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本文主要研究一下skywalking的httpclient-plugin
skywalking-plugin.def
skywalking-6.6.0/apm-sniffer/apm-sdk-plugin/httpClient-4.x-plugin/src/main/resources/skywalking-plugin.def
httpclient-4.x=org.apache.skywalking.apm.plugin.httpClient.v4.define.AbstractHttpClientInstrumentation
httpclient-4.x=org.apache.skywalking.apm.plugin.httpClient.v4.define.InternalHttpClientInstrumentation
httpclient-4.x=org.apache.skywalking.apm.plugin.httpClient.v4.define.MinimalHttpClientInstrumentation
httpclient-4.x=org.apache.skywalking.apm.plugin.httpClient.v4.define.DefaultRequestDirectorInstrumentation
- httpClient-4.x-plugin定义了四个增强，分别是AbstractHttpClientInstrumentation、InternalHttpClientInstrumentation、MinimalHttpClientInstrumentation、DefaultRequestDirectorInstrumentation；它们都继承了HttpClientInstrumentation
HttpClientInstrumentation
skywalking-6.6.0/apm-sniffer/apm-sdk-plugin/httpClient-4.x-plugin/src/main/java/org/apache/skywalking/apm/plugin/httpClient/v4/define/HttpClientInstrumentation.java
public abstract class HttpClientInstrumentation extends ClassInstanceMethodsEnhancePluginDefine {
private static final String INTERCEPT_CLASS = "org.apache.skywalking.apm.plugin.httpClient.v4.HttpClientExecuteInterceptor";
@Override
public ConstructorInterceptPoint[] getConstructorsInterceptPoints() {
return null;
}
protected String getInstanceMethodsInterceptor() {
return INTERCEPT_CLASS;
}
}
- HttpClientInstrumentation继承了ClassInstanceMethodsEnhancePluginDefine，其使用的interceptor为org.apache.skywalking.apm.plugin.httpClient.v4.HttpClientExecuteInterceptor
AbstractHttpClientInstrumentation
skywalking-6.6.0/apm-sniffer/apm-sdk-plugin/httpClient-4.x-plugin/src/main/java/org/apache/skywalking/apm/plugin/httpClient/v4/define/AbstractHttpClientInstrumentation.java
public class AbstractHttpClientInstrumentation extends HttpClientInstrumentation {
private static final String ENHANCE_CLASS = "org.apache.http.impl.client.AbstractHttpClient";
@Override
public ClassMatch enhanceClass() {
return byName(ENHANCE_CLASS);
}
/**
* version 4.2, intercept method: execute, intercept
* public final HttpResponse execute(HttpHost target, HttpRequest request, HttpContext context)
*/
@Override
public InstanceMethodsInterceptPoint[] getInstanceMethodsInterceptPoints() {
return new InstanceMethodsInterceptPoint[] {
new InstanceMethodsInterceptPoint() {
@Override
public ElementMatcher getMethodsMatcher() {
return named("doExecute");
}
@Override
public String getMethodsInterceptor() {
return getInstanceMethodsInterceptor();
}
@Override
public boolean isOverrideArgs() {
return false;
}
}
};
}
}
- AbstractHttpClientInstrumentation继承了HttpClientInstrumentation，其增强的是org.apache.http.impl.client.DefaultRequestDirector的doExecute方法
InternalHttpClientInstrumentation
skywalking-6.6.0/apm-sniffer/apm-sdk-plugin/httpClient-4.x-plugin/src/main/java/org/apache/skywalking/apm/plugin/httpClient/v4/define/InternalHttpClientInstrumentation.java
public class InternalHttpClientInstrumentation extends HttpClientInstrumentation {
private static final String ENHANCE_CLASS = "org.apache.http.impl.client.InternalHttpClient";
@Override
public ClassMatch enhanceClass() {
return NameMatch.byName(ENHANCE_CLASS);
}
@Override
