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Go源码阅读——github.com/medcl/esm —— v0.go

时间：2023-05-12 10:11:25浏览次数：45  
标签：body github err nil settings 源码 medcl interface string

esm（An Elasticsearch Migration Tool）—— v0.go

https://github.com/medcl/esm release: 8.7.1

通过阅读好的源代码，细致思考，理性分析并借鉴优秀实践经验，提高 zuoyang 的编程水平，所谓 "他山之石，可以攻玉"  该是如此吧。 

/*
Copyright 2016 Medcl (m AT medcl.net)

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package main

import (
	"bytes"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"io/ioutil"
	"regexp"
	"strings"

	log "github.com/cihub/seelog"
)

type ESAPIV0 struct {
	Host      string //eg: http://localhost:9200
	Auth      *Auth  //eg: user:pass
	HttpProxy string //eg: http://proxyIp:proxyPort
	Compress  bool
}

/*获取 Elasticsearch 集群的健康状况。*/
func (s *ESAPIV0) ClusterHealth() *ClusterHealth {

	/*使用 fmt.Sprintf() 函数构造了请求 URL，并调用了 Get() 方法发起了 GET 请求。*/
	url := fmt.Sprintf("%s/_cluster/health", s.Host)
	/*Get() 方法返回的 r、body 和 errs 变量分别代表 HTTP 响应、响应体和请求错误。*/
	r, body, errs := Get(url, s.Auth, s.HttpProxy)

	if r != nil && r.Body != nil {
		//如果 r 的值不为空，同时 r.Body 也不为空，则说明请求成功,并通过 io.Copy()函数把 r.Body 中的数据流扔到 ioutil.Discard 中丢弃。
		//ioutil.Discard 是一个 Go 语言标准库中的变量，它是一个 io.Writer 接口的实现，可以用于写入任何数据但会直接丢弃它们。
		//这个变量通常在执行某些操作时不需要输出结果时使用，例如在日志库中，当日志级别低于某个阈值时，可以将日志输出重定向到 ioutil.Discard，这样就可以避免不必要的输出
		//io.Copy() 是一个 Go 语言标准库中的函数，用于复制一个 Reader 的内容到一个 Writer 中，它的函数签名如下： func Copy(dst Writer, src Reader) (written int64, err error)
		io.Copy(ioutil.Discard, r.Body)
		defer r.Body.Close()
	}

	/*判断 errs 变量是否为空，如果存在请求错误，则返回一个 ClusterHealth 对象，将集群状态设置为 "unreachable"。*/
	if errs != nil {
		return &ClusterHealth{Name: s.Host, Status: "unreachable"}
	}

	log.Debug(url)
	log.Debug(body)

	health := &ClusterHealth{}
	/*
	   使用 json.Unmarshal() 函数解析 HTTP 响应体，将响应体中的数据解析为一个 ClusterHealth struct对象
	*/
	err := json.Unmarshal([]byte(body), health)

	if err != nil {
		log.Error(body)
		return &ClusterHealth{Name: s.Host, Status: "unreachable"}
	}
	return health
}

func (s *ESAPIV0) Bulk(data *bytes.Buffer) {
	if data == nil || data.Len() == 0 {
		log.Trace("data is empty, skip")
		return
	}
	data.WriteRune('\n')
	url := fmt.Sprintf("%s/_bulk", s.Host)

	body, err := DoRequest(s.Compress, "POST", url, s.Auth, data.Bytes(), s.HttpProxy)

	if err != nil {
		log.Error(err)
		return
	}
	response := BulkResponse{}
	err = DecodeJson(body, &response)
	if err == nil {
		if response.Errors {
			fmt.Println(body)
		}
	}

	data.Reset()
}

func (s *ESAPIV0) GetIndexSettings(indexNames string) (*Indexes, error) {

	// get all settings
	allSettings := &Indexes{}

	url := fmt.Sprintf("%s/%s/_settings", s.Host, indexNames)
	resp, body, errs := Get(url, s.Auth, s.HttpProxy)

	if resp != nil && resp.Body != nil {
		io.Copy(ioutil.Discard, resp.Body)
		defer resp.Body.Close()
	}

	if errs != nil {
		return nil, errs[0]
	}

	if resp.StatusCode != 200 {
		return nil, errors.New(body)
	}

	log.Debug(body)

	err := json.Unmarshal([]byte(body), allSettings)
	if err != nil {
		panic(err)
		return nil, err
	}

