Handle Python layer exceptions correctly

include/caffe/python_layer.hpp

@@ -18,44 +18,23 @@ class PythonLayer : public Layer<Dtype> {
 
   virtual void LayerSetUp(const vector<Blob<Dtype>*>& bottom,
       const vector<Blob<Dtype>*>& top) {
-    try {
-      self_.attr("setup")(bottom, top);
-    } catch (bp::error_already_set) {
-      PyErr_Print();
-      throw;
-    }
+    self_.attr("setup")(bottom, top);
   }
-
   virtual void Reshape(const vector<Blob<Dtype>*>& bottom,
       const vector<Blob<Dtype>*>& top) {
-    try {
-      self_.attr("reshape")(bottom, top);
-    } catch (bp::error_already_set) {
-      PyErr_Print();
-      throw;
-    }
+    self_.attr("reshape")(bottom, top);
   }
 
   virtual inline const char* type() const { return "Python"; }
 
  protected:
   virtual void Forward_cpu(const vector<Blob<Dtype>*>& bottom,
       const vector<Blob<Dtype>*>& top) {
-    try {
-      self_.attr("forward")(bottom, top);
-    } catch (bp::error_already_set) {
-      PyErr_Print();
-      throw;
-    }
+    self_.attr("forward")(bottom, top);
   }
   virtual void Backward_cpu(const vector<Blob<Dtype>*>& top,
       const vector<bool>& propagate_down, const vector<Blob<Dtype>*>& bottom) {
-    try {
-      self_.attr("backward")(top, propagate_down, bottom);
-    } catch (bp::error_already_set) {
-      PyErr_Print();
-      throw;
-    }
+    self_.attr("backward")(top, propagate_down, bottom);
   }
 
  private:

python/caffe/test/test_python_layer.py

@@ -21,6 +21,13 @@ def backward(self, top, propagate_down, bottom):
         bottom[0].diff[...] = 10 * top[0].diff
 
 
+class ExceptionLayer(caffe.Layer):
+    """A layer for checking exceptions from Python"""
+
+    def setup(self, bottom, top):
+        raise RuntimeError
+
+
 def python_net_file():
     with tempfile.NamedTemporaryFile(delete=False) as f:
         f.write("""name: 'pythonnet' force_backward: true
@@ -34,6 +41,16 @@ def python_net_file():
         return f.name
 
 
+def exception_net_file():
+    with tempfile.NamedTemporaryFile(delete=False) as f:
+        f.write("""name: 'pythonnet' force_backward: true
+        input: 'data' input_shape { dim: 10 dim: 9 dim: 8 }
+        layer { type: 'Python' name: 'layer' bottom: 'data' top: 'top'
+          python_param { module: 'test_python_layer' layer: 'ExceptionLayer' } }
+          """)
+        return f.name
+
+
 class TestPythonLayer(unittest.TestCase):
     def setUp(self):
         net_file = python_net_file()
@@ -61,3 +78,8 @@ def test_reshape(self):
         for blob in self.net.blobs.itervalues():
             for d in blob.data.shape:
                 self.assertEqual(s, d)
+
+    def test_exception(self):
+        net_file = exception_net_file()
+        self.assertRaises(RuntimeError, caffe.Net, net_file, caffe.TEST)
+        os.remove(net_file)

tools/caffe.cpp

@@ -8,6 +8,11 @@
 #include "boost/algorithm/string.hpp"
 #include "caffe/caffe.hpp"
 
+#ifdef WITH_PYTHON_LAYER
+#include "boost/python.hpp"
+namespace bp = boost::python;
+#endif
+
 using caffe::Blob;
 using caffe::Caffe;
 using caffe::Net;
@@ -304,7 +309,16 @@ int main(int argc, char** argv) {
   // Run tool or show usage.
   caffe::GlobalInit(&argc, &argv);
   if (argc == 2) {
-    return GetBrewFunction(caffe::string(argv[1]))();
+#ifdef WITH_PYTHON_LAYER
+    try {
+#endif
+      return GetBrewFunction(caffe::string(argv[1]))();
+#ifdef WITH_PYTHON_LAYER
+    } catch (bp::error_already_set) {
+      PyErr_Print();
+      return 1;
+    }
+#endif
   } else {
     gflags::ShowUsageWithFlagsRestrict(argv[0], "tools/caffe");
   }