序
本文主要研究一下 Elasticsearch 的 NodesSniffer
NodesSniffer
elasticsearch-7.0.1/client/sniffer/src/main/java/org/elasticsearch/client/sniff/NodesSniffer.java
/**
* Responsible for sniffing the http hosts
*/
public interface NodesSniffer {
/**
* Returns the sniffed Elasticsearch nodes.
*/
List<Node> sniff() throws IOException;}- NodesSniffer 接口定义了 sniff 方法用于获取 sniffed Elasticsearch nodes，它有一个实现类为 ElasticsearchNodesSniffer
ElasticsearchNodesSniffer
elasticsearch-7.0.1/client/sniffer/src/main/java/org/elasticsearch/client/sniff/ElasticsearchNodesSniffer.java
public final class ElasticsearchNodesSniffer implements NodesSniffer {private static final Log logger = LogFactory.getLog(ElasticsearchNodesSniffer.class);
public static final long DEFAULT_SNIFF_REQUEST_TIMEOUT = TimeUnit.SECONDS.toMillis(1);
private final RestClient restClient;
private final Request request;
private final Scheme scheme;
private final JsonFactory jsonFactory = new JsonFactory();
public ElasticsearchNodesSniffer(RestClient restClient) {this(restClient, DEFAULT_SNIFF_REQUEST_TIMEOUT, ElasticsearchNodesSniffer.Scheme.HTTP);
}
public ElasticsearchNodesSniffer(RestClient restClient, long sniffRequestTimeoutMillis, Scheme scheme) {this.restClient = Objects.requireNonNull(restClient, "restClient cannot be null");
if (sniffRequestTimeoutMillis < 0) {throw new IllegalArgumentException("sniffRequestTimeoutMillis must be greater than 0");
}
this.request = new Request("GET", "/_nodes/http");
request.addParameter("timeout", sniffRequestTimeoutMillis + "ms");
this.scheme = Objects.requireNonNull(scheme, "scheme cannot be null");
}
/**
* Calls the elasticsearch nodes info api, parses the response and returns all the found http hosts
*/
@Override
public List<Node> sniff() throws IOException {Response response = restClient.performRequest(request);
return readHosts(response.getEntity(), scheme, jsonFactory);
}
static List<Node> readHosts(HttpEntity entity, Scheme scheme, JsonFactory jsonFactory) throws IOException {try (InputStream inputStream = entity.getContent()) {JsonParser parser = jsonFactory.createParser(inputStream);
if (parser.nextToken() != JsonToken.START_OBJECT) {throw new IOException("expected data to start with an object");
}
List<Node> nodes = new ArrayList<>();
while (parser.nextToken() != JsonToken.END_OBJECT) {if (parser.getCurrentToken() == JsonToken.START_OBJECT) {if ("nodes".equals(parser.getCurrentName())) {while (parser.nextToken() != JsonToken.END_OBJECT) {JsonToken token = parser.nextToken();
assert token == JsonToken.START_OBJECT;
String nodeId = parser.getCurrentName();
Node node = readNode(nodeId, parser, scheme);
if (node != null) {nodes.add(node);
}
}
} else {parser.skipChildren();
}
}
}
return nodes;
}
}
//......
