debian-mirror-gitlab/app/models/concerns/fast_destroy_all.rb
2018-10-15 14:42:47 +05:30

91 lines
3 KiB
Ruby

##
# This module is for replacing `dependent: :destroy` and `before_destroy` hooks.
#
# In general, `destroy_all` is inefficient because it calls each callback with `DELETE` queries i.e. O(n), whereas,
# `delete_all` is efficient as it deletes all rows with a single `DELETE` query.
#
# It's better to use `delete_all` as our best practice, however,
# if external data (e.g. ObjectStorage, FileStorage or Redis) are assosiated with database records,
# it is difficult to accomplish it.
#
# This module defines a format to use `delete_all` and delete associated external data.
# Here is an exmaple
#
# Situation
# - `Project` has many `Ci::BuildTraceChunk` through `Ci::Build`
# - `Ci::BuildTraceChunk` stores associated data in Redis, so it relies on `dependent: :destroy` and `before_destroy` for the deletion
#
# How to use
# - Define `use_fast_destroy :build_trace_chunks` in `Project` model.
# - Define `begin_fast_destroy` and `finalize_fast_destroy(params)` in `Ci::BuildTraceChunk` model.
# - Use `fast_destroy_all` instead of `destroy` and `destroy_all`
# - Remove `dependent: :destroy` and `before_destroy` as it's no longer need
#
# Expectation
# - When a project is `destroy`ed, the associated trace_chunks will be deleted by `delete_all`,
# and the associated data will be removed, too.
# - When `fast_destroy_all` is called, it also performns as same.
module FastDestroyAll
extend ActiveSupport::Concern
ForbiddenActionError = Class.new(StandardError)
included do
before_destroy do
raise ForbiddenActionError, '`destroy` and `destroy_all` are forbbiden. Please use `fast_destroy_all`'
end
end
class_methods do
##
# This method delete rows and associated external data efficiently
#
# This method can replace `destroy` and `destroy_all` without having `after_destroy` hook
def fast_destroy_all
params = begin_fast_destroy
delete_all
finalize_fast_destroy(params)
end
##
# This method returns identifiers to delete associated external data (e.g. file paths, redis keys)
#
# This method must be defined in fast destroyable model
def begin_fast_destroy
raise NotImplementedError
end
##
# This method deletes associated external data with the identifiers returned by `begin_fast_destroy`
#
# This method must be defined in fast destroyable model
def finalize_fast_destroy(params)
raise NotImplementedError
end
end
module Helpers
extend ActiveSupport::Concern
class_methods do
##
# This method is to be defined on models which have fast destroyable models as children,
# and let us avoid to use `dependent: :destroy` hook
def use_fast_destroy(relation)
before_destroy(prepend: true) do
perform_fast_destroy(public_send(relation)) # rubocop:disable GitlabSecurity/PublicSend
end
end
end
def perform_fast_destroy(subject)
params = subject.begin_fast_destroy
run_after_commit do
subject.finalize_fast_destroy(params)
end
end
end
end