Coverage for python/lsst/daf/butler/registry/interfaces/_opaque.py: 78%
34 statements
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1# This file is part of daf_butler.
2#
3# Developed for the LSST Data Management System.
4# This product includes software developed by the LSST Project
5# (http://www.lsst.org).
6# See the COPYRIGHT file at the top-level directory of this distribution
7# for details of code ownership.
8#
9# This program is free software: you can redistribute it and/or modify
10# it under the terms of the GNU General Public License as published by
11# the Free Software Foundation, either version 3 of the License, or
12# (at your option) any later version.
13#
14# This program is distributed in the hope that it will be useful,
15# but WITHOUT ANY WARRANTY; without even the implied warranty of
16# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17# GNU General Public License for more details.
18#
19# You should have received a copy of the GNU General Public License
20# along with this program. If not, see <http://www.gnu.org/licenses/>.
21from __future__ import annotations
23"""Interfaces for the objects that manage opaque (logical) tables within a
24`Registry`.
25"""
27__all__ = ["OpaqueTableStorageManager", "OpaqueTableStorage"]
29from abc import ABC, abstractmethod
30from typing import TYPE_CHECKING, Any, Iterable, Iterator, Mapping, Optional
32from ...core.ddl import TableSpec
33from ._database import Database, StaticTablesContext
34from ._versioning import VersionedExtension, VersionTuple
36if TYPE_CHECKING:
37 from ...core.datastore import DatastoreTransaction
40class OpaqueTableStorage(ABC):
41 """An interface that manages the records associated with a particular
42 opaque table in a `Registry`.
44 Parameters
45 ----------
46 name : `str`
47 Name of the opaque table.
48 """
50 def __init__(self, name: str):
51 self.name = name
53 @abstractmethod
54 def insert(self, *data: dict, transaction: DatastoreTransaction | None = None) -> None:
55 """Insert records into the table
57 Parameters
58 ----------
59 *data
60 Each additional positional argument is a dictionary that represents
61 a single row to be added.
62 transaction : `DatastoreTransaction`, optional
63 Transaction object that can be used to enable an explicit rollback
64 of the insert to be registered. Can be ignored if rollback is
65 handled via a different mechanism, such as by a database. Can be
66 `None` if no external transaction is available.
67 """
68 raise NotImplementedError()
70 @abstractmethod
71 def fetch(self, **where: Any) -> Iterator[Mapping[Any, Any]]:
72 """Retrieve records from an opaque table.
74 Parameters
75 ----------
76 **where
77 Additional keyword arguments are interpreted as equality
78 constraints that restrict the returned rows (combined with AND);
79 keyword arguments are column names and values are the values they
80 must have.
82 Yields
83 ------
84 row : `dict`
85 A dictionary representing a single result row.
86 """
87 raise NotImplementedError()
89 @abstractmethod
90 def delete(self, columns: Iterable[str], *rows: dict) -> None:
91 """Remove records from an opaque table.
93 Parameters
94 ----------
95 columns: `~collections.abc.Iterable` of `str`
96 The names of columns that will be used to constrain the rows to
97 be deleted; these will be combined via ``AND`` to form the
98 ``WHERE`` clause of the delete query.
99 *rows
100 Positional arguments are the keys of rows to be deleted, as
101 dictionaries mapping column name to value. The keys in all
102 dictionaries must be exactly the names in ``columns``.
103 """
104 raise NotImplementedError()
106 name: str
107 """The name of the logical table this instance manages (`str`).
108 """
111class OpaqueTableStorageManager(VersionedExtension):
112 """An interface that manages the opaque tables in a `Registry`.
114 `OpaqueTableStorageManager` primarily serves as a container and factory for
115 `OpaqueTableStorage` instances, which each provide access to the records
116 for a different (logical) opaque table.
118 Notes
119 -----
120 Opaque tables are primarily used by `Datastore` instances to manage their
121 internal data in the same database that hold the `Registry`, but are not
122 limited to this.
124 While an opaque table in a multi-layer `Registry` may in fact be the union
125 of multiple tables in different layers, we expect this to be rare, as
126 `Registry` layers will typically correspond to different leaf `Datastore`
127 instances (each with their own opaque table) in a `ChainedDatastore`.
128 """
130 def __init__(self, *, registry_schema_version: VersionTuple | None = None):
131 super().__init__(registry_schema_version=registry_schema_version)
133 @classmethod
134 @abstractmethod
135 def initialize(
136 cls, db: Database, context: StaticTablesContext, registry_schema_version: VersionTuple | None = None
137 ) -> OpaqueTableStorageManager:
138 """Construct an instance of the manager.
140 Parameters
141 ----------
142 db : `Database`
143 Interface to the underlying database engine and namespace.
144 context : `StaticTablesContext`
145 Context object obtained from `Database.declareStaticTables`; used
146 to declare any tables that should always be present in a layer
147 implemented with this manager.
148 registry_schema_version : `VersionTuple` or `None`
149 Schema version of this extension as defined in registry.
151 Returns
152 -------
153 manager : `OpaqueTableStorageManager`
154 An instance of a concrete `OpaqueTableStorageManager` subclass.
155 """
156 raise NotImplementedError()
158 def __getitem__(self, name: str) -> OpaqueTableStorage:
159 """Interface to `get` that raises `LookupError` instead of returning
160 `None` on failure.
161 """
162 r = self.get(name)
163 if r is None:
164 raise LookupError(f"No logical table with name '{name}' found.")
165 return r
167 @abstractmethod
168 def get(self, name: str) -> Optional[OpaqueTableStorage]:
169 """Return an object that provides access to the records associated with
170 an opaque logical table.
172 Parameters
173 ----------
174 name : `str`
175 Name of the logical table.
177 Returns
178 -------
179 records : `OpaqueTableStorage` or `None`
180 The object representing the records for the given table in this
181 layer, or `None` if there are no records for that table in this
182 layer.
184 Notes
185 -----
186 Opaque tables must be registered with the layer (see `register`) by
187 the same client before they can safely be retrieved with `get`.
188 Unlike most other manager classes, the set of opaque tables cannot be
189 obtained from an existing data repository.
190 """
191 raise NotImplementedError()
193 @abstractmethod
194 def register(self, name: str, spec: TableSpec) -> OpaqueTableStorage:
195 """Ensure that this layer can hold records for the given opaque logical
196 table, creating new tables as necessary.
198 Parameters
199 ----------
200 name : `str`
201 Name of the logical table.
202 spec : `TableSpec`
203 Schema specification for the table to be created.
205 Returns
206 -------
207 records : `OpaqueTableStorage`
208 The object representing the records for the given element in this
209 layer.
211 Notes
212 -----
213 This operation may not be invoked within a transaction context block.
214 """
215 raise NotImplementedError()