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1 # Copyright 2016 The Chromium Authors. All rights reserved. | |
2 # Use of this source code is governed by a BSD-style license that can be | |
3 # found in the LICENSE file. | |
4 | |
5 import collections | |
6 import itertools | |
7 | |
8 from dashboard.pinpoint.models.change import commit as commit_module | |
9 from dashboard.pinpoint.models.change import patch as patch_module | |
10 | |
11 | |
12 class Change(collections.namedtuple('Change', ('commits', 'patch'))): | |
13 """A particular set of Commits with or without an additional patch applied. | |
14 | |
15 For example, a Change might sync to src@9064a40 and catapult@8f26966, | |
16 then apply patch 2423293002. | |
17 """ | |
18 | |
19 def __new__(cls, commits, patch=None): | |
20 """Creates a Change. | |
21 | |
22 Args: | |
23 commits: An iterable of Commits representing this Change's dependencies. | |
24 patch: An optional Patch to apply to the Change. | |
25 """ | |
26 if not commits: | |
27 raise TypeError('At least one commit required.') | |
28 return super(Change, cls).__new__(cls, tuple(commits), patch) | |
29 | |
30 def __str__(self): | |
31 string = ' '.join(str(commit) for commit in self.commits) | |
32 if self.patch: | |
33 string += ' + ' + str(self.patch) | |
34 return string | |
35 | |
36 @property | |
37 def id_string(self): | |
perezju
2017/09/12 10:59:54
add docstrings explaining difference between str(c
dtu
2017/09/12 22:31:16
Done.
| |
38 string = ' '.join(commit.id_string for commit in self.commits) | |
39 if self.patch: | |
40 string += ' + ' + self.patch.id_string | |
41 return string | |
42 | |
43 @property | |
44 def base_commit(self): | |
45 return self.commits[0] | |
46 | |
47 @property | |
48 def deps(self): | |
49 return tuple(self.commits[1:]) | |
50 | |
51 def AsDict(self): | |
52 return { | |
53 'commits': [commit.AsDict() for commit in self.commits], | |
54 'patch': self.patch.AsDict() if self.patch else None, | |
55 } | |
56 | |
57 @classmethod | |
58 def FromDict(cls, data): | |
59 commits = tuple(commit_module.Commit.FromDict(commit) | |
60 for commit in data['commits']) | |
61 if 'patch' in data: | |
62 patch = patch_module.Patch.FromDict(data['patch']) | |
63 else: | |
64 patch = None | |
65 | |
66 return cls(commits, patch=patch) | |
67 | |
68 @classmethod | |
69 def Midpoint(cls, change_a, change_b): | |
70 """Returns a Change halfway between the two given Changes. | |
71 | |
72 This function does two passes over the Changes' Commits: | |
73 * The first pass attempts to match the lengths of the Commit lists by | |
74 expanding DEPS to fill in any repositories that are missing from one, | |
75 but included in the other. | |
76 * The second pass takes the midpoint of every matched pair of Commits, | |
77 expanding DEPS rolls as it comes across them. | |
78 | |
79 A NonLinearError is raised if there is no valid midpoint. The Changes are | |
80 not linear if any of the following is true: | |
81 * They have different patches. | |
82 * Their repositories don't match even after expanding DEPS rolls. | |
83 * The left Change comes after the right Change. | |
84 * They are the same or adjacent. | |
85 See change_test.py for examples of linear and nonlinear Changes. | |
86 | |
87 Args: | |
88 change_a: The first Change in the range. | |
89 change_b: The last Change in the range. | |
90 | |
91 Returns: | |
92 A new Change representing the midpoint. | |
93 The Change before the midpoint if the range has an even number of commits. | |
94 | |
95 Raises: | |
96 NonLinearError: The Changes are not linear. | |
97 """ | |
98 if change_a.patch != change_b.patch: | |
99 raise commit_module.NonLinearError( | |
100 'Change A has patch "%s" and Change B has patch "%s".' % | |
101 (change_a.patch, change_b.patch)) | |
102 | |
103 commits_a = list(change_a.commits) | |
104 commits_b = list(change_b.commits) | |
105 | |
106 _ExpandDepsToMatchRepositories(commits_a, commits_b) | |
107 commits_midpoint = _FindMidpoints(commits_a, commits_b) | |
108 | |
109 if commits_a == commits_midpoint: | |
110 raise commit_module.NonLinearError('Changes are the same or adjacent.') | |
111 | |
112 return cls(commits_midpoint, change_a.patch) | |
113 | |
114 | |
115 def _ExpandDepsToMatchRepositories(commits_a, commits_b): | |
