Python cpp sync (#4816)

* add sync_with_cpp to Python Program and Block

* sync vars and ops in block from cpp

* optimize code and add some comment

* add more check for sync

python/paddle/v2/framework/framework.py

@@ -308,6 +308,9 @@ class Block(object):
     def create_var(self, *args, **kwargs):
         return Variable(self, *args, **kwargs)
 
+    def has_var(self, name):
+        return name in self.vars
+
     def create_parameter(self, *args, **kwargs):
         global_block = self.program.global_block()
         return Parameter(global_block, *args, **kwargs)
@@ -324,6 +327,43 @@ class Block(object):
         self.ops.appendleft(op)
         return op
 
+    def sync_with_cpp(self):
+        # sync variables from cpp
+        for var in self.desc.all_vars():
+            if not self.has_var(var.name()):
+                self.create_var(name=var.name(), desc=var, type=var.type())
+
+        # sync operators from cpp
+        ops_in_cpp = self.desc.all_ops()
+        first_op_in_python = self.ops[0].desc
+        last_op_in_python = self.ops[len(self.ops) - 1].desc
+        start_index = None
+        end_index = None
+        for index in range(len(ops_in_cpp)):
+            if first_op_in_python == ops_in_cpp[index]:
+                start_index = index
+            if last_op_in_python == ops_in_cpp[index]:
+                end_index = index
+        assert start_index is not None
+        assert end_index is not None
+        assert start_index <= end_index
+
+        # sync ops append to the head of cpp_ops
+        for index in range((start_index - 1 - 1), -1, -1):
+            op_desc = ops_in_cpp[index]
+            op = Operator(self, op_desc)
+            self.ops.appendleft(op)
+
+        # sync ops append to the end of cpp_ops
+        for index in range((end_index + 1), len(ops_in_cpp)):
+            op_desc = ops_in_cpp[index]
+            op = Operator(self, op_desc)
+            self.ops.append(op)
+
+        assert len(self.ops) == len(ops_in_cpp)
+        for index in range(len(self.ops)):
+            assert self.ops[index].desc == ops_in_cpp[index]
+
 
 class Program(object):
     @classmethod
@@ -354,6 +394,12 @@ class Program(object):
     def current_block(self):
         return self.blocks[self.current_block_idx]
 
+    def append_backward(self, target, no_grad_set):
+        assert isinstance(target, Variable)
+        param_to_grad_info = self.desc.append_backward(target.desc, no_grad_set)
+        self.sync_with_cpp()
+        return param_to_grad_info
+
     def create_block(self):
         new_block_idx = len(self.blocks)
         self.desc.append_block(self.current_block().desc)
@@ -364,6 +410,12 @@ class Program(object):
     def rollback(self):
         self.current_block_idx = self.current_block().parent_idx
 
+    def sync_with_cpp(self):
+        for block_idx in range(len(self.blocks), self.desc.num_blocks()):
+            self.blocks.append(Block(self, block_idx))
+        for block in self.blocks:
+            block.sync_with_cpp()
+
 
 class Parameter(Variable):
     def __init__(self, block, shape, dtype, **kwargs):

python/paddle/v2/framework/tests/test_program.py

@@ -1,6 +1,7 @@
 import unittest
 
 import paddle.v2.framework.core as core
+from paddle.v2.framework.framework import Program
 from paddle.v2.framework.framework import g_program
 
 
@@ -33,7 +34,7 @@ class TestProgram(unittest.TestCase):
         self.assertEqual(1, b.idx)
         self.assertEqual(0, b.parent_idx)
 
-    def test_append_backward(self):
+    def test_desc_append_backward(self):
         prog = core.ProgramDesc.__create_program_desc__()
         self.assertIsNotNone(prog)
         block = prog.block(0)
@@ -71,6 +72,24 @@ class TestProgram(unittest.TestCase):
             actual_ops.append(op.type())
         self.assertEqual(actual_ops, expect_ops)
 
+    def test_append_backward(self):
+        prog = Program.instance()
+        block = prog.global_block()
+
+        mul_x = block.create_parameter(
+            dtype="float32", shape=[5, 10], lod_level=0, name="mul.x")
+        mul_y = block.create_var(
+            dtype="float32", shape=[10, 8], lod_level=0, name="mul.y")
+        mul_out = block.create_var(
+            dtype="float32", shape=[5, 8], lod_level=0, name="mul.out")
+        mul_op = block.append_op(
+            type="mul",
+            inputs={"X": [mul_x],
+                    "Y": mul_y},
+            outputs={"Out": [mul_out]},
+            attrs={"x_num_col_dims": 1})
+        param_to_grad = prog.append_backward(mul_out, set())
+
 
 if __name__ == '__main__':
     unittest.main()