	return allSettings, nil
}

func (s *ESAPIV0) GetIndexMappings(copyAllIndexes bool, indexNames string) (string, int, *Indexes, error) {
	url := fmt.Sprintf("%s/%s/_mapping", s.Host, indexNames)
	resp, body, errs := Get(url, s.Auth, s.HttpProxy)

	if resp != nil && resp.Body != nil {
		io.Copy(ioutil.Discard, resp.Body)
		defer resp.Body.Close()
	}

	if errs != nil {
		log.Error(errs)
		return "", 0, nil, errs[0]
	}

	if resp.StatusCode != 200 {
		return "", 0, nil, errors.New(body)
	}

	idxs := Indexes{}
	er := json.Unmarshal([]byte(body), &idxs)

	if er != nil {
		log.Error(body)
		return "", 0, nil, er
	}

	// remove indexes that start with . if user asked for it
	//if copyAllIndexes == false {
	//      for name := range idxs {
	//              switch name[0] {
	//              case '.':
	//                      delete(idxs, name)
	//              case '_':
	//                      delete(idxs, name)
	//
	//
	//                      }
	//              }
	//      }

	// if _all indexes limit the list of indexes to only these that we kept
	// after looking at mappings
	if indexNames == "_all" {

		var newIndexes []string
		for name := range idxs {
			newIndexes = append(newIndexes, name)
		}
		indexNames = strings.Join(newIndexes, ",")

	} else if strings.Contains(indexNames, "*") || strings.Contains(indexNames, "?") {

		r, _ := regexp.Compile(indexNames)

		//check index patterns
		var newIndexes []string
		for name := range idxs {
			matched := r.MatchString(name)
			if matched {
				newIndexes = append(newIndexes, name)
			}
		}
		indexNames = strings.Join(newIndexes, ",")

	}

	i := 0
	// wrap in mappings if moving from super old es
	for name, idx := range idxs {
		i++
		if _, ok := idx.(map[string]interface{})["mappings"]; !ok {
			(idxs)[name] = map[string]interface{}{
				"mappings": idx,
			}
		}
	}

	return indexNames, i, &idxs, nil
}

func getEmptyIndexSettings() map[string]interface{} {
	tempIndexSettings := map[string]interface{}{}
	tempIndexSettings["settings"] = map[string]interface{}{}
	tempIndexSettings["settings"].(map[string]interface{})["index"] = map[string]interface{}{}
	return tempIndexSettings
}

func cleanSettings(settings map[string]interface{}) {
	//clean up settings
	delete(settings["settings"].(map[string]interface{})["index"].(map[string]interface{}), "creation_date")
	delete(settings["settings"].(map[string]interface{})["index"].(map[string]interface{}), "uuid")
	delete(settings["settings"].(map[string]interface{})["index"].(map[string]interface{}), "version")
	delete(settings["settings"].(map[string]interface{})["index"].(map[string]interface{}), "provided_name")
}

func (s *ESAPIV0) UpdateIndexSettings(name string, settings map[string]interface{}) error {

	log.Debug("update index: ", name, settings)
	cleanSettings(settings)
	url := fmt.Sprintf("%s/%s/_settings", s.Host, name)

	if _, ok := settings["settings"].(map[string]interface{})["index"]; ok {
		if set, ok := settings["settings"].(map[string]interface{})["index"].(map[string]interface{})["analysis"]; ok {
			log.Debug("update static index settings: ", name)
			staticIndexSettings := getEmptyIndexSettings()
			staticIndexSettings["settings"].(map[string]interface{})["index"].(map[string]interface{})["analysis"] = set
			Post(fmt.Sprintf("%s/%s/_close", s.Host, name), s.Auth, "", s.HttpProxy)
			body := bytes.Buffer{}
			enc := json.NewEncoder(&body)
			enc.Encode(staticIndexSettings)
			bodyStr, err := Request("PUT", url, s.Auth, &body, s.HttpProxy)
			if err != nil {
				log.Error(bodyStr, err)
				panic(err)
				return err
			}
			delete(settings["settings"].(map[string]interface{})["index"].(map[string]interface{}), "analysis")
			Post(fmt.Sprintf("%s/%s/_open", s.Host, name), s.Auth, "", s.HttpProxy)
		}
	}

	log.Debug("update dynamic index settings: ", name)

	body := bytes.Buffer{}
	enc := json.NewEncoder(&body)
	enc.Encode(settings)
	_, err := Request("PUT", url, s.Auth, &body, s.HttpProxy)

