[MXNET-1357] Fix the cpp-examples to add exception handling (#14441)

* Adding exception handling to the cpp-package examples.

* Updating exception handling to catch dmlc::error.

* Removed the catch all exception.

cpp-package/example/alexnet.cpp

@@ -228,6 +228,7 @@ int main(int argc, char const *argv[]) {
   }
 #endif
 
+  TRY
   /*net symbol*/
   auto Net = AlexnetSymbol(10);
 
@@ -352,5 +353,6 @@ int main(int argc, char const *argv[]) {
   delete exec;
   delete opt;
   MXNotifyShutdown();
+  CATCH
   return 0;
 }

cpp-package/example/charRNN.cpp

@@ -42,6 +42,7 @@
 #include <thread>
 #include <chrono>
 #include "mxnet-cpp/MxNetCpp.h"
+#include "utils.h"
 
 using namespace mxnet::cpp;
 
@@ -721,6 +722,7 @@ int main(int argc, char** argv) {
   TIME_MAJOR = task.find("TimeMajor") != std::string::npos;
   std::cout << "use BuiltIn cuDNN RNN: " << builtIn << std::endl
          << "use data as TimeMajor: " << TIME_MAJOR << std::endl;
+  TRY
   if (task.find("train") == 0) {
     std::cout << "train batch size:      " << argv[3] << std::endl
            << "train max epoch:       " << argv[4] << std::endl;
@@ -746,5 +748,6 @@ int main(int argc, char** argv) {
   }
 
   MXNotifyShutdown();
+  CATCH
   return 0;
 }

cpp-package/example/googlenet.cpp

@@ -124,6 +124,7 @@ int main(int argc, char const *argv[]) {
   ctx = Context::cpu();;
 #endif
 
+  TRY
   auto googlenet = GoogleNetSymbol(10);
   std::map<std::string, NDArray> args_map;
   std::map<std::string, NDArray> aux_map;
@@ -192,5 +193,6 @@ int main(int argc, char const *argv[]) {
   delete exec;
   delete opt;
   MXNotifyShutdown();
+  CATCH
   return 0;
 }

cpp-package/example/inception_bn.cpp

@@ -172,6 +172,7 @@ int main(int argc, char const *argv[]) {
   }
 #endif
 
+  TRY
   auto inception_bn_net = InceptionSymbol(10);
   std::map<std::string, NDArray> args_map;
   std::map<std::string, NDArray> aux_map;
@@ -255,5 +256,6 @@ int main(int argc, char const *argv[]) {
   delete exec;
   delete opt;
   MXNotifyShutdown();
+  CATCH
   return 0;
 }

cpp-package/example/lenet.cpp

@@ -25,6 +25,7 @@
 #include <vector>
 #include <cstdlib>
 #include "mxnet-cpp/MxNetCpp.h"
+#include "utils.h"
 
 using namespace mxnet::cpp;
 
@@ -257,8 +258,10 @@ class Lenet {
 };
 
 int main(int argc, char const *argv[]) {
+  TRY
   Lenet lenet;
   lenet.Run(argc > 1 ? strtol(argv[1], NULL, 10) : 100000);
   MXNotifyShutdown();
+  CATCH
   return 0;
 }

cpp-package/example/lenet_with_mxdataiter.cpp

@@ -94,6 +94,7 @@ int main(int argc, char const *argv[]) {
   }
 #endif
 
+  TRY
   auto lenet = LenetSymbol();
   std::map<std::string, NDArray> args_map;
 
@@ -197,5 +198,6 @@ int main(int argc, char const *argv[]) {
   delete exec;
   delete opt;
   MXNotifyShutdown();
+  CATCH
   return 0;
 }

cpp-package/example/mlp.cpp

@@ -24,6 +24,7 @@
 #include <vector>
 #include <string>
 #include "mxnet-cpp/MxNetCpp.h"
+#include "utils.h"
 
 using namespace mxnet::cpp;
 
