modify pserver client C API, create better test

Please refer to the change design doc for what in API have changed.

doc/design/cluster_train/pserver_client.md

@@ -74,14 +74,25 @@ typedef enum {
 typedef struct {
   char*               name;
   paddle_element_type element_type;
-  void*               content;
+  unsigned char*      content;
   int                 content_len;
 } paddle_parameter, paddle_gradient;
 
-typedef struct paddle_pserver_client paddle_pserver_client;
+typedef int paddle_pserver_client;
 
-paddle_pserver_client* paddle_new_pserver_client();
-void paddle_pserver_client_release(paddle_pserver_client* client);
+/**
+ * @brief creates a pserver client that talks to etcd for coordination.
+ */
+paddle_pserver_client paddle_new_etcd_pserver_client(char* etcd_addr);
+
+/**
+ * @brief creates a pserver client given pserver addresses.
+ *
+ * @param pserver_addrs comma-separated pserver addresses.
+ * @param selected if current pserver client is selected to initialize all parameter servers.
+ */
+paddle_pserver_client paddle_new_pserver_client(char* pserver_addrs, int selected);
+void paddle_pserver_client_release(paddle_pserver_client c);
 
 /**
  * @brief paddle_begin_init_params begins to initialize parameters on
@@ -95,7 +106,7 @@ void paddle_pserver_client_release(paddle_pserver_client* client);
  * @return 1 if the trainer is selected to initialize parameter
  * servers, otherwise 0.
  */
-int paddle_begin_init_params(paddle_pserver_client* client);
+int paddle_begin_init_params(paddle_pserver_client client);
 
 /**
  * @brief paddle_init_param initializes the parameter on parameter
@@ -109,7 +120,7 @@ int paddle_begin_init_params(paddle_pserver_client* client);
  * @paddle_begin_init_param). Or simply exit the program and wait for
  * the cluster management system to restart the trainer.
  */
-int paddle_init_param(paddle_pserver_client* client, paddle_parameter param, const unsigned char* param_config_proto, int config_len);
+int paddle_init_param(paddle_pserver_client client, paddle_parameter param, const unsigned char* param_config_proto, int config_len);
 
 /**
  * @brief paddle_finish_init_params tells parameter servers client has
@@ -120,7 +131,7 @@ int paddle_init_param(paddle_pserver_client* client, paddle_parameter param, con
  * @paddle_begin_init_param). Or simply exit the program and wait for
  * the cluster management system to restart the trainer.
  */
-int paddle_finish_init_params(paddle_pserver_client* client);
+int paddle_finish_init_params(paddle_pserver_client client);
 
 /**
  * @brief paddle_send_grads sends gradients to parameter servers for
@@ -131,7 +142,7 @@ int paddle_finish_init_params(paddle_pserver_client* client);
  * @param learning_rate the learning rate for the gradients.
  * @return 0 if successful, otherwise -1.
  */
-int paddle_send_grads(paddle_pserver_client* client, const paddle_gradient* grads, int len);
+int paddle_send_grads(paddle_pserver_client client, const paddle_gradient* grads, int len);
 
 /**
  * @brief paddle_get_params gets parameters from parameter servers.
@@ -139,13 +150,15 @@ int paddle_send_grads(paddle_pserver_client* client, const paddle_gradient* grad
  * paddle_get_params will block until parameters are initialized on
  * the parameter servers.
  *
- * @param names the array of names of the parameters to get.
- * @param dst the destination array of parameters to save to.
+ * @param dst the destination array of parameter pointers to save to.
+ * The parameter pointer must be pre-popullated with required parameter name,
+ * and the content of parameter must be pre-allocated of the size of required
+ * parameter on pserver.
  * @param len the length of the names array and the paddle_parameter
  * array.
  * @return 0 if successful, otherwise -1.
  */
-int paddle_get_params(paddle_pserver_client* client, const char** names, paddle_parameter* dst, int len);
+int paddle_get_params(paddle_pserver_client client, paddle_parameter** dst, int len);
 
