diff options
Diffstat (limited to 'activerecord/lib')
| -rwxr-xr-x | activerecord/lib/active_record.rb | 4 | ||||
| -rwxr-xr-x | activerecord/lib/active_record/base.rb | 7 | ||||
| -rw-r--r-- | activerecord/lib/active_record/locking/optimistic.rb (renamed from activerecord/lib/active_record/locking.rb) | 9 | ||||
| -rw-r--r-- | activerecord/lib/active_record/locking/pessimistic.rb | 77 |
4 files changed, 92 insertions, 5 deletions
diff --git a/activerecord/lib/active_record.rb b/activerecord/lib/active_record.rb index ddd1f9ff4c..0fb36dbfb3 100755 --- a/activerecord/lib/active_record.rb +++ b/activerecord/lib/active_record.rb @@ -46,7 +46,8 @@ require 'active_record/timestamp' require 'active_record/acts/list' require 'active_record/acts/tree' require 'active_record/acts/nested_set' -require 'active_record/locking' +require 'active_record/locking/optimistic' +require 'active_record/locking/pessimistic' require 'active_record/migration' require 'active_record/schema' require 'active_record/calculations' @@ -55,6 +56,7 @@ require 'active_record/xml_serialization' ActiveRecord::Base.class_eval do include ActiveRecord::Validations include ActiveRecord::Locking::Optimistic + include ActiveRecord::Locking::Pessimistic include ActiveRecord::Callbacks include ActiveRecord::Observing include ActiveRecord::Timestamp diff --git a/activerecord/lib/active_record/base.rb b/activerecord/lib/active_record/base.rb index 55befcd29f..da4ade6e36 100755 --- a/activerecord/lib/active_record/base.rb +++ b/activerecord/lib/active_record/base.rb @@ -1541,10 +1541,13 @@ module ActiveRecord #:nodoc: end # Reloads the attributes of this object from the database. - def reload + # The optional options argument is passed to find when reloading so you + # may do e.g. record.reload(:lock => true) to reload the same record with + # an exclusive row lock. + def reload(options = nil) clear_aggregation_cache clear_association_cache - @attributes.update(self.class.find(self.id).instance_variable_get('@attributes')) + @attributes.update(self.class.find(self.id, options).instance_variable_get('@attributes')) self end diff --git a/activerecord/lib/active_record/locking.rb b/activerecord/lib/active_record/locking/optimistic.rb index 9e7564ed25..7bae573924 100644 --- a/activerecord/lib/active_record/locking.rb +++ b/activerecord/lib/active_record/locking/optimistic.rb @@ -49,8 +49,8 @@ module ActiveRecord affected_rows = connection.update(<<-end_sql, "#{self.class.name} Update with optimistic locking") UPDATE #{self.class.table_name} SET #{quoted_comma_pair_list(connection, attributes_with_quotes(false))} - WHERE #{self.class.primary_key} = #{quote(id)} - AND #{lock_col} = #{quote(previous_value)} + WHERE #{self.class.primary_key} = #{quote(id)} + AND #{self.class.quoted_locking_column} = #{quote(previous_value)} end_sql unless affected_rows == 1 @@ -74,6 +74,11 @@ module ActiveRecord reset_locking_column end + # Quote the column name used for optimistic locking. + def quoted_locking_column + connection.quote_column_name(locking_column) + end + # Reset the column used for optimistic locking back to the lock_version default. def reset_locking_column set_locking_column DEFAULT_LOCKING_COLUMN diff --git a/activerecord/lib/active_record/locking/pessimistic.rb b/activerecord/lib/active_record/locking/pessimistic.rb new file mode 100644 index 0000000000..caad760742 --- /dev/null +++ b/activerecord/lib/active_record/locking/pessimistic.rb @@ -0,0 +1,77 @@ +# Copyright (c) 2006 Shugo Maeda <shugo@ruby-lang.org> +# +# Permission is hereby granted, free of charge, to any person obtaining +# a copy of this software and associated documentation files (the +# "Software"), to deal in the Software without restriction, including +# without limitation the rights to use, copy, modify, merge, publish, +# distribute, sublicense, and/or sell copies of the Software, and to +# permit persons to whom the Software is furnished to do so, subject +# to the following conditions: +# +# The above copyright notice and this permission notice shall be +# included in all copies or substantial portions of the Software. +# +# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, +# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF +# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. +# IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR +# ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF +# CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION +# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. + + +module ActiveRecord + module Locking + # Locking::Pessimistic provides support for row-level locking using + # SELECT ... FOR UPDATE and other lock types. + # + # Pass :lock => true to ActiveRecord::Base.find to obtain an exclusive + # lock on the selected rows: + # # select * from accounts where id=1 for update + # Account.find(1, :lock => true) + # + # Pass :lock => 'some locking clause' to give a database-specific locking clause + # of your own such as 'LOCK IN SHARE MODE' or 'FOR UPDATE NOWAIT'. + # + # Example: + # Account.transaction do + # # select * from accounts where name = 'shugo' limit 1 for update + # shugo = Account.find(:first, :conditions => "name = 'shugo'", :lock => true) + # yuko = Account.find(:first, :conditions => "name = 'yuko'", :lock => true) + # shugo.balance -= 100 + # shugo.save! + # yuko.balance += 100 + # yuko.save! + # end + # + # You can also use ActiveRecord::Base#lock! method to lock one record by id. + # This may be better if you don't need to lock every row. Example: + # Account.transaction do + # # select * from accounts where ... + # accounts = Account.find(:all, :conditions => ...) + # account1 = accounts.detect { |account| ... } + # account2 = accounts.detect { |account| ... } + # # select * from accounts where id=? for update + # account1.lock! + # account2.lock! + # account1.balance -= 100 + # account1.save! + # account2.balance += 100 + # account2.save! + # end + # + # Database-specific information on row locking: + # MySQL: http://dev.mysql.com/doc/refman/5.1/en/innodb-locking-reads.html + # PostgreSQL: http://www.postgresql.org/docs/8.1/interactive/sql-select.html#SQL-FOR-UPDATE-SHARE + module Pessimistic + # Obtain a row lock on this record. Reloads the record to obtain the requested + # lock. Pass an SQL locking clause to append the end of the SELECT statement + # or pass true for "FOR UPDATE" (the default, an exclusive row lock). Returns + # the locked record. + def lock!(lock = true) + reload(:lock => lock) unless new_record? + self + end + end + end +end |