114 lines
4.5 KiB
Ruby
114 lines
4.5 KiB
Ruby
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# frozen_string_literal: true
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module Projects
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module Forks
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# A service for fetching upstream default branch and merging it to the fork's specified branch.
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class SyncService < BaseService
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ONGOING_MERGE_ERROR = 'The synchronization did not happen due to another merge in progress'
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MergeError = Class.new(StandardError)
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def initialize(project, user, target_branch)
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super(project, user)
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@source_project = project.fork_source
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@head_sha = project.repository.commit(target_branch).sha
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@target_branch = target_branch
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@details = Projects::Forks::Details.new(project, target_branch)
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end
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def execute
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execute_service
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ServiceResponse.success
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rescue MergeError => e
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Gitlab::ErrorTracking.log_exception(e, { project_id: project.id, user_id: current_user.id })
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ServiceResponse.error(message: e.message)
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ensure
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details.exclusive_lease.cancel
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end
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private
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attr_reader :source_project, :head_sha, :target_branch, :details
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# The method executes multiple steps:
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#
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# 1. Gitlab::Git::CrossRepo fetches upstream default branch into a temporary ref and returns new source sha.
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# 2. New divergence counts are calculated using the source sha.
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# 3. If the fork is not behind, there is nothing to merge -> exit.
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# 4. Otherwise, continue with the new source sha.
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# 5. If Gitlab::Git::CommandError is raised it means that merge couldn't happen due to a merge conflict. The
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# details are updated to transfer this error to the user.
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def execute_service
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counts = []
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source_sha = source_project.commit.sha
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Gitlab::Git::CrossRepo.new(repository, source_project.repository)
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.execute(source_sha) do |cross_repo_source_sha|
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counts = repository.diverging_commit_count(head_sha, cross_repo_source_sha)
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ahead, behind = counts
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next if behind == 0
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execute_with_fetched_source(cross_repo_source_sha, ahead)
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end
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rescue Gitlab::Git::CommandError => e
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details.update!({ sha: head_sha, source_sha: source_sha, counts: counts, has_conflicts: true })
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raise MergeError, e.message
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end
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def execute_with_fetched_source(cross_repo_source_sha, ahead)
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with_linked_lfs_pointers(cross_repo_source_sha) do
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merge_commit_id = perform_merge(cross_repo_source_sha, ahead)
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raise MergeError, ONGOING_MERGE_ERROR unless merge_commit_id
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end
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end
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# This method merges the upstream default branch to the fork specified branch.
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# Depending on whether the fork branch is ahead of upstream or not, a different type of
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# merge is performed.
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#
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# If the fork's branch is not ahead of the upstream (only behind), fast-forward merge is performed.
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# However, if the fork's branch contains commits that don't exist upstream, a merge commit is created.
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# In this case, a conflict may happen, which interrupts the merge and returns a message to the user.
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def perform_merge(cross_repo_source_sha, ahead)
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if ahead > 0
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message = "Merge branch #{source_project.path}:#{source_project.default_branch} into #{target_branch}"
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repository.merge_to_branch(current_user,
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source_sha: cross_repo_source_sha,
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target_branch: target_branch,
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target_sha: head_sha,
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message: message)
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else
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repository.ff_merge(current_user, cross_repo_source_sha, target_branch, target_sha: head_sha)
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end
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end
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# This method links the newly merged lfs objects (if any) with the existing ones upstream.
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# The LfsLinkService service has a limit and may raise an error if there are too many lfs objects to link.
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# This is the reason why the block is passed:
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#
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# 1. Verify that there are not too many lfs objects to link
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# 2. Execute the block (which basically performs the merge)
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# 3. Link lfs objects
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def with_linked_lfs_pointers(newrev, &block)
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return yield unless project.lfs_enabled?
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oldrev = head_sha
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new_lfs_oids =
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Gitlab::Git::LfsChanges
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.new(repository, newrev)
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.new_pointers(not_in: [oldrev])
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.map(&:lfs_oid)
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Projects::LfsPointers::LfsLinkService.new(project).execute(new_lfs_oids, &block)
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rescue Projects::LfsPointers::LfsLinkService::TooManyOidsError => e
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raise MergeError, e.message
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end
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end
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end
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end
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