 /**
  * @brief paddle_save_model indicates parameters to save the parameter
@@ -154,5 +167,5 @@ int paddle_get_params(paddle_pserver_client* client, const char** names, paddle_
  * @param path the path to save parameters.
  * @return 0 if successful, otherwise -1.
  */
-int paddle_save_model(paddle_pserver_client* client, const char* path);
+int paddle_save_model(paddle_pserver_client client, const char* path);
 ```

go/pserver/cclient/cclient.go

@@ -19,21 +19,7 @@ typedef struct {
   int                 content_len;
 } paddle_parameter, paddle_gradient;
 
-static inline void paddle_release_param(paddle_parameter* param) {
-  if (param != NULL) {
-    if (param->name != NULL) {
-      free(param->name);
-    }
-
-    if (param->content != NULL) {
-      free(param->content);
-    }
-
-    free(param);
-  }
-}
-
-typedef int client;
+typedef int paddle_pserver_client;
 */
 import "C"
 
@@ -48,10 +34,10 @@ import (
 
 var nullPtr = unsafe.Pointer(uintptr(0))
 var mu sync.Mutex
-var handleMap = make(map[C.client]*pserver.Client)
-var curHandle C.client
+var handleMap = make(map[C.paddle_pserver_client]*pserver.Client)
+var curHandle C.paddle_pserver_client
 
-func add(c *pserver.Client) C.client {
+func add(c *pserver.Client) C.paddle_pserver_client {
 	mu.Lock()
 	defer mu.Unlock()
 	client := curHandle
@@ -60,13 +46,13 @@ func add(c *pserver.Client) C.client {
 	return client
 }
 
-func get(client C.client) *pserver.Client {
+func get(client C.paddle_pserver_client) *pserver.Client {
 	mu.Lock()
 	defer mu.Unlock()
 	return handleMap[client]
 }
 
-func remove(client C.client) *pserver.Client {
+func remove(client C.paddle_pserver_client) *pserver.Client {
 	mu.Lock()
 	defer mu.Unlock()
 	h := handleMap[client]
@@ -100,7 +86,7 @@ func (l lister) List() []pserver.Server {
 }
 
 //export paddle_new_pserver_client
-func paddle_new_pserver_client(addrs *C.char, selected int) C.client {
+func paddle_new_pserver_client(addrs *C.char, selected int) C.paddle_pserver_client {
 	a := C.GoString(addrs)
 	as := strings.Split(a, ",")
 	servers := make([]pserver.Server, len(as))
@@ -113,18 +99,18 @@ func paddle_new_pserver_client(addrs *C.char, selected int) C.client {
 }
 
 //export paddle_new_etcd_pserver_client
-func paddle_new_etcd_pserver_client(etcd_addr *C.char) C.client {
+func paddle_new_etcd_pserver_client(etcd_addr *C.char) C.paddle_pserver_client {
 	// TODO(helin): fault tolerant pserver client using etcd.
 	panic("not implemented.")
 }
 
 //export paddle_pserver_client_release
-func paddle_pserver_client_release(client C.client) {
+func paddle_pserver_client_release(client C.paddle_pserver_client) {
 	remove(client)
 }
 
 //export paddle_begin_init_params
-func paddle_begin_init_params(client C.client) C.int {
+func paddle_begin_init_params(client C.paddle_pserver_client) C.int {
 	c := get(client)
 	if selected := c.BeginInitParams(); selected {
 		return 1
@@ -133,7 +119,7 @@ func paddle_begin_init_params(client C.client) C.int {
 }
 
 //export paddle_init_param
-func paddle_init_param(client C.client, param C.paddle_parameter, param_config unsafe.Pointer, config_len C.int) C.int {
+func paddle_init_param(client C.paddle_pserver_client, param C.paddle_parameter, param_config unsafe.Pointer, config_len C.int) C.int {
 	et := pserver.ElementType(param.element_type)
 	name := C.GoString(param.name)
 	content := cArrayToSlice(unsafe.Pointer(param.content), int(param.content_len))
@@ -143,7 +129,12 @@ func paddle_init_param(client C.client, param C.paddle_parameter, param_config u
 	}
 	c := get(client)
 	err := c.InitParam(pc)
+
 	if err != nil {
+		if err.Error() == pserver.AlreadyInitialized {
+			log.Println("parameter", name, "already initialized, treat paddle_init_param as sucessful.")
