add Filter.isEnabled()

Author: sergiitk

xds/src/main/java/io/grpc/xds/Filter.java

@@ -38,6 +38,10 @@ interface Filter {
    */
   String[] typeUrls();
 
+  default boolean isEnabled() {
+    return true;
+  }
+
   /**
    * Parses the top-level filter config from raw proto message. The message may be either a {@link
    * com.google.protobuf.Any} or a {@link com.google.protobuf.Struct}.

xds/src/main/java/io/grpc/xds/FilterRegistry.java

@@ -51,6 +51,9 @@ static FilterRegistry newRegistry() {
   @VisibleForTesting
   FilterRegistry register(Filter... filters) {
     for (Filter filter : filters) {
+      if (!filter.isEnabled()) {
+        continue;
+      }
       for (String typeUrl : filter.typeUrls()) {
         supportedFilters.put(typeUrl, filter);
       }

xds/src/main/java/io/grpc/xds/RlqsFilter.java

@@ -32,6 +32,7 @@
 import io.grpc.ServerCall.Listener;
 import io.grpc.ServerCallHandler;
 import io.grpc.ServerInterceptor;
+import io.grpc.internal.GrpcUtil;
 import io.grpc.xds.Filter.ServerInterceptorBuilder;
 import io.grpc.xds.internal.datatype.GrpcService;
 import io.grpc.xds.internal.matchers.HttpMatchInput;
@@ -50,7 +51,7 @@
 // TODO(sergiitk): introduce a layer between the filter and interceptor.
 // lds has filter names and the names are unique - even for server instances.
 final class RlqsFilter implements Filter, ServerInterceptorBuilder {
-  // private static final Logger logger = Logger.getLogger(RlqsFilter.class.getName());
+  static final boolean enabled = GrpcUtil.getFlag("GRPC_EXPERIMENTAL_XDS_ENABLE_RLQS", false);
 
   static final RlqsFilter INSTANCE = new RlqsFilter();
 
@@ -66,6 +67,11 @@ public String[] typeUrls() {
     return new String[]{TYPE_URL, TYPE_URL_OVERRIDE_CONFIG};
   }
 
+  @Override
+  public boolean isEnabled() {
+    return enabled;
+  }
+
   @Override
   public ConfigOrError<RlqsFilterConfig> parseFilterConfig(Message rawProtoMessage) {
     try {

xds/src/test/java/io/grpc/xds/XdsServerWrapperTest.java

@@ -1118,6 +1118,8 @@ public void run() {
     Filter filter = mock(Filter.class, withSettings()
         .extraInterfaces(ServerInterceptorBuilder.class));
     when(filter.typeUrls()).thenReturn(new String[]{"filter-type-url"});
+    when(filter.isEnabled()).thenCallRealMethod();
+    assertThat(filter.isEnabled()).isTrue();
     filterRegistry.register(filter);
     FilterConfig f0 = mock(FilterConfig.class);
     FilterConfig f0Override = mock(FilterConfig.class);
@@ -1191,6 +1193,8 @@ public void run() {
     Filter filter = mock(Filter.class, withSettings()
         .extraInterfaces(ServerInterceptorBuilder.class));
     when(filter.typeUrls()).thenReturn(new String[]{"filter-type-url"});
+    when(filter.isEnabled()).thenCallRealMethod();
+    assertThat(filter.isEnabled()).isTrue();
     filterRegistry.register(filter);
     FilterConfig f0 = mock(FilterConfig.class);
     FilterConfig f0Override = mock(FilterConfig.class);