Add Tag, TagKind and ManifestChild tables in prep for new data model

data/database.py

@@ -1385,6 +1385,58 @@ class Manifest(BaseModel):
     )
 
 
+class TagKind(BaseModel):
+  """ TagKind describes the various kinds of tags that can be found in the registry.
+  """
+  name = CharField(index=True, unique=True)
+
+
+class Tag(BaseModel):
+  """ Tag represents a user-facing alias for referencing a Manifest or as an alias to another tag.
+  """
+  name = CharField()
+  repository = ForeignKeyField(Repository)
+  manifest = ForeignKeyField(Manifest, null=True)
+  lifetime_start_ms = BigIntegerField(default=get_epoch_timestamp_ms)
+  lifetime_end_ms = BigIntegerField(null=True, index=True)
+  hidden = BooleanField(default=False)
+  reverted = BooleanField(default=False)
+  tag_kind = EnumField(TagKind)
+  linked_tag = ForeignKeyField('self', null=True, backref='tag_parents')
+
+  class Meta:
+    database = db
+    read_slaves = (read_slave,)
+    indexes = (
+      (('repository', 'name'), False),
+      (('repository', 'name', 'hidden'), False),
+      (('repository', 'name', 'tag_kind'), False),
+
+      # This unique index prevents deadlocks when concurrently moving and deleting tags
+      (('repository', 'name', 'lifetime_end_ms'), True),
+    )
+
+
+class ManifestChild(BaseModel):
+  """ ManifestChild represents a relationship between a manifest and its child manifest(s).
+      Multiple manifests can share the same children. Note that since Manifests are stored
+      per-repository, the repository here is a bit redundant, but we do so to make cleanup easier.
+  """
+  repository = ForeignKeyField(Repository)
+  manifest = ForeignKeyField(Manifest)
+  child_manifest = ForeignKeyField(Manifest)
+
+  class Meta:
+    database = db
+    read_slaves = (read_slave,)
+    indexes = (
+      (('repository', 'manifest'), False),
+      (('repository', 'child_manifest'), False),
+      (('repository', 'manifest', 'child_manifest'), False),
+      (('manifest', 'child_manifest'), True),
+    )
+
+
 class ManifestLabel(BaseModel):
   """ ManifestLabel represents a label applied to a Manifest, within a repository.
       Note that since Manifests are stored per-repository, the repository here is
@@ -1470,7 +1522,8 @@ class TagManifestLabelMap(BaseModel):
 appr_classes = set([ApprTag, ApprTagKind, ApprBlobPlacementLocation, ApprManifestList,
                     ApprManifestBlob, ApprBlob, ApprManifestListManifest, ApprManifest,
                     ApprBlobPlacement])
-v22_classes = set([Manifest, ManifestLabel, ManifestBlob, ManifestLegacyImage])
+v22_classes = set([Manifest, ManifestLabel, ManifestBlob, ManifestLegacyImage, TagKind,
+                   ManifestChild, Tag])
 transition_classes = set([TagManifestToManifest, TagManifestLabelMap])
 
 is_model = lambda x: inspect.isclass(x) and issubclass(x, BaseModel) and x is not BaseModel