Add tfhub url support

Fixes deepjavalibrary#1122

Change-Id: Ia1a2fafc502cb07878ed23dea66f1914b8b3159a

api/src/main/java/ai/djl/repository/RepositoryFactoryImpl.java

@@ -23,6 +23,7 @@
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.util.Collections;
+import java.util.Locale;
 import java.util.Map;
 import java.util.ServiceLoader;
 import java.util.Set;
@@ -59,6 +60,23 @@ public Repository newInstance(String name, URI uri) {
             throw new IllegalArgumentException("Malformed URL: " + uri, e);
         }
 
+        if ("tfhub.dev".equals(uri.getHost().toLowerCase(Locale.ROOT))) {
+            // Handle tfhub case
+            String path = uri.getPath();
+            if (path.endsWith("/")) {
+                path = path.substring(0, path.length() - 1);
+            }
+            path = "/tfhub-modules" + path + ".tar.gz";
+            try {
+                uri = new URI("https", null, "storage.googleapis.com", -1, path, null, null);
+            } catch (URISyntaxException e) {
+                throw new IllegalArgumentException("Failed to append query string: " + uri, e);
+            }
+            String[] tokens = path.split("/");
+            String modelName = tokens[tokens.length - 2];
+            return new SimpleUrlRepository(name, uri, modelName);
+        }
+
         Path path = parseFilePath(uri);
         String fileName = path.toFile().getName();
         if (FilenameUtils.isArchiveFile(fileName)) {

api/src/test/java/ai/djl/repository/TfhubRepositoryTest.java

@@ -0,0 +1,28 @@
+/*
+ * Copyright 2021 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"). You may not use this file except in compliance
+ * with the License. A copy of the License is located at
+ *
+ * http://aws.amazon.com/apache2.0/
+ *
+ * or in the "license" file accompanying this file. This file is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES
+ * OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions
+ * and limitations under the License.
+ */
+package ai.djl.repository;
+
+import org.testng.Assert;
+import org.testng.annotations.Test;
+
+public class TfhubRepositoryTest {
+
+    @Test
+    public void testResource() {
+        Repository repo =
+                Repository.newInstance(
+                        "tfhub",
+                        "https://tfhub.dev/tensorflow/faster_rcnn/inception_resnet_v2_640x640/1/");
+        Assert.assertEquals(repo.getResources().size(), 1);
+    }
+}

extensions/benchmark/README.md

@@ -87,10 +87,10 @@ they have different CUDA version to support. Please check the individual Engine
 Here is a few sample benchmark script for you to refer. You can also skip this and directly follow
 the 4-step instructions for your own model.
 
-Benchmark on a Tensorflow model from http url with all-ones NDArray input for 10 times:
+Benchmark on a Tensorflow model from [tfhub](https://tfhub.dev/) url with all-zeros NDArray input for 10 times:
 
 ```
-djl-bench -e TensorFlow -u https://storage.googleapis.com/tfhub-modules/tensorflow/resnet_50/classification/1.tar.gz -c 10 -s 1,224,224,3
+djl-bench -e TensorFlow -u https://tfhub.dev/tensorflow/resnet_50/classification/1 -c 10 -s 1,224,224,3
 ```
 
 Similarly, this is for PyTorch