+			return 0
+		}
 		log.Println(err)
 		return -1
 	}
@@ -152,10 +143,15 @@ func paddle_init_param(client C.client, param C.paddle_parameter, param_config u
 }
 
 //export paddle_finish_init_params
-func paddle_finish_init_params(client C.client) C.int {
+func paddle_finish_init_params(client C.paddle_pserver_client) C.int {
 	c := get(client)
 	err := c.FinishInitParams()
 	if err != nil {
+		if err.Error() == pserver.AlreadyInitialized {
+			log.Println("parameters already initialized, treat paddle_finish_init_params as sucessful.")
+			return 0
+		}
+
 		log.Println(err)
 		return -1
 	}
@@ -164,7 +160,7 @@ func paddle_finish_init_params(client C.client) C.int {
 }
 
 //export paddle_send_grads
-func paddle_send_grads(client C.client, grads *C.paddle_gradient, total C.int) C.int {
+func paddle_send_grads(client C.paddle_pserver_client, grads *C.paddle_gradient, total C.int) C.int {
 	var gs []pserver.Gradient
 	for i := 0; i < int(total); i++ {
 		grad := (*C.paddle_gradient)(unsafe.Pointer((uintptr(unsafe.Pointer(grads)) + uintptr(i)*unsafe.Sizeof(*grads))))
@@ -185,11 +181,11 @@ func paddle_send_grads(client C.client, grads *C.paddle_gradient, total C.int) C
 }
 
 //export paddle_get_params
-func paddle_get_params(client C.client, names **C.char, dst **C.paddle_parameter, total C.int) C.int {
+func paddle_get_params(client C.paddle_pserver_client, dst **C.paddle_parameter, total C.int) C.int {
 	var ns []string
 	for i := 0; i < int(total); i++ {
-		name := *(**C.char)(unsafe.Pointer((uintptr(unsafe.Pointer(names)) + uintptr(i)*unsafe.Sizeof(*names))))
-		ns = append(ns, C.GoString(name))
+		param := *(**C.paddle_parameter)(unsafe.Pointer((uintptr(unsafe.Pointer(dst)) + uintptr(i)*unsafe.Sizeof(*dst))))
+		ns = append(ns, C.GoString(param.name))
 	}
 	c := get(client)
 	ps, err := c.GetParams(ns)
@@ -198,44 +194,32 @@ func paddle_get_params(client C.client, names **C.char, dst **C.paddle_parameter
 		return -1
 	}
 
-	for i := 0; i < int(total); i++ {
-		if i >= len(ps) {
-			break
+	if len(ps) != len(ns) {
+		return -1
+	}
+
+	for i := range ps {
+		if ns[i] != ps[i].Name {
+			return -1
 		}
+	}
 
+	for i := 0; i < int(total); i++ {
 		p := ps[i]
 		param := *(**C.paddle_parameter)(unsafe.Pointer((uintptr(unsafe.Pointer(dst)) + uintptr(i)*unsafe.Sizeof(*dst))))
-		nameReady := false
-		contentAllocated := false
 
 		if unsafe.Pointer(param) == nullPtr {
-			param = (*C.paddle_parameter)(C.calloc(1, C.size_t(unsafe.Sizeof(*param))))
+			log.Println("Error: must pre-allocate parameter.")
+			return -1
 		} else {
-			if unsafe.Pointer(param.name) != nullPtr {
-				if n := C.GoString(param.name); n != p.Name {
-					log.Println("Warning: the pre-allocated parameter name does not match the parameter name, it will be freed.", n, p.Name)
-					C.free(unsafe.Pointer(param.name))
-				} else {
-					nameReady = true
-				}
-			}
-
 			if unsafe.Pointer(param.content) != nullPtr {
-				if int(param.content_len) == len(p.Content) {
-					contentAllocated = true
-				} else {
-					log.Println("Warning: the pre-allocated content len does not match parameter content len, the pre-allocated content will be freed.", param.content_len, len(p.Content))
-					C.free(unsafe.Pointer(param.content))
+				if int(param.content_len) != len(p.Content) {
+					log.Println("Error: the pre-allocated content len does not match parameter content len.", param.content_len, len(p.Content))
+					return -1
 				}
 			}
 		}
 
-		if !nameReady {
-			param.name = C.CString(p.Name)
-		}
-		if !contentAllocated {
-			param.content = (*C.uchar)(C.malloc(C.size_t(len(p.Content))))
-		}
 		C.memcpy(unsafe.Pointer(param.content), unsafe.Pointer(&p.Content[0]), C.size_t(len(p.Content)))
 		param.content_len = C.int(len(p.Content))
