1 files changed, 55 insertions, 0 deletions
diff --git a/activestorage/lib/active_storage/service/mirror_service.rb b/activestorage/lib/active_storage/service/mirror_service.rb
new file mode 100644
index 0000000000..aa41df304e
--- /dev/null
+++ b/activestorage/lib/active_storage/service/mirror_service.rb
@@ -0,0 +1,55 @@
+# frozen_string_literal: true
+
+require "active_support/core_ext/module/delegation"
+
+module ActiveStorage
+  # Wraps a set of mirror services and provides a single ActiveStorage::Service object that will all
+  # have the files uploaded to them. A +primary+ service is designated to answer calls to +download+, +exists?+,
+  # and +url+.
+  class Service::MirrorService < Service
+    attr_reader :primary, :mirrors
+
+    delegate :download, :download_chunk, :exist?, :url, :path_for, to: :primary
+
+    # Stitch together from named services.
+    def self.build(primary:, mirrors:, configurator:, **options) #:nodoc:
+      new \
+        primary: configurator.build(primary),
+        mirrors: mirrors.collect { |name| configurator.build name }
+    end
+
+    def initialize(primary:, mirrors:)
+      @primary, @mirrors = primary, mirrors
+    end
+
+    # Upload the +io+ to the +key+ specified to all services. If a +checksum+ is provided, all services will
+    # ensure a match when the upload has completed or raise an ActiveStorage::IntegrityError.
+    def upload(key, io, checksum: nil, **options)
+      each_service.collect do |service|
+        service.upload key, io.tap(&:rewind), checksum: checksum, **options
+      end
+    end
+
+    # Delete the file at the +key+ on all services.
+    def delete(key)
+      perform_across_services :delete, key
+    end
+
+    # Delete files at keys starting with the +prefix+ on all services.
+    def delete_prefixed(prefix)
+      perform_across_services :delete_prefixed, prefix
+    end
+
+    private
+      def each_service(&block)
+        [ primary, *mirrors ].each(&block)
+      end
+
+      def perform_across_services(method, *args)
+        # FIXME: Convert to be threaded
+        each_service.collect do |service|
+          service.public_send method, *args
+        end
+      end
+  end
+end