Make asset paths operations idempotent

dandiapi/api/asset_paths.py

@@ -108,10 +108,13 @@ def insert_asset_paths(asset: Asset, version: Version):
     return leaf
 
 
-# TODO: Make idempotent
 def _add_asset_paths(asset: Asset, version: Version):
     leaf = insert_asset_paths(asset, version)
 
+    # Only increment if it hasn't been performed yet
+    if leaf.aggregate_files == 1:
+        return
+
     # Increment the size and file count of all parent paths.
     # Get all relations (including leaf node)
     parent_ids = (
@@ -128,7 +131,9 @@ def _add_asset_paths(asset: Asset, version: Version):
 
 
 def _delete_asset_paths(asset: Asset, version: Version):
-    leaf: AssetPath = AssetPath.objects.get(asset=asset, version=version)
+    leaf: AssetPath | None = AssetPath.objects.filter(asset=asset, version=version).first()
+    if leaf is None:
+        return
 
     # Fetch parents
     parent_ids = (
@@ -178,7 +183,9 @@ def add_version_asset_paths(version: Version):
     # Compute aggregate file size + count for each asset path, instead of when each asset
     # is added. This is done because updating the same row many times within a transaction is slow.
     # https://stackoverflow.com/a/60221875
-    nodes = AssetPath.objects.filter(version=version)
+
+    # Get all nodes which haven't been computed yet
+    nodes = AssetPath.objects.filter(version=version, aggregate_files=0)
     for node in nodes:
         child_link_ids = node.child_links.distinct('child_id').values_list('child_id', flat=True)
         child_leaves = AssetPath.objects.filter(id__in=child_link_ids, asset__isnull=False)

dandiapi/api/migrations/0039_assetpath_consistent-leaf-paths.py

@@ -0,0 +1,24 @@
+# Generated by Django 4.1.1 on 2022-11-03 18:54
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('api', '0038_assetpath_assetpathrelation_alter_asset_path_and_more'),
+    ]
+
+    operations = [
+        migrations.AddConstraint(
+            model_name='assetpath',
+            constraint=models.CheckConstraint(
+                check=models.Q(
+                    ('asset__isnull', True),
+                    models.Q(('aggregate_files__lte', 1), ('asset__isnull', False)),
+                    _connector='OR',
+                ),
+                name='consistent-leaf-paths',
+            ),
+        ),
+    ]

dandiapi/api/models/asset_paths.py

@@ -28,6 +28,14 @@ class Meta:
             models.CheckConstraint(check=~models.Q(path__endswith='/'), name='consistent-slash'),
             models.UniqueConstraint(fields=['asset', 'version'], name='unique-asset-version'),
             models.UniqueConstraint(fields=['version', 'path'], name='unique-version-path'),
+            # Ensure all leaf paths have at most 1 associated file
+            models.CheckConstraint(
+                check=(
+                    models.Q(asset__isnull=True)
+                    | models.Q(asset__isnull=False, aggregate_files__lte=1)
+                ),
+                name='consistent-leaf-paths',
+            ),
         ]
 
 

dandiapi/api/tests/test_asset_paths.py

@@ -79,6 +79,23 @@ def test_asset_path_add_asset(draft_version_factory, asset_factory):
         )
 
 
+@pytest.mark.django_db
+def test_asset_path_add_asset_idempotent(draft_version_factory, asset_factory):
+    # Create asset with version
+    asset: Asset = asset_factory()
+    version: Version = draft_version_factory()
+    version.assets.add(asset)
+
+    # Add asset to paths
+    add_asset_paths(asset, version)
+    add_asset_paths(asset, version)
+
+    # Get asset path
+    path: AssetPath = AssetPath.objects.get(asset=asset, version=version)
+    assert path.aggregate_files == 1
+    assert path.aggregate_size == asset.size
+
+
 @pytest.mark.django_db
 def test_asset_path_add_version_asset_paths(draft_version_factory, asset_factory):
     # Create asset with version
@@ -113,6 +130,28 @@ def test_asset_path_add_version_asset_paths(draft_version_factory, asset_factory
     )
 
 
+@pytest.mark.django_db
+def test_asset_path_add_version_asset_paths_idempotent(draft_version_factory, asset_factory):
+    # Create asset with version
+    version: Version = draft_version_factory()
+    version.assets.add(asset_factory(path='foo/bar/baz.txt'))
+    version.assets.add(asset_factory(path='foo/bar/baz2.txt'))
+    version.assets.add(asset_factory(path='foo/baz/file.txt'))
+    version.assets.add(asset_factory(path='top.txt'))
+
+    # Add verison asset paths
+    add_version_asset_paths(version)
+    add_version_asset_paths(version)
+
+    # Ensure no duplicate counts
+    leafpaths = AssetPath.objects.select_related('asset').filter(
+        version=version, asset__isnull=False
+    )
+    for path in leafpaths:
+        assert path.aggregate_files == 1