1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
|
# frozen_string_literal: true
module Projects
module Forks
# Class for calculating the divergence of a fork with the source project
class DivergenceCounts
LATEST_COMMITS_COUNT = 10
EXPIRATION_TIME = 8.hours
def initialize(project, ref)
@project = project
@fork_repo = project.repository
@source_repo = project.fork_source.repository
@ref = ref
end
def counts
ahead, behind = divergence_counts
{ ahead: ahead, behind: behind }
end
private
attr_reader :project, :fork_repo, :source_repo, :ref
def cache_key
@cache_key ||= ['project_forks', project.id, ref, 'divergence_counts']
end
def divergence_counts
fork_sha = fork_repo.commit(ref).sha
source_sha = source_repo.commit.sha
cached_source_sha, cached_fork_sha, counts = Rails.cache.read(cache_key)
return counts if cached_source_sha == source_sha && cached_fork_sha == fork_sha
counts = calculate_divergence_counts(fork_sha, source_sha)
Rails.cache.write(cache_key, [source_sha, fork_sha, counts], expires_in: EXPIRATION_TIME)
counts
end
def calculate_divergence_counts(fork_sha, source_sha)
# If the upstream latest commit exists in the fork repo, then
# it's possible to calculate divergence counts within the fork repository.
return fork_repo.diverging_commit_count(fork_sha, source_sha) if fork_repo.commit(source_sha)
# Otherwise, we need to find a commit that exists both in the fork and upstream
# in order to use this commit as a base for calculating divergence counts.
# Considering the fact that a user usually creates a fork to contribute to the upstream,
# it is expected that they have a limited number of commits ahead of upstream.
# Let's take the latest N commits and check their existence upstream.
last_commits_shas = fork_repo.commits(ref, limit: LATEST_COMMITS_COUNT).map(&:sha)
existence_hash = source_repo.check_objects_exist(last_commits_shas)
first_matched_commit_sha = last_commits_shas.find { |sha| existence_hash[sha] }
# If we can't find such a commit, we return early and tell the user that the branches
# have diverged and action is required.
return unless first_matched_commit_sha
# Otherwise, we use upstream to calculate divergence counts from the matched commit
ahead, behind = source_repo.diverging_commit_count(first_matched_commit_sha, source_sha)
# And add the number of commits a fork is ahead of the first matched commit
ahead += last_commits_shas.index(first_matched_commit_sha)
[ahead, behind]
end
end
end
end
|
