4 files changed, 232 insertions, 0 deletions
diff --git a/app/lib/importer/accounts_index_importer.rb b/app/lib/importer/accounts_index_importer.rb
new file mode 100644
index 000000000..792a31b1b
--- /dev/null
+++ b/app/lib/importer/accounts_index_importer.rb
@@ -0,0 +1,30 @@
+# frozen_string_literal: true
+
+class Importer::AccountsIndexImporter < Importer::BaseImporter
+  def import!
+    scope.includes(:account_stat).find_in_batches(batch_size: @batch_size) do |tmp|
+      in_work_unit(tmp) do |accounts|
+        bulk = Chewy::Index::Import::BulkBuilder.new(index, to_index: accounts).bulk_body
+
+        indexed = bulk.select { |entry| entry[:index] }.size
+        deleted = bulk.select { |entry| entry[:delete] }.size
+
+        Chewy::Index::Import::BulkRequest.new(index).perform(bulk)
+
+        [indexed, deleted]
+      end
+    end
+
+    wait!
+  end
+
+  private
+
+  def index
+    AccountsIndex
+  end
+
+  def scope
+    Account.searchable
+  end
+end
diff --git a/app/lib/importer/base_importer.rb b/app/lib/importer/base_importer.rb
new file mode 100644
index 000000000..ea522c600
--- /dev/null
+++ b/app/lib/importer/base_importer.rb
@@ -0,0 +1,87 @@
+# frozen_string_literal: true
+
+class Importer::BaseImporter
+  # @param [Integer] batch_size
+  # @param [Concurrent::ThreadPoolExecutor] executor
+  def initialize(batch_size:, executor:)
+    @batch_size = batch_size
+    @executor   = executor
+    @wait_for   = Concurrent::Set.new
+  end
+
+  # Callback to run when a concurrent work unit completes
+  # @param [Proc]
+  def on_progress(&block)
+    @on_progress = block
+  end
+
+  # Callback to run when a concurrent work unit fails
+  # @param [Proc]
+  def on_failure(&block)
+    @on_failure = block
+  end
+
+  # Reduce resource usage during and improve speed of indexing
+  def optimize_for_import!
+    Chewy.client.indices.put_settings index: index.index_name, body: { index: { refresh_interval: -1 } }
+  end
+
+  # Restore original index settings
+  def optimize_for_search!
+    Chewy.client.indices.put_settings index: index.index_name, body: { index: { refresh_interval: index.settings_hash[:settings][:index][:refresh_interval] } }
+  end
+
+  # Estimate the amount of documents that would be indexed. Not exact!
+  # @returns [Integer]
+  def estimate!
+    ActiveRecord::Base.connection_pool.with_connection { |connection| connection.select_one("SELECT reltuples AS estimate FROM pg_class WHERE relname = '#{index.adapter.target.table_name}'")['estimate'].to_i }
+  end
+
+  # Import data from the database into the index
+  def import!
+    raise NotImplementedError
+  end
+
+  # Remove documents from the index that no longer exist in the database
+  def clean_up!
+    index.scroll_batches do |documents|
+      ids           = documents.map { |doc| doc['_id'] }
+      existence_map = index.adapter.target.where(id: ids).pluck(:id).each_with_object({}) { |id, map| map[id.to_s] = true }
+      tmp           = ids.reject { |id| existence_map[id] }
+
+      next if tmp.empty?
+
+      in_work_unit(tmp) do |deleted_ids|
+        bulk = Chewy::Index::Import::BulkBuilder.new(index, delete: deleted_ids).bulk_body
+
+        Chewy::Index::Import::BulkRequest.new(index).perform(bulk)
+
+        [0, bulk.size]
+      end
+    end
+
+    wait!
+  end
+
+  protected
+
+  def in_work_unit(*args, &block)
+    work_unit = Concurrent::Promises.future_on(@executor, *args, &block)
+
+    work_unit.on_fulfillment!(&@on_progress)
+    work_unit.on_rejection!(&@on_failure)
+    work_unit.on_resolution! { @wait_for.delete(work_unit) }
+
+    @wait_for << work_unit
+  rescue Concurrent::RejectedExecutionError
+    sleep(0.1) && retry # Backpressure
+  end
+
+  def wait!
