Feature/pyuda fork check

source/wrappers/python/CMakeLists.txt

@@ -9,6 +9,11 @@ install( FILES ${INSTALL_FILES} DESTINATION python_installer/pyuda )
 configure_file( ${CMAKE_CURRENT_LIST_DIR}/pyuda/_version.py.in ${CMAKE_CURRENT_BINARY_DIR}/pyuda/_version.py @ONLY )
 install( FILES ${CMAKE_CURRENT_BINARY_DIR}/pyuda/_version.py DESTINATION python_installer/pyuda )
 
+file( GLOB EXAMPLE_SCRIPTS examples/*.py )
+install( FILES ${EXAMPLE_SCRIPTS} DESTINATION python_installer/examples )
+file( GLOB DEV_TEST_SCRIPTS devscripts/*.py )
+install( FILES ${DEV_TEST_SCRIPTS} DESTINATION python_installer/devscripts )
+
 ### extra install steps for the dummy "uda" repo which will mirror "pyuda" on pypi
 set( DUMMY_REPO_FILES 
     uda/README.md

source/wrappers/python/examples/parallel_client_demo.py

@@ -0,0 +1,46 @@
+import pyuda
+import multiprocessing as mp
+from enum import Enum, auto
+from collections import namedtuple
+
+ConnectionDetails = namedtuple('ConnectionDetails', ['name', 'port'])
+RequestData = namedtuple('RequestData', ['signal', 'source'])
+client = pyuda.Client()
+
+class Result(Enum):
+    SOME = auto()
+    ERROR = auto()
+
+
+def task(queue: mp.Queue, server: ConnectionDetails, request: RequestData):
+    # move client instantiation here to avoid errors
+    # client = pyuda.Client()
+    pyuda.Client.port = server.port
+    pyuda.Client.server = server.name
+
+    try:
+        result = client.get(*request)
+        queue.put((Result.SOME, result))
+    except Exception as e:
+        queue.put((Result.ERROR, e))
+
+
+def main():
+    server = ConnectionDetails("uda2.mast.l", 56565)
+    request = RequestData("help::help()", "")
+
+    # No error if start method is "spawn" or if client is only 
+    # instantiated in task (after fork)
+    mp.set_start_method('fork')
+    print("process start method is: " + mp.get_start_method())
+
+    results_q = mp.Queue()
+    p = mp.Process(target=task, args=(results_q, server, request))
+    p.start()
+    item = results_q.get()
+    print(item)
+    p.join()
+
+
+if __name__ == "__main__":
+    main()

source/wrappers/python/pyuda/_client.py

@@ -66,6 +66,8 @@ class Client(with_metaclass(ClientMeta, object)):
     __metaclass__ = ClientMeta
 
     def __init__(self, debug_level=logging.ERROR):
+        cpyuda.set_pid()
+
         self.version = __version__
         assert self.version == cpyuda.get_build_version().decode(), "mismatching pyuda and c-library versions"
 

source/wrappers/python/pyuda/cpyuda/client.pyx

@@ -1,5 +1,6 @@
 #cython: language_level=3
 
+import os
 import numpy as np
 cimport uda
 cimport numpy as np
@@ -9,6 +10,7 @@ from libc.stdlib cimport malloc, free
 from libc.string cimport strlen
 
 
+_pid = None
 _properties = {
     "get_datadble": ("GET_DATA_DOUBLE", False),
     "get_dimdble": ("GET_DIM_DOUBLE", False),
@@ -39,6 +41,12 @@ if PY_MAJOR_VERSION >= 3.0:
 else:
     Properties = type(b'Properties', (), {v[0]:k for k,v in _properties.items()})
 
+
+def set_pid():
+    global _pid
+    _pid = os.getpid()
+
+
 def set_property(prop_name, value):
     if prop_name.lower() not in _properties:
         raise ValueError('invalid property ' + prop_name)
@@ -98,6 +106,8 @@ def get_server_uuid():
 
 
 def get_data(signal, source):
+    if _pid != os.getpid():
+        raise ClientException("Calling client from a process different to process in which library was initialised")
     handle = uda.idamGetAPI(signal.encode(), source.encode())
     cdef const char* err_msg
     cdef int err_code
@@ -114,6 +124,8 @@ def get_data(signal, source):
 
 
 def get_data_batch(signals, sources):
+    if _pid != os.getpid():
+        raise ClientException("Calling client from a process different to process in which library was initialised")
     assert len(signals) == len(sources)
     cdef const char** signals_array = <const char**>malloc(len(signals) * sizeof(char*))
     cdef const char** sources_array = <const char**>malloc(len(sources) * sizeof(char*))
@@ -301,6 +313,8 @@ cdef put_string(const char* instruction, const char* data):
 
 
 def put_data(instruction, data=None):
+    if _pid != os.getpid():
+        raise ClientException("Calling client from a process different to process in which library was initialised")
     if isinstance(data, np.ndarray):
         if np.PyArray_TYPE(data) not in (np.NPY_STRING, np.NPY_UNICODE):
             return put_ndarray(instruction, data)