Refactoring with a number of improvements:

* can use the regular #save or #save! instead of #save_optimistic!
* can now use locking with #destroy
* can use #unlock to persist without locking

.gitignore

@@ -3,4 +3,5 @@
 Gemfile.lock
 pkg/*
 .idea
-*.iml
+*.iml
+.rvmrc

README.md

@@ -27,7 +27,7 @@ To use it, all you have to do is add include Mongoid::Lockable
     end
 
 This will add a _lock_version field in the document which will be incremented every time a save is called.
-In order a to save a document in a save manner, use the new <code>save_optimistic!</code> and <code>rescue Mongoid::Errors::StaleDocument</code> to handle applicative logic in case the object was changed.
+Be sure to rescue `Mongoid::Errors::StaleDocument` to handle applicative logic in case the object was changed.
 
 For example:
 
@@ -37,7 +37,7 @@ For example:
             begin
                 post = Post.find(params[:id])
                 post.text += "---UPDATE---  " + params[:more_text]
-                post.save_optimistic!
+                post.save
             rescue Mongoid::Errors::StaleDocument
                 retry
             end

Rakefile

@@ -1 +1,6 @@
 require "bundler/gem_tasks"
+
+require 'rspec/core/rake_task'
+RSpec::Core::RakeTask.new(:spec)
+
+task :default => :spec

lib/config/locales/en.yml

@@ -2,5 +2,8 @@ en:
   mongoid:
     errors:
       messages:
-        stale:
-          Document class %{klass} with id(s) is stale and should be reloaded.
+        stale_document:
+          update:
+            "Attempted to update a stale document: %{klass}"
+          destroy:
+            "Attempted to destroy a stale document: %{klass}"

lib/mongoid/errors/stale_document.rb

@@ -0,0 +1,28 @@
+require 'mongoid/errors/mongoid_error'
+
+module Mongoid
+  module Errors
+
+    # Raised when trying to update a document that has been updated by
+    # another process.
+    #
+    # @example Create the error.
+    #   StaleDocument.new('update', document)
+    class StaleDocument < MongoidError
+
+      attr_reader :action, :document
+
+      def initialize(action, document)
+        @action = action
+        @document = document
+
+        super(
+          translate(
+            "stale_document.#{action}",
+            { :klass => document.class.name }
+          )
+        )
+      end
+    end
+  end
+end

lib/mongoid/lockable.rb

@@ -0,0 +1,13 @@
+module Mongoid
+
+  module Lockable
+
+    extend ActiveSupport::Concern
+
+    included do
+      ActiveSupport::Deprecation.warn 'Mongoid::Lockable is deprecated and will be removed. Use Mongoid::OptimisticLocking instead.', caller
+      include Mongoid::OptimisticLocking
+    end
+
+  end
+end

lib/mongoid/optimistic_locking.rb

@@ -0,0 +1,39 @@
+require 'mongoid'
+require 'mongoid/errors/stale_document'
+require 'mongoid/lockable'
+require 'mongoid/optimistic_locking/deprecated'
+require 'mongoid/optimistic_locking/lock_version'
+require 'mongoid/optimistic_locking/operations'
+require 'mongoid/optimistic_locking/threaded_with_unlocked'
+require 'mongoid/optimistic_locking/unlocked'
+require 'mongoid/optimistic_locking/version'
+
+# monkey patch Threaded
+Mongoid::Threaded.send :include, Mongoid::OptimisticLocking::ThreadedWithUnlocked
+
+# add english load path to translations
+I18n.load_path << File.expand_path('../../config/locales/en.yml', __FILE__)
+
+module Mongoid
+  # == What is Optimistic Locking
+  #
+  # See <http://api.rubyonrails.org/classes/ActiveRecord/Locking/Optimistic.html>.
+  #
+  # == Usage
+  #
+  # TODO ...
+  module OptimisticLocking
+
+    extend ActiveSupport::Concern
+
+    include Deprecated
+    include LockVersion
+    include Operations
+    include Unlocked
+
+    included do
+      field LOCKING_FIELD, :type => Integer, :default => 0
+    end
+
+  end
+end

lib/mongoid/optimistic_locking/deprecated.rb

@@ -0,0 +1,12 @@
+module Mongoid
+  module OptimisticLocking
+    module Deprecated
+
+      def save_optimistic!(*args)
+        ActiveSupport::Deprecation.warn 'save_optimistic! is deprecated and will be removed. Use save or save! instead', caller
+        save! *args
+      end
+
+    end
+  end
+end

