Optimize empty directory cleanup for recordings (#21695)

The previous empty directory cleanup did a full recursive directory
walk, which can be extremely slow. This new implementation only removes
directories which have a chance of being empty due to a recent file
deletion.

frigate/record/cleanup.py

@@ -11,7 +11,7 @@ from pathlib import Path
 from playhouse.sqlite_ext import SqliteExtDatabase
 
 from frigate.config import CameraConfig, FrigateConfig, RetainModeEnum
-from frigate.const import CACHE_DIR, CLIPS_DIR, MAX_WAL_SIZE, RECORD_DIR
+from frigate.const import CACHE_DIR, CLIPS_DIR, MAX_WAL_SIZE
 from frigate.models import Previews, Recordings, ReviewSegment, UserReviewStatus
 from frigate.util.builtin import clear_and_unlink
 from frigate.util.media import remove_empty_directories
@@ -60,7 +60,7 @@ class RecordingCleanup(threading.Thread):
             db.execute_sql("PRAGMA wal_checkpoint(TRUNCATE);")
             db.close()
 
-    def expire_review_segments(self, config: CameraConfig, now: datetime) -> None:
+    def expire_review_segments(self, config: CameraConfig, now: datetime) -> set[Path]:
         """Delete review segments that are expired"""
         alert_expire_date = (
             now - datetime.timedelta(days=config.record.alerts.retain.days)
@@ -84,9 +84,12 @@ class RecordingCleanup(threading.Thread):
             .namedtuples()
         )
 
+        maybe_empty_dirs = set()
         thumbs_to_delete = list(map(lambda x: x[1], expired_reviews))
         for thumb_path in thumbs_to_delete:
-            Path(thumb_path).unlink(missing_ok=True)
+            thumb_path = Path(thumb_path)
+            thumb_path.unlink(missing_ok=True)
+            maybe_empty_dirs.add(thumb_path.parent)
 
         max_deletes = 100000
         deleted_reviews_list = list(map(lambda x: x[0], expired_reviews))
@@ -99,13 +102,15 @@ class RecordingCleanup(threading.Thread):
                 << deleted_reviews_list[i : i + max_deletes]
             ).execute()
 
+        return maybe_empty_dirs
+
     def expire_existing_camera_recordings(
         self,
         continuous_expire_date: float,
         motion_expire_date: float,
         config: CameraConfig,
         reviews: ReviewSegment,
-    ) -> None:
+    ) -> set[Path]:
         """Delete recordings for existing camera based on retention config."""
         # Get the timestamp for cutoff of retained days
 
@@ -134,6 +139,8 @@ class RecordingCleanup(threading.Thread):
             .iterator()
         )
 
+        maybe_empty_dirs = set()
+
         # loop over recordings and see if they overlap with any non-expired reviews
         # TODO: expire segments based on segment stats according to config
         review_start = 0
@@ -187,8 +194,10 @@ class RecordingCleanup(threading.Thread):
                 )
                 or (mode == RetainModeEnum.active_objects and recording.objects == 0)
             ):
-                Path(recording.path).unlink(missing_ok=True)
+                recording_path = Path(recording.path)
+                recording_path.unlink(missing_ok=True)
                 deleted_recordings.add(recording.id)
+                maybe_empty_dirs.add(recording_path.parent)
             else:
                 kept_recordings.append((recording.start_time, recording.end_time))
 
@@ -249,8 +258,10 @@ class RecordingCleanup(threading.Thread):
 
             # Delete previews without any relevant recordings
             if not keep:
-                Path(preview.path).unlink(missing_ok=True)
+                preview_path = Path(preview.path)
+                preview_path.unlink(missing_ok=True)
                 deleted_previews.add(preview.id)
+                maybe_empty_dirs.add(preview_path.parent)
 
         # expire previews
         logger.debug(f"Expiring {len(deleted_previews)} previews")
@@ -262,7 +273,9 @@ class RecordingCleanup(threading.Thread):
                 Previews.id << deleted_previews_list[i : i + max_deletes]
             ).execute()
 
-    def expire_recordings(self) -> None:
+        return maybe_empty_dirs
+
+    def expire_recordings(self) -> set[Path]:
         """Delete recordings based on retention config."""
         logger.debug("Start expire recordings.")
         logger.debug("Start deleted cameras.")
@@ -287,10 +300,14 @@ class RecordingCleanup(threading.Thread):
             .iterator()
         )
 
+        maybe_empty_dirs = set()
+
         deleted_recordings = set()
         for recording in no_camera_recordings:
-            Path(recording.path).unlink(missing_ok=True)
+            recording_path = Path(recording.path)
+            recording_path.unlink(missing_ok=True)
             deleted_recordings.add(recording.id)
+            maybe_empty_dirs.add(recording_path.parent)
 
         logger.debug(f"Expiring {len(deleted_recordings)} recordings")
         # delete up to 100,000 at a time
@@ -307,7 +324,7 @@ class RecordingCleanup(threading.Thread):
             logger.debug(f"Start camera: {camera}.")
             now = datetime.datetime.now()
 
-            self.expire_review_segments(config, now)
+            maybe_empty_dirs |= self.expire_review_segments(config, now)
             continuous_expire_date = (
                 now - datetime.timedelta(days=config.record.continuous.days)
             ).timestamp()
@@ -337,7 +354,7 @@ class RecordingCleanup(threading.Thread):
                 .namedtuples()
             )
 
-            self.expire_existing_camera_recordings(
+            maybe_empty_dirs |= self.expire_existing_camera_recordings(
                 continuous_expire_date, motion_expire_date, config, reviews
             )
             logger.debug(f"End camera: {camera}.")
@@ -345,6 +362,8 @@ class RecordingCleanup(threading.Thread):
         logger.debug("End all cameras.")
         logger.debug("End expire recordings.")
 
+        return maybe_empty_dirs
+
     def run(self) -> None:
         # Expire tmp clips every minute, recordings and clean directories every hour.
         for counter in itertools.cycle(range(self.config.record.expire_interval)):
@@ -356,6 +375,6 @@ class RecordingCleanup(threading.Thread):
 
             if counter == 0:
                 self.clean_tmp_clips()
-                self.expire_recordings()
+                maybe_empty_dirs = self.expire_recordings()
-                remove_empty_directories(RECORD_DIR)
+                remove_empty_directories(maybe_empty_dirs)
                 self.truncate_wal()

frigate/util/media.py

@@ -1,9 +1,12 @@
 """Recordings Utilities."""
 
 import datetime
+import errno
 import logging
 import os
 from dataclasses import dataclass, field
+from pathlib import Path
+from typing import Iterable
 
 from peewee import DatabaseError, chunked
 
@@ -47,20 +50,23 @@ class SyncResult:
         }
 
 
-def remove_empty_directories(directory: str) -> None:
+def remove_empty_directories(paths: Iterable[Path]) -> None:
-    # list all directories recursively and sort them by path,
+    """
-    # longest first
+    Remove directories if they exist and are empty.
-    paths = sorted(
+    Silently ignores non-existent and non-empty directories.
-        [x[0] for x in os.walk(directory)],
+    """
-        key=lambda p: len(str(p)),
+    count = 0
-        reverse=True,
-    )
     for path in paths:
-        # don't delete the parent
+        try:
-        if path == directory:
+            path.rmdir()
+        except FileNotFoundError:
             continue
-        if len(os.listdir(path)) == 0:
+        except OSError as e:
-            os.rmdir(path)
+            if e.errno == errno.ENOTEMPTY:
+                continue
+            raise
+        count += 1
+    logger.debug("Removed {count} empty directories")
 
 
 def sync_recordings(