Dynamic Library Loading Support

CMakeLists.txt

@@ -701,6 +701,7 @@ if(UNIX)
   add_library(mxnet SHARED ${DUMMY_SOURCE})
   target_link_libraries(mxnet PRIVATE ${BEGIN_WHOLE_ARCHIVE} $<TARGET_FILE:mxnet_static> ${END_WHOLE_ARCHIVE})
   target_link_libraries(mxnet PRIVATE mxnet_static)
+  target_link_libraries(mxnet_static PUBLIC ${CMAKE_DL_LIBS})
   set_target_properties(mxnet_static PROPERTIES OUTPUT_NAME mxnet)
 else()
   add_library(mxnet SHARED ${SOURCE})

Makefile

@@ -107,7 +107,7 @@ else
 	CFLAGS += -O3 -DNDEBUG=1
 endif
 CFLAGS += -I$(TPARTYDIR)/mshadow/ -I$(TPARTYDIR)/dmlc-core/include -fPIC -I$(NNVM_PATH)/include -I$(DLPACK_PATH)/include -I$(TPARTYDIR)/tvm/include -Iinclude $(MSHADOW_CFLAGS)
-LDFLAGS = -pthread $(MSHADOW_LDFLAGS) $(DMLC_LDFLAGS)
+LDFLAGS = -pthread -ldl $(MSHADOW_LDFLAGS) $(DMLC_LDFLAGS)
 
 ifeq ($(ENABLE_TESTCOVERAGE), 1)
         CFLAGS += --coverage

example/lib_api/Makefile

@@ -0,0 +1,31 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+all:
+	g++ -shared -fPIC mylib.cc -o mylib.so -I ../../include/mxnet
+
+test:
+	g++ -std=c++11 -O3 -o libtest libtest.cc -ldl -I ../../include/mxnet
+
+windows:
+	cl /LD mylib.cc
+
+win_test:
+	cl libtest.cc
+
+clean:
+	rm -rf mylib.so libtest

example/lib_api/libtest.cc

@@ -0,0 +1,78 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+/*!
+ * Copyright (c) 2015 by Contributors
+ * \file libtest.cc
+ * \brief This test checks if the library is implemented correctly
+ * and does not involve dynamic loading of library into MXNet
+ * This test is supposed to be run before test.py
+ */
+
+#if defined(_WIN32) || defined(_WIN64) || defined(__WINDOWS__)
+#include <windows.h>
+#else
+#include <dlfcn.h>
+#endif
+
+#include <iostream>
+#include "lib_api.h"
+
+#define MXNET_VERSION 10500
+
+int main(void) {
+  // Get a handle to the library.
+#if defined(_WIN32) || defined(_WIN64) || defined(__WINDOWS__)
+  HINSTANCE handle;
+  handle = LoadLibrary(TEXT("mylib.dll"));
+#else
+  void *handle;
+  handle = dlopen("mylib.so", RTLD_LAZY);
+#endif
+
+  if (!handle) {
+    std::cerr << "Unable to load library" << std::endl;
+    return 1;
+  }
+
+  // get initialize function address from the library
+  initialize_t init_lib;
+#if defined(_WIN32) || defined(_WIN64) || defined(__WINDOWS__)
+  init_lib = (initialize_t) GetProcAddress(handle, MXLIB_INITIALIZE_STR);
+#else
+  init_lib = (initialize_t) dlsym(handle, MXLIB_INITIALIZE_STR);
+#endif
+
+  if (!init_lib) {
+    std::cerr << "Unable to get function 'intialize' from library" << std::endl;
+    return 1;
+  }
+
+  // Call the function.
+  (init_lib)(MXNET_VERSION);
+
+  // Deallocate memory.
+#if defined(_WIN32) || defined(_WIN64) || defined(__WINDOWS__)
+  FreeLibrary(handle);
+#else
+  dlclose(handle);
+#endif
+
+  return 0;
+}

example/lib_api/mylib.cc

@@ -0,0 +1,37 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+/*!
+ * Copyright (c) 2015 by Contributors
+ * \file mylib.cc
+ * \brief Sample library file
+ */
+
+#include <iostream>
+#include "lib_api.h"
+
+int initialize(int version) {
+  if (version >= 10400) {
+    std::cout << "MXNet version " << version << " supported" << std::endl;
+    return 1;
+  } else {
+    std::cout << "MXNet version " << version << " not supported" << std::endl;
+    return 0;
+  }
+}

example/lib_api/test.py

@@ -0,0 +1,31 @@
+#!/usr/bin/env python3
+
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+# coding: utf-8
+# pylint: disable=arguments-differ
+
+# This test checks if dynamic loading of library into MXNet is successful
+
+import mxnet as mx
+import os
+
+if (os.name=='posix'):
+    mx.library.load('mylib.so')
+elif (os.name=='nt'):
+    mx.library.load('mylib.dll')

include/mxnet/c_api.h

@@ -226,6 +226,13 @@ MXNET_DLL const char *MXGetLastError();
 // Part 0: Global State setups
 //-------------------------------------
 
