Class: MergeRequests::OldestPerCommitFinder

Inherits:
Object
  • Object
show all
Defined in:
app/finders/merge_requests/oldest_per_commit_finder.rb

Overview

OldestPerCommitFinder is used to retrieve the oldest merge requests for every given commit, grouped per commit SHA.

This finder is useful when you need to efficiently retrieve the first/oldest merge requests for multiple commits, and you want to do so in batches; instead of running a query for every commit.

Instance Method Summary collapse

Constructor Details

#initialize(project) ⇒ OldestPerCommitFinder

Returns a new instance of OldestPerCommitFinder.


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# File 'app/finders/merge_requests/oldest_per_commit_finder.rb', line 11

def initialize(project)
  @project = project
end

Instance Method Details

#execute(commits) ⇒ Object

Returns a Hash that maps a commit ID to the oldest merge request that introduced that commit.


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# File 'app/finders/merge_requests/oldest_per_commit_finder.rb', line 17

def execute(commits)
  mapping = {}
  shas = commits.map(&:id)

  # To include merge requests by the merge/squash SHA, we don't need to go
  # through any diff rows.
  #
  # We can't squeeze all this into a single query, as the diff based data
  # relies on a GROUP BY. On the other hand, retrieving MRs by their merge
  # SHAs separately is much easier, and plenty fast.
  @project
    .merge_requests
    .preload_target_project
    .by_merge_or_squash_commit_sha(shas)
    .each do |mr|
      # Merge/squash SHAs can't be in the merge request itself. It _is_
      # possible a newer merge request includes the commit, but in that case
      # we still want the oldest merge request.
      #
      # It's also possible that a merge request produces both a squashed
      # commit and a merge commit. In that case we want to store the mapping
      # for both the SHAs.
      mapping[mr.squash_commit_sha] = mr if mr.squash_commit_sha
      mapping[mr.merge_commit_sha] = mr if mr.merge_commit_sha
    end

  remaining = shas - mapping.keys

  return mapping if remaining.empty?

  id_rows = MergeRequestDiffCommit
    .oldest_merge_request_id_per_commit(@project.id, remaining)

  mrs = MergeRequest
    .preload_target_project
    .id_in(id_rows.map { |r| r[:merge_request_id] })
    .index_by(&:id)

  id_rows.each do |row|
    if (mr = mrs[row[:merge_request_id]])
      mapping[row[:sha]] = mr
    end
  end

  mapping
end