sim: Integrate simulator into UHD

This commit adds a device::register_device which allows uhd to start up
a simulator when uhd is called with the arguments type=sim. Creating the
device object creates a subprocess using pybind and an embedded
interpreter, and destroying the object cleans up those subprocesses.

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

2 files changed, 61 insertions, 0 deletions

diff --git a/mpm/python/usrp_mpm/CMakeLists.txt b/mpm/python/usrp_mpm/CMakeLists.txt
index 293892337..f1637ab03 100644
--- a/mpm/python/usrp_mpm/CMakeLists.txt
+++ b/mpm/python/usrp_mpm/CMakeLists.txt
@@ -23,6 +23,7 @@ set(USRP_MPM_TOP_FILES
     ${CMAKE_CURRENT_SOURCE_DIR}/mpmutils.py
     ${CMAKE_CURRENT_SOURCE_DIR}/prefs.py
     ${CMAKE_CURRENT_SOURCE_DIR}/rpc_server.py
+    ${CMAKE_CURRENT_SOURCE_DIR}/process_manager.py
 )
 list(APPEND USRP_MPM_FILES ${USRP_MPM_TOP_FILES})
 add_subdirectory(chips)
diff --git a/mpm/python/usrp_mpm/process_manager.py b/mpm/python/usrp_mpm/process_manager.py
new file mode 100644
index 000000000..eb1215ad7
--- /dev/null
+++ b/mpm/python/usrp_mpm/process_manager.py
@@ -0,0 +1,60 @@
+#
+# Copyright 2020 Ettus Research, a National Instruments Brand
+#
+# SPDX-License-Identifier: GPL-3.0-or-later
+#
+"""
+This module is used as an interface between the sim_find.cpp discovery
+and mboard_iface in uhd and the usrp_hwd python file. It manages
+starting and stopping the simulator subprocess and configuring logging
+"""
+from multiprocessing import Process, Event
+import sys
+try:
+    # Location if installed from using make install
+    import usrp_hwd
+except ImportError:
+    # Location if installed from libpyuhd using setuptools
+    from usrp_mpm import usrp_hwd
+
+class ProcessManager:
+    """This object is used to manage a simulator process which is launched
+    from a python interpreter rather than from an os shell or using systemd
+    """
+    def __init__(self, args):
+        """args are the command line arguments received by the simulator"""
+        self.stop_event = Event()
+        self.process = Process(target=_bootstrap, args=[args, self.stop_event])
+
+    def start(self):
+        """Launch the simulator's process"""
+        self.process.start()
+
+    def stop(self, timeout):
+        """Attempt to stop the simulator cleanly. Returns True if successful"""
+        self.stop_event.set()
+        self.process.join(timeout)
+        return self.process.exitcode is not None
+
+    def terminate(self):
+        """Forcefully terminates the simulator"""
+        self.process.terminate()
+
+    def pid(self):
+        """Returns the PID of the simulator subprocess"""
+        return int(self.process.pid)
+
+def _bootstrap(args, stop_event):
+    # Set args for new process
+    #
+    # Disable UHD log forwarding to avoid
+    # duplicate messages
+    sys.argv = ["usrp_hwd.py"] + args + ["--no-logbuf"]
+    # tell main() not to block
+    usrp_hwd.JOIN_PROCESSES = False
+    # Start the discovery and RPC processes
+    usrp_hwd.main()
+    # Wait for signal from other process
+    stop_event.wait()
+    # Stop the discovery and RPC processes
+    usrp_hwd.kill_time(None, None)