Enable use json for graph attr exchange (#5)

nnvm/include/nnvm/c_api.h

@@ -248,26 +248,33 @@ NNVM_DLL int NNGraphFree(GraphHandle handle);
  */
 NNVM_DLL int NNGraphGetSymbol(GraphHandle graph, SymbolHandle *symbol);
 /*!
- * \brief Get Set a std::string typed attribute to graph.
+ * \brief Get Set a attribute in json format.
+ * This feature allows pass graph attributes back and forth in reasonable speed.
+ *
  * \param handle The graph handle.
  * \param key The key to the attribute.
- * \param value The value to be exposed.
+ * \param json_value The value need to be in format [type_name, value],
+ *  Where type_name is a registered type string in C++ side via DMLC_JSON_ENABLE_ANY.
  * \return 0 when success, -1 when failure happens
  */
-NNVM_DLL int NNGraphSetStrAttr(GraphHandle handle,
+NNVM_DLL int NNGraphSetJSONAttr(GraphHandle handle,
                                 const char* key,
-                               const char* value);
+                                const char* json_value);
 /*!
- * \brief Get Set a std::string typed attribute from graph attribute.
+ * \brief Get a serialized attrirbute from graph.
+ * This feature allows pass graph attributes back and forth in reasonable speed.
+ *
  * \param handle The graph handle.
  * \param key The key to the attribute.
- * \param out The result attribute, can be NULL if the attribute do not exist.
+ * \param json_out The result attribute, can be NULL if the attribute do not exist.
+ *  The json_out is an array of [type_name, value].
+ *  Where the type_name is a registered type string in C++ side via DMLC_JSON_ENABLE_ANY.
  * \param success Whether the result is contained in out.
  * \return 0 when success, -1 when failure happens
  */
-NNVM_DLL int NNGraphGetStrAttr(SymbolHandle handle,
+NNVM_DLL int NNGraphGetJSONAttr(SymbolHandle handle,
                                 const char* key,
-                               const char** out,
+                                const char** json_out,
                                 int *success);
 /*!
  * \brief Apply pass on the src graph.

nnvm/python/nnvm/base.py

@@ -47,6 +47,7 @@ SymbolCreatorHandle = ctypes.c_void_p
 SymbolHandle = ctypes.c_void_p
 GraphHandle = ctypes.c_void_p
 
+
 #----------------------------
 # helper function definition
 #----------------------------

nnvm/python/nnvm/graph.py

@@ -5,12 +5,14 @@ from __future__ import absolute_import as _abs
 
 import ctypes
 import sys
+import json
 from .base import _LIB
 from .base import c_array, c_str, nn_uint, py_str, string_types
 from .base import GraphHandle, SymbolHandle
 from .base import check_call
 from .symbol import Symbol
 
+
 class Graph(object):
     """Graph is the graph object that can be used to apply optimization pass.
     It contains additional graphwise attribute besides the internal symbol.
@@ -31,7 +33,7 @@ class Graph(object):
     def __del__(self):
         check_call(_LIB.NNGraphFree(self.handle))
 
-    def attr(self, key):
+    def json_attr(self, key):
         """Get attribute string from the graph.
 
         Parameters
@@ -46,24 +48,33 @@ class Graph(object):
         """
         ret = ctypes.c_char_p()
         success = ctypes.c_int()
-        check_call(_LIB.NNGraphGetStrAttr(
+        check_call(_LIB.NNGraphGetJSONAttr(
             self.handle, c_str(key), ctypes.byref(ret), ctypes.byref(success)))
         if success.value != 0:
-            return py_str(ret.value)
+            json_str = py_str(ret.value)
+            return json.loads(json_str)[1]
         else:
             return None
 
-    def _set_attr(self, **kwargs):
+    def _set_json_attr(self, key, value, type_name=None):
         """Set the attribute of the symbol.
 