 		param.element_type = C.paddle_element_type(p.ElementType)
@@ -245,7 +229,7 @@ func paddle_get_params(client C.client, names **C.char, dst **C.paddle_parameter
 }
 
 //export paddle_save_model
-func paddle_save_model(client C.client, path *C.char) C.int {
+func paddle_save_model(client C.paddle_pserver_client, path *C.char) C.int {
 	p := C.GoString(path)
 	c := get(client)
 	err := c.Save(p)

go/pserver/cclient/test/CMakeLists.txt

@@ -7,5 +7,7 @@ add_dependencies(main client)
 
 if(APPLE)
   set(CMAKE_EXE_LINKER_FLAGS "-framework CoreFoundation -framework Security")
+else()
+  set(CMAKE_EXE_LINKER_FLAGS "-pthread")  
 endif()
 target_link_libraries(main ${CMAKE_BINARY_DIR}/libclient.a)

go/pserver/cclient/test/main.c

@@ -2,67 +2,87 @@
 
 #include "libclient.h"
 
-void fail() {
-  // TODO(helin): fix: gtest using cmake is not working, using this
-  // hacky way for now.
-  printf("test failed.\n");
+// TODO(helin): fix: gtest using cmake is not working, using this
+// hacky way for now.
+#define fail()                                          \
+  fprintf(stderr, "info: %s:%d: ", __FILE__, __LINE__); \
   exit(-1);
+
+void sendGrads(paddle_pserver_client c) {
+  unsigned char grad_a[2000] = {2};
+  unsigned char grad_b[3000] = {3};
+  paddle_gradient grads[2] = {
+      {"param_a", PADDLE_ELEMENT_TYPE_FLOAT32, grad_a, 2000},
+      {"param_b", PADDLE_ELEMENT_TYPE_FLOAT32, grad_b, 3000}};
+
+  if (paddle_send_grads(c, grads, 2)) {
+    fail();
+  }
+}
+
+void getParams(paddle_pserver_client c) {
+  paddle_parameter param_a;
+  paddle_parameter param_b;
+  char name_a[] = "param_a";
+  char name_b[] = "param_b";
+  // must pre-allocate the content for parameter to receive.
+  unsigned char content_a[2000] = {};
+  unsigned char content_b[3000] = {};
+  param_a.element_type = PADDLE_ELEMENT_TYPE_FLOAT32;
+  param_a.name = name_a;
+  param_a.content = content_a;
+  param_a.content_len = 2000;
+  param_b.element_type = PADDLE_ELEMENT_TYPE_FLOAT32;
+  param_b.name = name_b;
+  param_b.content = content_b;
+  param_b.content_len = 3000;
+
+  paddle_parameter* params[2] = {&param_a, &param_b};
+  if (paddle_get_params(c, params, 2)) {
+    fail();
+  }
 }
 
 int main() {
   char addr[] = "localhost:3000";
-  client c = paddle_new_pserver_client(addr, 1);
+  paddle_pserver_client c = paddle_new_pserver_client(addr, 1);
 retry:
   if (paddle_begin_init_params(c)) {
     paddle_parameter param;
     char name_a[] = "param_a";
     char name_b[] = "param_b";
-    unsigned char content[] = {0x00, 0x11, 0x22};
+    unsigned char content_a[2000] = {1};
+    unsigned char content_b[3000] = {0};
     param.element_type = PADDLE_ELEMENT_TYPE_FLOAT32;
     param.name = name_a;
-    param.content = content;
-    param.content_len = 3;
-    if (paddle_init_param(c, param, NULL, 0) != 0) {
+    param.content = content_a;
+    param.content_len = 2000;
+    int error = paddle_init_param(c, param, NULL, 0);
+    if (error != 0) {
       goto retry;
     }
-    param.element_type = PADDLE_ELEMENT_TYPE_INT32;
+
+    param.element_type = PADDLE_ELEMENT_TYPE_FLOAT32;
     param.name = name_b;
-    param.content = content;
-    param.content_len = 3;
-    if (paddle_init_param(c, param, NULL, 0) != 0) {
+    param.content = content_b;
+    param.content_len = 3000;
+    error = paddle_init_param(c, param, NULL, 0);
+    if (error != 0) {
       goto retry;
     }
-    if (paddle_finish_init_params(c) != 0) {
+
+    error = paddle_finish_init_params(c);
+    if (error != 0) {
       goto retry;
     }
-  } else {
-    fail();
-  }
-
-  unsigned char content[] = {0x00, 0x11, 0x22};
-  paddle_gradient grads[2] = {
-      {"param_a", PADDLE_ELEMENT_TYPE_INT32, content, 3},
-      {"param_b", PADDLE_ELEMENT_TYPE_FLOAT32, content, 3}};
