Coverage for python/lsst/daf/persistence/storage.py: 24%
90 statements
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« prev ^ index » next coverage.py v6.4.4, created at 2022-09-07 09:51 +0000
1#!/usr/bin/env python
3#
4# LSST Data Management System
5# Copyright 2016 LSST Corporation.
6#
7# This product includes software developed by the
8# LSST Project (http://www.lsst.org/).
9#
10# This program is free software: you can redistribute it and/or modify
11# it under the terms of the GNU General Public License as published by
12# the Free Software Foundation, either version 3 of the License, or
13# (at your option) any later version.
14#
15# This program is distributed in the hope that it will be useful,
16# but WITHOUT ANY WARRANTY; without even the implied warranty of
17# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18# GNU General Public License for more details.
19#
20# You should have received a copy of the LSST License Statement and
21# the GNU General Public License along with this program. If not,
22# see <http://www.lsstcorp.org/LegalNotices/>.
23#
25import urllib.parse
26from . import NoRepositroyAtRoot
29class Storage:
30 """Base class for storages"""
32 storages = {}
34 def __init__(self):
35 self.repositoryCfgs = {}
37 @staticmethod
38 def registerStorageClass(scheme, cls):
39 """Register derived classes for lookup by URI scheme.
41 A scheme is a name that describes the form a resource at the beginning of a URI
42 e.g. 'http' indicates HTML and related code, such as is found in http://www.lsst.org
44 The only currently supported schemes are:
45 * 'file' where the portion of the URI after the // indicates an absolute locaiton on disk.
46 for example: file:/my_repository_folder/
47 * '' (no scheme) where the entire string is a relative path on the local system
48 for example "my_repository_folder" will indicate a folder in the current working directory with the
49 same name.
51 See documentation for the urlparse python library for more information.
53 .. warning::
55 Storage is 'wet paint' and very likely to change during factorization of Butler back end and
56 storage formats (DM-6225). Use of it in production code other than via the 'old butler' API is
57 strongly discouraged.
59 Parameters
60 ----------
61 scheme : str
62 Name of the `scheme` the class is being registered for, which appears at the beginning of a URI.
63 cls : class object
64 A class object that should be used for a given scheme.
65 """
66 if scheme in Storage.storages: 66 ↛ 67line 66 didn't jump to line 67, because the condition on line 66 was never true
67 raise RuntimeError("Scheme '%s' already registered:%s" % (scheme, Storage.storages[scheme]))
68 Storage.storages[scheme] = cls
70 def getRepositoryCfg(self, uri):
71 """Get a RepositoryCfg from a location specified by uri.
73 If a cfg is found then it is cached by the uri, so that multiple lookups
74 are not performed on storages that might be remote.
76 RepositoryCfgs are not supposed to change once they are created so this
77 should not lead to stale data.
78 """
79 cfg = self.repositoryCfgs.get(uri, None)
80 if cfg:
81 return cfg
82 parseRes = urllib.parse.urlparse(uri)
83 if parseRes.scheme in Storage.storages:
84 cfg = Storage.storages[parseRes.scheme].getRepositoryCfg(uri)
85 if cfg:
86 self.repositoryCfgs[uri] = cfg
87 else:
88 raise RuntimeError("No storage registered for scheme %s" % parseRes.scheme)
89 return cfg
91 @staticmethod
92 def putRepositoryCfg(cfg, uri):
93 """Write a RepositoryCfg object to a location described by uri"""
94 ret = None
95 parseRes = urllib.parse.urlparse(uri)
96 if parseRes.scheme in Storage.storages:
97 ret = Storage.storages[parseRes.scheme].putRepositoryCfg(cfg, uri)
98 else:
99 raise RuntimeError("No storage registered for scheme %s" % parseRes.scheme)
100 return ret
102 @staticmethod
103 def getMapperClass(uri):
104 """Get a mapper class cfg value from location described by uri.
106 Note that in legacy repositories the mapper may be specified by a file called _mapper at the uri
107 location, and in newer repositories the mapper would be specified by a RepositoryCfg stored at the uri
108 location.
110 .. warning::
112 Storage is 'wet paint' and very likely to change during factorization of Butler back end and
113 storage formats (DM-6225). Use of it in production code other than via the 'old butler' API is
114 strongly discouraged.
116 """
117 ret = None
118 parseRes = urllib.parse.urlparse(uri)
119 if parseRes.scheme in Storage.storages:
120 ret = Storage.storages[parseRes.scheme].getMapperClass(uri)
121 else:
122 raise RuntimeError("No storage registered for scheme %s" % parseRes.scheme)
123 return ret
125 @staticmethod
126 def makeFromURI(uri, create=True):
127 '''Instantiate a StorageInterface sublcass from a URI.
