Mercurial > hg
comparison mercurial/revlog.py @ 39877:f8eb71f9e3bd
storageutil: new module for storage primitives (API)
There will exist common code between storage backends. It would
be nice to have a central place to put that code.
This commit attempts to create that place by creating the
"storageutil" module.
The first thing we move is revlog.hash(), which is the function for
computing the SHA-1 hash of revision fulltext and parents.
Differential Revision: https://phab.mercurial-scm.org/D4753
author | Gregory Szorc <gregory.szorc@gmail.com> |
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date | Mon, 24 Sep 2018 14:23:54 -0700 |
parents | 733db72f0f54 |
children | 3e896b51aa5d |
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39876:a269fa55467e | 39877:f8eb71f9e3bd |
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14 from __future__ import absolute_import | 14 from __future__ import absolute_import |
15 | 15 |
16 import collections | 16 import collections |
17 import contextlib | 17 import contextlib |
18 import errno | 18 import errno |
19 import hashlib | |
20 import os | 19 import os |
21 import re | 20 import re |
22 import struct | 21 import struct |
23 import zlib | 22 import zlib |
24 | 23 |
72 from .revlogutils import ( | 71 from .revlogutils import ( |
73 deltas as deltautil, | 72 deltas as deltautil, |
74 ) | 73 ) |
75 from .utils import ( | 74 from .utils import ( |
76 interfaceutil, | 75 interfaceutil, |
76 storageutil, | |
77 stringutil, | 77 stringutil, |
78 ) | 78 ) |
79 | 79 |
80 # blanked usage of all the name to prevent pyflakes constraints | 80 # blanked usage of all the name to prevent pyflakes constraints |
81 # We need these name available in the module for extensions. | 81 # We need these name available in the module for extensions. |
194 | 194 |
195 def offset_type(offset, type): | 195 def offset_type(offset, type): |
196 if (type & ~REVIDX_KNOWN_FLAGS) != 0: | 196 if (type & ~REVIDX_KNOWN_FLAGS) != 0: |
197 raise ValueError('unknown revlog index flags') | 197 raise ValueError('unknown revlog index flags') |
198 return int(int(offset) << 16 | type) | 198 return int(int(offset) << 16 | type) |
199 | |
200 _nullhash = hashlib.sha1(nullid) | |
201 | |
202 def hash(text, p1, p2): | |
203 """generate a hash from the given text and its parent hashes | |
204 | |
205 This hash combines both the current file contents and its history | |
206 in a manner that makes it easy to distinguish nodes with the same | |
207 content in the revision graph. | |
208 """ | |
209 # As of now, if one of the parent node is null, p2 is null | |
210 if p2 == nullid: | |
211 # deep copy of a hash is faster than creating one | |
212 s = _nullhash.copy() | |
213 s.update(p1) | |
214 else: | |
215 # none of the parent nodes are nullid | |
216 if p1 < p2: | |
217 a = p1 | |
218 b = p2 | |
219 else: | |
220 a = p2 | |
221 b = p1 | |
222 s = hashlib.sha1(a) | |
223 s.update(b) | |
224 s.update(text) | |
225 return s.digest() | |
226 | 199 |
227 @attr.s(slots=True, frozen=True) | 200 @attr.s(slots=True, frozen=True) |
228 class _revisioninfo(object): | 201 class _revisioninfo(object): |
229 """Information about a revision that allows building its fulltext | 202 """Information about a revision that allows building its fulltext |
230 node: expected hash of the revision | 203 node: expected hash of the revision |
1381 """compare text with a given file revision | 1354 """compare text with a given file revision |
1382 | 1355 |
1383 returns True if text is different than what is stored. | 1356 returns True if text is different than what is stored. |
1384 """ | 1357 """ |
1385 p1, p2 = self.parents(node) | 1358 p1, p2 = self.parents(node) |
1386 return hash(text, p1, p2) != node | 1359 return storageutil.hashrevisionsha1(text, p1, p2) != node |
1387 | 1360 |
1388 def _cachesegment(self, offset, data): | 1361 def _cachesegment(self, offset, data): |
1389 """Add a segment to the revlog cache. | 1362 """Add a segment to the revlog cache. |
1390 | 1363 |
1391 Accepts an absolute offset and the data that is at that location. | 1364 Accepts an absolute offset and the data that is at that location. |
1670 """Compute a node hash. | 1643 """Compute a node hash. |
1671 | 1644 |
1672 Available as a function so that subclasses can replace the hash | 1645 Available as a function so that subclasses can replace the hash |
1673 as needed. | 1646 as needed. |
1674 """ | 1647 """ |
1675 return hash(text, p1, p2) | 1648 return storageutil.hashrevisionsha1(text, p1, p2) |
1676 | 1649 |
1677 def _processflags(self, text, flags, operation, raw=False): | 1650 def _processflags(self, text, flags, operation, raw=False): |
1678 """Inspect revision data flags and applies transforms defined by | 1651 """Inspect revision data flags and applies transforms defined by |
1679 registered flag processors. | 1652 registered flag processors. |
1680 | 1653 |