mpm: sys_utils: Add watchdog module

Reviewed-by: Moritz Fischer <moritz.fischer@ettus.com>

2 files changed, 64 insertions, 0 deletions

diff --git a/mpm/python/usrp_mpm/sys_utils/CMakeLists.txt b/mpm/python/usrp_mpm/sys_utils/CMakeLists.txt
index bb91418ac..5a9d79034 100644
--- a/mpm/python/usrp_mpm/sys_utils/CMakeLists.txt
+++ b/mpm/python/usrp_mpm/sys_utils/CMakeLists.txt
@@ -13,6 +13,7 @@ SET(USRP_MPM_SYSUTILS_FILES
     ${CMAKE_CURRENT_SOURCE_DIR}/sysfs_thermal.py
     ${CMAKE_CURRENT_SOURCE_DIR}/udev.py
     ${CMAKE_CURRENT_SOURCE_DIR}/uio.py
+    ${CMAKE_CURRENT_SOURCE_DIR}/watchdog.py
 )
 LIST(APPEND USRP_MPM_FILES ${USRP_MPM_SYSUTILS_FILES})
 SET(USRP_MPM_FILES ${USRP_MPM_FILES} PARENT_SCOPE)
diff --git a/mpm/python/usrp_mpm/sys_utils/watchdog.py b/mpm/python/usrp_mpm/sys_utils/watchdog.py
new file mode 100644
index 000000000..125a42c62
--- /dev/null
+++ b/mpm/python/usrp_mpm/sys_utils/watchdog.py
@@ -0,0 +1,63 @@
+#
+# Copyright 2018 Ettus Research, National Instruments Company
+#
+# SPDX-License-Identifier: GPL-3.0
+#
+"""
+systemd watchdog control module
+"""
+
+import os
+import time
+import threading
+from systemd import daemon
+
+MPM_WATCHDOG_DEFAULT_TIMEOUT = 30
+# How often per watchdog interval we send a ping
+MPM_WATCHDOG_TIMEOUT_FRAC = 3.0
+
+def has_watchdog():
+    """Check if the system has a watchdog checking on us.
+
+    We do this by checking on a set value for WATCHDOG_USEC.
+    """
+    return bool(os.environ.get('WATCHDOG_USEC', False))
+
+def watchdog_task(shared_state, log):
+    """
+    Continuously ping the watchdog to tell him that we're still alive.
+
+    This will keep running until the parent thread dies, or
+    shared_state.system_ready gets set to False by someone.
+    """
+    log.info("launching task")
+    watchdog_timeout = \
+            float(os.environ.get(
+                'WATCHDOG_USEC',
+                MPM_WATCHDOG_DEFAULT_TIMEOUT
+            )) / 1e6
+    watchdog_interval = watchdog_timeout / MPM_WATCHDOG_TIMEOUT_FRAC
+    daemon.notify("READY=1")
+    log.info("READY=1, interval %f", watchdog_interval)
+    while shared_state.system_ready.value:
+        log.trace("Pinging watchdog....")
+        daemon.notify("WATCHDOG=1")
+        time.sleep(watchdog_interval)
+    log.error("Terminating watchdog thread!")
+    return
+
+def spawn_watchdog_task(shared_state, log):
+    """Spawn and return watchdog thread.
+
+    Creates a daemonic thread, because we don't want the watchdog task to
+    outlive the main thread.
+    """
+    task = threading.Thread(
+        target=watchdog_task,
+        args=[shared_state, log],
+        name="MPMWatchdogTask",
+        daemon=True,
+    )
+    task.start()
+    return task
+