add by ck.

* 根据IP地址，返回可用的Node信息。 这里的Node并不包含es配置信息。 仅仅是集群的状态(是否可用) 如果根据IP从hosts(sync.Map)查询不到Node，则根据入参(host string,clusterID string)创建Node并保存 */.

* 初始化: ElasticsearchMetadata = ElasticsearchConfig + cache 并保存到metas(sync.Map) */.

NOTE: we assume GetPartitions returned sorted buckets from ES, if not, we need to manually sort source & target partitions by keys sourcePartitions & targetPartitions must've been generated with same bucket step & offset.

* 注册elastic实例,初始化elastic metadata并保存到metas(sync.Map{}) cfg.ID = cfg.Name = 集群名称 把handle(API)保存到apis(sync.Map) 把ElasticsearchConfig保存到cfgs(sync.Map) */.

RegisterMetadataChangeEvent register a metadata change event.

最后返回的为判断是否继续 walk.

BoolQuery wrapper queries.

{ "index" : ".monitoring-es-7-2020.12.29", "shard" : "0", "prirep" : "p", "state" : "STARTED", "unassigned.reason" : null, "docs" : "227608", "store" : "132.5mb", "id" : "qIgTsxtuQ8mzAGiBATkqHw", "node" : "dev", "ip" : "192.168.3.98" }.

CountResponse is a count response object.

DeleteResponse is a delete response object.

ElasticsearchConfig contains common settings for elasticsearch.

GetResponse is a get response object.

IndexDocument used to construct indexing document.

InsertResponse is a index response object.

Query is the root query object.

RangeQuery is used to find value in range.

SearchRequest is the root search query object.

SearchResponse is a count response object.

EventAction represents a metadata change operation.

MetadataChangeEvent represents a callback of metadata change.