[Example] Update runtime examples (#1542)

* Add notes for tensors

* Optimize some apis

* move some warnings

examples/runtime/cpp/infer_paddle_paddle_inference_trt.cc

@@ -0,0 +1,77 @@
+// Copyright (c) 2022 PaddlePaddle 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 "fastdeploy/runtime.h"
+#include <cassert>
+
+namespace fd = fastdeploy;
+
+int main(int argc, char* argv[]) {
+  // Download from https://bj.bcebos.com/paddle2onnx/model_zoo/pplcnet.tar.gz
+  std::string model_file = "pplcnet/inference.pdmodel";
+  std::string params_file = "pplcnet/inference.pdiparams";
+
+  // configure runtime
+  // How to configure by RuntimeOption, refer its api doc for more information
+  // https://baidu-paddle.github.io/fastdeploy-api/cpp/html/structfastdeploy_1_1RuntimeOption.html
+  fd::RuntimeOption runtime_option;
+  runtime_option.SetModelPath(model_file, params_file);
+  runtime_option.UsePaddleInferBackend();
+   runtime_option.UseGpu(0);
+ 
+  // Enable Paddle Inference + TensorRT
+  // If need to configure Paddle Inference backend for more option, we can configure runtime_option.paddle_infer_option
+  // refer https://baidu-paddle.github.io/fastdeploy-api/cpp/html/structfastdeploy_1_1PaddleBackendOption.html
+  runtime_option.paddle_infer_option.enable_trt = true;
+
+  // If need to configure TensorRT backend for more option, we can configure runtime_option.trt_option
+  // refer https://baidu-paddle.github.io/fastdeploy-api/cpp/html/structfastdeploy_1_1TrtBackendOption.html
+  // Use float16 inference to improve performance
+  runtime_option.trt_option.enable_fp16 = true;
+  // Cache trt engine to reduce time cost in model initialize
+  runtime_option.trt_option.serialize_file = "./pplcnet_model.trt";
+
+  fd::Runtime runtime;
+  assert(runtime.Init(runtime_option));
+
+  // Get model's inputs information
+  // API doc refer https://baidu-paddle.github.io/fastdeploy-api/cpp/html/structfastdeploy_1_1Runtime.html
+  std::vector<fd::TensorInfo> inputs_info = runtime.GetInputInfos();
+
+  // Create dummy data fill with 0.5
+  std::vector<float> dummy_data(1 * 3 * 224 * 224, 0.5);
+
+  // Create inputs/outputs tensors
+  std::vector<fd::FDTensor> inputs(inputs_info.size());
+  std::vector<fd::FDTensor> outputs;
+
+  // Initialize input tensors
+  // API doc refer https://baidu-paddle.github.io/fastdeploy-api/cpp/html/structfastdeploy_1_1FDTensor.html
+  inputs[0].SetData({1, 3, 224, 224}, fd::FDDataType::FP32, dummy_data.data());
+  inputs[0].name = inputs_info[0].name;
+
+  // Inference
+  assert(runtime.Infer(inputs, &outputs));
+ 
+  // Print debug information of outputs 
+  outputs[0].PrintInfo();
+
+  // Get data pointer and print it's elements
+  const float* data_ptr = reinterpret_cast<const float*>(outputs[0].GetData());
+  for (size_t i = 0; i < 10 && i < outputs[0].Numel(); ++i) {
+    std::cout << data_ptr[i] << " ";
+  }
+  std::cout << std::endl;
+  return 0;
+}