public InstanceMethodsInterceptPoint[] getInstanceMethodsInterceptPoints() {
return new InstanceMethodsInterceptPoint[] {
new InstanceMethodsInterceptPoint() {
@Override
public ElementMatcher getMethodsMatcher() {
return named("doExecute");
}
@Override
public String getMethodsInterceptor() {
return getInstanceMethodsInterceptor();
}
@Override
public boolean isOverrideArgs() {
return false;
}
}
};
}
}
- InternalHttpClientInstrumentation继承了HttpClientInstrumentation，其增强的是org.apache.http.impl.client.InternalHttpClient的doExecute方法
MinimalHttpClientInstrumentation
skywalking-6.6.0/apm-sniffer/apm-sdk-plugin/httpClient-4.x-plugin/src/main/java/org/apache/skywalking/apm/plugin/httpClient/v4/define/MinimalHttpClientInstrumentation.java
public class MinimalHttpClientInstrumentation extends HttpClientInstrumentation {
private static final String ENHANCE_CLASS = "org.apache.http.impl.client.MinimalHttpClient";
@Override
public ClassMatch enhanceClass() {
return NameMatch.byName(ENHANCE_CLASS);
}
@Override
public InstanceMethodsInterceptPoint[] getInstanceMethodsInterceptPoints() {
return new InstanceMethodsInterceptPoint[] {
new InstanceMethodsInterceptPoint() {
@Override
public ElementMatcher getMethodsMatcher() {
return named("doExecute");
}
@Override
public String getMethodsInterceptor() {
return getInstanceMethodsInterceptor();
}
@Override
public boolean isOverrideArgs() {
return false;
}
}
};
}
}
- MinimalHttpClientInstrumentation继承了HttpClientInstrumentation，其增强的是org.apache.http.impl.client.MinimalHttpClient的doExecute方法
DefaultRequestDirectorInstrumentation
skywalking-6.6.0/apm-sniffer/apm-sdk-plugin/httpClient-4.x-plugin/src/main/java/org/apache/skywalking/apm/plugin/httpClient/v4/define/DefaultRequestDirectorInstrumentation.java
public class DefaultRequestDirectorInstrumentation extends HttpClientInstrumentation {
/**
* Enhance class.
*/
private static final String ENHANCE_CLASS = "org.apache.http.impl.client.DefaultRequestDirector";
/**
* DefaultRequestDirector is default implement.
* usually use in version 4.0-4.2
* since 4.3, this class is Deprecated.
*/
@Override
public ClassMatch enhanceClass() {
return NameMatch.byName(ENHANCE_CLASS);
}
@Override
public InstanceMethodsInterceptPoint[] getInstanceMethodsInterceptPoints() {
return new InstanceMethodsInterceptPoint[] {
new InstanceMethodsInterceptPoint() {
@Override
public ElementMatcher getMethodsMatcher() {
return named("execute");
}
@Override
public String getMethodsInterceptor() {
return getInstanceMethodsInterceptor();
}
@Override
public boolean isOverrideArgs() {
return false;
}
}
};
}
}
- DefaultRequestDirectorInstrumentation继承了HttpClientInstrumentation，其增强的是org.apache.http.impl.client.DefaultRequestDirector的execute方法
HttpClientExecuteInterceptor
skywalking-6.6.0/apm-sniffer/apm-sdk-plugin/httpClient-4.x-plugin/src/main/java/org/apache/skywalking/apm/plugin/httpClient/v4/HttpClientExecuteInterceptor.java
public class HttpClientExecuteInterceptor implements InstanceMethodsAroundInterceptor {
@Override public void beforeMethod(EnhancedInstance objInst, Method method, Object[] allArguments,
Class[] argumentsTypes, MethodInterceptResult result) throws Throwable {
if (allArguments[0] == null || allArguments[1] == null) {
// illegal args, can't trace. ignore.
