improve queue shutdown to avoid stale files

owrx/__main__.py

@@ -13,6 +13,7 @@ from owrx.service import Services
 from owrx.websocket import WebSocketConnection
 from owrx.reporting import ReportingEngine
 from owrx.version import openwebrx_version
+from owrx.audio import DecoderQueue
 
 
 class ThreadedHttpServer(ThreadingMixIn, HTTPServer):
@@ -68,3 +69,4 @@ Support and info:       https://groups.io/g/openwebrx
         WebSocketConnection.closeAll()
         Services.stop()
         ReportingEngine.stopAll()
+        DecoderQueue.stopAll()

owrx/audio.py

@@ -7,7 +7,7 @@ import subprocess
 import os
 from multiprocessing.connection import Pipe, wait
 from datetime import datetime, timedelta
-from queue import Queue, Full
+from queue import Queue, Full, Empty
 
 
 import logging
@@ -32,22 +32,30 @@ class QueueJob(object):
             pass
 
 
+PoisonPill = object()
+
+
 class QueueWorker(threading.Thread):
     def __init__(self, queue):
         self.queue = queue
         self.doRun = True
-        super().__init__(daemon=True)
+        super().__init__()
 
     def run(self) -> None:
         while self.doRun:
             job = self.queue.get()
-            try:
-                job.run()
-            except Exception:
-                logger.exception("failed to decode job")
-                self.queue.onError()
-            finally:
-                job.unlink()
+            if job is PoisonPill:
+                self.doRun = False
+                # put the poison pill back on the queue for the next worker
+                self.queue.put(PoisonPill)
+            else:
+                try:
+                    job.run()
+                except Exception:
+                    logger.exception("failed to decode job")
+                    self.queue.onError()
+                finally:
+                    job.unlink()
 
             self.queue.task_done()
 
@@ -64,6 +72,13 @@ class DecoderQueue(Queue):
                 DecoderQueue.sharedInstance = DecoderQueue(maxsize=pm["decoding_queue_length"], workers=pm["decoding_queue_workers"])
         return DecoderQueue.sharedInstance
 
+    @staticmethod
+    def stopAll():
+        with DecoderQueue.creationLock:
+            if DecoderQueue.sharedInstance is not None:
+                DecoderQueue.sharedInstance.stop()
+                DecoderQueue.sharedInstance = None
+
     def __init__(self, maxsize, workers):
         super().__init__(maxsize)
         metrics = Metrics.getSharedInstance()
@@ -78,6 +93,18 @@ class DecoderQueue(Queue):
         metrics.addMetric("decoding.queue.error", self.errorCounter)
         self.workers = [self.newWorker() for _ in range(0, workers)]
 
+    def stop(self):
+        logger.debug("shutting down the queue")
+        try:
+            # purge all remaining jobs
+            while not self.empty():
+                job = self.get()
+                job.unlink()
+        except Empty:
+            pass
+        # put() PoisonPill to tell workers to shut down
+        self.put(PoisonPill)
+
     def put(self, item, **kwars):
         self.inCounter.inc()
         try:
@@ -161,11 +188,10 @@ class AudioWriter(object):
         self.timer.start()
 
     def switchFiles(self):
-        self.switchingLock.acquire()
-        file = self.wavefile
-        filename = self.wavefilename
-        (self.wavefilename, self.wavefile) = self.getWaveFile()
-        self.switchingLock.release()
+        with self.switchingLock:
+            file = self.wavefile
+            filename = self.wavefilename
+            (self.wavefilename, self.wavefile) = self.getWaveFile()
 
         file.close()
         job = QueueJob(self, filename, self.dsp.get_operating_freq())
@@ -205,9 +231,8 @@ class AudioWriter(object):
         self._scheduleNextSwitch()
 
     def write(self, data):
-        self.switchingLock.acquire()
-        self.wavefile.writeframes(data)
-        self.switchingLock.release()
+        with self.switchingLock:
+            self.wavefile.writeframes(data)
 
     def stop(self):
         self.outputWriter.close()
@@ -229,7 +254,8 @@ class AudioWriter(object):
         except Exception:
             logger.exception("error closing wave file")
         try:
-            os.unlink(self.wavefilename)
+            with self.switchingLock:
+                os.unlink(self.wavefilename)
         except Exception:
             logger.exception("error removing undecoded file")
         self.wavefile = None