129 .. warning::
131 Storage is 'wet paint' and very likely to change during factorization of Butler back end and
132 storage formats (DM-6225). Use of it in production code other than via the 'old butler' API is
133 strongly discouraged.
135 Parameters
136 ----------
137 uri : string
138 The uri to the root location of a repository.
139 create : bool, optional
140 If True The StorageInterface subclass should create a new
141 repository at the root location. If False then a new repository
142 will not be created.
144 Returns
145 -------
146 A Storage subclass instance, or if create is False and a repository
147 does not exist at the root location then returns None.
149 Raises
150 ------
151 RuntimeError
152 When a StorageInterface subclass does not exist for the scheme
153 indicated by the uri.
154 '''
155 ret = None
156 parseRes = urllib.parse.urlparse(uri)
157 if parseRes.scheme in Storage.storages:
158 theClass = Storage.storages[parseRes.scheme]
159 try:
160 ret = theClass(uri=uri, create=create)
161 except NoRepositroyAtRoot:
162 pass
163 else:
164 raise RuntimeError("No storage registered for scheme %s" % parseRes.scheme)
165 return ret
167 @staticmethod
168 def isPosix(uri):
169 """Test if a URI is for a local filesystem storage.
171 This is mostly for backward compatibility; Butler V1 repositories were only ever on the local
172 filesystem. They may exist but not have a RepositoryCfg class. This enables conditional checking for a
173 V1 Repository.
175 This function treats 'file' and '' (no scheme) as posix storages, see
176 the class docstring for more details.
178 Parameters
179 ----------
180 uri : string
181 URI to the root of a Repository.
183 Returns
184 -------
185 Bool
186 True if the URI is associated with a posix storage, else false.
187 """
188 parseRes = urllib.parse.urlparse(uri)
189 if parseRes.scheme in ('file', ''):
190 return True
191 return False
193 @staticmethod
194 def relativePath(fromUri, toUri):
195 """Get a relative path from a location to a location, if a relative path for these 2 locations exists.
197 Parameters
198 ----------
199 fromPath : string
200 A URI that describes a location at which to start.
201 toPath : string
202 A URI that describes a target location.
204 Returns
205 -------
206 string
207 A relative path that describes the path from fromUri to toUri, provided one exists. If a relative
208 path between the two URIs does not exist then the entire toUri path is returned.
209 """
210 fromUriParseRes = urllib.parse.urlparse(fromUri)
211 toUriParseRes = urllib.parse.urlparse(toUri)
212 if fromUriParseRes.scheme != toUriParseRes.scheme:
213 return toUri
214 storage = Storage.storages.get(fromUriParseRes.scheme, None)
215 if not storage:
216 return toUri
217 return storage.relativePath(fromUri, toUri)
219 @staticmethod
220 def absolutePath(fromUri, toUri):
221 """Get an absolute path for the path from fromUri to toUri
223 Parameters
224 ----------
225 fromUri : the starting location
226 Description
227 toUri : the location relative to fromUri
228 Description
230 Returns
231 -------
232 string
233 URI that is absolutepath fromUri + toUri, if one exists. If toUri is absolute or if fromUri is not
234 related to toUri (e.g. are of different storage types) then toUri will be returned.
235 """
236 fromUriParseRes = urllib.parse.urlparse(fromUri)
237 toUriParseRes = urllib.parse.urlparse(toUri)
238 if fromUriParseRes.scheme != toUriParseRes.scheme:
239 return toUri
240 storage = Storage.storages.get(fromUriParseRes.scheme, None)
241 if not storage:
242 return toUri
243 return storage.absolutePath(fromUri, toUri)
245 @staticmethod
246 def search(uri, path):
247 """Look for the given path in a storage root at URI; return None if it can't be found.
249 If the path contains an HDU indicator (a number in brackets before the
250 dot, e.g. 'foo.fits[1]', this will be stripped when searching and so
251 will match filenames without the HDU indicator, e.g. 'foo.fits'. The
252 path returned WILL contain the indicator though, e.g. ['foo.fits[1]'].
255 Parameters
256 ----------
257 root : string
258 URI to the the root location to search
259 path : string
260 A filename (and optionally prefix path) to search for within root.
262 Returns
263 -------
264 string or None
265 The location that was found, or None if no location was found.
266 """
267 parseRes = urllib.parse.urlparse(uri)
268 storage = Storage.storages.get(parseRes.scheme, None)
269 if storage:
270 return storage.search(uri, path)
271 return None
273 @staticmethod
274 def storageExists(uri):
275 """Ask if a storage at the location described by uri exists
277 Parameters
278 ----------
279 root : string
280 URI to the the root location of the storage
282 Returns
283 -------
284 bool
285 True if the storage exists, false if not
286 """
287 parseRes = urllib.parse.urlparse(uri)
288 storage = Storage.storages.get(parseRes.scheme, None)
289 if storage:
290 return storage.storageExists(uri)
291 return None