[refactor] Split GraphBuilder out of Graph class

python/taichi/examples/graph/mpm88_graph.py

@@ -119,11 +119,11 @@ def init_particles(x: ti.any_arr(field_dim=1), v: ti.any_arr(field_dim=1),
         sym_J = ti.graph.Arg(ti.graph.ArgKind.NDARRAY, 'J', ti.f32)
         sym_grid_v = ti.graph.Arg(ti.graph.ArgKind.NDARRAY, 'grid_v', ti.f32, element_shape=(2, ))
         sym_grid_m = ti.graph.Arg(ti.graph.ArgKind.NDARRAY, 'grid_m', ti.f32)
-        g_init = ti.graph.Graph()
-        g_init.dispatch(init_particles, sym_x, sym_v, sym_J)
+        g_init_builder = ti.graph.GraphBuilder()
+        g_init_builder.dispatch(init_particles, sym_x, sym_v, sym_J)
 
-        g_update = ti.graph.Graph()
-        substep = g_update.create_sequential()
+        g_update_builder = ti.graph.GraphBuilder()
+        substep = g_update_builder.create_sequential()
 
         substep.dispatch(substep_reset_grid, sym_grid_v, sym_grid_m)
         substep.dispatch(substep_p2g, sym_x, sym_v, sym_C, sym_J, sym_grid_v,
@@ -132,11 +132,11 @@ def init_particles(x: ti.any_arr(field_dim=1), v: ti.any_arr(field_dim=1),
         substep.dispatch(substep_g2p, sym_x, sym_v, sym_C, sym_J, sym_grid_v)
 
         for i in range(N_ITER):
-            g_update.append(substep)
+            g_update_builder.append(substep)
 
         # Compile
-        g_init.compile()
-        g_update.compile()
+        g_init = g_init_builder.compile()
+        g_update = g_update_builder.compile()
 
         # Run
         g_init.run({'x': x, 'v': v, 'J': J})

python/taichi/graph/_graph.py

@@ -25,10 +25,9 @@ def dispatch(self, kernel_fn, *args):
         self.seq_.dispatch(kernel_cpp, args)
 
 
-class Graph:
+class GraphBuilder:
     def __init__(self):
         self._graph_builder = _ti_core.GraphBuilder()
-        self._compiled_graph = None
 
     def dispatch(self, kernel_fn, *args):
         kernel_cpp = gen_cpp_kernel(kernel_fn, args)
@@ -43,7 +42,12 @@ def append(self, node):
         self._graph_builder.seq().append(node.seq_)
 
     def compile(self):
-        self._compiled_graph = self._graph_builder.compile()
+        return Graph(self._graph_builder.compile())
+
+
+class Graph:
+    def __init__(self, compiled_graph) -> None:
+        self._compiled_graph = compiled_graph
 
     def run(self, args):
         arg_ptrs = {}
@@ -65,4 +69,4 @@ def run(self, args):
         self._compiled_graph.run(arg_ptrs, arg_ints, arg_floats)
 
 
-__all__ = ['Graph', 'Arg', 'ArgKind']
+__all__ = ['GraphBuilder', 'Graph', 'Arg', 'ArgKind']

tests/python/test_aot.py

@@ -736,11 +736,11 @@ def init_particles(x: ti.any_arr(field_dim=1), v: ti.any_arr(field_dim=1),
                               'grid_m',
                               ti.f32,
                               element_shape=())
-    g_init = ti.graph.Graph()
-    g_init.dispatch(init_particles, sym_x, sym_v, sym_J)
+    g_init_builder = ti.graph.GraphBuilder()
+    g_init_builder.dispatch(init_particles, sym_x, sym_v, sym_J)
 
-    g_update = ti.graph.Graph()
-    substep = g_update.create_sequential()
+    g_update_builder = ti.graph.GraphBuilder()
+    substep = g_update_builder.create_sequential()
 
     substep.dispatch(substep_reset_grid, sym_grid_v, sym_grid_m)
     substep.dispatch(substep_p2g, sym_x, sym_v, sym_C, sym_J, sym_grid_v,
@@ -749,10 +749,10 @@ def init_particles(x: ti.any_arr(field_dim=1), v: ti.any_arr(field_dim=1),
     substep.dispatch(substep_g2p, sym_x, sym_v, sym_C, sym_J, sym_grid_v)
 
     for i in range(N_ITER):
-        g_update.append(substep)
+        g_update_builder.append(substep)
 
-    g_init.compile()
-    g_update.compile()
+    g_init = g_init_builder.compile()
+    g_update = g_update_builder.compile()
 
     x = ti.Vector.ndarray(2, ti.f32, shape=(n_particles))
     v = ti.Vector.ndarray(2, ti.f32, shape=(n_particles))

tests/python/test_graph.py

@@ -14,10 +14,10 @@ def test(pos: ti.types.ndarray(field_dim=1, element_shape=())):
             pos[i] = 1
 
     sym_pos = ti.graph.Arg(ti.graph.ArgKind.NDARRAY, 'pos', ti.i32)
-    g_init = ti.graph.Graph()
+    g_init = ti.graph.GraphBuilder()
     g_init.dispatch(test, sym_pos)
-    g_init.compile()
+    g = g_init.compile()
 
     a = ti.ndarray(ti.i32, shape=(n, ))
-    g_init.run({'pos': a})
+    g.run({'pos': a})
     assert (a.to_numpy() == np.ones(4)).all()