Let workers get tasks from local scheduler. (#5)

* Restructure to have separate client and scheduler files. Shared stuff is in photon.h.

* Let workers get tasks from local scheduler.

lib/python/photon.py

@@ -6,9 +6,57 @@ photon_client_library = ctypes.cdll.LoadLibrary(photon_client_library_path)
 photon_client_library.alloc_task_spec.restype = ctypes.c_void_p
 photon_client_library.photon_connect.restype = ctypes.c_void_p
 photon_client_library.photon_submit.restype = None
+photon_client_library.photon_get_task.restype = ctypes.c_void_p
 
 ID = ctypes.c_ubyte * 20
 
+buffer_from_read_write_memory = ctypes.pythonapi.PyBuffer_FromReadWriteMemory
+buffer_from_read_write_memory.argtypes = [ctypes.c_void_p, ctypes.c_int64]
+buffer_from_read_write_memory.restype = ctypes.py_object
+
+buffer_from_memory = ctypes.pythonapi.PyBuffer_FromMemory
+buffer_from_memory.argtypes = [ctypes.c_void_p, ctypes.c_int64]
+buffer_from_memory.restype = ctypes.py_object
+
+photon_client_library.task_function.restype = ctypes.c_void_p
+photon_client_library.task_num_args.restype = ctypes.c_int64
+photon_client_library.task_num_returns.restype = ctypes.c_int64
+photon_client_library.task_arg_type.restype = ctypes.c_int8
+photon_client_library.task_arg_id.restype = ctypes.c_void_p
+photon_client_library.task_arg_val.restype = ctypes.c_void_p
+photon_client_library.task_arg_length.restype = ctypes.c_void_p
+photon_client_library.task_return.restype = ctypes.c_void_p
+
+
+class TaskInfo(object):
+  def __init__(self, function_id, args, return_ids):
+    self.function_id = function_id
+    self.args = args
+    self.return_ids = return_ids
+
+def extract_task(c_task):
+  function_id = buffer_from_memory(photon_client_library.task_function(c_task), 20)[:]
+  num_args = photon_client_library.task_num_args(c_task)
+  num_returns = photon_client_library.task_num_returns(c_task)
+  arg_vals_and_ids = []
+  for i in range(num_args):
+    arg_type = photon_client_library.task_arg_type(c_task, i)
+    if arg_type == 0:
+      arg_id = buffer_from_memory(photon_client_library.task_arg_id(c_task, i), 20)
+      arg_vals_and_ids.append((arg_type, arg_id))
+    elif arg_type == 1:
+      arg_val = photon_client_library.task_arg_val(c_task, i)[:]
+      arg_length = photon_client_library.task_arg_length(c_task, i)
+      arg_value = buffer_from_memory(arg_val, arg_length)[:]
+      arg_vals_and_ids.append((arg_type, arg_value))
+    else:
+      raise Exception("arg_type must be 0 or 1")
+  return_ids = []
+  for i in range(num_returns):
+    ret_id = buffer_from_memory(photon_client_library.task_return(c_task, i), 20)
+    return_ids.append(ret_id[:])
+  return TaskInfo(function_id, arg_vals_and_ids, return_ids)
+
 class UniqueID(ctypes.Structure):
   _fields_ = [("unique_id", ID)]
 
@@ -19,11 +67,18 @@ def make_id(string):
   return UniqueID(unique_id=ID(*unique_id))
 
 class Task(object):
-  def __init__(self, function_id, args):
+  def __init__(self, function_id, args, return_ids):
     function_id = make_id(function_id)
     self.task_spec = ctypes.c_void_p(photon_client_library.alloc_task_spec(function_id, len(args), 1, 0))
     for arg in args:
-      photon_client_library.task_args_add_ref(self.task_spec, arg)
+      photon_client_library.task_args_add_ref(self.task_spec, make_id(arg))
+
+    # Add return IDs. This may not be the appropriate place for this.
+    num_returns = photon_client_library.task_num_returns(self.task_spec)
+    for i in range(num_returns):
+      ret_id = buffer_from_read_write_memory(photon_client_library.task_return(self.task_spec, i), 20)
+      for j in range(20):
+        ret_id[j] = return_ids[i][j]
 
   def __del__(self):
     photon_client_library.free_task_spec(self.task_spec)
@@ -33,6 +88,12 @@ class PhotonClient(object):
   def __init__(self, socket_name):
     self.photon_conn = ctypes.c_void_p(photon_client_library.photon_connect(socket_name))
 
-  def submit(self, function_id, args):
-    task = Task(function_id, args)
+  def submit(self, function_id, args, return_ids):
+    task = Task(function_id, args, return_ids)
     photon_client_library.photon_submit(self.photon_conn, task.task_spec)
+
+  def get_task(self):
+    c_task = ctypes.c_void_p(photon_client_library.photon_get_task(self.photon_conn))
+    task = c_task # TODO Extract the actual task. EXTRACT...(c_task)
+    # photon_client_library.free_task_spec(c_task)
+    return extract_task(task)