sim: Support Out of Tree Sources and Sinks

This commit adds the ability to specify a path to an arbitrary python
file in a simulator config file, which will be imported and used to
construct a SampleSink or SampleSource for use with data streaming.

Signed-off-by: Samuel O'Brien <sam.obrien@ni.com>

2 files changed, 24 insertions, 2 deletions

diff --git a/mpm/python/usrp_mpm/simulator/config.py b/mpm/python/usrp_mpm/simulator/config.py
index 6698f9fd0..d97a30266 100644
--- a/mpm/python/usrp_mpm/simulator/config.py
+++ b/mpm/python/usrp_mpm/simulator/config.py
@@ -11,7 +11,7 @@ it identifies itself as.
 """
 
 import configparser
-from .sample_source import sinks, sources, NullSamples
+from .sample_source import sinks, sources, NullSamples, from_import_path
 from .hardware_presets import presets
 import numbers
 
@@ -105,7 +105,12 @@ class Config:
     def _read_sample_section(section, lookup):
         args = dict(section)
         class_name = args.pop("class")
-        constructor = lookup[class_name]
+        constructor = None
+        if "import_path" in args:
+            import_path = args.pop("import_path")
+            constructor = from_import_path(class_name, import_path)
+        else:
+            constructor = lookup[class_name]
         def section_gen():
             return constructor(**args)
         return section_gen
diff --git a/mpm/python/usrp_mpm/simulator/sample_source.py b/mpm/python/usrp_mpm/simulator/sample_source.py
index 36278efd8..98fc6ff0b 100644
--- a/mpm/python/usrp_mpm/simulator/sample_source.py
+++ b/mpm/python/usrp_mpm/simulator/sample_source.py
@@ -7,6 +7,7 @@
 This module contains the interface for providing data to a simulator
 stream and receiving data from a simulator stream.
 """
+import importlib.util
 
 sources = {}
 sinks = {}
@@ -21,6 +22,22 @@ def cli_sink(cls):
     sinks[cls.__name__] = cls
     return cls
 
+name_index = 0
+module_lookup = {}
+def from_import_path(class_name, import_path):
+    global name_index
+    global module_lookup
+    module = None
+    if import_path in module_lookup:
+        module = module_lookup[import_path]
+    else:
+        spec = importlib.util.spec_from_file_location("simsample." + str(name_index), import_path)
+        name_index =+ 1
+        module = importlib.util.module_from_spec(spec)
+        spec.loader.exec_module(module)
+        module_lookup[import_path] = module
+    return getattr(module, class_name)
+
 class SampleSource:
     """This class defines the interface of a SampleSource. It
     provides samples to the simulator which are then sent over the