Handle special case

Author: sergiitk

xds/src/main/java/io/grpc/xds/internal/rlqs/RlqsEngine.java

@@ -56,6 +56,10 @@ public RlqsEngine(
   public RlqsRateLimitResult rateLimit(HttpMatchInput input) {
     RlqsBucketSettings bucketSettings = bucketMatchers.match(input);
     RlqsBucketId bucketId = bucketSettings.toBucketId(input);
+    // Special case when bucket id builder not set.
+    if (bucketId == null) {
+      return rateLimitWithoutReports(bucketSettings);
+    }
     RlqsBucket bucket = bucketCache.getOrCreate(bucketId, bucketSettings, newBucket -> {
       // Called if a new bucket was created.
       scheduleImmediateReport(newBucket);
@@ -64,6 +68,13 @@ public RlqsRateLimitResult rateLimit(HttpMatchInput input) {
     return bucket.rateLimit();
   }
 
+  private static RlqsRateLimitResult rateLimitWithoutReports(RlqsBucketSettings bucketSettings) {
+    if (bucketSettings.noAssignmentStrategy().rateLimit()) {
+      return RlqsRateLimitResult.deny(bucketSettings.denyResponse());
+    }
+    return RlqsRateLimitResult.allow();
+  }
+
   private void onBucketsUpdate(List<RlqsUpdateBucketAction> bucketActions) {
     // TODO(sergiitk): [impl] ensure no more than 1 update at a time.
     for (RlqsUpdateBucketAction bucketAction : bucketActions) {