gitlab-org--gitlab-foss/lib/gitlab/github_import/parallel_scheduling.rb

162 lines
5.4 KiB
Ruby

# frozen_string_literal: true
module Gitlab
module GithubImport
module ParallelScheduling
attr_reader :project, :client, :page_counter, :already_imported_cache_key
# The base cache key to use for tracking already imported objects.
ALREADY_IMPORTED_CACHE_KEY =
'github-importer/already-imported/%{project}/%{collection}'
# project - An instance of `Project`.
# client - An instance of `Gitlab::GithubImport::Client`.
# parallel - When set to true the objects will be imported in parallel.
def initialize(project, client, parallel: true)
@project = project
@client = client
@parallel = parallel
@page_counter = PageCounter.new(project, collection_method)
@already_imported_cache_key = ALREADY_IMPORTED_CACHE_KEY %
{ project: project.id, collection: collection_method }
end
def parallel?
@parallel
end
def execute
retval =
if parallel?
parallel_import
else
sequential_import
end
# Once we have completed all work we can remove our "already exists"
# cache so we don't put too much pressure on Redis.
#
# We don't immediately remove it since it's technically possible for
# other instances of this job to still run, instead we set the
# expiration time to a lower value. This prevents the other jobs from
# still scheduling duplicates while. Since all work has already been
# completed those jobs will just cycle through any remaining pages while
# not scheduling anything.
Caching.expire(already_imported_cache_key, 15.minutes.to_i)
retval
end
# Imports all the objects in sequence in the current thread.
def sequential_import
each_object_to_import do |object|
repr = representation_class.from_api_response(object)
importer_class.new(repr, project, client).execute
end
end
# Imports all objects in parallel by scheduling a Sidekiq job for every
# individual object.
def parallel_import
waiter = JobWaiter.new
each_object_to_import do |object|
repr = representation_class.from_api_response(object)
sidekiq_worker_class
.perform_async(project.id, repr.to_hash, waiter.key)
waiter.jobs_remaining += 1
end
waiter
end
# The method that will be called for traversing through all the objects to
# import, yielding them to the supplied block.
def each_object_to_import
repo = project.import_source
# We inject the page number here to make sure that all importers always
# start where they left off. Simply starting over wouldn't work for
# repositories with a lot of data (e.g. tens of thousands of comments).
options = collection_options.merge(page: page_counter.current)
client.each_page(collection_method, repo, options) do |page|
# Technically it's possible that the same work is performed multiple
# times, as Sidekiq doesn't guarantee there will ever only be one
# instance of a job. In such a scenario it's possible for one job to
# have a lower page number (e.g. 5) compared to another (e.g. 10). In
# this case we skip over all the objects until we have caught up,
# reducing the number of duplicate jobs scheduled by the provided
# block.
next unless page_counter.set(page.number)
page.objects.each do |object|
next if already_imported?(object)
yield object
# We mark the object as imported immediately so we don't end up
# scheduling it multiple times.
mark_as_imported(object)
end
end
end
# Returns true if the given object has already been imported, false
# otherwise.
#
# object - The object to check.
def already_imported?(object)
id = id_for_already_imported_cache(object)
Caching.set_includes?(already_imported_cache_key, id)
end
# Marks the given object as "already imported".
def mark_as_imported(object)
id = id_for_already_imported_cache(object)
Caching.set_add(already_imported_cache_key, id)
end
# Returns the ID to use for the cache used for checking if an object has
# already been imported or not.
#
# object - The object we may want to import.
def id_for_already_imported_cache(object)
raise NotImplementedError
end
# The class used for converting API responses to Hashes when performing
# the import.
def representation_class
raise NotImplementedError
end
# The class to use for importing objects when importing them sequentially.
def importer_class
raise NotImplementedError
end
# The Sidekiq worker class used for scheduling the importing of objects in
# parallel.
def sidekiq_worker_class
raise NotImplementedError
end
# The name of the method to call to retrieve the data to import.
def collection_method
raise NotImplementedError
end
# Any options to be passed to the method used for retrieving the data to
# import.
def collection_options
{}
end
end
end
end