return;
}
final HttpHost httpHost = (HttpHost)allArguments[0];
HttpRequest httpRequest = (HttpRequest)allArguments[1];
final ContextCarrier contextCarrier = new ContextCarrier();
String remotePeer = httpHost.getHostName() + ":" + port(httpHost);
String uri = httpRequest.getRequestLine().getUri();
String requestURI = getRequestURI(uri);
String operationName = requestURI;
AbstractSpan span = ContextManager.createExitSpan(operationName, contextCarrier, remotePeer);
span.setComponent(ComponentsDefine.HTTPCLIENT);
Tags.URL.set(span, buildSpanValue(httpHost,uri));
Tags.HTTP.METHOD.set(span, httpRequest.getRequestLine().getMethod());
SpanLayer.asHttp(span);
CarrierItem next = contextCarrier.items();
while (next.hasNext()) {
next = next.next();
httpRequest.setHeader(next.getHeadKey(), next.getHeadValue());
}
}
@Override public Object afterMethod(EnhancedInstance objInst, Method method, Object[] allArguments,
Class[] argumentsTypes, Object ret) throws Throwable {
if (allArguments[0] == null || allArguments[1] == null) {
return ret;
}
if (ret != null) {
HttpResponse response = (HttpResponse)ret;
StatusLine responseStatusLine = response.getStatusLine();
if (responseStatusLine != null) {
int statusCode = responseStatusLine.getStatusCode();
AbstractSpan span = ContextManager.activeSpan();
if (statusCode >= 400) {
span.errorOccurred();
Tags.STATUS_CODE.set(span, Integer.toString(statusCode));
}
}
}
ContextManager.stopSpan();
return ret;
}
@Override public void handleMethodException(EnhancedInstance objInst, Method method, Object[] allArguments,
Class[] argumentsTypes, Throwable t) {
AbstractSpan activeSpan = ContextManager.activeSpan();
activeSpan.errorOccurred();
activeSpan.log(t);
}
private String getRequestURI(String uri) throws MalformedURLException {
if (isUrl(uri)) {
String requestPath = new URL(uri).getPath();
return requestPath != null && requestPath.length() > 0 ? requestPath : "/";
} else {
return uri;
}
}
private boolean isUrl(String uri) {
String lowerUrl = uri.toLowerCase();
return lowerUrl.startsWith("http") || lowerUrl.startsWith("https");
}
private String buildSpanValue(HttpHost httpHost, String uri) {
if (isUrl(uri)) {
return uri;
} else {
StringBuilder buff = new StringBuilder();
buff.append(httpHost.getSchemeName().toLowerCase());
buff.append("://");
buff.append(httpHost.getHostName());
buff.append(":");
buff.append(port(httpHost));
buff.append(uri);
return buff.toString();
}
}
private int port(HttpHost httpHost) {
int port = httpHost.getPort();
return port > 0 ? port : "https".equals(httpHost.getSchemeName().toLowerCase()) ? 443 : 80;
}
}
- HttpClientExecuteInterceptor实现了InstanceMethodsAroundInterceptor接口，其beforeMethod方法根据httpHost及httpRequest参数来构造requestURI、operationName等信息，并通过httpRequest的header透传contextCarrier.items()；其afterMethod方法解析statusCode，对于statusCode大于等于400的标记span.errorOccurred()并设置tag，最后ContextManager.stopSpan()；其handleMethodException方法主要是执行activeSpan.errorOccurred()及activeSpan.log(t)
小结
httpClient-4.x-plugin定义了四个增强，分别是AbstractHttpClientInstrumentation、InternalHttpClientInstrumentation、MinimalHttpClientInstrumentation、DefaultRequestDirectorInstrumentation；它们都继承了HttpClientInstrumentation；使用HttpClientExecuteInterceptor去增强org.apache.http.impl.client.DefaultRequestDirector的doExecute方法、org.apache.http.impl.client.InternalHttpClient的doExecute方法、org.apache.http.impl.client.MinimalHttpClient的doExecute方法、org.apache.http.impl.client.DefaultRequestDirector的execute方法
doc
- skywalking-plugin