Improve performance of triggered chat commandszj-slow-service-fetch

When the trigger endpoint is called, it has to find the right service
for the given project. However, the old implementation did much more.

For example, it build a list of the missing services on this project.
This whole process took about 750ms _each time_. The current
implementation is expected to perform 10x better, as it only searches in
the current projects services. Given the service has to be configured
anyway, this can be done.

2 files changed, 14 insertions, 3 deletions

diff --git a/changelogs/unreleased/zj-slow-service-fetch.yml b/changelogs/unreleased/zj-slow-service-fetch.yml
new file mode 100644
index 00000000000..8037361d2fc
--- /dev/null
+++ b/changelogs/unreleased/zj-slow-service-fetch.yml
@@ -0,0 +1,4 @@
+---
+title: Improve performance of slash commands
+merge_request: 8876
+author:
diff --git a/lib/api/services.rb b/lib/api/services.rb
index a0abec49438..1456fe4688b 100644
--- a/lib/api/services.rb
+++ b/lib/api/services.rb
@@ -661,6 +661,14 @@ module API
     end
 
     trigger_services.each do |service_slug, settings|
+      helpers do
+        def chat_command_service(project, service_slug, params)
+          project.services.active.where(template: false).find do |service|
+            service.try(:token) == params[:token] && service.to_param == service_slug.underscore
+          end
+        end
+      end
+
       params do
         requires :id, type: String, desc: 'The ID of a project'
       end
@@ -679,9 +687,8 @@ module API
           # This is not accurate, but done to prevent leakage of the project names
           not_found!('Service') unless project
 
-          service = project.find_or_initialize_service(service_slug.underscore)
-
-          result = service.try(:active?) && service.try(:trigger, params)
+          service = chat_command_service(project, service_slug, params)
+          result = service.try(:trigger, params)
 
           if result
             status result[:status] || 200