Finish migration to the new events setupevents-migration-cleanup

This finishes the procedure for migrating events from the old format
into the new format. Code no longer uses the old setup and the database
tables used during the migration process are swapped, with the old table
being dropped.

While the database migration can be reversed this will 1) take a lot of
time as data has to be coped around 2) won't restore data in the
"events.data" column as we have no way of restoring this.

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/37241

3 files changed, 22 insertions, 162 deletions

diff --git a/app/models/event.rb b/app/models/event.rb
index 996768a267b..c313bbb66f8 100644
--- a/app/models/event.rb
+++ b/app/models/event.rb
@@ -1,5 +1,6 @@
 class Event < ActiveRecord::Base
   include Sortable
+  include IgnorableColumn
   default_scope { reorder(nil).where.not(author_id: nil) }
 
   CREATED   = 1
@@ -50,13 +51,9 @@ class Event < ActiveRecord::Base
   belongs_to :target, polymorphic: true # rubocop:disable Cop/PolymorphicAssociations
   has_one :push_event_payload, foreign_key: :event_id
 
-  # For Hash only
-  serialize :data # rubocop:disable Cop/ActiveRecordSerialize
-
   # Callbacks
   after_create :reset_project_activity
   after_create :set_last_repository_updated_at, if: :push?
-  after_create :replicate_event_for_push_events_migration
 
   # Scopes
   scope :recent, -> { reorder(id: :desc) }
@@ -82,6 +79,10 @@ class Event < ActiveRecord::Base
 
   self.inheritance_column = 'action'
 
+  # "data" will be removed in 10.0 but it may be possible that JOINs happen that
+  # include this column, hence we're ignoring it as well.
+  ignore_column :data
+
   class << self
     def model_name
       ActiveModel::Name.new(self, nil, 'event')
@@ -159,7 +160,7 @@ class Event < ActiveRecord::Base
   end
 
   def push?
-    action == PUSHED && valid_push?
+    false
   end
 
   def merged?
@@ -272,87 +273,6 @@ class Event < ActiveRecord::Base
     end
   end
 
-  def valid_push?
-    data[:ref] && ref_name.present?
-  rescue
-    false
-  end
-
-  def tag?
-    Gitlab::Git.tag_ref?(data[:ref])
-  end
-
-  def branch?
-    Gitlab::Git.branch_ref?(data[:ref])
-  end
-
-  def new_ref?
-    Gitlab::Git.blank_ref?(commit_from)
-  end
-
-  def rm_ref?
-    Gitlab::Git.blank_ref?(commit_to)
-  end
-
-  def md_ref?
-    !(rm_ref? || new_ref?)
-  end
-
-  def commit_from
-    data[:before]
-  end
-
-  def commit_to
-    data[:after]
-  end
-
-  def ref_name
-    if tag?
-      tag_name
-    else
-      branch_name
-    end
-  end
-
-  def branch_name
-    @branch_name ||= Gitlab::Git.ref_name(data[:ref])
-  end
-
-  def tag_name
-    @tag_name ||= Gitlab::Git.ref_name(data[:ref])
-  end
-
-  # Max 20 commits from push DESC
-  def commits
-    @commits ||= (data[:commits] || []).reverse
-  end
-
-  def commit_title
-    commit = commits.last
-
-    commit[:message] if commit
-  end
-
-  def commit_id
-    commit_to || commit_from
-  end
-
-  def commits_count
-    data[:total_commits_count] || commits.count || 0
-  end
-
-  def ref_type
-    tag? ? "tag" : "branch"
-  end
-
-  def push_with_commits?
-    !commits.empty? && commit_from && commit_to
-  end
-
-  def last_push_to_non_root?
-    branch? && project.default_branch != branch_name
-  end
-
   def target_iid
     target.respond_to?(:iid) ? target.iid : target_id
   end
@@ -432,16 +352,6 @@ class Event < ActiveRecord::Base
     user ? author_id == user.id : false
   end
 
