1 files changed, 16 insertions, 4 deletions
diff --git a/activerecord/lib/active_record/errors.rb b/activerecord/lib/active_record/errors.rb
index c8c06375a3..0f110b4536 100644
--- a/activerecord/lib/active_record/errors.rb
+++ b/activerecord/lib/active_record/errors.rb
@@ -106,7 +106,7 @@ module ActiveRecord
   # Wraps the underlying database error as +cause+.
   class StatementInvalid < ActiveRecordError
     def initialize(message = nil, sql: nil, binds: nil)
-      super(message || $!.try(:message))
+      super(message || $!&.message)
       @sql = sql
       @binds = binds
     end
@@ -187,6 +187,10 @@ module ActiveRecord
   class NoDatabaseError < StatementInvalid
   end
 
+  # Raised when creating a database if it exists.
+  class DatabaseAlreadyExists < StatementInvalid
+  end
+
   # Raised when PostgreSQL returns 'cached plan must not change result type' and
   # we cannot retry gracefully (e.g. inside a transaction)
   class PreparedStatementCacheExpired < StatementInvalid
@@ -334,7 +338,7 @@ module ActiveRecord
   # See the following:
   #
   # * https://www.postgresql.org/docs/current/static/transaction-iso.html
-  # * https://dev.mysql.com/doc/refman/5.7/en/error-messages-server.html#error_er_lock_deadlock
+  # * https://dev.mysql.com/doc/refman/5.7/en/server-error-reference.html#error_er_lock_deadlock
   class TransactionRollbackError < StatementInvalid
   end
 
@@ -353,16 +357,24 @@ module ActiveRecord
   class IrreversibleOrderError < ActiveRecordError
   end
 
+  # Superclass for errors that have been aborted (either by client or server).
+  class QueryAborted < StatementInvalid
+  end
+
   # LockWaitTimeout will be raised when lock wait timeout exceeded.
   class LockWaitTimeout < StatementInvalid
   end
 
   # StatementTimeout will be raised when statement timeout exceeded.
-  class StatementTimeout < StatementInvalid
+  class StatementTimeout < QueryAborted
   end
 
   # QueryCanceled will be raised when canceling statement due to user request.
-  class QueryCanceled < StatementInvalid
+  class QueryCanceled < QueryAborted
+  end
+
+  # AdapterTimeout will be raised when database clients times out while waiting from the server.
+  class AdapterTimeout < QueryAborted
   end
 
   # UnknownAttributeReference is raised when an unknown and potentially unsafe