Protect against running out of disk space

Disk space availability will be checked regularly. When a minimum
threshold value is undershot, recording will get suspended. After enough
disk space will be free again, the recording will be resumed.

By default, disk space checks will run each 60 seconds and will check
for a minimum free disk space of 10%.

CHANGES.rst

@@ -7,6 +7,7 @@ in progress
 ===========
 
 - Use 5 minutes recording chunk size as default
+- Protect against running out of disk space
 
 
 2021-06-20 0.2.0

saraswati/recorder.py

@@ -3,6 +3,7 @@
 # Saraswati is a robust, multi-channel audio recording, transmission and storage system
 # (c) 2018-2021 Andreas Motl <andreas@hiveeyes.org>
 # (c) 2019 Diren Senger <diren@diren.de>
+import shutil
 import threading
 from functools import partial
 from typing import List
@@ -40,6 +41,12 @@ class SaraswatiRecorder(threading.Thread):
 
     """
 
+    # How often to check for disk usage (seconds).
+    SERVICE_TASK_INTERVAL = 60
+
+    # How much disk space should be free to sustain recording.
+    DISK_SPACE_MINIMUM_THRESHOLD = 0.1
+
     def __init__(self, settings: SaraswatiSettings):
 
         super().__init__()
@@ -68,13 +75,19 @@ def __init__(self, settings: SaraswatiSettings):
     # Invoke the pipeline.
     def run(self):
         logger.info("Starting audio recorder")
+        # GLib.idle_add(self.service_idle)
         self.mainloop.run()
 
+    def service_idle(self):
+        logger.info("Service idle")
+
     def record(self):
         try:
+            self.check_disk_usage()
             self.play()
         except Exception as ex:
             logger.error(f"Recording suspended: {ex}")
+            self.stop()
         finally:
             GLib.timeout_add_seconds(self.SERVICE_TASK_INTERVAL, self.record)
 
@@ -89,6 +102,25 @@ def play(self):
         if success:
             logger.info("Started recording")
 
+    def stop(self):
+        # https://www.programcreek.com/python/example/69113/gi.repository.GLib.MainLoop
+        success = False
+        for i, pipeline in enumerate(self.pipelines):
+            (outcome, state, pending) = pipeline.gst.get_state(timeout=Gst.SECOND)
+            if state == Gst.State.PLAYING:
+                logger.info(f"Stopping pipeline: {pipeline}")
+                pipeline.gst.set_state(Gst.State.NULL)
+                success = True
+        if success:
+            logger.info("Stopped recording")
+
+    def check_disk_usage(self):
+        usage = shutil.disk_usage(self.settings.spool_path)
+        if usage.free / usage.total < self.DISK_SPACE_MINIMUM_THRESHOLD:
+            raise ResourceWarning(
+                f"Disk space minimum threshold {self.DISK_SPACE_MINIMUM_THRESHOLD * 100}% reached"
+            )
+
     @property
     def output_location(self):
         """