start and shutdown dsps in a more controlled manner

owrx/controllers.py

@@ -97,7 +97,6 @@ class OpenWebRxClient(object):
             self.configProps.unwire(self.sendConfig)
 
         self.sdr = SdrService.getSource(id)
-        self.sdr.start()
 
         # send initial config
         self.configProps = self.sdr.getProps().collect(*OpenWebRxClient.config_keys).defaults(PropertyManager.getSharedInstance())
@@ -105,7 +104,7 @@ class OpenWebRxClient(object):
         self.configProps.wire(self.sendConfig)
         self.sendConfig(None, None)
 
-        self.sdr.spectrumThread.add_client(self)
+        self.sdr.getSpectrumThread().add_client(self)
 
     def startDsp(self):
         if self.dsp is None:

owrx/source.py

@@ -68,11 +68,18 @@ class SdrSource(object):
 
         def restart(name, value):
             print("restarting sdr source due to property change: {0} changed to {1}".format(name, value))
+            for c in self.clients:
+                c.onSdrPause()
             self.stop()
             self.start()
+            for c in self.clients:
+                c.onSdrResume()
         self.rtlProps.wire(restart)
         self.port = port
         self.monitor = None
+        self.clients = []
+        self.spectrumThread = None
+        self.modificationLock = threading.Lock()
 
         # override these in subclasses as necessary
         self.command = None
@@ -85,7 +92,10 @@ class SdrSource(object):
         return self.port
 
     def start(self):
-        if self.monitor: return
+        self.modificationLock.acquire()
+        if self.monitor:
+            self.modificationLock.release()
+            return
 
         props = self.rtlProps
 
@@ -106,13 +116,13 @@ class SdrSource(object):
         while nmux_bufsize * nmux_bufcnt < props["nmux_memory"] * 1e6: nmux_bufcnt += 1
         if nmux_bufcnt == 0 or nmux_bufsize == 0:
             print("[RtlNmuxSource] Error: nmux_bufsize or nmux_bufcnt is zero. These depend on nmux_memory and samp_rate options in config_webrx.py")
+            self.modificationLock.release()
             return
         print("[RtlNmuxSource] nmux_bufsize = %d, nmux_bufcnt = %d" % (nmux_bufsize, nmux_bufcnt))
         cmd = start_sdr_command + " | nmux --bufsize %d --bufcnt %d --port %d --address 127.0.0.1" % (nmux_bufsize, nmux_bufcnt, self.port)
         self.process = subprocess.Popen(cmd, shell=True, preexec_fn=os.setpgrp)
         print("[RtlNmuxSource] Started rtl source: " + cmd)
 
-        # TODO use this to monitor unexpected failures / shutdowns and react accordingly
         def wait_for_process_to_end():
             rc = self.process.wait()
             print("[RtlNmuxSource] shut down with RC={0}".format(rc))
@@ -121,16 +131,38 @@ class SdrSource(object):
         self.monitor = threading.Thread(target = wait_for_process_to_end)
         self.monitor.start()
 
-        self.spectrumThread = SpectrumThread(self)
+        self.modificationLock.release()
+
+    def getSpectrumThread(self):
+        if self.spectrumThread is None:
+            self.spectrumThread = SpectrumThread(self)
+        return self.spectrumThread
 
     def stop(self):
-        os.killpg(os.getpgid(self.process.pid), signal.SIGTERM)
+        self.modificationLock.acquire()
+        try:
+            os.killpg(os.getpgid(self.process.pid), signal.SIGTERM)
+        except ProcessLookupError:
+            # been killed by something else, ignore
+            pass
         self.monitor.join()
         self.sleepOnRestart()
+        self.modificationLock.release()
 
     def sleepOnRestart(self):
         pass
 
+    def addClient(self, c):
+        self.clients.append(c)
+        self.start()
+    def removeClient(self, c):
+        try:
+            self.clients.remove(c)
+        except ValueError:
+            pass
+        if not self.clients:
+            self.stop()
+
 class RtlSdrSource(SdrSource):
     def __init__(self, props, port):
         super().__init__(props, port)
@@ -162,12 +194,13 @@ class SpectrumThread(object):
         threading.Thread(target = self.run).start()
 
     def run(self):
+        self.sdrSource.addClient(self)
         props = self.sdrSource.props.collect(
             "samp_rate", "fft_size", "fft_fps", "fft_voverlap_factor", "fft_compression",
             "csdr_dynamic_bufsize", "csdr_print_bufsizes", "csdr_through"
         ).defaults(PropertyManager.getSharedInstance())
 
-        dsp = csdr.dsp()
+        self.dsp = dsp = csdr.dsp()
         dsp.nc_port = self.sdrSource.getPort()
         dsp.set_demodulator("fft")
         props.getProperty("samp_rate").wire(dsp.set_samp_rate)
@@ -204,6 +237,7 @@ class SpectrumThread(object):
                     c.write_spectrum_data(data)
 
         dsp.stop()
+        self.sdrSource.removeClient(self)
         print("spectrum thread shut down")
 
     def add_client(self, c):
@@ -224,11 +258,19 @@ class SpectrumThread(object):
         print("shutting down spectrum thread")
         self.doRun = False
 
+    def onSdrPause(self):
+        if self.dsp is not None:
+            self.dsp.stop()
+    def onSdrResume(self):
+        if self.dsp is not None:
+            self.dsp.start()
+
 class DspManager(object):
     def __init__(self, handler, sdrSource):
         self.doRun = True
         self.handler = handler
         self.sdrSource = sdrSource
+        self.sdrSource.addClient(self)
 
         self.localProps = self.sdrSource.getProps().collect(
             "audio_compression", "fft_compression", "digimodes_fft_size", "csdr_dynamic_bufsize",
@@ -336,10 +378,19 @@ class DspManager(object):
         self.doRun = False
         self.runSecondary = False
         self.dsp.stop()
+        self.sdrSource.removeClient(self)
 
     def setProperty(self, prop, value):
         self.localProps.getProperty(prop).setValue(value)
 
+    def onSdrPause(self):
+        if self.dsp is not None:
+            self.dsp.stop()
+
+    def onSdrResume(self):
+        if self.dsp is not None:
+            self.dsp.start()
+
 class CpuUsageThread(threading.Thread):
     sharedInstance = None
     @staticmethod