gitlab-org--gitlab-foss/app/services/push_event_payload_service.rb

123 lines
2.4 KiB
Ruby
Raw Normal View History

# frozen_string_literal: true
Migrate events into a new format This commit migrates events data in such a way that push events are stored much more efficiently. This is done by creating a shadow table called "events_for_migration", and a table called "push_event_payloads" which is used for storing push data of push events. The background migration in this commit will copy events from the "events" table into the "events_for_migration" table, push events in will also have a row created in "push_event_payloads". This approach allows us to reclaim space in the next release by simply swapping the "events" and "events_for_migration" tables, then dropping the old events (now "events_for_migration") table. The new table structure is also optimised for storage space, and does not include the unused "title" column nor the "data" column (since this data is moved to "push_event_payloads"). == Newly Created Events Newly created events are inserted into both "events" and "events_for_migration", both using the exact same primary key value. The table "push_event_payloads" in turn has a foreign key to the _shadow_ table. This removes the need for recreating and validating the foreign key after swapping the tables. Since the shadow table also has a foreign key to "projects.id" we also don't have to worry about orphaned rows. This approach however does require some additional storage as we're duplicating a portion of the events data for at least 1 release. The exact amount is hard to estimate, but for GitLab.com this is expected to be between 10 and 20 GB at most. The background migration in this commit deliberately does _not_ update the "events" table as doing so would put a lot of pressure on PostgreSQL's auto vacuuming system. == Supporting Both Old And New Events Application code has also been adjusted to support push events using both the old and new data formats. This is done by creating a PushEvent class which extends the regular Event class. Using Rails' Single Table Inheritance system we can ensure the right class is used for the right data, which in this case is based on the value of `events.action`. To support displaying old and new data at the same time the PushEvent class re-defines a few methods of the Event class, falling back to their original implementations for push events in the old format. Once all existing events have been migrated the various push event related methods can be removed from the Event model, and the calls to `super` can be removed from the methods in the PushEvent model. The UI and event atom feed have also been slightly changed to better handle this new setup, fortunately only a few changes were necessary to make this work. == API Changes The API only displays push data of events in the new format. Supporting both formats in the API is a bit more difficult compared to the UI. Since the old push data was not really well documented (apart from one example that used an incorrect "action" nmae) I decided that supporting both was not worth the effort, especially since events will be migrated in a few days _and_ new events are created in the correct format.
2017-07-10 11:43:57 -04:00
# Service class for creating push event payloads as stored in the
# "push_event_payloads" table.
#
# Example:
#
# data = Gitlab::DataBuilder::Push.build(...)
# event = Event.create(...)
#
# PushEventPayloadService.new(event, data).execute
class PushEventPayloadService
# event - The event this push payload belongs to.
# push_data - A Hash produced by `Gitlab::DataBuilder::Push.build` to use for
# building the push payload.
def initialize(event, push_data)
@event = event
@push_data = push_data
end
# Creates and returns a new PushEventPayload row.
#
# This method will raise upon encountering validation errors.
#
# Returns an instance of PushEventPayload.
def execute
@event.build_push_event_payload(
commit_count: commit_count,
action: action,
ref_type: ref_type,
commit_from: commit_from_id,
commit_to: commit_to_id,
ref: trimmed_ref,
commit_title: commit_title,
event_id: @event.id
)
@event.push_event_payload.save!
@event.push_event_payload
end
# Returns the commit title to use.
#
# The commit title is limited to the first line and a maximum of 70
# characters.
def commit_title
commit = @push_data.fetch(:commits).last
return unless commit && commit[:message]
Migrate events into a new format This commit migrates events data in such a way that push events are stored much more efficiently. This is done by creating a shadow table called "events_for_migration", and a table called "push_event_payloads" which is used for storing push data of push events. The background migration in this commit will copy events from the "events" table into the "events_for_migration" table, push events in will also have a row created in "push_event_payloads". This approach allows us to reclaim space in the next release by simply swapping the "events" and "events_for_migration" tables, then dropping the old events (now "events_for_migration") table. The new table structure is also optimised for storage space, and does not include the unused "title" column nor the "data" column (since this data is moved to "push_event_payloads"). == Newly Created Events Newly created events are inserted into both "events" and "events_for_migration", both using the exact same primary key value. The table "push_event_payloads" in turn has a foreign key to the _shadow_ table. This removes the need for recreating and validating the foreign key after swapping the tables. Since the shadow table also has a foreign key to "projects.id" we also don't have to worry about orphaned rows. This approach however does require some additional storage as we're duplicating a portion of the events data for at least 1 release. The exact amount is hard to estimate, but for GitLab.com this is expected to be between 10 and 20 GB at most. The background migration in this commit deliberately does _not_ update the "events" table as doing so would put a lot of pressure on PostgreSQL's auto vacuuming system. == Supporting Both Old And New Events Application code has also been adjusted to support push events using both the old and new data formats. This is done by creating a PushEvent class which extends the regular Event class. Using Rails' Single Table Inheritance system we can ensure the right class is used for the right data, which in this case is based on the value of `events.action`. To support displaying old and new data at the same time the PushEvent class re-defines a few methods of the Event class, falling back to their original implementations for push events in the old format. Once all existing events have been migrated the various push event related methods can be removed from the Event model, and the calls to `super` can be removed from the methods in the PushEvent model. The UI and event atom feed have also been slightly changed to better handle this new setup, fortunately only a few changes were necessary to make this work. == API Changes The API only displays push data of events in the new format. Supporting both formats in the API is a bit more difficult compared to the UI. Since the old push data was not really well documented (apart from one example that used an incorrect "action" nmae) I decided that supporting both was not worth the effort, especially since events will be migrated in a few days _and_ new events are created in the correct format.
2017-07-10 11:43:57 -04:00
raw_msg = commit[:message]
# Find where the first line ends, without turning the entire message into an
# Array of lines (this is a waste of memory for large commit messages).
index = raw_msg.index("\n")
message = index ? raw_msg[0..index] : raw_msg
message.strip.truncate(70)
end
def commit_from_id
if create?
nil
else
revision_before
end
end
def commit_to_id
if remove?
nil
else
revision_after
end
end
def commit_count
@push_data.fetch(:total_commits_count)
end
def ref
@push_data.fetch(:ref)
end
def revision_before
@push_data.fetch(:before)
end
def revision_after
@push_data.fetch(:after)
end
def trimmed_ref
Gitlab::Git.ref_name(ref)
end
def create?
Gitlab::Git.blank_ref?(revision_before)
end
def remove?
Gitlab::Git.blank_ref?(revision_after)
end
def action
if create?
:created
elsif remove?
:removed
else
:pushed
end
end
def ref_type
if Gitlab::Git.tag_ref?(ref)
:tag
else
:branch
end
end
end