public enum Scheme {HTTP("http"), HTTPS("https");
private final String name;
Scheme(String name) {this.name = name;}
@Override
public String toString() {return name;}
}
}- ElasticsearchNodesSniffer 的构造器需要 restClient、sniffRequestTimeoutMillis、scheme 三个参数，其中 sniffRequestTimeoutMillis 默认为 1 秒，scheme 默认为 HTTP；它的构造器创建了 GET /_nodes/http 的 request；sniff 方法使用 restClient.performRequest 来执行这个 GET /_nodes/http 的 request，之后调用 readHosts 来解析 response，其中调用了 readNode 方法来解析 nodes 部分
GET /_nodes/http 实例
{
"_nodes" : {
"total" : 1,
"successful" : 1,
"failed" : 0
},
"cluster_name" : "docker-cluster",
"nodes" : {
"d7w2wdw7Q7SqERe5_fxZYA" : {
"name" : "d7w2wdw",
"transport_address" : "172.17.0.2:9300",
"host" : "172.17.0.2",
"ip" : "172.17.0.2",
"version" : "6.6.2",
"build_flavor" : "oss",
"build_type" : "tar",
"build_hash" : "3bd3e59",
"roles" : [
"master",
"data",
"ingest"
],
"http" : {
"bound_address" : ["0.0.0.0:9200"],
"publish_address" : "192.168.99.100:9200",
"max_content_length_in_bytes" : 104857600
}
}
}
}- 这里 http 部分有 publish_address 信息
readNode
elasticsearch-7.0.1/client/sniffer/src/main/java/org/elasticsearch/client/sniff/ElasticsearchNodesSniffer.java
public final class ElasticsearchNodesSniffer implements NodesSniffer {
//......
private static Node readNode(String nodeId, JsonParser parser, Scheme scheme) throws IOException {
HttpHost publishedHost = null;
/*
* We sniff the bound hosts so we can look up the node based on any
* address on which it is listening. This is useful in Elasticsearch's
* test framework where we sometimes publish ipv6 addresses but the
* tests contact the node on ipv4.
*/
Set<HttpHost> boundHosts = new HashSet<>();
String name = null;
String version = null;
/*
* Multi-valued attributes come with key = `real_key.index` and we
* unflip them after reading them because we can't rely on the order
* that they arive.
*/
final Map<String, String> protoAttributes = new HashMap<String, String>();
boolean sawRoles = false;
boolean master = false;
boolean data = false;
boolean ingest = false;
String fieldName = null;
while (parser.nextToken() != JsonToken.END_OBJECT) {if (parser.getCurrentToken() == JsonToken.FIELD_NAME) {fieldName = parser.getCurrentName();
} else if (parser.getCurrentToken() == JsonToken.START_OBJECT) {if ("http".equals(fieldName)) {while (parser.nextToken() != JsonToken.END_OBJECT) {if (parser.getCurrentToken() == JsonToken.VALUE_STRING && "publish_address".equals(parser.getCurrentName())) {URI publishAddressAsURI = URI.create(scheme + "://" + parser.getValueAsString());
publishedHost = new HttpHost(publishAddressAsURI.getHost(), publishAddressAsURI.getPort(),
publishAddressAsURI.getScheme());
} else if (parser.currentToken() == JsonToken.START_ARRAY && "bound_address".equals(parser.getCurrentName())) {while (parser.nextToken() != JsonToken.END_ARRAY) {URI boundAddressAsURI = URI.create(scheme + "://" + parser.getValueAsString());
boundHosts.add(new HttpHost(boundAddressAsURI.getHost(), boundAddressAsURI.getPort(),
boundAddressAsURI.getScheme()));
}
} else if (parser.getCurrentToken() == JsonToken.START_OBJECT) {parser.skipChildren();
}
}
} else if ("attributes".equals(fieldName)) {while (parser.nextToken() != JsonToken.END_OBJECT) {if (parser.getCurrentToken() == JsonToken.VALUE_STRING) {String oldValue = protoAttributes.put(parser.getCurrentName(), parser.getValueAsString());
if (oldValue != null) {throw new IOException("repeated attribute key [" + parser.getCurrentName() + "]");
}
} else {parser.skipChildren();
}
}
} else {parser.skipChildren();
}
} else if (parser.currentToken() == JsonToken.START_ARRAY) {if ("roles".equals(fieldName)) {
sawRoles = true;
while (parser.nextToken() != JsonToken.END_ARRAY) {switch (parser.getText()) {
case "master":
master = true;
break;
case "data":
data = true;
break;
case "ingest":
ingest = true;
break;
default:
logger.warn("unknown role [" + parser.getText() + "] on node [" + nodeId + "]");
}
}
} else {parser.skipChildren();
}
} else if (parser.currentToken().isScalarValue()) {if ("version".equals(fieldName)) {version = parser.getText();
} else if ("name".equals(fieldName)) {name = parser.getText();
}
}
}
//http section is not present if http is not enabled on the node, ignore such nodes
if (publishedHost == null) {logger.debug("skipping node [" + nodeId + "] with http disabled");
return null;
}
Map<String, List<String>> realAttributes = new HashMap<>(protoAttributes.size());
List<String> keys = new ArrayList<>(protoAttributes.keySet());
for (String key : keys) {if (key.endsWith(".0")) {String realKey = key.substring(0, key.length() - 2);
List<String> values = new ArrayList<>();
int i = 0;
while (true) {String value = protoAttributes.remove(realKey + "." + i);
if (value == null) {break;}
values.add(value);
i++;
}
realAttributes.put(realKey, unmodifiableList(values));
}
}
for (Map.Entry<String, String> entry : protoAttributes.entrySet()) {realAttributes.put(entry.getKey(), singletonList(entry.getValue()));
}
if (version.startsWith("2.")) {
/*
* 2.x doesn't send roles, instead we try to read them from
* attributes.
