99 lines
3.4 KiB
Ruby
Executable File
99 lines
3.4 KiB
Ruby
Executable File
#!/usr/bin/ruby
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require 'set'
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# Get commits in one branch, but not in another, accounting for cherry-picks.
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# Accepts two arguments: base branch and old branch. Commits in base branch that
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# are not in old branch will be reported.
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# Preface: I know exactly enough ruby to be dangerous with it.
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# For anyone reading this who is actually skilled at writing Ruby, I can only
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# say I'm very, very sorry.
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# Utility functions:
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# Check if a given Git branch exists
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def CheckBranchExists(branch)
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return `git branch --list #{branch}`.rstrip.empty?
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end
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# Returns author (email) and commit subject for the given hash
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def GetCommitInfo(hash)
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info = `git log -n 1 --format='%ae%n%s' #{hash}`.split("\n")
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if info.length != 2
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puts("Badly-formatted commit with hash #{hash}")
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exit(127)
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end
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return info[0], info[1]
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end
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# Actual script begins here
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if ARGV.length != 2
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puts("Must provide exactly 2 arguments, base branch and old branch")
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exit(127)
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end
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# Both branches must exist
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ARGV.each do |branch|
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if !CheckBranchExists(branch)
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puts("Branch #{branch} does not exist")
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exit(127)
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end
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end
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base = ARGV[0]
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old = ARGV[1]
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# Get a base list of commits
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commits = `git log --no-merges --format=%H #{base} ^#{old}`.split("\n")
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# Alright, now for the hacky bit.
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# We want to remove every commit with a shortlog precisely matching something in
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# the old branch. This is an effort to catch cherry-picks, where commit ID has
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# almost certainly changed because the committer is different (and possibly
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# conflicts needed to be resolved).
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# We will match also try and match author, but not committer (which is reset to
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# whoever did the cherry-pick). We will *not* match full commit body - I
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# routinely edit these when I fix cherry-pick conflicts to indicate that I made
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# changes. A more ambitious future committer could attempt to see if the body of
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# the commit message in the old branch is a subset of the full commit message
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# from the base branch, but there are potential performance implications in that
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# due to the size of the string comparison that would be needed.
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# This will not catch commits where the shortlog is deliberately altered as part
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# of the cherry pick... But we can just ask folks not to do that, I guess?
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# (A classic example of something this wouldn't catch: cherry-picking a commit
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# to a branch and then prepending the branch name to the commit subject. I see
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# this a lot in Github PR subjects, but fortunately not much at all in actual
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# commit subjects).
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# Begin by fetching commit author + subject for each commit in old branch.
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# Map each author to an array of potential commit subjects.
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oldIndex = {}
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# TODO: This could probably be made a whole lot more efficient by unifying the
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# GetCommitInfo bits into two big `git log --format` calls.
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# But I'm not really ambitious enough to do that...
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oldCommits = `git log --no-merges --format=%H #{old}`.split("\n")
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oldCommits.each do |hash|
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name, subject = GetCommitInfo(hash)
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if oldIndex[name] == nil
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oldIndex[name] = Set[]
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end
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oldIndex[name].add(subject)
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end
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# Go through our earlier commits list and check for matches.
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filtered = commits.reject do |hash|
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name, subject = GetCommitInfo(hash)
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oldIndex[name] != nil && oldIndex[name].include?(subject)
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end
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# We have now filtered out all commits we want to filter.
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# Now we just have to print all remaining commits.
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# This breaks the default pager, but we can just pipe to less.
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filtered.each do |hash|
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puts `git log -n 1 #{hash}`
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puts "\n"
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end
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