Added workaround for corrupted zip chunks

changelog.d/20231208_152516_andrey_workarround_cache_corrupted_data.md

@@ -0,0 +1,4 @@
+### Fixed
+
+- Added workaround for corrupted cached chunks
+  (<https://github.com/opencv/cvat/pull/7243>)

cvat/apps/engine/cache.py

@@ -10,6 +10,7 @@
 from io import BytesIO
 import shutil
 import tempfile
+import zlib
 
 from typing import Optional, Tuple
 
@@ -43,17 +44,30 @@ def __init__(self, dimension=DimensionType.DIM_2D):
         self._cache = caches['media']
 
     def _get_or_set_cache_item(self, key, create_function):
-        slogger.glob.info(f'Starting to get chunk from cache: key {key}')
-        item = self._cache.get(key)
-        slogger.glob.info(f'Ending to get chunk from cache: key {key}, is_cached {bool(item)}')
-        if not item:
+        def create_item():
             slogger.glob.info(f'Starting to prepare chunk: key {key}')
             item = create_function()
             slogger.glob.info(f'Ending to prepare chunk: key {key}')
+
             if item[0]:
+                item = (item[0], item[1], zlib.crc32(item[0].getbuffer()))
                 self._cache.set(key, item)
 
-        return item
+            return item
+
+        slogger.glob.info(f'Starting to get chunk from cache: key {key}')
+        item = self._cache.get(key)
+        slogger.glob.info(f'Ending to get chunk from cache: key {key}, is_cached {bool(item)}')
+        if not item:
+            item = create_item()
+        else:
+            # compare checksum
+            item_checksum = item[2] if len(item) == 3 else None
+            if item_checksum != zlib.crc32(item[0].getbuffer()):
+                slogger.glob.info(f'Recreating cache item {key} due to checksum mismatch')
+                item = create_item()
+
+        return item[0], item[1]
 
     def get_task_chunk_data_with_mime(self, chunk_number, quality, db_data):
         item = self._get_or_set_cache_item(
@@ -323,6 +337,5 @@ def _prepare_context_image(self, db_data, frame_number):
                 if not success:
                     raise Exception('Failed to encode image to ".jpeg" format')
                 zip_file.writestr(f'{name}.jpg', result.tobytes())
-        buff = zip_buffer.getvalue()
         mime_type = 'application/zip'
-        return buff, mime_type
+        return zip_buffer, mime_type

cvat/apps/engine/views.py

@@ -679,7 +679,7 @@ def __call__(self, request, start: int, stop: int, db_data: Optional[Data]):
                 buff, mime = cache.get_frame_context_images(db_data, self.number)
                 if not buff:
                     return HttpResponseNotFound()
-                return HttpResponse(io.BytesIO(buff), content_type=mime)
+                return HttpResponse(buff, content_type=mime)
             else:
                 return Response(data='unknown data type {}.'.format(self.type),
                     status=status.HTTP_400_BAD_REQUEST)