
if (indexSettingsBuilder.get(SETTING_NUMBER_OF_REPLICAS) == null) {
if (request.index().equals(riverIndexName)) {
indexSettingsBuilder.put(SETTING_NUMBER_OF_REPLICAS, settings.getAsInt(SETTING_NUMBER_OF_REPLICAS, 1));
} else {
indexSettingsBuilder.put(SETTING_NUMBER_OF_REPLICAS, settings.getAsInt(SETTING_NUMBER_OF_REPLICAS, 1));
}
}
}
//处理副本
if (settings.get(SETTING_AUTO_EXPAND_REPLICAS) != null && indexSettingsBuilder.get(SETTING_AUTO_EXPAND_REPLICAS) == null) {
indexSettingsBuilder.put(SETTING_AUTO_EXPAND_REPLICAS, settings.get(SETTING_AUTO_EXPAND_REPLICAS));
}
if (indexSettingsBuilder.get(SETTING_VERSION_CREATED) == null) {
DiscoveryNodes nodes = currentState.nodes();
final Version createdVersion = Version.smallest(version, nodes.smallestNonClientNodeVersion());
indexSettingsBuilder.put(SETTING_VERSION_CREATED, createdVersion);
}
if (indexSettingsBuilder.get(SETTING_CREATION_DATE) == null) {
indexSettingsBuilder.put(SETTING_CREATION_DATE, System.currentTimeMillis());
}
indexSettingsBuilder.put(SETTING_UUID, Strings.randomBase64UUID());
//创建setting
Settings actualIndexSettings = indexSettingsBuilder.build();
// 通过indiceservice创建索引
indicesService.createIndex(request.index(), actualIndexSettings, clusterService.localNode().id());
indexCreated = true;
//如果创建成功这里就可以获取到对应的indexservice，否则会抛出异常
IndexService indexService = indicesService.indexServiceSafe(request.index());
//获取mappingService试图放置mapping
MapperService mapperService = indexService.mapperService();
// 为索引添加mapping，首先是默认mapping
if (mappings.containsKey(MapperService.DEFAULT_MAPPING)) {
try {
mapperService.merge(MapperService.DEFAULT_MAPPING, new CompressedString(XContentFactory.jsonBuilder().map(mappings.get(MapperService.DEFAULT_MAPPING)).string()), false);
} catch (Exception e) {
removalReason = "failed on parsing default mapping on index creation";
throw new MapperParsingException("mapping [" + MapperService.DEFAULT_MAPPING + "]", e);
}
}
for (Map.Entry<String, Map<String, Object>> entry : mappings.entrySet()) {
if (entry.getKey().equals(MapperService.DEFAULT_MAPPING)) {
continue;
}
try {
// apply the default here, its the first time we parse it
mapperService.merge(entry.getKey(), new CompressedString(XContentFactory.jsonBuilder().map(entry.getValue()).string()), true);
} catch (Exception e) {
removalReason = "failed on parsing mappings on index creation";
throw new MapperParsingException("mapping [" + entry.getKey() + "]", e);
}
}
//添加request中的别称
IndexQueryParserService indexQueryParserService = indexService.queryParserService();
for (Alias alias : request.aliases()) {
if (Strings.hasLength(alias.filter())) {
aliasValidator.validateAliasFilter(alias.name(), alias.filter(), indexQueryParserService);
}
}
for (AliasMetaData aliasMetaData : templatesAliases.values()) {
if (aliasMetaData.filter() != null) {
aliasValidator.validateAliasFilter(aliasMetaData.alias(), aliasMetaData.filter().uncompressed(), indexQueryParserService);
}
}
// 以下更新Index的matedata，
Map<String, MappingMetaData> mappingsMetaData = Maps.newHashMap();
for (DocumentMapper mapper : mapperService.docMappers(true)) {
MappingMetaData mappingMd = new MappingMetaData(mapper);
mappingsMetaData.put(mapper.type(), mappingMd);
}
final IndexMetaData.Builder indexMetaDataBuilder = IndexMetaData.builder(request.index()).settings(actualIndexSettings);
for (MappingMetaData mappingMd : mappingsMetaData.values()) {
indexMetaDataBuilder.putMapping(mappingMd);
}
for (AliasMetaData aliasMetaData : templatesAliases.values()) {
indexMetaDataBuilder.putAlias(aliasMetaData);
}
for (Alias alias : request.aliases()) {
AliasMetaData aliasMetaData = AliasMetaData.builder(alias.name()).filter(alias.filter())
.indexRouting(alias.indexRouting()).searchRouting(alias.searchRouting()).build();
indexMetaDataBuilder.putAlias(aliasMetaData);
}
for (Map.Entry<String, Custom> customEntry : customs.entrySet()) {
indexMetaDataBuilder.putCustom(customEntry.getKey(), customEntry.getValue());
}
indexMetaDataBuilder.state(request.state());
//matedata更新完毕，build新的matedata
final IndexMetaData indexMetaData;
try {
indexMetaData = indexMetaDataBuilder.build();
} catch (Exception e) {
removalReason = "failed to build index metadata";
throw e;
}
indexService.indicesLifecycle().beforeIndexAddedToCluster(new Index(request.index()),
indexMetaData.settings());
//更新集群的matedata，将新build的indexmatadata加入到metadata中
MetaData newMetaData = MetaData.builder(currentState.metaData())
.put(indexMetaData, false)
.build();
logger.info("[{}] creating index, cause [{}], templates {}, shards [{}]/[{}], mappings {}", request.index(), request.cause(), templateNames, indexMetaData.numberOfShards(), indexMetaData.numberOfReplicas(), mappings.keySet());
//阻塞集群，更新matadata
ClusterBlocks.Builder blocks = ClusterBlocks.builder().blocks(currentState.blocks());
if (!request.blocks().isEmpty()) {
for (ClusterBlock block : request.blocks()) {
blocks.addIndexBlock(request.index(), block);
}
}
if (request.state() == State.CLOSE) {
blocks.addIndexBlock(request.index(), MetaDataIndexStateService.INDEX_CLOSED_BLOCK);
}
ClusterState updatedState = ClusterState.builder(currentState).blocks(blocks).metaData(newMetaData).build();
if (request.state() == State.OPEN) {
RoutingTable.Builder routingTableBuilder = RoutingTable.builder(updatedState.routingTable())
.addAsNew(updatedState.metaData().index(request.index()));
RoutingAllocation.Result routingResult = allocationService.reroute(ClusterState.builder(updatedState).routingTable(routingTableBuilder).build());
updatedState = ClusterState.builder(updatedState).routingResult(routingResult).build();
}
removalReason = "cleaning up after validating index on master";
return updatedState;
} finally {
if (indexCreated) {
// Index was already partially created - need to clean up
indicesService.removeIndex(request.index(), removalReason != null ? removalReason : "failed to create index");
}
}
}
});
}
