optimise view performance with prefetching imageversions and thumbnails, change ImageVersion fk from Image to BaseFile to make prefetching possible across polymorphic models

Author: tykling

src/files/managers.py

@@ -19,7 +19,7 @@ class BaseFileManager(PolymorphicManager):
     """Custom manager for file operations."""
 
     def get_queryset(self) -> models.QuerySet["BaseFile"]:
-        """Prefetch active albums into a list."""
+        """Prefetch and annotate."""
         return (  # type: ignore[no-any-return]
             super()
             .get_queryset()
@@ -36,6 +36,8 @@ def get_queryset(self) -> models.QuerySet["BaseFile"]:
             .annotate(jobs_unfinished=Count("jobs", filter=models.Q(jobs__finished=False)))
             .prefetch_active_albums_list(recursive=True)
             .prefetch_related("thumbnails")
+            .prefetch_related(models.Prefetch("thumbnails", to_attr="thumbnail_list"))
+            .prefetch_related(models.Prefetch("image_versions", to_attr="image_version_list"))
         )
 
 

src/images/migrations/0003_alter_imageversion_image.py

@@ -0,0 +1,20 @@
+# Generated by Django 5.1.4 on 2024-12-08 07:37
+
+import utils.models
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('files', '0004_initial'),
+        ('images', '0002_initial'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='imageversion',
+            name='image',
+            field=models.ForeignKey(help_text='The Image this is a smaller version of.', on_delete=utils.models.NP_CASCADE, related_name='image_versions', to='files.basefile'),
+        ),
+    ]

src/images/models.py

@@ -67,11 +67,15 @@ class Image(BaseFile):
     )
 
     def get_fullsize_version(self, mimetype: str) -> "ImageVersion | None":
-        """Return the ImageVersion for the fullsize version of this mimetype for this Image."""
-        try:
-            return self.image_versions.get(width=self.width, aspect_ratio=self.aspect_ratio, mimetype=mimetype)  # type: ignore[no-any-return]
-        except ImageVersion.DoesNotExist:
-            return None
+        """Return the ImageVersion for the fullsize version of this mimetype for this Image.
+
+        Performance sensitive, called from template tags, do not break prefetching. Loop over
+        self.image_version_list instead of self.image_versions.filter().
+        """
+        for image in self.image_version_list:
+            if image.width == self.width and image.aspect_ratio == self.aspect_ratio and image.mimetype == mimetype:
+                return image  # type: ignore[no-any-return]
+        return None
 
     def create_jobs(self) -> None:
         """Create jobs for exif, smaller versions and thumbnails for this image."""
@@ -131,7 +135,11 @@ def create_smaller_version_jobs(self) -> None:
     def get_versions(
         self, mimetype: str | None = None, aspect_ratio: Fraction | None = None
     ) -> dict[Fraction | None, dict[str, dict[int, "ImageVersion"]]]:
-        """Get image versions. Return a dict with ratio: mimetype: size: ImageVersion dicts."""
+        """Get image versions. Return a dict with ratio: mimetype: size: ImageVersion dicts.
+
+        Performance sensitive, called from template tags, do not break prefetching. Loop over
+        self.image_version_list instead of self.image_versions.filter().
+        """
         versions = {}
         kwargs = {
             "aspect_ratio": aspect_ratio or self.aspect_ratio,
@@ -140,7 +148,11 @@ def get_versions(
         if mimetype:
             kwargs["mimetype"] = mimetype
         # use requested custom AR or Image original AR
-        for version in self.image_versions.filter(**kwargs):
+        for version in self.image_version_list:
+            if version.aspect_ratio != kwargs["aspect_ratio"]:
+                continue
+            if "mimetype" in kwargs and version.mimetype != kwargs["mimetype"]:
+                continue
             if version.aspect_ratio not in versions:
                 versions[version.aspect_ratio] = {}
             if version.mimetype not in versions[version.aspect_ratio]:
@@ -229,7 +241,7 @@ class ImageVersion(ImageModel, BaseModel):
     )
 
     image = models.ForeignKey(
-        "images.Image",
+        "files.BaseFile",
         on_delete=NP_CASCADE,  # delete all versions when an Image is deleted
         related_name="image_versions",
         help_text="The Image this is a smaller version of.",

src/utils/templatetags/bma_utils.py

@@ -9,7 +9,6 @@
 from django.template.context import RequestContext
 from django.utils.safestring import mark_safe
 
-from files.models import Thumbnail
 from pictures.templatetags.pictures import picture
 from pictures.utils import sizes
 
@@ -39,7 +38,7 @@ def get_group_icons(
 
 
 @register.simple_tag()
-def thumbnail(basefile: "BaseFile", width: int, ratio: str) -> str:
+def thumbnail(basefile: "BaseFile", width: int, ratio: str, mimetype: str = "image/webp") -> str:
     """BMA thumbnail tag. Depends on the hardcoded 50,100,150,200px (and 2x)."""
     from files.models import ThumbnailSource
 
@@ -54,31 +53,31 @@ def thumbnail(basefile: "BaseFile", width: int, ratio: str) -> str:
             f"<!-- Error creating thumbnail markup, aspect ratio {ratio} is not supported, "
             f"only {ThumbnailSource.source.field.aspect_ratios} are supported -->"  # type: ignore[attr-defined]
         )
-
-    thumbnails = basefile.thumbnails.filter(
-        width__in=[width, width * 2], aspect_ratio=str(Fraction(ratio)), mimetype="image/webp"
-    )
-    if not thumbnails:
-        # neither requested size or 2x available, return default
-        return mark_safe(  # noqa: S308
-            '<img class="img-fluid img-thumbnail" '
-            f'src="{settings.DEFAULT_THUMBNAIL_URLS[basefile.filetype]}" width="{width}">'
-        )
-    try:
-        t = thumbnails.get(width=width, height=width / Fraction(ratio))
-        url = t.imagefile.url
-    except Thumbnail.DoesNotExist:
-        # requested size not available, return default
+    t = None
+    t2 = None
+    for thumbnail in basefile.thumbnail_list:
+        if thumbnail.mimetype != mimetype:
+            continue
+        if thumbnail.aspect_ratio != str(Fraction(ratio)):
+            continue
+        if thumbnail.width == width:
+            t = thumbnail
+            continue
+        if thumbnail.width == width * 2:
+            t2 = thumbnail
+            continue
+
+    if not t:
+        # request size not available
         return mark_safe(  # noqa: S308
             '<img class="img-fluid img-thumbnail" '
             f'src="{settings.DEFAULT_THUMBNAIL_URLS[basefile.filetype]}" width="{width}">'
         )
-
-    try:
-        url2x = thumbnails.get(width=width * 2).imagefile.url
+    url = t.imagefile.url
+    if t2:
+        url2x = t2.imagefile.url
         url2x = f", {url2x} 2x"
-    except Thumbnail.DoesNotExist:
-        # 2x requested size not available, skip 2x for this thumbnail
+    else:
         url2x = ""
 
     title = basefile.original_filename