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-rwxr-xr-xactiverecord/lib/active_record.rb2
-rw-r--r--activerecord/lib/active_record/locking.rb131
2 files changed, 70 insertions, 63 deletions
diff --git a/activerecord/lib/active_record.rb b/activerecord/lib/active_record.rb
index fc70b0de68..ddd1f9ff4c 100755
--- a/activerecord/lib/active_record.rb
+++ b/activerecord/lib/active_record.rb
@@ -54,7 +54,7 @@ require 'active_record/xml_serialization'
ActiveRecord::Base.class_eval do
include ActiveRecord::Validations
- include ActiveRecord::Locking
+ include ActiveRecord::Locking::Optimistic
include ActiveRecord::Callbacks
include ActiveRecord::Observing
include ActiveRecord::Timestamp
diff --git a/activerecord/lib/active_record/locking.rb b/activerecord/lib/active_record/locking.rb
index ee4224c004..9e7564ed25 100644
--- a/activerecord/lib/active_record/locking.rb
+++ b/activerecord/lib/active_record/locking.rb
@@ -1,77 +1,84 @@
module ActiveRecord
- # Active Records support optimistic locking if the field <tt>lock_version</tt> is present. Each update to the
- # record increments the lock_version column and the locking facilities ensure that records instantiated twice
- # will let the last one saved raise a StaleObjectError if the first was also updated. Example:
- #
- # p1 = Person.find(1)
- # p2 = Person.find(1)
- #
- # p1.first_name = "Michael"
- # p1.save
- #
- # p2.first_name = "should fail"
- # p2.save # Raises a ActiveRecord::StaleObjectError
- #
- # 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 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>
module Locking
- def self.included(base) #:nodoc:
- base.class_eval do
- alias_method_chain :update, :lock
+ # Active Records support optimistic locking if the field <tt>lock_version</tt> is present. Each update to the
+ # record increments the lock_version column and the locking facilities ensure that records instantiated twice
+ # will let the last one saved raise a StaleObjectError if the first was also updated. Example:
+ #
+ # p1 = Person.find(1)
+ # p2 = Person.find(1)
+ #
+ # p1.first_name = "Michael"
+ # p1.save
+ #
+ # p2.first_name = "should fail"
+ # p2.save # Raises a ActiveRecord::StaleObjectError
+ #
+ # 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 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>
+ module Optimistic
+ def self.included(base) #:nodoc:
+ super
+ base.extend ClassMethods
+
+ base.cattr_accessor :lock_optimistically
+ base.lock_optimistically = true
+
+ base.alias_method_chain :update, :lock
+ class << base
+ alias_method :locking_column=, :set_locking_column
+ end
end
- end
- def update_with_lock #:nodoc:
- return update_without_lock unless locking_enabled?
+ def locking_enabled? #:nodoc:
+ lock_optimistically && respond_to?(self.class.locking_column)
+ end
+
+ def update_with_lock #:nodoc:
+ return update_without_lock unless locking_enabled?
+
+ lock_col = self.class.locking_column
+ previous_value = send(lock_col)
+ send(lock_col + '=', previous_value + 1)
- lock_col = self.class.locking_column
- previous_value = send(lock_col)
- send(lock_col + '=', previous_value + 1)
+ 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)}
+ end_sql
- 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)}
- end_sql
+ unless affected_rows == 1
+ raise ActiveRecord::StaleObjectError, "Attempted to update a stale object"
+ end
- unless affected_rows == 1
- raise ActiveRecord::StaleObjectError, "Attempted to update a stale object"
+ return true
end
- return true
- end
- end
+ module ClassMethods
+ DEFAULT_LOCKING_COLUMN = 'lock_version'
- class Base
- @@lock_optimistically = true
- cattr_accessor :lock_optimistically
+ # 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
+ end
- def locking_enabled? #:nodoc:
- lock_optimistically && respond_to?(self.class.locking_column)
- end
-
- class << self
- def set_locking_column(value = nil, &block)
- define_attr_method :locking_column, value, &block
- end
-
- def locking_column #:nodoc:
- reset_locking_column
- end
-
- def reset_locking_column #:nodoc:
- default = 'lock_version'
- set_locking_column(default)
- default
+ # The version column used for optimistic locking. Defaults to lock_version.
+ def locking_column
+ reset_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
+ end
end
end
-
end
end