Merge branch 'user-recent-push' into 'master'

Rework how recent push events are retrieved

Closes #35990

See merge request !13995

6 files changed, 139 insertions, 26 deletions

diff --git a/app/helpers/projects_helper.rb b/app/helpers/projects_helper.rb
index c0114dd0256..0c8cb9ba235 100644
--- a/app/helpers/projects_helper.rb
+++ b/app/helpers/projects_helper.rb
@@ -137,15 +137,7 @@ module ProjectsHelper
   end
 
   def last_push_event
-    return unless current_user
-    return current_user.recent_push unless @project
-
-    project_ids = [@project.id]
-    if fork = current_user.fork_of(@project)
-      project_ids << fork.id
-    end
-
-    current_user.recent_push(project_ids)
+    current_user&.recent_push(@project)
   end
 
   def project_feature_access_select(field)
diff --git a/app/models/event.rb b/app/models/event.rb
index c313bbb66f8..8e9490b66f4 100644
--- a/app/models/event.rb
+++ b/app/models/event.rb
@@ -49,7 +49,7 @@ class Event < ActiveRecord::Base
   belongs_to :author, class_name: "User"
   belongs_to :project
   belongs_to :target, polymorphic: true # rubocop:disable Cop/PolymorphicAssociations
-  has_one :push_event_payload, foreign_key: :event_id
+  has_one :push_event_payload
 
   # Callbacks
   after_create :reset_project_activity
diff --git a/app/models/push_event.rb b/app/models/push_event.rb
index 23ffb0d4ea8..708513c7861 100644
--- a/app/models/push_event.rb
+++ b/app/models/push_event.rb
@@ -30,6 +30,44 @@ class PushEvent < Event
   delegate :commit_count, to: :push_event_payload
   alias_method :commits_count, :commit_count
 
+  # Returns events of pushes that either pushed to an existing ref or created a
+  # new one.
+  def self.created_or_pushed
+    actions = [
+      PushEventPayload.actions[:pushed],
+      PushEventPayload.actions[:created]
+    ]
+
+    joins(:push_event_payload)
+      .where(push_event_payloads: { action: actions })
+  end
+
+  # Returns events of pushes to a branch.
+  def self.branch_events
+    ref_type = PushEventPayload.ref_types[:branch]
+
+    joins(:push_event_payload)
+      .where(push_event_payloads: { ref_type: ref_type })
+  end
+
+  # Returns PushEvent instances for which no merge requests have been created.
+  def self.without_existing_merge_requests
+    existing_mrs = MergeRequest.except(:order)
+      .select(1)
+      .where('merge_requests.source_project_id = events.project_id')
+      .where('merge_requests.source_branch = push_event_payloads.ref')
+
+    # For reasons unknown the use of #eager_load will result in the
+    # "push_event_payload" association not being set. Because of this we're
+    # using "joins" here, which does mean an additional query needs to be
+    # executed in order to retrieve the "push_event_association" when the
+    # returned PushEvent is used.
+    joins(:push_event_payload)
+      .where('NOT EXISTS (?)', existing_mrs)
+      .created_or_pushed
+      .branch_events
+  end
+
   def self.sti_name
     PUSHED
   end
diff --git a/app/models/user.rb b/app/models/user.rb
index 26b14ade5ca..358b04ac71f 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -650,20 +650,13 @@ class User < ActiveRecord::Base
     @personal_projects_count ||= personal_projects.count
   end
 
-  def recent_push(project_ids = nil)
-    # Get push events not earlier than 2 hours ago
-    events = recent_events.code_push.where("created_at > ?", Time.now - 2.hours)
-    events = events.where(project_id: project_ids) if project_ids
+  def recent_push(project = nil)
+    service = Users::LastPushEventService.new(self)
 
-    # Use the latest event that has not been pushed or merged recently
-    events.includes(:project).recent.find do |event|
-      next unless event.project.repository.branch_exists?(event.branch_name)
-
-      merge_requests = MergeRequest.where("created_at >= ?", event.created_at)
-        .where(source_project_id: event.project.id,
-               source_branch: event.branch_name)
-
-      merge_requests.empty?
+    if project
+      service.last_event_for_project(project)
+    else
+      service.last_event_for_user
     end
   end
 
diff --git a/app/services/event_create_service.rb b/app/services/event_create_service.rb
index 0b7e4f187f7..6328d567a07 100644
--- a/app/services/event_create_service.rb
+++ b/app/services/event_create_service.rb
@@ -74,12 +74,19 @@ class EventCreateService
     # We're using an explicit transaction here so that any errors that may occur
     # when creating push payload data will result in the event creation being
     # rolled back as well.
-    Event.transaction do
-      event = create_event(project, current_user, Event::PUSHED)
+    event = Event.transaction do
+      new_event = create_event(project, current_user, Event::PUSHED)
 
-      PushEventPayloadService.new(event, push_data).execute
+      PushEventPayloadService
+        .new(new_event, push_data)
+        .execute
+
+      new_event
     end
 
+    Users::LastPushEventService.new(current_user)
+      .cache_last_push_event(event)
+
     Users::ActivityService.new(current_user, 'push').execute
   end
 
diff --git a/app/services/users/last_push_event_service.rb b/app/services/users/last_push_event_service.rb
new file mode 100644
index 00000000000..f2bfb60604f
--- /dev/null
+++ b/app/services/users/last_push_event_service.rb
@@ -0,0 +1,83 @@
+module Users
+  # Service class for caching and retrieving the last push event of a user.
+  class LastPushEventService
+    EXPIRATION = 2.hours
+
+    def initialize(user)
+      @user = user
+    end
+
+    # Caches the given push event for the current user in the Rails cache.
+    #
+    # event - An instance of PushEvent to cache.
+    def cache_last_push_event(event)
+      keys = [
+        project_cache_key(event.project),
+        user_cache_key
+      ]
+
+      if event.project.forked?
+        keys << project_cache_key(event.project.forked_from_project)
+      end
+
+      keys.each { |key| set_key(key, event.id) }
+    end
+
+    # Returns the last PushEvent for the current user.
+    #
+    # This method will return nil if no event was found.
+    def last_event_for_user
+      find_cached_event(user_cache_key)
+    end
+
+    # Returns the last PushEvent for the current user and the given project.
+    #
+    # project - An instance of Project for which to retrieve the PushEvent.
+    #
+    # This method will return nil if no event was found.
+    def last_event_for_project(project)
+      find_cached_event(project_cache_key(project))
+    end
+
+    def find_cached_event(cache_key)
+      event_id = get_key(cache_key)
+
+      return unless event_id
+
+      unless (event = find_event_in_database(event_id))
+        # We don't want to keep querying the same data over and over when a
+        # merge request has been created, thus we remove the key if no event
+        # (meaning an MR was created) is returned.
+        Rails.cache.delete(cache_key)
+      end
+
+      event
+    end
+
+    private
+
+    def find_event_in_database(id)
+      PushEvent
+        .without_existing_merge_requests
+        .find_by(id: id)
+    end
+
+    def user_cache_key
+      "last-push-event/#{@user.id}"
+    end
+
+    def project_cache_key(project)
+      "last-push-event/#{@user.id}/#{project.id}"
+    end
+
+    def get_key(key)
+      Rails.cache.read(key, raw: true)
+    end
+
+    def set_key(key, value)
+      # We're using raw values here since this takes up less space and we don't
+      # store complex objects.
+      Rails.cache.write(key, value, raw: true, expires_in: EXPIRATION)
+    end
+  end
+end