+/*!
+ * \brief Load library dynamically
+ * \param path to the library .so file
+ * \return 0 when success, -1 when failure happens.
+ */
+MXNET_DLL int MXLoadLib(const char *path);
+
 /*!
  * \brief Get list of features supported on the runtime
  * \param libFeature pointer to array of LibFeature

include/mxnet/lib_api.h

@@ -0,0 +1,50 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+/*!
+ * Copyright (c) 2015 by Contributors
+ * \file lib_api.h
+ * \brief APIs to interact with libraries
+ */
+#ifndef MXNET_LIB_API_H_
+#define MXNET_LIB_API_H_
+
+/*!
+ * \brief Following are the APIs implemented in the external library
+ * Each API has a #define string that is used to lookup the function in the library
+ * Followed by the function declaration
+ */
+#define MXLIB_INITIALIZE_STR "initialize"
+typedef int (*initialize_t)(int);
+
+extern "C" {
+    /*!
+     * \brief Checks if the MXNet version is supported by the library.
+     * If supported, initializes the library.
+     * \param version MXNet version number passed to library and defined as:
+     *                MXNET_VERSION = (MXNET_MAJOR*10000 + MXNET_MINOR*100 + MXNET_PATCH)
+     * \return Non-zero value on error i.e. library incompatible with passed MXNet version
+     */
+#if defined(_WIN32) || defined(_WIN64) || defined(__WINDOWS__)
+    __declspec(dllexport) int __cdecl initialize(int);
+#else
+    int initialize(int);
+#endif
+}
+#endif  // MXNET_LIB_API_H_

python/mxnet/__init__.py

@@ -26,6 +26,7 @@
 from .base import MXNetError
 from .util import is_np_shape, set_np_shape, np_shape, use_np_shape
 from . import base
+from . import library
 from . import contrib
 from . import ndarray
 from . import ndarray as nd

python/mxnet/base.py

@@ -86,7 +86,7 @@ def __repr__(self):
 
 
 class MXNetError(Exception):
-    """Error that will be throwed by all mxnet functions."""
+    """Error that will be thrown by all mxnet functions."""
     pass
 
 

python/mxnet/library.py

@@ -0,0 +1,49 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+# coding: utf-8
+"""Library management API of mxnet."""
+from __future__ import absolute_import
+import ctypes
+import os
+from .base import _LIB, check_call, MXNetError
+
+def load(path):
+    """Loads library dynamically.
+
+    Parameters
+    ---------
+    path : Path to library .so/.dll file
+
+    Returns
+    ---------
+    void
+    """
+    #check if path exists
+    if not os.path.exists(path):
+        raise MXNetError("load path %s does NOT exist" % path)
+    #check if path is an absolute path
+    if not os.path.isabs(path):
+        raise MXNetError("load path %s is not an absolute path" % path)
+    #check if path is to a library file
+    _, file_ext = os.path.splitext(path)
+    if not file_ext in ['.so', '.dll']:
+        raise MXNetError("load path %s is NOT a library file" % path)
+
+    byt_obj = path.encode('utf-8')
+    chararr = ctypes.c_char_p(byt_obj)
+    check_call(_LIB.MXLoadLib(chararr))

src/c_api/c_api.cc

@@ -45,11 +45,13 @@
 #include "mxnet/storage.h"
 #include "mxnet/libinfo.h"
 #include "mxnet/imperative.h"
+#include "mxnet/lib_api.h"
 #include "./c_api_common.h"
 #include "../operator/custom/custom-inl.h"
 #include "../operator/tensor/matrix_op-inl.h"
 #include "../operator/tvmop/op_module.h"
 #include "../common/utils.h"
+#include "../common/library.h"
 
 using namespace mxnet;
 
@@ -90,6 +92,19 @@ inline int MXAPIGetFunctionRegInfo(const FunRegType *e,
 
 // NOTE: return value is added in API_END
 
+// Loads library and initializes it
+int MXLoadLib(const char *path) {
+  API_BEGIN();
+  void *lib = load_lib(path);
+  if (!lib)
+    LOG(FATAL) << "Unable to load library";
+
+  initialize_t initialize = get_func<initialize_t>(lib, const_cast<char*>(MXLIB_INITIALIZE_STR));
+  if (!initialize(static_cast<int>(MXNET_VERSION)))
+    LOG(FATAL) << "Library failed to initialize";
+  API_END();
+}
+
 int MXLibInfoFeatures(const struct LibFeature **lib_features, size_t *size) {
   using namespace features;
   API_BEGIN();