+    Concurrent::Promises.zip(*@wait_for).wait
+  end
+
+  def index
+    raise NotImplementedError
+  end
+end
diff --git a/app/lib/importer/statuses_index_importer.rb b/app/lib/importer/statuses_index_importer.rb
new file mode 100644
index 000000000..7c6532560
--- /dev/null
+++ b/app/lib/importer/statuses_index_importer.rb
@@ -0,0 +1,89 @@
+# frozen_string_literal: true
+
+class Importer::StatusesIndexImporter < Importer::BaseImporter
+  def import!
+    # The idea is that instead of iterating over all statuses in the database
+    # and calculating the searchable_by for each of them (majority of which
+    # would be empty), we approach the index from the other end
+
+    scopes.each do |scope|
+      # We could be tempted to keep track of status IDs we have already processed
+      # from a different scope to avoid indexing them multiple times, but that
+      # could end up being a very large array
+
+      scope.find_in_batches(batch_size: @batch_size) do |tmp|
+        in_work_unit(tmp.map(&:status_id)) do |status_ids|
+          bulk = ActiveRecord::Base.connection_pool.with_connection do
+            Chewy::Index::Import::BulkBuilder.new(index, to_index: Status.includes(:media_attachments, :preloadable_poll).where(id: status_ids)).bulk_body
+          end
+
+          indexed = 0
+          deleted = 0
+
+          # We can't use the delete_if proc to do the filtering because delete_if
+          # is called before rendering the data and we need to filter based
+          # on the results of the filter, so this filtering happens here instead
+          bulk.map! do |entry|
+            new_entry = begin
+              if entry[:index] && entry.dig(:index, :data, 'searchable_by').blank?
+                { delete: entry[:index].except(:data) }
+              else
+                entry
+              end
+            end
+
+            if new_entry[:index]
+              indexed += 1
+            else
+              deleted += 1
+            end
+
+            new_entry
+          end
+
+          Chewy::Index::Import::BulkRequest.new(index).perform(bulk)
+
+          [indexed, deleted]
+        end
+      end
+    end
+
+    wait!
+  end
+
+  private
+
+  def index
+    StatusesIndex
+  end
+
+  def scopes
+    [
+      local_statuses_scope,
+      local_mentions_scope,
+      local_favourites_scope,
+      local_votes_scope,
+      local_bookmarks_scope,
+    ]
+  end
+
+  def local_mentions_scope
+    Mention.where(account: Account.local, silent: false).select(:id, :status_id)
+  end
+
+  def local_favourites_scope
+    Favourite.where(account: Account.local).select(:id, :status_id)
+  end
+
+  def local_bookmarks_scope
+    Bookmark.select(:id, :status_id)
+  end
+
+  def local_votes_scope
+    Poll.joins(:votes).where(votes: { account: Account.local }).select('polls.id, polls.status_id')
+  end
+
+  def local_statuses_scope
+    Status.local.select('id, coalesce(reblog_of_id, id) as status_id')
+  end
+end
diff --git a/app/lib/importer/tags_index_importer.rb b/app/lib/importer/tags_index_importer.rb
new file mode 100644
index 000000000..f5bd8f052
--- /dev/null
+++ b/app/lib/importer/tags_index_importer.rb
@@ -0,0 +1,26 @@
+# frozen_string_literal: true
+
+class Importer::TagsIndexImporter < Importer::BaseImporter
+  def import!
+    index.adapter.default_scope.find_in_batches(batch_size: @batch_size) do |tmp|
+      in_work_unit(tmp) do |tags|
+        bulk = Chewy::Index::Import::BulkBuilder.new(index, to_index: tags).bulk_body
+
+        indexed = bulk.select { |entry| entry[:index] }.size
+        deleted = bulk.select { |entry| entry[:delete] }.size
+
+        Chewy::Index::Import::BulkRequest.new(index).perform(bulk)
+
+        [indexed, deleted]
+      end
+    end
+
+    wait!
+  end
+
+  private
+
+  def index
+    TagsIndex
+  end
+end