Resolve "Hashed Storage: Make possible to migrate single project"

3 files changed, 89 insertions, 3 deletions

diff --git a/lib/gitlab/hashed_storage/migrator.rb b/lib/gitlab/hashed_storage/migrator.rb
new file mode 100644
index 00000000000..9251ed654cd
--- /dev/null
+++ b/lib/gitlab/hashed_storage/migrator.rb
@@ -0,0 +1,57 @@
+module Gitlab
+  module HashedStorage
+    # Hashed Storage Migrator
+    #
+    # This is responsible for scheduling and flagging projects
+    # to be migrated from Legacy to Hashed storage, either one by one or in bulk.
+    class Migrator
+      BATCH_SIZE = 100
+
+      # Schedule a range of projects to be bulk migrated with #bulk_migrate asynchronously
+      #
+      # @param [Object] start first project id for the range
+      # @param [Object] finish last project id for the range
+      def bulk_schedule(start, finish)
+        StorageMigratorWorker.perform_async(start, finish)
+      end
+
+      # Start migration of projects from specified range
+      #
+      # Flagging a project to be migrated is a synchronous action,
+      # but the migration runs through async jobs
+      #
+      # @param [Object] start first project id for the range
+      # @param [Object] finish last project id for the range
+      def bulk_migrate(start, finish)
+        projects = build_relation(start, finish)
+
+        projects.with_route.find_each(batch_size: BATCH_SIZE) do |project|
+          migrate(project)
+        end
+      end
+
+      # Flag a project to me migrated
+      #
+      # @param [Object] project that will be migrated
+      def migrate(project)
+        Rails.logger.info "Starting storage migration of #{project.full_path} (ID=#{project.id})..."
+
+        project.migrate_to_hashed_storage!
+      rescue => err
+        Rails.logger.error("#{err.message} migrating storage of #{project.full_path} (ID=#{project.id}), trace - #{err.backtrace}")
+      end
+
+      private
+
+      def build_relation(start, finish)
+        relation = Project
+        table = Project.arel_table
+
+        relation = relation.where(table[:id].gteq(start)) if start
+        relation = relation.where(table[:id].lteq(finish)) if finish
+
+        relation
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/hashed_storage/rake_helper.rb b/lib/gitlab/hashed_storage/rake_helper.rb
index 8aba42ccfce..303b05e6a9a 100644
--- a/lib/gitlab/hashed_storage/rake_helper.rb
+++ b/lib/gitlab/hashed_storage/rake_helper.rb
@@ -9,8 +9,20 @@ module Gitlab
         ENV.fetch('LIMIT', 500).to_i
       end
 
+      def self.range_from
+        ENV['ID_FROM']
+      end
+
+      def self.range_to
+        ENV['ID_TO']
+      end
+
+      def self.range_single_item?
+        !range_from.nil? && range_from == range_to
+      end
+
       def self.project_id_batches(&block)
-        Project.with_unmigrated_storage.in_batches(of: batch_size, start: ENV['ID_FROM'], finish: ENV['ID_TO']) do |relation| # rubocop: disable Cop/InBatches
+        Project.with_unmigrated_storage.in_batches(of: batch_size, start: range_from, finish: range_to) do |relation| # rubocop: disable Cop/InBatches
           ids = relation.pluck(:id)
 
           yield ids.min, ids.max
diff --git a/lib/tasks/gitlab/storage.rake b/lib/tasks/gitlab/storage.rake
index 68d6f9d7cb1..f539b1df955 100644
--- a/lib/tasks/gitlab/storage.rake
+++ b/lib/tasks/gitlab/storage.rake
@@ -2,9 +2,26 @@ namespace :gitlab do
   namespace :storage do
     desc 'GitLab | Storage | Migrate existing projects to Hashed Storage'
     task migrate_to_hashed: :environment do
-      legacy_projects_count = Project.with_unmigrated_storage.count
+      storage_migrator = Gitlab::HashedStorage::Migrator.new
       helper = Gitlab::HashedStorage::RakeHelper
 
+      if helper.range_single_item?
+        project = Project.with_unmigrated_storage.find_by(id: helper.range_from)
+
+        unless project
+          puts "There are no projects requiring storage migration with ID=#{helper.range_from}"
+
+          next
+        end
+
+        puts "Enqueueing storage migration of #{project.full_path} (ID=#{project.id})..."
+        storage_migrator.migrate(project)
+
+        next
+      end
+
+      legacy_projects_count = Project.with_unmigrated_storage.count
+
       if legacy_projects_count == 0
         puts 'There are no projects requiring storage migration. Nothing to do!'
 
@@ -14,7 +31,7 @@ namespace :gitlab do
       print "Enqueuing migration of #{legacy_projects_count} projects in batches of #{helper.batch_size}"
 
       helper.project_id_batches do |start, finish|
-        StorageMigratorWorker.perform_async(start, finish)
+        storage_migrator.bulk_schedule(start, finish)
 
         print '.'
       end