-  # We're manually replicating data into the new table since database triggers
-  # are not dumped to db/schema.rb. This could mean that a new installation
-  # would not have the triggers in place, thus losing events data in GitLab
-  # 10.0.
-  def replicate_event_for_push_events_migration
-    new_attributes = attributes.with_indifferent_access.except(:title, :data)
-
-    EventForMigration.create!(new_attributes)
-  end
-
   def to_partial_path
     # We are intentionally using `Event` rather than `self.class` so that
     # subclasses also use the `Event` implementation.
diff --git a/app/models/event_for_migration.rb b/app/models/event_for_migration.rb
deleted file mode 100644
index a1672da5eec..00000000000
--- a/app/models/event_for_migration.rb
+++ /dev/null
@@ -1,5 +0,0 @@
-# This model is used to replicate events between the old "events" table and the
-# new "events_for_migration" table that will replace "events" in GitLab 10.0.
-class EventForMigration < ActiveRecord::Base
-  self.table_name = 'events_for_migration'
-end
diff --git a/app/models/push_event.rb b/app/models/push_event.rb
index 3f1ff979de6..23ffb0d4ea8 100644
--- a/app/models/push_event.rb
+++ b/app/models/push_event.rb
@@ -15,15 +15,21 @@ class PushEvent < Event
   # should ensure the ID points to a valid project.
   validates :project_id, presence: true
 
-  # The "data" field must not be set for push events since it's not used and a
-  # waste of space.
-  validates :data, absence: true
-
   # These fields are also not used for push events, thus storing them would be a
   # waste.
   validates :target_id, absence: true
   validates :target_type, absence: true
 
+  delegate :branch?, to: :push_event_payload
+  delegate :tag?, to: :push_event_payload
+  delegate :commit_from, to: :push_event_payload
+  delegate :commit_to, to: :push_event_payload
+  delegate :ref_type, to: :push_event_payload
+  delegate :commit_title, to: :push_event_payload
+
+  delegate :commit_count, to: :push_event_payload
+  alias_method :commits_count, :commit_count
+
   def self.sti_name
     PUSHED
   end
@@ -36,86 +42,35 @@ class PushEvent < Event
     !!(commit_from && commit_to)
   end
 
-  def tag?
-    return super unless push_event_payload
-
-    push_event_payload.tag?
-  end
-
-  def branch?
-    return super unless push_event_payload
-
-    push_event_payload.branch?
-  end
-
   def valid_push?
-    return super unless push_event_payload
-
     push_event_payload.ref.present?
   end
 
   def new_ref?
-    return super unless push_event_payload
-
     push_event_payload.created?
   end
 
   def rm_ref?
-    return super unless push_event_payload
-
     push_event_payload.removed?
   end
 
-  def commit_from
-    return super unless push_event_payload
-
-    push_event_payload.commit_from
-  end
-
-  def commit_to
-    return super unless push_event_payload
-
-    push_event_payload.commit_to
+  def md_ref?
+    !(rm_ref? || new_ref?)
   end
 
   def ref_name
-    return super unless push_event_payload
-
     push_event_payload.ref
   end
 
-  def ref_type
-    return super unless push_event_payload
-
-    push_event_payload.ref_type
-  end
-
-  def branch_name
-    return super unless push_event_payload
-
-    ref_name
-  end
-
-  def tag_name
-    return super unless push_event_payload
-
-    ref_name
-  end
-
-  def commit_title
-    return super unless push_event_payload
-
-    push_event_payload.commit_title
-  end
+  alias_method :branch_name, :ref_name
+  alias_method :tag_name, :ref_name
 
   def commit_id
     commit_to || commit_from
   end
 
-  def commits_count
-    return super unless push_event_payload
-
-    push_event_payload.commit_count
+  def last_push_to_non_root?
+    branch? && project.default_branch != branch_name
   end
 
   def validate_push_action