         Parameters
         ----------
-        **kwargs
-            The attributes to set
+        key : string
+            The key of the attribute
+        value : value
+            The any type that can be dumped to json
+        type_name : string
+            The typename registered on c++ side.
         """
-        for k, v in kwargs.items():
-            check_call(_LIB.NNGraphSetStrAttr(
-                self.handle, c_str(k), c_str(v)))
+        if isinstance(value, string_types):
+            type_name = 'str'
+        elif type_name is None:
+            raise ValueError("Need to specify type_name")
+        json_value = json.dumps([type_name, value])
+        check_call(_LIB.NNGraphSetJSONAttr(
+            self.handle, c_str(key), c_str(json_value)))
 
     @property
     def symbol(self):

nnvm/src/c_api/c_api_graph.cc

@@ -8,6 +8,7 @@
 #include <nnvm/symbolic.h>
 #include <nnvm/graph.h>
 #include <nnvm/pass.h>
+#include <dmlc/json.h>
 #include "./c_api_common.h"
 
 using namespace nnvm;
@@ -34,26 +35,35 @@ int NNGraphGetSymbol(GraphHandle graph, SymbolHandle *symbol) {
   API_END_HANDLE_ERROR(delete s);
 }
 
-int NNGraphSetStrAttr(GraphHandle handle,
+int NNGraphSetJSONAttr(GraphHandle handle,
                        const char* key,
-                      const char* value) {
+                       const char* json_value) {
   API_BEGIN();
   Graph* g = static_cast<Graph*>(handle);
-  g->attrs[std::string(key)] = std::make_shared<any>(std::string(value));
+  std::string temp(json_value);
+  std::istringstream is(temp);
+  dmlc::JSONReader reader(&is);
+  nnvm::any value;
+  reader.Read(&value);
+  g->attrs[std::string(key)] = std::make_shared<any>(std::move(value));
   API_END();
 }
 
-int NNGraphGetStrAttr(GraphHandle handle,
+int NNGraphGetJSONAttr(GraphHandle handle,
                       const char* key,
-                      const char** out,
+                      const char** json_out,
                       int *success) {
+  NNAPIThreadLocalEntry *ret = NNAPIThreadLocalStore::Get();
   API_BEGIN();
   Graph* g = static_cast<Graph*>(handle);
   std::string skey(key);
   auto it = g->attrs.find(skey);
   if (it != g->attrs.end()) {
-    const std::string& str = nnvm::get<std::string>(*it->second.get());
-    *out = str.c_str();
+    std::ostringstream os;
+    dmlc::JSONWriter writer(&os);
+    writer.Write(*it->second.get());
+    ret->ret_str = os.str();
+    *json_out = (ret->ret_str).c_str();
     *success = 1;
   } else {
     *success = 0;

nnvm/src/pass/saveload_json.cc

@@ -203,5 +203,9 @@ NNVM_REGISTER_PASS(SaveJSON)
 .set_change_graph(true)
 .provide_graph_attr("json");
 
+
+DMLC_JSON_ENABLE_ANY(std::string, str);
+DMLC_JSON_ENABLE_ANY(std::vector<int>, list_int);
+
 }  // namespace pass
 }  // namespace nnvm

nnvm/tests/python/test_graph.py

@@ -6,9 +6,18 @@ def test_json_pass():
     y = sym.conv2d(data=x, name='conv', stride=(2,2))
     g = graph.create(y)
     ret = g.apply('SaveJSON')
+    ret._set_json_attr('json', ret.json_attr('json'))
     g2 = ret.apply('LoadJSON')
-    assert g2.apply('SaveJSON').attr('json') == ret.attr('json')
+    assert g2.apply('SaveJSON').json_attr('json') == ret.json_attr('json')
+
+def test_graph_json_attr():
+    x = sym.Variable('x')
+    y = sym.conv2d(data=x, name='conv', stride=(2,2))
+    g = graph.create(y)
+    g._set_json_attr('ilist', [1,2,3], 'list_int')
+    assert g.json_attr('ilist') == [1,2,3]
 
 
 if __name__ == "__main__":
+    test_graph_json_attr()
     test_json_pass()