116 """Expands DEPS in a Commit list to match the repositories in another. | |
117 | |
118 Given two lists of Commits, with one bigger than the other, this function | |
119 looks through the DEPS files for smaller commit list to fill out any missing | |
120 Commits that are already in the bigger commit list. | |
121 | |
122 Mutates the lists in-place, and doesn't return anything. | |
123 | |
124 Example: | |
125 commits_a == [chromium@a, v8@c] | |
126 commits_b == [chromium@b] | |
127 This function looks through the DEPS file at chromium@b to find v8, then | |
128 appends that v8 Commit to commits_b, making the lists match. | |
129 | |
130 Args: | |
131 commits_a: A list of Commits. | |
132 commits_b: A list of Commits. | |
133 """ | |
134 # The lists may be given in any order. Let's make commits_b the bigger list. | |
135 if len(commits_a) > len(commits_b): | |
136 commits_a, commits_b = commits_b, commits_a | |
137 | |
138 # Loop through every DEPS file in commits_a. | |
139 for commit_a in commits_a: | |
perezju
2017/09/12 10:59:54
this looks scary, modifying the list while iterati
dtu
2017/09/12 22:31:16
Is it any less scary if we're not modifying the ex
perezju
2017/09/13 12:52:23
(Let's revisit again on a follow up CL)
It's stil
dtu
2017/09/13 15:49:26
It keeps going. I've used izip specifically instea
| |
140 if len(commits_a) == len(commits_b): | |
141 break | |
142 deps_a = commit_a.Deps() | |
143 | |
144 # Look through commits_b for any extra slots to fill with the DEPS. | |
145 for commit_b in commits_b[len(commits_a):]: | |
146 dep_a = _FindCommitWithRepository(deps_a, commit_b.repository) | |
147 if dep_a: | |
148 commits_a.append(dep_a) | |
149 else: | |
150 break | |
151 | |
152 | |
153 def _FindMidpoints(commits_a, commits_b): | |
154 """Returns the midpoint of two Commit lists. | |
155 | |
156 Loops through each pair of Commits and takes the midpoint. If the repositories | |
157 don't match, a NonLinearError is raised. If the Commits are adjacent and | |
158 represent a DEPS roll, the differing DEPs are added to the end of the lists. | |
159 | |
160 Args: | |
161 commits_a: A list of Commits. | |
162 commits_b: A list of Commits. | |
163 | |
164 Returns: | |
165 A list of Commits, each of which is the midpoint of the respective Commit in | |
166 commits_a and commits_b. | |
167 | |
168 Raises: | |
169 NonLinearError: The lists have a different number of commits even after | |
170 expanding DEPS rolls, a Commit pair contains differing repositories, or a | |
171 Commit pair is in the wrong order. | |
172 """ | |
173 commits_midpoint = [] | |
174 | |
175 for commit_a, commit_b in itertools.izip_longest(commits_a, commits_b): | |
perezju
2017/09/12 10:59:54
at this point the two lists should be the same siz
dtu
2017/09/12 22:31:16
In practical cases, yes, but there's no invariant
perezju
2017/09/13 12:52:23
(Let's revisit again on a follow up CL)
I was goi
dtu
2017/09/13 15:49:26
That's right. If a DEPS roll adds or removes a DEP
| |
176 if not (commit_a and commit_b): | |
177 raise commit_module.NonLinearError( | |
178 'Changes have a different number of commits.') | |
179 | |
180 try: | |
181 # Commits are not adjacent. | |
182 commit_midpoint = commit_module.Commit.Midpoint(commit_a, commit_b) | |
183 except commit_module.SameCommitWarning: | |
184 # Commits are the same. | |
185 commit_midpoint = commit_a | |
186 except commit_module.AdjacentCommitsWarning: | |
187 # Commits are adjacent. | |
188 commit_midpoint = commit_a | |
189 | |
190 # Add any DEPS changes to the commit lists. | |
191 deps_a = commit_a.Deps() | |
192 deps_b = commit_b.Deps() | |
193 commits_a += sorted( | |
194 dep for dep in deps_a.difference(deps_b) | |
195 if not _FindCommitWithRepository(commits_a, dep.repository)) | |
196 commits_b += sorted( | |
197 dep for dep in deps_b.difference(deps_a) | |
198 if not _FindCommitWithRepository(commits_b, dep.repository)) | |
199 | |
200 commits_midpoint.append(commit_midpoint) | |
201 | |
202 return commits_midpoint | |
203 | |
204 | |
205 def _FindCommitWithRepository(commits, repository): | |
206 for commit in commits: | |
207 if commit.repository == repository: | |
208 return commit | |
209 return None | |
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