diff options
Diffstat (limited to 'activerecord/lib/active_record/locking/optimistic.rb')
-rw-r--r-- | activerecord/lib/active_record/locking/optimistic.rb | 87 |
1 files changed, 45 insertions, 42 deletions
diff --git a/activerecord/lib/active_record/locking/optimistic.rb b/activerecord/lib/active_record/locking/optimistic.rb index 2df3309648..a3412582fa 100644 --- a/activerecord/lib/active_record/locking/optimistic.rb +++ b/activerecord/lib/active_record/locking/optimistic.rb @@ -37,21 +37,22 @@ module ActiveRecord # You're then responsible for dealing with the conflict by rescuing the exception and either rolling back, merging, # or otherwise apply the business logic needed to resolve the conflict. # - # You must ensure that your database schema defaults the +lock_version+ column to 0. + # This locking mechanism will function inside a single Ruby process. To make it work across all + # web requests, the recommended approach is to add +lock_version+ as a hidden field to your form. # # This behavior can be turned off by setting <tt>ActiveRecord::Base.lock_optimistically = false</tt>. - # To override the name of the +lock_version+ column, invoke the <tt>set_locking_column</tt> method. - # This method uses the same syntax as <tt>set_table_name</tt> + # To override the name of the +lock_version+ column, set the <tt>locking_column</tt> class attribute: + # + # class Person < ActiveRecord::Base + # self.locking_column = :lock_person + # end + # module Optimistic extend ActiveSupport::Concern included do - cattr_accessor :lock_optimistically, :instance_writer => false + config_attribute :lock_optimistically, :global => true self.lock_optimistically = true - - class << self - alias_method :locking_column=, :set_locking_column - end end def locking_enabled? #:nodoc: @@ -65,21 +66,6 @@ module ActiveRecord send(lock_col + '=', previous_lock_value + 1) end - def attributes_from_column_definition - result = super - - # If the locking column has no default value set, - # start the lock version at zero. Note we can't use - # <tt>locking_enabled?</tt> at this point as - # <tt>@attributes</tt> may not have been initialized yet. - - if result.key?(self.class.locking_column) && lock_optimistically - result[self.class.locking_column] ||= 0 - end - - result - end - def update(attribute_names = @attributes.keys) #:nodoc: return super unless locking_enabled? return 0 if attribute_names.empty? @@ -98,7 +84,7 @@ module ActiveRecord relation.table[self.class.primary_key].eq(id).and( relation.table[lock_col].eq(quote_value(previous_lock_value)) ) - ).arel.compile_update(arel_attributes_values(false, false, attribute_names)) + ).arel.compile_update(arel_attributes_with_values_for_update(attribute_names)) affected_rows = connection.update stmt @@ -115,24 +101,29 @@ module ActiveRecord end end - def destroy #:nodoc: - return super unless locking_enabled? + def destroy_row + affected_rows = super - if persisted? - table = self.class.arel_table - lock_col = self.class.locking_column - predicate = table[self.class.primary_key].eq(id). - and(table[lock_col].eq(send(lock_col).to_i)) + if locking_enabled? && affected_rows != 1 + raise ActiveRecord::StaleObjectError.new(self, "destroy") + end - affected_rows = self.class.unscoped.where(predicate).delete_all + affected_rows + end - unless affected_rows == 1 - raise ActiveRecord::StaleObjectError.new(self, "destroy") - end + def relation_for_destroy + relation = super + + if locking_enabled? + column_name = self.class.locking_column + column = self.class.columns_hash[column_name] + substitute = connection.substitute_at(column, relation.bind_values.length) + + relation = relation.where(self.class.arel_table[column_name].eq(substitute)) + relation.bind_values << [column, self[column_name].to_i] end - @destroyed = true - freeze + relation end module ClassMethods @@ -146,14 +137,14 @@ module ActiveRecord end # Set the column to use for optimistic locking. Defaults to +lock_version+. - def set_locking_column(value = nil, &block) - define_attr_method :locking_column, value, &block - value + def locking_column=(value) + @locking_column = value.to_s end # The version column used for optimistic locking. Defaults to +lock_version+. def locking_column - reset_locking_column + reset_locking_column unless defined?(@locking_column) + @locking_column end # Quote the column name used for optimistic locking. @@ -163,7 +154,7 @@ module ActiveRecord # Reset the column used for optimistic locking back to the +lock_version+ default. def reset_locking_column - set_locking_column DEFAULT_LOCKING_COLUMN + self.locking_column = DEFAULT_LOCKING_COLUMN end # Make sure the lock version column gets updated when counters are @@ -172,6 +163,18 @@ module ActiveRecord counters = counters.merge(locking_column => 1) if locking_enabled? super end + + # If the locking column has no default value set, + # start the lock version at zero. Note we can't use + # <tt>locking_enabled?</tt> at this point as + # <tt>@attributes</tt> may not have been initialized yet. + def initialize_attributes(attributes) #:nodoc: + if attributes.key?(locking_column) && lock_optimistically + attributes[locking_column] ||= 0 + end + + attributes + end end end end |