Add "web-context-unify" config in Spring WebMVC adapter to support "c…

…hain" relation flow strategy (#1328)

sentinel-adapter/sentinel-spring-webmvc-adapter/README.md

@@ -97,6 +97,7 @@ config.setBlockExceptionHandler((request, response, e) -> {
 | urlCleaner | The `UrlCleaner` interface is designed for clean and unify the URL resource. | `UrlCleaner` | - |
 | requestAttributeName | Attribute key in request used by Sentinel (internal) | `String` | `$$sentinel_spring_web_entry_attr` |
 | httpMethodSpecify | Specify whether the URL resource name should contain the HTTP method prefix (e.g. `POST:`). | `boolean` | `false` |
+| webContextUnify | Specify whether unify web context(i.e. use the default context name). | `boolean` | `true` |
 
 - `SentinelWebMvcTotalConfig` configuration:
 

sentinel-adapter/sentinel-spring-webmvc-adapter/src/main/java/com/alibaba/csp/sentinel/adapter/spring/webmvc/AbstractSentinelInterceptor.java

@@ -59,7 +59,8 @@ public boolean preHandle(HttpServletRequest request, HttpServletResponse respons
             if (StringUtil.isNotEmpty(resourceName)) {
                 // Parse the request origin using registered origin parser.
                 String origin = parseOrigin(request);
-                ContextUtil.enter(SENTINEL_SPRING_WEB_CONTEXT_NAME, origin);
+                String contextName = getContextName(request);
+                ContextUtil.enter(contextName, origin);
                 Entry entry = SphU.entry(resourceName, ResourceTypeConstants.COMMON_WEB, EntryType.IN);
 
                 setEntryInRequest(request, baseWebMvcConfig.getRequestAttributeName(), entry);
@@ -79,6 +80,16 @@ public boolean preHandle(HttpServletRequest request, HttpServletResponse respons
      */
     protected abstract String getResourceName(HttpServletRequest request);
 
+    /**
+     * Return the context name of the target web resource.
+     *
+     * @param request web request
+     * @return the context name of the target web resource.
+     */
+    protected String getContextName(HttpServletRequest request) {
+        return SENTINEL_SPRING_WEB_CONTEXT_NAME;
+    }
+
     @Override
     public void afterCompletion(HttpServletRequest request, HttpServletResponse response,
                                 Object handler, Exception ex) throws Exception {

sentinel-adapter/sentinel-spring-webmvc-adapter/src/main/java/com/alibaba/csp/sentinel/adapter/spring/webmvc/SentinelWebInterceptor.java

@@ -66,4 +66,12 @@ protected String getResourceName(HttpServletRequest request) {
         return resourceName;
     }
 
+    @Override
+    protected String getContextName(HttpServletRequest request) {
+        if (config.isWebContextUnify()) {
+            return super.getContextName(request);
+        }
+
+        return getResourceName(request);
+    }
 }

sentinel-adapter/sentinel-spring-webmvc-adapter/src/main/java/com/alibaba/csp/sentinel/adapter/spring/webmvc/config/SentinelWebMvcConfig.java

@@ -29,11 +29,19 @@ public class SentinelWebMvcConfig extends BaseWebMvcConfig {
      * Specify the URL cleaner that unifies the URL resources.
      */
     private UrlCleaner urlCleaner;
+
     /**
      * Specify whether the URL resource name should contain the HTTP method prefix (e.g. {@code POST:}).
      */
     private boolean httpMethodSpecify;
 
+    /**
+     * Specify whether unify web context(i.e. use the default context name), and is true by default.
+     *
+     * @since 1.7.2
+     */
+    private boolean webContextUnify = true;
+
     public SentinelWebMvcConfig() {
         super();
         setRequestAttributeName(DEFAULT_REQUEST_ATTRIBUTE_NAME);
@@ -57,11 +65,21 @@ public SentinelWebMvcConfig setHttpMethodSpecify(boolean httpMethodSpecify) {
         return this;
     }
 
+    public boolean isWebContextUnify() {
+        return webContextUnify;
+    }
+
+    public SentinelWebMvcConfig setWebContextUnify(boolean webContextUnify) {
+        this.webContextUnify = webContextUnify;
+        return this;
+    }
+
     @Override
     public String toString() {
         return "SentinelWebMvcConfig{" +
             "urlCleaner=" + urlCleaner +
             ", httpMethodSpecify=" + httpMethodSpecify +
+            ", webContextUnify=" + webContextUnify +
             ", requestAttributeName='" + requestAttributeName + '\'' +
             ", blockExceptionHandler=" + blockExceptionHandler +
             ", originParser=" + originParser +

sentinel-adapter/sentinel-spring-webmvc-adapter/src/test/java/com/alibaba/csp/sentinel/adapter/spring/webmvc/config/InterceptorConfig.java

@@ -66,6 +66,7 @@ public void handle(HttpServletRequest request, HttpServletResponse response, Blo
 
         //Custom configuration if necessary
         config.setHttpMethodSpecify(false);
+        config.setWebContextUnify(true);
         config.setOriginParser(new RequestOriginParser() {
             @Override
             public String parseOrigin(HttpServletRequest request) {

sentinel-adapter/sentinel-web-servlet/src/main/java/com/alibaba/csp/sentinel/adapter/servlet/CommonFilter.java

@@ -54,7 +54,7 @@ public class CommonFilter implements Filter {
      */
     public static final String HTTP_METHOD_SPECIFY = "HTTP_METHOD_SPECIFY";
     /**
-     * If enabled, use the URL path as the context name, or else use the default
+     * If enabled, use the default context name, or else use the URL path as the context name,
      * {@link WebServletConfig#WEB_SERVLET_CONTEXT_NAME}. Please pay attention to the number of context (EntranceNode),
      * which may affect the memory footprint.
      *

sentinel-demo/sentinel-demo-spring-webmvc/src/main/java/com/alibaba/csp/sentinel/demo/spring/webmvc/config/InterceptorConfig.java

@@ -53,6 +53,12 @@ private void addSpringMvcInterceptor(InterceptorRegistry registry) {
 
         // Custom configuration if necessary
         config.setHttpMethodSpecify(true);
+        // By default web context is true, means that unify web context(i.e. use the default context name),
+        // in most scenarios that's enough, and it could reduce the memory footprint.
+        // If set it to false, entrance contexts will be separated by different URLs,
+        // which is useful to support "chain" relation flow strategy.
+        // We can change it and view different result in `Resource Chain` menu of dashboard.
+        config.setWebContextUnify(true);
         config.setOriginParser(request -> request.getHeader("S-user"));
 
         // Add sentinel interceptor