Reimplement cache support for blobs in the registry data model

data/registry_model/test/test_pre_oci_model.py

@@ -5,14 +5,15 @@ from datetime import datetime, timedelta
 
 import pytest
 
+from mock import patch
 from playhouse.test_utils import assert_query_count
 
-from app import docker_v2_signing_key
 from data import model
 from data.database import (TagManifestLabelMap, TagManifestToManifest, Manifest, ManifestBlob,
                            ManifestLegacyImage, ManifestLabel, TagManifest, RepositoryTag, Image,
                            TagManifestLabel, TagManifest, TagManifestLabel, DerivedStorageForImage,
-                           TorrentInfo)
+                           TorrentInfo, close_db_filter)
+from data.cache.impl import InMemoryDataModelCache
 from data.registry_model.registry_pre_oci_model import PreOCIModel
 from data.registry_model.datatypes import RepositoryReference
 
@@ -638,3 +639,49 @@ def test_mount_blob_into_repository(pre_oci_model):
     # Ensure it now exists.
     found = pre_oci_model.get_repo_blob_by_digest(target_repository_ref, layer.blob.digest)
     assert found == layer.blob
+
+
+class SomeException(Exception):
+  pass
+
+
+def test_get_cached_repo_blob(pre_oci_model):
+  model_cache = InMemoryDataModelCache()
+
+  repository_ref = pre_oci_model.lookup_repository('devtable', 'simple')
+  latest_tag = pre_oci_model.get_repo_tag(repository_ref, 'latest')
+  manifest = pre_oci_model.get_manifest_for_tag(latest_tag)
+
+  layers = pre_oci_model.list_manifest_layers(manifest, include_placements=True)
+  assert layers
+
+  blob = layers[0].blob
+
+  # Load a blob to add it to the cache.
+  found = pre_oci_model.get_cached_repo_blob(model_cache, 'devtable', 'simple', blob.digest)
+  assert found.digest == blob.digest
+  assert found.uuid == blob.uuid
+  assert found.compressed_size == blob.compressed_size
+  assert found.uncompressed_size == blob.uncompressed_size
+  assert found.uploading == blob.uploading
+  assert found.placements == blob.placements
+
+  # Disconnect from the database by overwriting the connection.
+  def fail(x, y):
+    raise SomeException('Not connected!')
+
+  with patch('data.registry_model.registry_pre_oci_model.model.blob.get_repository_blob_by_digest',
+             fail):
+    # Make sure we can load again, which should hit the cache.
+    cached = pre_oci_model.get_cached_repo_blob(model_cache, 'devtable', 'simple', blob.digest)
+    assert cached.digest == blob.digest
+    assert cached.uuid == blob.uuid
+    assert cached.compressed_size == blob.compressed_size
+    assert cached.uncompressed_size == blob.uncompressed_size
+    assert cached.uploading == blob.uploading
+    assert cached.placements == blob.placements
+
+    # Try another blob, which should fail since the DB is not connected and the cache
+    # does not contain the blob.
+    with pytest.raises(SomeException):
+      pre_oci_model.get_cached_repo_blob(model_cache, 'devtable', 'simple', 'some other digest')