miriamtech/table_locks

TableLocks¶ ↑

Description¶ ↑

TableLocks is an ActiveSupport::Concern concern for acheiving locking in Rails using PostgreSQL table locking.

Usage¶ ↑

Create a model:

class CreateExampleLocks < ActiveRecord::Migration
  def change
    create_table :example_locks do |t|
    end
  end
end

Include the TableLocks concern:

class ExampleLock < ActiveRecord::Base
  include TableLocks
end

Lock in NOWAIT mode (SHARE UPDATE EXCLUSIVE MODE NOWAIT):

begin
  ExampleLock.exclusive_nowait do
    # You're the only one executing this code right now
  end
rescue PG::LockNotAvailable
  # Someone else beat us to it
end

Lock but wait (SHARE UPDATE EXCLUSIVE MODE):

ExampleLock.exclusive do
  # You're the only one executing this code right now
end

See PostgreSQL locking documentation for more information: www.postgresql.org/docs/9.6/static/explicit-locking.html