*/
boolean clientAttribute = v2RoleAttributeValue(realAttributes, "client", false);
Boolean masterAttribute = v2RoleAttributeValue(realAttributes, "master", null);
Boolean dataAttribute = v2RoleAttributeValue(realAttributes, "data", null);
master = masterAttribute == null ? false == clientAttribute : masterAttribute;
data = dataAttribute == null ? false == clientAttribute : dataAttribute;
} else {assert sawRoles : "didn't see roles for ["+ nodeId +"]";
}
assert boundHosts.contains(publishedHost) :
"[" + nodeId + "] doesn't make sense! publishedHost should be in boundHosts";
logger.trace("adding node [" + nodeId + "]");
return new Node(publishedHost, boundHosts, name, version, new Roles(master, data, ingest),
unmodifiableMap(realAttributes));
}
/**
* Returns {@code defaultValue} if the attribute didn't come back,
* {@code true} or {@code false} if it did come back as
* either of those, or throws an IOException if the attribute
* came back in a strange way.
*/
private static Boolean v2RoleAttributeValue(Map<String, List<String>> attributes,
String name, Boolean defaultValue) throws IOException {List<String> valueList = attributes.remove(name);
if (valueList == null) {return defaultValue;}
if (valueList.size() != 1) {throw new IOException("expected only a single attribute value for [" + name + "] but got"
+ valueList);
}
switch (valueList.get(0)) {
case "true":
return true;
case "false":
return false;
default:
throw new IOException("expected [" + name + "] to be either [true] or [false] but was ["
+ valueList.get(0) + "]");
}
}
//......
}- readNode 方法用于解析 nodes 部分的数据，它会解析 http、attributes、roles、version；然后会对 2.x 版本的进行特殊处理，最后使用 publishedHost、boundHosts、name、version、master、data、ingest、realAttributes 构建 Node 实例并返回
小结
- NodesSniffer 接口定义了 sniff 方法用于获取 sniffed Elasticsearch nodes，它有一个实现类为 ElasticsearchNodesSniffer
- ElasticsearchNodesSniffer 的构造器需要 restClient、sniffRequestTimeoutMillis、scheme 三个参数，其中 sniffRequestTimeoutMillis 默认为 1 秒，scheme 默认为 HTTP；它的构造器创建了 GET /_nodes/http 的 request；sniff 方法使用 restClient.performRequest 来执行这个 GET /_nodes/http 的 request，之后调用 readHosts 来解析 response，其中调用了 readNode 方法来解析 nodes 部分
- readNode 方法用于解析 nodes 部分的数据，它会解析 http、attributes、roles、version；然后会对 2.x 版本的进行特殊处理，最后使用 publishedHost、boundHosts、name、version、master、data、ingest、realAttributes 构建 Node 实例并返回
doc
- NodesSniffer