gitlab-org--gitlab-foss/lib/api/snippets.rb
Yorick Peterse d171ff6016
Rewrite SnippetsFinder to improve performance
This completely rewrites the SnippetsFinder class from the ground up in
order to improve its performance. The old code was beyond salvaging. It
was complex, included various Rails 5 workarounds, comments that
shouldn't be necessary, and most important of all: it produced a really
poorly performing database query.

As a result, I opted for rewriting the finder from scratch, instead of
trying to patch the existing code. Instead of trying to reuse as many
existing methods as possible, I opted for defining new methods
specifically meant for the SnippetsFinder. This requires some extra code
here and there, but allows us to have much more control over the
resulting SQL queries. It is these changes that then allow us to produce
a _much_ more efficient query.

To illustrate how bad the old query was, we will use my own snippets as
an example. Currently I have 52 snippets, most of which are global ones.
To retrieve these, you would run the following Ruby code:

    user = User.find_by(username: 'yorickpeterse')

    SnippetsFinder.new(user, author: user).execute

On GitLab.com the resulting query will take between 10 and 15 seconds to
run, producing the query plan found at
https://explain.depesz.com/s/Y5IX. Apart from the long execution time,
the total number of buffers (the sum of all shared hits) is around 185
GB, though the real number is probably (hopefully) much lower as I doubt
simply summing these numbers produces the true total number of buffers
used.

The new query's plan can be found at https://explain.depesz.com/s/wHdN,
and this query takes between 10 and 100-ish milliseconds to run. The
total number of buffers used is only about 30 MB.

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/52639
2018-11-05 14:28:29 +01:00

172 lines
5.7 KiB
Ruby

# frozen_string_literal: true
module API
# Snippets API
class Snippets < Grape::API
include PaginationParams
before { authenticate! }
resource :snippets do
helpers do
def snippets_for_current_user
SnippetsFinder.new(current_user, author: current_user).execute
end
def public_snippets
SnippetsFinder.new(current_user, scope: :are_public).execute
end
end
desc 'Get a snippets list for authenticated user' do
detail 'This feature was introduced in GitLab 8.15.'
success Entities::PersonalSnippet
end
params do
use :pagination
end
get do
present paginate(snippets_for_current_user), with: Entities::PersonalSnippet
end
desc 'List all public snippets current_user has access to' do
detail 'This feature was introduced in GitLab 8.15.'
success Entities::PersonalSnippet
end
params do
use :pagination
end
get 'public' do
present paginate(public_snippets), with: Entities::PersonalSnippet
end
desc 'Get a single snippet' do
detail 'This feature was introduced in GitLab 8.15.'
success Entities::PersonalSnippet
end
params do
requires :id, type: Integer, desc: 'The ID of a snippet'
end
get ':id' do
snippet = snippets_for_current_user.find(params[:id])
present snippet, with: Entities::PersonalSnippet
end
desc 'Create new snippet' do
detail 'This feature was introduced in GitLab 8.15.'
success Entities::PersonalSnippet
end
params do
requires :title, type: String, desc: 'The title of a snippet'
requires :file_name, type: String, desc: 'The name of a snippet file'
requires :content, type: String, desc: 'The content of a snippet'
optional :description, type: String, desc: 'The description of a snippet'
optional :visibility, type: String,
values: Gitlab::VisibilityLevel.string_values,
default: 'internal',
desc: 'The visibility of the snippet'
end
post do
attrs = declared_params(include_missing: false).merge(request: request, api: true)
snippet = CreateSnippetService.new(nil, current_user, attrs).execute
render_spam_error! if snippet.spam?
if snippet.persisted?
present snippet, with: Entities::PersonalSnippet
else
render_validation_error!(snippet)
end
end
desc 'Update an existing snippet' do
detail 'This feature was introduced in GitLab 8.15.'
success Entities::PersonalSnippet
end
params do
requires :id, type: Integer, desc: 'The ID of a snippet'
optional :title, type: String, desc: 'The title of a snippet'
optional :file_name, type: String, desc: 'The name of a snippet file'
optional :content, type: String, desc: 'The content of a snippet'
optional :description, type: String, desc: 'The description of a snippet'
optional :visibility, type: String,
values: Gitlab::VisibilityLevel.string_values,
desc: 'The visibility of the snippet'
at_least_one_of :title, :file_name, :content, :visibility
end
# rubocop: disable CodeReuse/ActiveRecord
put ':id' do
snippet = snippets_for_current_user.find_by(id: params.delete(:id))
break not_found!('Snippet') unless snippet
authorize! :update_personal_snippet, snippet
attrs = declared_params(include_missing: false).merge(request: request, api: true)
UpdateSnippetService.new(nil, current_user, snippet, attrs).execute
render_spam_error! if snippet.spam?
if snippet.persisted?
present snippet, with: Entities::PersonalSnippet
else
render_validation_error!(snippet)
end
end
# rubocop: enable CodeReuse/ActiveRecord
desc 'Remove snippet' do
detail 'This feature was introduced in GitLab 8.15.'
success Entities::PersonalSnippet
end
params do
requires :id, type: Integer, desc: 'The ID of a snippet'
end
# rubocop: disable CodeReuse/ActiveRecord
delete ':id' do
snippet = snippets_for_current_user.find_by(id: params.delete(:id))
break not_found!('Snippet') unless snippet
authorize! :destroy_personal_snippet, snippet
destroy_conditionally!(snippet)
end
# rubocop: enable CodeReuse/ActiveRecord
desc 'Get a raw snippet' do
detail 'This feature was introduced in GitLab 8.15.'
end
params do
requires :id, type: Integer, desc: 'The ID of a snippet'
end
# rubocop: disable CodeReuse/ActiveRecord
get ":id/raw" do
snippet = snippets_for_current_user.find_by(id: params.delete(:id))
break not_found!('Snippet') unless snippet
env['api.format'] = :txt
content_type 'text/plain'
present snippet.content
end
# rubocop: enable CodeReuse/ActiveRecord
desc 'Get the user agent details for a snippet' do
success Entities::UserAgentDetail
end
params do
requires :id, type: Integer, desc: 'The ID of a snippet'
end
# rubocop: disable CodeReuse/ActiveRecord
get ":id/user_agent_detail" do
authenticated_as_admin!
snippet = Snippet.find_by!(id: params[:id])
break not_found!('UserAgentDetail') unless snippet.user_agent_detail
present snippet.user_agent_detail, with: Entities::UserAgentDetail
end
# rubocop: enable CodeReuse/ActiveRecord
end
end
end