use function pointer for updater dispatching

paddle/go/pserver/optimizer.c

@@ -2,21 +2,35 @@
 
 #include "optimizer.h"
 
-typedef struct {
-  double learning_rate;
-} SGD_optimizer;
+typedef int (*update_func)(void*, void *, paddle_element_type, const void*, int);
 
-paddle_optimizer* paddle_create_SGD_optimizer(double learning_rate) {
-  SGD_optimizer* o = (SGD_optimizer*)malloc(sizeof(SGD_optimizer));
-  o->learning_rate = learning_rate;
-  return (paddle_optimizer*)o;
-}
+typedef struct paddle_optimizer{
+  update_func func;
+  void* optimizer;
+} paddle_optimizer;
 
 void paddle_release_optimizer(paddle_optimizer* o) {
   free(o);
 }
 
-int paddle_update_parameter(paddle_optimizer* o, void *buffer, paddle_element_type datatype, const void* gradient, int num_bytes) {
+int paddle_update_parameter(paddle_optimizer* o, void *buffer, paddle_element_type element_type, const void* gradient, int num_bytes) {
+  return o->func(o->optimizer, buffer, element_type, gradient, num_bytes);
+}
+
+typedef struct {
+  double learning_rate;
+} SGD_optimizer;
+
+int paddle_SGD_update_parameter(void* optimizer, void *buffer, paddle_element_type element_type, const void* gradient, int num_bytes) {
   // TODO
   return 0;
 }
+
+paddle_optimizer* paddle_create_SGD_optimizer(double learning_rate) {
+  SGD_optimizer* o = (SGD_optimizer*)malloc(sizeof(SGD_optimizer));
+  o->learning_rate = learning_rate;
+  paddle_optimizer* container = (paddle_optimizer*)malloc(sizeof(paddle_optimizer));
+  container->func = paddle_SGD_update_parameter;
+  container->optimizer = o;
+  return container;
+}

paddle/go/pserver/optimizer.go

@@ -18,7 +18,7 @@ const (
 var nullPtr = unsafe.Pointer(uintptr(0))
 
 type optimizer struct {
-	opt *C.paddle_optimizer
+	opt *C.struct_paddle_optimizer
 }
 
 func newOptimizer(t optimizerType, learning_rate float64) *optimizer {
@@ -46,6 +46,6 @@ func (o *optimizer) UpdateParameter(p Parameter, g Gradient) error {
 func (o *optimizer) Cleanup() {
 	if unsafe.Pointer(o.opt) != nullPtr {
 		C.paddle_release_optimizer(o.opt)
-		o.opt = (*C.paddle_optimizer)(nullPtr)
+		o.opt = (*C.struct_paddle_optimizer)(nullPtr)
 	}
 }

paddle/go/pserver/optimizer.h

@@ -10,10 +10,9 @@ typedef enum {
   PADDLE_ELEMENT_TYPE_FLOAT64 = 5,
 } paddle_element_type;
 
-typedef struct paddle_optimizer paddle_optimizer;
-
-paddle_optimizer* paddle_create_SGD_optimizer(double learning_rate);
-void paddle_release_optimizer(paddle_optimizer* o);
-int paddle_update_parameter(paddle_optimizer* o, void *buffer, paddle_element_type datatype, const void* gradient, int num_bytes);
+struct paddle_optimizer;
+struct paddle_optimizer* paddle_create_SGD_optimizer(double learning_rate);
+void paddle_release_optimizer(struct paddle_optimizer* o);
+int paddle_update_parameter(struct paddle_optimizer* o, void *buffer, paddle_element_type element_type, const void* gradient, int num_bytes);
 
 #endif /* PADDLE_PSERVER_OPTIMIZER_H */