	return err
}

func (s *ESAPIV0) UpdateIndexMapping(indexName string, settings map[string]interface{}) error {

	log.Debug("start update mapping: ", indexName, settings)

	for name, mapping := range settings {

		log.Debug("start update mapping: ", indexName, name, mapping)

		url := fmt.Sprintf("%s/%s/%s/_mapping", s.Host, indexName, name)

		body := bytes.Buffer{}
		enc := json.NewEncoder(&body)
		enc.Encode(mapping)
		res, err := Request("POST", url, s.Auth, &body, s.HttpProxy)
		if err != nil {
			log.Error(url)
			log.Error(body.String())
			log.Error(err, res)
			panic(err)
		}
	}
	return nil
}

func (s *ESAPIV0) DeleteIndex(name string) (err error) {

	log.Debug("start delete index: ", name)

	url := fmt.Sprintf("%s/%s", s.Host, name)

	Request("DELETE", url, s.Auth, nil, s.HttpProxy)

	log.Debug("delete index: ", name)

	return nil
}

func (s *ESAPIV0) CreateIndex(name string, settings map[string]interface{}) (err error) {
	cleanSettings(settings)

	body := bytes.Buffer{}
	enc := json.NewEncoder(&body)
	enc.Encode(settings)
	log.Debug("start create index: ", name, settings)

	url := fmt.Sprintf("%s/%s", s.Host, name)

	resp, err := Request("PUT", url, s.Auth, &body, s.HttpProxy)
	log.Debugf("response: %s", resp)

	return err
}

func (s *ESAPIV0) Refresh(name string) (err error) {

	log.Debug("refresh index: ", name)

	url := fmt.Sprintf("%s/%s/_refresh", s.Host, name)

	resp, _, _ := Post(url, s.Auth, "", s.HttpProxy)
	if resp != nil && resp.Body != nil {
		io.Copy(ioutil.Discard, resp.Body)
		defer resp.Body.Close()
	}

	return nil
}

func (s *ESAPIV0) NewScroll(indexNames string, scrollTime string, docBufferCount int, query string, slicedId, maxSlicedCount int, fields string) (scroll interface{}, err error) {

	// curl -XGET 'http://es-0.9:9200/_search?search_type=scan&scroll=10m&size=50'
	url := fmt.Sprintf("%s/%s/_search?search_type=scan&scroll=%s&size=%d", s.Host, indexNames, scrollTime, docBufferCount)

	var jsonBody []byte
	if len(query) > 0 || len(fields) > 0 {
		queryBody := map[string]interface{}{}
		if len(fields) > 0 {
			if !strings.Contains(fields, ",") {
				queryBody["_source"] = fields
			} else {
				queryBody["_source"] = strings.Split(fields, ",")
			}
		}

		if len(query) > 0 {
			queryBody["query"] = map[string]interface{}{}
			queryBody["query"].(map[string]interface{})["query_string"] = map[string]interface{}{}
			queryBody["query"].(map[string]interface{})["query_string"].(map[string]interface{})["query"] = query
		}

		jsonBody, err = json.Marshal(queryBody)
		if err != nil {
			log.Error(err)
			return nil, err
		}

	}
	//resp, body, errs := Post(url, s.Auth,jsonBody,s.HttpProxy)
	body, err := DoRequest(s.Compress, "POST", url, s.Auth, jsonBody, s.HttpProxy)
	if err != nil {
		log.Error(err)
		return nil, err
	}

	scroll = &Scroll{}
	err = DecodeJson(body, scroll)
	if err != nil {
		log.Error(err)
		return nil, err
	}

	return scroll, err
}

func (s *ESAPIV0) NextScroll(scrollTime string, scrollId string) (interface{}, error) {
	//  curl -XGET 'http://es-0.9:9200/_search/scroll?scroll=5m'
	id := bytes.NewBufferString(scrollId)
	url := fmt.Sprintf("%s/_search/scroll?scroll=%s&scroll_id=%s", s.Host, scrollTime, id)
	body, err := DoRequest(s.Compress, "GET", url, s.Auth, nil, s.HttpProxy)

	if err != nil {
		log.Error(err)
		return nil, err
	}

	// decode elasticsearch scroll response
	scroll := &Scroll{}
	err = DecodeJson(body, &scroll)
	if err != nil {
		log.Error(err)
		return nil, err
	}

	return scroll, nil
}

标签：body,github,err,nil,settings,源码,medcl,interface,string
From： https://www.cnblogs.com/zuoyang/p/17392999.html

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