Merge pull request #22122 from samphilipd/sam/manual_locking_on_schema_migrations

Make migrations concurrent safe (using advisory locks)

1 files changed, 18 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
index 787dadfdbf..6200cc8d29 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
@@ -284,6 +284,10 @@ module ActiveRecord
         true
       end
 
+      def supports_advisory_locks?
+        true
+      end
+
       def supports_explain?
         true
       end
@@ -302,6 +306,20 @@ module ActiveRecord
         postgresql_version >= 90300
       end
 
+      def get_advisory_lock(key) # :nodoc:
+        unless key.is_a?(Integer) && key.bit_length <= 63
+          raise(ArgumentError, "Postgres requires advisory lock keys to be a signed 64 bit integer")
+        end
+        select_value("SELECT pg_try_advisory_lock(#{key});")
+      end
+
+      def release_advisory_lock(key) # :nodoc:
+        unless key.is_a?(Integer) && key.bit_length <= 63
+          raise(ArgumentError, "Postgres requires advisory lock keys to be a signed 64 bit integer")
+        end
+        select_value("SELECT pg_advisory_unlock(#{key})")
+      end
+
       def enable_extension(name)
         exec_query("CREATE EXTENSION IF NOT EXISTS \"#{name}\"").tap {
           reload_type_map