-
-  if (!paddle_send_grads(c, grads, 2)) {
-    fail();
-  }
-
-  paddle_parameter* params[2] = {NULL, NULL};
-  char* names[] = {"param_a", "param_b"};
-  if (!paddle_get_params(c, names, params, 2)) {
-    fail();
   }
 
-  // get parameters again by reusing the allocated parameter buffers.
-  if (!paddle_get_params(c, names, params, 2)) {
-    fail();
+  for (int i = 0; i < 100; i++) {
+    sendGrads(c);
+    getParams(c);
   }
 
-  paddle_release_param(params[0]);
-  paddle_release_param(params[1]);
-
-  if (!paddle_save_model(c, "/tmp/")) {
+  if (paddle_save_model(c, "/tmp/")) {
     fail();
   }
 

go/pserver/client_test.go

@@ -117,7 +117,7 @@ func TestClientFull(t *testing.T) {
 
 	for i := range params {
 		if names[i] != params[i].Name {
-			t.Fatalf("order of returned parameter does not required: parameter name: %s, required name: %s", names[i], params[i])
+			t.Fatalf("order of returned parameter does not required: parameter name: %s, required name: %s", names[i], params[i].Name)
 		}
 	}
 }

go/pserver/service.go

@@ -9,8 +9,10 @@ import (
 // ElementType is the type of elements of a Parameter.
 type ElementType int
 
-var ErrAlreadyInitialized = errors.New("pserver already initialized")
-var ErrUninitialized = errors.New("pserver not fully initialized")
+const (
+	AlreadyInitialized = "pserver already initialized"
+	Uninitialized      = "pserver not fully initialized"
+)
 
 // Supported element types
 const (
@@ -59,7 +61,7 @@ func NewService() *Service {
 func (s *Service) InitParam(paramWithConfigs ParameterWithConfig, dummy *int) error {
 	select {
 	case <-s.initialized:
-		return ErrAlreadyInitialized
+		return errors.New(AlreadyInitialized)
 	default:
 	}
 
@@ -80,7 +82,7 @@ func (s *Service) InitParam(paramWithConfigs ParameterWithConfig, dummy *int) er
 func (s *Service) FinishInitParams(dummy0 int, dummy1 *int) error {
 	select {
 	case <-s.initialized:
-		return ErrAlreadyInitialized
+		return errors.New(AlreadyInitialized)
 	default:
 	}
 
@@ -94,7 +96,7 @@ func (s *Service) SendGrad(g Gradient, dummy *int) error {
 	select {
 	case <-s.initialized:
 	default:
-		return ErrUninitialized
+		return errors.New(Uninitialized)
 	}
 
 	s.mu.Lock()

go/pserver/service_test.go

@@ -16,7 +16,7 @@ func TestFull(t *testing.T) {
 	p.Content = []byte{1, 0, 0, 0, 2, 0, 0, 0, 3, 0, 0, 0}
 	p.ElementType = pserver.Int32
 	var dummy int
-	err := s.InitParam(pserver.ParameterWithConfig{p, nil}, &dummy)
+	err := s.InitParam(pserver.ParameterWithConfig{Param: p, Config: nil}, &dummy)
 	if err != nil {
 		t.FailNow()
 	}
@@ -25,7 +25,7 @@ func TestFull(t *testing.T) {
 	p1.Name = "param_b"
 	p1.Content = []byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
 	p1.ElementType = pserver.Float32
-	err = s.InitParam(pserver.ParameterWithConfig{p1, nil}, &dummy)
+	err = s.InitParam(pserver.ParameterWithConfig{Param: p1, Config: nil}, &dummy)
 	if err != nil {
 		t.FailNow()
 	}
@@ -81,7 +81,7 @@ func TestMultipleInit(t *testing.T) {
 	}
 
 	err = s.FinishInitParams(0, &dummy)
-	if err != pserver.ErrAlreadyInitialized {
+	if err.Error() != pserver.AlreadyInitialized {
 		t.FailNow()
 	}
 }
@@ -90,7 +90,7 @@ func TestUninitialized(t *testing.T) {
 	s := pserver.NewService()
 	var dummy int
 	err := s.SendGrad(pserver.Gradient{}, &dummy)
-	if err != pserver.ErrUninitialized {
+	if err.Error() != pserver.Uninitialized {
 		t.FailNow()
 	}
 }
@@ -135,7 +135,7 @@ func TestBlockUntilInitialized(t *testing.T) {
 	p.Content = []byte{1, 0, 0, 0, 2, 0, 0, 0, 3, 0, 0, 0}
 	p.ElementType = pserver.Int32
 	var dummy int
-	err := s.InitParam(pserver.ParameterWithConfig{p, nil}, &dummy)
+	err := s.InitParam(pserver.ParameterWithConfig{Param: p, Config: nil}, &dummy)
 	if err != nil {
 		t.FailNow()
 	}