@@ -173,7 +174,9 @@ void MLP(int max_epoch) {
 
 int main(int argc, char** argv) {
   int max_epoch = argc > 1 ? strtol(argv[1], NULL, 10) : 15000;
+  TRY
   MLP(max_epoch);
   MXNotifyShutdown();
+  CATCH
   return 0;
 }

cpp-package/example/mlp_cpu.cpp

@@ -72,6 +72,7 @@ int main(int argc, char** argv) {
     return 1;
   }
 
+  TRY
   auto net = mlp(layers);
 
   Context ctx = Context::cpu();  // Use CPU for training
@@ -141,5 +142,6 @@ int main(int argc, char** argv) {
   delete exec;
   delete opt;
   MXNotifyShutdown();
+  CATCH
   return 0;
 }

cpp-package/example/mlp_csv.cpp

@@ -156,6 +156,7 @@ int main(int argc, char** argv) {
     .SetParam("shuffle", 0)
     .CreateDataIter();
 
+    TRY
     auto net = mlp(hidden_units);
 
     Context ctx = Context::cpu();
@@ -269,5 +270,6 @@ int main(int argc, char** argv) {
     delete exec;
     delete opt;
     MXNotifyShutdown();
+    CATCH
     return 0;
 }

cpp-package/example/mlp_gpu.cpp

@@ -72,6 +72,7 @@ int main(int argc, char** argv) {
     return 1;
   }
 
+  TRY
   auto net = mlp(layers);
 
   Context ctx = Context::gpu();  // Use GPU for training
@@ -157,5 +158,6 @@ int main(int argc, char** argv) {
   delete exec;
   delete opt;
   MXNotifyShutdown();
+  CATCH
   return 0;
 }

cpp-package/example/resnet.cpp

@@ -172,6 +172,7 @@ int main(int argc, char const *argv[]) {
   float learning_rate = 1e-4;
   float weight_decay = 1e-4;
 
+  TRY
   auto resnet = ResNetSymbol(10);
   std::map<std::string, NDArray> args_map;
   std::map<std::string, NDArray> aux_map;
@@ -277,5 +278,6 @@ int main(int argc, char const *argv[]) {
   delete exec;
   delete opt;
   MXNotifyShutdown();
+  CATCH
   return 0;
 }

cpp-package/example/test_score.cpp

@@ -62,6 +62,7 @@ int main(int argc, char** argv) {
   const int max_epoch = 10;
   const float learning_rate = 0.1;
   const float weight_decay = 1e-2;
+  float score = 0;
 
   std::vector<std::string> data_files = { "./data/mnist_data/train-images-idx3-ubyte",
                                           "./data/mnist_data/train-labels-idx1-ubyte",
@@ -79,6 +80,7 @@ int main(int argc, char** argv) {
     return 1;
   }
 
+  TRY
   auto net = mlp(layers);
 
   Context ctx = Context::gpu();  // Use GPU for training
@@ -111,7 +113,6 @@ int main(int argc, char** argv) {
   auto *exec = net.SimpleBind(ctx, args);
   auto arg_names = net.ListArguments();
 
-  float score = 0;
   // Start training
   for (int iter = 0; iter < max_epoch; ++iter) {
     int samples = 0;
@@ -158,5 +159,6 @@ int main(int argc, char** argv) {
   delete exec;
   delete opt;
   MXNotifyShutdown();
+  CATCH
   return score >= MIN_SCORE ? 0 : 1;
 }

cpp-package/example/utils.h

@@ -27,6 +27,15 @@
 
 using namespace mxnet::cpp;
 
+#define TRY \
+  try {
+#define CATCH \
+  } catch(dmlc::Error &err) { \
+    LG << "Status: FAIL";\
+    LG << "With Error: " << MXGetLastError(); \
+    return 1; \
+  }
+
 bool isFileExists(const std::string &filename) {
   std::ifstream fhandle(filename.c_str());
   return fhandle.good();