Base sink: add buffer util functions (#65)

* Pull waterfall get_plot_data binding to base_sink

And make is so returned array has proper length

* Add function to poll number of items in buffer of base_sinks

include/bokehgui/base_sink.h

@@ -123,11 +123,16 @@ namespace gr {
 
       int get_buff_size(){
         if (!d_buffers.size()) {
+          // printf("The buffer is empty, returning 0\n");
           return 0;
         }
         return d_buffers.front()[0].size();
       }
 
+      int get_buff_num_items(){
+        return d_buffers.size();
+      }
+
       int get_buff_cols(){
         return (sizeof(T)/sizeof(float))*d_nconnections;
       }

python/bindings/base_sink_python.cc

@@ -51,9 +51,14 @@ void bind_base_sink_template(py::module& m, const char* classname)
             D(base_sink,get_nconnections)
         )
 
+        .def("get_buff_num_items",&base_sink::get_buff_num_items,
+            D(base_sink,get_buff_num_items)
+        )
+
         .def("get_plot_data", [](base_sink &m){
+          int buff_size = m.get_buff_size();
           return py::array_t<float>(
-            {m.get_buff_cols(), m.get_buff_size()}, // shape
+            {m.get_buff_cols(), buff_size}, // shape
             m.get_plot_data() // the data pointer
           );
         });

python/bindings/docstrings/base_sink_pydoc_template.h

@@ -40,4 +40,7 @@
  static const char *__doc_gr_bokehgui_base_sink_get_nconnections = R"doc()doc";
 
 
+ static const char *__doc_gr_bokehgui_base_sink_get_buff_num_items = R"doc()doc";
+
+
  static const char *__doc_gr_bokehgui_base_sink_get_plot_data = R"doc()doc";

python/bindings/waterfall_sink_f_proc_python.cc

@@ -105,12 +105,6 @@ void bind_waterfall_sink_f_proc(py::module& m)
         )
 
 
-        .def("get_plot_data", [](waterfall_sink_f_proc &m){
-          return py::array_t<float>(
-            {m.get_buff_cols(), m.get_buff_size()}, // shape
-            m.get_plot_data() // the data pointer
-          );
-        });
         // .def_buffer([] (waterfall_sink_f_proc &m) -> py::buffer_info {
         //     return py::buffer_info(
         //     m.get_plot_data(),                      /* Pointer to buffer */