lib/mongoid/optimistic_locking/lock_version.rb

@@ -0,0 +1,29 @@
+module Mongoid
+  module OptimisticLocking
+    module LockVersion
+
+      LOCKING_FIELD = :_lock_version
+
+      private
+
+      attr_reader :lock_version_for_selector
+
+      def set_lock_version_for_selector
+        @lock_version_for_selector = self[LOCKING_FIELD]
+        yield
+      rescue Exception
+        @lock_version_for_selector = nil
+        raise
+      end
+
+      def increment_lock_version
+        self[LOCKING_FIELD] = self[LOCKING_FIELD] ? self[LOCKING_FIELD] + 1 : 1
+        yield
+      rescue Exception
+        self[LOCKING_FIELD] = self[LOCKING_FIELD] ? self[LOCKING_FIELD] - 1 : 0
+        raise
+      end
+
+    end
+  end
+end

lib/mongoid/optimistic_locking/operations.rb

@@ -0,0 +1,53 @@
+module Mongoid
+  module OptimisticLocking
+    module Operations
+
+      def insert(*args)
+        return super unless optimistic_locking?
+        increment_lock_version do
+          super
+        end
+      end
+
+      def update(*args)
+        return super unless optimistic_locking?
+        set_lock_version_for_selector do
+          increment_lock_version do
+            result = super
+            unless Mongoid.database.command({:getlasterror => 1})['updatedExisting']
+              raise Mongoid::Errors::StaleDocument.new('update', self)
+            end
+            result
+          end
+        end
+      end
+
+      def remove(*args)
+        return super unless optimistic_locking?
+        set_lock_version_for_selector do
+          result = super
+          unless Mongoid.database.command({:getlasterror => 1})['updatedExisting']
+            raise Mongoid::Errors::StaleDocument.new('destroy', self)
+          end
+          result
+        end
+      end
+
+      def atomic_selector
+        result = super
+        if optimistic_locking? && lock_version_for_selector
+          key =
+            if metadata && metadata.embedded?
+              path = metadata.path(self)
+              "#{path.path}._lock_version"
+            else
+              '_lock_version'
+            end
+          result[key] = lock_version_for_selector
+        end
+        result
+      end
+
+    end
+  end
+end

lib/mongoid/optimistic_locking/threaded_with_unlocked.rb

@@ -0,0 +1,30 @@
+module Mongoid
+  module OptimisticLocking
+    module ThreadedWithUnlocked
+
+      extend ActiveSupport::Concern
+
+      module ClassMethods
+
+        def optimistic_locking?
+          !unlocked
+        end
+
+        def unlocked
+          !!Thread.current["[mongoid]:unlocked"]
+        end
+
+        def unlocked=(value)
+          Thread.current["[mongoid]:unlocked"] = value
+        end
+
+        def clear_options!
+          self.unlocked = false
+          super
+        end
+
+      end
+
+    end
+  end
+end

lib/mongoid/optimistic_locking/unlocked.rb

@@ -0,0 +1,26 @@
+module Mongoid
+  module OptimisticLocking
+    module Unlocked
+
+      extend ActiveSupport::Concern
+
+      def unlocked
+        Threaded.unlocked = true
+        self
+      end
+
+      def optimistic_locking?
+        Threaded.optimistic_locking?
+      end
+
+      module ClassMethods
+
+        def unlocked
+          Threaded.unlocked = true
+        end
+
+      end
+
+    end
+  end
+end

lib/mongoid/optimistic_locking/version.rb

@@ -0,0 +1,5 @@
+module Mongoid
+  module OptimisticLocking
+    VERSION = '0.0.1'
+  end
+end

lib/mongoid_optimistic_locking.rb

@@ -1,3 +1 @@
-require "mongoid_optimistic_locking/version"
-require File.join(File.dirname(__FILE__), 'mongoid_optimistic_locking/lockable')
-I18n.load_path << File.join(File.dirname(__FILE__), "config", "locales", "en.yml")
+require 'mongoid/optimistic_locking'

mongoid_optimistic_locking.gemspec

@@ -1,15 +1,15 @@
 # -*- encoding: utf-8 -*-
 $:.push File.expand_path("../lib", __FILE__)
-require "mongoid_optimistic_locking/version"
+require "mongoid/optimistic_locking/version"
 
 Gem::Specification.new do |s|
   s.name        = "mongoid_optimistic_locking"
-  s.version     = MongoidOptimisticLocking::VERSION
+  s.version     = Mongoid::OptimisticLocking::VERSION
   s.authors     = ["Alon Burg"]
   s.email       = ["burgalon@gmail.com"]
   s.homepage    = ""
   s.summary     = %q{Allows optimisitic locking for Mongoid models}
-  s.description = %q{Allows optimisitic locking for Mongoid models. See https://github.com/burgalon/mongoid-optimistic-locking}
+  s.description = %q{Allows optimisitic locking for Mongoid models. See https://github.com/burgalon/mongoid_optimistic_locking}
 
   s.add_development_dependency 'rspec', '~> 2.6'
   s.add_development_dependency 'mongoid', '~> 2.4'