[tflite] enable using the new NNAPI delegate in Java

tensorflow/lite/delegates/nnapi/java/src/main/java/org/tensorflow/lite/nnapi/BUILD

@@ -0,0 +1,7 @@
+licenses(["notice"])  # Apache 2.0
+
+filegroup(
+    name = "nnapi_delegate_src",
+    srcs = ["NnApiDelegate.java"],
+    visibility = ["//visibility:public"],
+)

tensorflow/lite/delegates/nnapi/java/src/main/java/org/tensorflow/lite/nnapi/NnApiDelegate.java

@@ -0,0 +1,49 @@
+/* Copyright 2019 The TensorFlow Authors. 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.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License 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 org.tensorflow.lite.nnapi;
+
+import org.tensorflow.lite.Delegate;
+import org.tensorflow.lite.Tensor;
+
+/** {@link Delegate} for NNAPI inference. */
+public class NnApiDelegate implements Delegate, AutoCloseable {
+
+  private static final long INVALID_DELEGATE_HANDLE = 0;
+
+  private long delegateHandle;
+
+  public NnApiDelegate() {
+    delegateHandle = createDelegate();
+  }
+
+  @Override
+  public long getNativeHandle() {
+    return delegateHandle;
+  }
+
+  /**
+   * The NNAPI delegate is singleton. Nothing to delete
+   * for now, so mark the handle invalid only.
+   */
+  @Override
+  public void close() {
+    if (delegateHandle != INVALID_DELEGATE_HANDLE) {
+      delegateHandle = INVALID_DELEGATE_HANDLE;
+    }
+  }
+
+  private static native long createDelegate();
+}

tensorflow/lite/delegates/nnapi/java/src/main/native/BUILD

@@ -0,0 +1,25 @@
+# Description:
+# Java Native Interface (JNI) library intended for implementing the
+# TensorFlow Lite GPU delegate Java API using the TensorFlow Lite CC library.
+
+package(default_visibility = ["//visibility:public"])
+
+load("//tensorflow/lite:build_def.bzl", "tflite_copts")
+
+licenses(["notice"])  # Apache 2.0
+
+cc_library(
+    name = "native",
+    srcs = ["nnapi_delegate_jni.cc"],
+    hdrs = ["nnapi_delegate_jni.h"],
+    copts = tflite_copts(),
+    tags = [
+        "manual",
+        "notap",
+    ],
+    deps = [
+        "//tensorflow/lite/delegates/nnapi:nnapi_delegate",
+        "//tensorflow/lite/java/jni",
+    ],
+    alwayslink = 1,
+)

tensorflow/lite/delegates/nnapi/java/src/main/native/nnapi_delegate_jni.cc

@@ -0,0 +1,22 @@
+/* Copyright 2019 The TensorFlow Authors. 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.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License 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.
+==============================================================================*/
+
+#include "tensorflow/lite/delegates/nnapi/nnapi_delegate.h"
+#include "tensorflow/lite/delegates/nnapi/java/src/main/native/nnapi_delegate_jni.h"
+
+JNIEXPORT jlong JNICALL Java_org_tensorflow_lite_nnapi_NnApiDelegate_createDelegate(
+    JNIEnv* env, jclass clazz) {
+  return reinterpret_cast<jlong>(tflite::NnApiDelegate());
+}

tensorflow/lite/delegates/nnapi/java/src/main/native/nnapi_delegate_jni.h

@@ -0,0 +1,37 @@
+/* Copyright 2019 The TensorFlow Authors. 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.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License 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.
+==============================================================================*/
+
+#ifndef TENSORFLOW_LITE_DELEGATES_NNAPI_JAVA_SRC_MAIN_NATIVE_NNAPI_DELEGATE_JNI_H_
+#define TENSORFLOW_LITE_DELEGATES_NNAPI_JAVA_SRC_MAIN_NATIVE_NNAPI_DELEGATE_JNI_H_
+
+#include <jni.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif  // __cplusplus
+
+/*
+ * Class:     org_tensorflow_lite_nnapi_NnApiDelegate
+ * Method:    createDelegate
+ * Signature: ()J
+ */
+JNIEXPORT jlong JNICALL Java_org_tensorflow_lite_nnapi_NnApiDelegate_createDelegate(
+    JNIEnv* env, jclass clazz);
+
+#ifdef __cplusplus
+}  // extern "C"
+#endif  // __cplusplus
+
+#endif  // TENSORFLOW_LITE_DELEGATES_NNAPI_JAVA_SRC_MAIN_NATIVE_NNAPI_DELEGATE_JNI_H_

tensorflow/lite/java/BUILD

@@ -13,7 +13,12 @@ load("//tensorflow/lite/java:aar_with_jni.bzl", "aar_with_jni")
 
 JAVA_SRCS = glob([
     "src/main/java/org/tensorflow/lite/*.java",
-])
+]) + select({
+    "//tensorflow:android": [
+      "//tensorflow/lite/delegates/nnapi/java/src/main/java/org/tensorflow/lite/nnapi:nnapi_delegate_src"
+    ],
+    "//conditions:default": []
+})
 
 # Building tensorflow-lite.aar including 4 variants of .so
 # To build an aar for release, run below command:
@@ -262,6 +267,8 @@ tflite_jni_binary(
     name = "libtensorflowlite_jni.so",
     deps = [
         "//tensorflow/lite/java/src/main/native",
+        "//tensorflow/lite/delegates/nnapi:nnapi_delegate",
+        "//tensorflow/lite/delegates/nnapi/java/src/main/native:native",
     ],
 )
 

tensorflow/lite/java/demo/app/src/main/java/com/example/android/tflitecamerademo/ImageClassifier.java

@@ -40,6 +40,7 @@
 import java.util.PriorityQueue;
 import org.tensorflow.lite.Interpreter;
 import org.tensorflow.lite.gpu.GpuDelegate;
+import org.tensorflow.lite.nnapi.NnApiDelegate;
 
 /**
  * Classifies images with Tensorflow Lite.
@@ -96,6 +97,8 @@ public int compare(Map.Entry<String, Float> o1, Map.Entry<String, Float> o2) {
 
   /** holds a gpu delegate */
   GpuDelegate gpuDelegate = null;
+  /** holds an nnapi delegate */
+  NnApiDelegate nnapiDelegate = null;
 
   /** Initializes an {@code ImageClassifier}. */
   ImageClassifier(Activity activity) throws IOException {
@@ -176,12 +179,12 @@ public void useGpu() {
   }
 
   public void useCPU() {
-    tfliteOptions.setUseNNAPI(false);
     recreateInterpreter();
   }
 
   public void useNNAPI() {
-    tfliteOptions.setUseNNAPI(true);
+    nnapiDelegate = new NnApiDelegate();
+    tfliteOptions.addDelegate(nnapiDelegate);
     recreateInterpreter();
   }
 
@@ -198,6 +201,10 @@ public void close() {
       gpuDelegate.close();
       gpuDelegate = null;
     }
+    if (nnapiDelegate != null) {
+      nnapiDelegate.close();
+      nnapiDelegate = null;
+    }
     tfliteModel = null;
   }