diff options
| author | Olek Janiszewski <olek.janiszewski@gmail.com> | 2012-01-18 23:03:55 +0100 |
|---|---|---|
| committer | Olek Janiszewski <olek.janiszewski@gmail.com> | 2012-01-18 23:23:41 +0100 |
| commit | 7afbc89c37e56531c9ef4e34369e329aab1b21de (patch) | |
| tree | b2647a40311d813c21712dd5f78fe53f7b76ede8 /activerecord | |
| parent | 423b2626d85f75bb5fec03909ff8963bded7c7d5 (diff) | |
| download | rails-7afbc89c37e56531c9ef4e34369e329aab1b21de.tar.gz rails-7afbc89c37e56531c9ef4e34369e329aab1b21de.tar.bz2 rails-7afbc89c37e56531c9ef4e34369e329aab1b21de.zip | |
Add ActiveRecord::Base#with_lock
Add a `with_lock` method to ActiveRecord objects, which starts
a transaction, locks the object (pessimistically) and yields to the block.
The method takes one (optional) parameter and passes it to `lock!`.
Before:
class Order < ActiveRecord::Base
def cancel!
transaction do
lock!
# ... cancelling logic
end
end
end
After:
class Order < ActiveRecord::Base
def cancel!
with_lock do
# ... cancelling logic
end
end
end
Diffstat (limited to 'activerecord')
| -rw-r--r-- | activerecord/CHANGELOG.md | 29 | ||||
| -rw-r--r-- | activerecord/lib/active_record/locking/pessimistic.rb | 22 | ||||
| -rw-r--r-- | activerecord/test/cases/locking_test.rb | 20 |
3 files changed, 70 insertions, 1 deletions
diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md index f7de341fbe..a458f9e6e4 100644 --- a/activerecord/CHANGELOG.md +++ b/activerecord/CHANGELOG.md @@ -72,6 +72,33 @@ ## Rails 3.2.0 (unreleased) ## +* Added a `with_lock` method to ActiveRecord objects, which starts + a transaction, locks the object (pessimistically) and yields to the block. + The method takes one (optional) parameter and passes it to `lock!`. + + Before: + + class Order < ActiveRecord::Base + def cancel! + transaction do + lock! + # ... cancelling logic + end + end + end + + After: + + class Order < ActiveRecord::Base + def cancel! + with_lock do + # ... cancelling logic + end + end + end + + *Olek Janiszewski* + * 'on' and 'ON' boolean columns values are type casted to true *Santiago Pastorino* @@ -82,7 +109,7 @@ Example: rake db:migrate SCOPE=blog - *Piotr Sarnacki* + *Piotr Sarnacki* * Migrations copied from engines are now scoped with engine's name, for example 01_create_posts.blog.rb. *Piotr Sarnacki* diff --git a/activerecord/lib/active_record/locking/pessimistic.rb b/activerecord/lib/active_record/locking/pessimistic.rb index 66994e4797..58af92f0b1 100644 --- a/activerecord/lib/active_record/locking/pessimistic.rb +++ b/activerecord/lib/active_record/locking/pessimistic.rb @@ -38,6 +38,18 @@ module ActiveRecord # account2.save! # end # + # You can start a transaction and acquire the lock in one go by calling + # <tt>with_lock</tt> with a block. The block is called from within + # a transaction, the object is already locked. Example: + # + # account = Account.first + # account.with_lock do + # # This block is called within a transaction, + # # account is already locked. + # account.balance -= 100 + # account.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/current/interactive/sql-select.html#SQL-FOR-UPDATE-SHARE @@ -50,6 +62,16 @@ module ActiveRecord reload(:lock => lock) if persisted? self end + + # Wraps the passed block in a transaction, locking the object + # before yielding. You pass can the SQL locking clause + # as argument (see <tt>lock!</tt>). + def with_lock(lock = true) + transaction do + lock!(lock) + yield + end + end end end end diff --git a/activerecord/test/cases/locking_test.rb b/activerecord/test/cases/locking_test.rb index 0c458d5318..807274ca67 100644 --- a/activerecord/test/cases/locking_test.rb +++ b/activerecord/test/cases/locking_test.rb @@ -388,6 +388,26 @@ unless current_adapter?(:SybaseAdapter, :OpenBaseAdapter) || in_memory_db? end end + def test_with_lock_commits_transaction + person = Person.find 1 + person.with_lock do + person.first_name = 'fooman' + person.save! + end + assert_equal 'fooman', person.reload.first_name + end + + def test_with_lock_rolls_back_transaction + person = Person.find 1 + old = person.first_name + person.with_lock do + person.first_name = 'fooman' + person.save! + raise 'oops' + end rescue nil + assert_equal old, person.reload.first_name + end + if current_adapter?(:PostgreSQLAdapter, :OracleAdapter) def test_no_locks_no_wait first, second = duel { Person.find 1 } |