Merge branch '3822-ensure-unique-names' refs #3822

[arvados.git] / services / api / app / controllers / application_controller.rb

diff --git a/services/api/app/controllers/application_controller.rb b/services/api/app/controllers/application_controller.rb
index 2400365fd85d1e27b522a252654afa0234916115..3465a7832050ff08543e80e9441edd2e60b68c74 100644 (file)
--- a/services/api/app/controllers/application_controller.rb
+++ b/services/api/app/controllers/application_controller.rb
@@ -70,7 +70,47 @@ class ApplicationController < ActionController::Base
 
   def create
     @object = model_class.new resource_attrs
-    @object.save!
+    retry_save = true
+
+    if @object.respond_to? :name and params[:ensure_unique_name]
+      # Record the original name.  See below.
+      name_stem = @object.name
+      counter = 1
+    end
+
+    while retry_save
+      begin
+        retry_save = false
+        @object.save!
+      rescue ActiveRecord::RecordNotUnique => rn
+        # Dig into the error to determine if it is specifically calling out a
+        # (owner_uuid, name) uniqueness violation.  In this specific case, and
+        # the client requested a unique name with ensure_unique_name==true,
+        # update the name field and try to save again.  Loop as necessary to
+        # discover a unique name.  It is necessary to handle name choosing at
+        # this level (as opposed to the client) to ensure that record creation
+        # never fails due to a race condition.
+        if rn.original_exception.is_a? PG::UniqueViolation
+          # Unfortunately ActiveRecord doesn't abstract out any of the
+          # necessary information to figure out if this the error is actually
+          # the specific case where we want to apply the ensure_unique_name
+          # behavior, so the following code is specialized to Postgres.
+          err = rn.original_exception
+          detail = err.result.error_field(PG::Result::PG_DIAG_MESSAGE_DETAIL)
+          if /^Key \(owner_uuid, name\)=\([a-z0-9]{5}-[a-z0-9]{5}-[a-z0-9]{15}, .*?\) already exists\./.match detail
+            logger.error "params[:ensure_unique_name] is #{params[:ensure_unique_name]}"
+            if params[:ensure_unique_name]
+              counter += 1
+              @object.name = "#{name_stem} (#{counter})"
+              retry_save = true
+            end
+          end
+        end
+        if not retry_save
+          raise
+        end
+      end
+    end
     show
   end