Add Counter#getset method which resets a counter and returns its old …

…value.

lib/redis/counter.rb

@@ -28,6 +28,14 @@ def reset(to=options[:start])
       true  # hack for redis-rb regression
     end
 
+    # Reset the counter to its starting value, and return previous value.
+    # Use this to "reap" the counter and save it somewhere else. This is
+    # atomic in that no increments or decrements are lost if you process
+    # the returned value.
+    def getset(to=options[:start])
+      redis.getset(key, to.to_i).to_i
+    end
+
     # Returns the current value of the counter.  Normally just calling the
     # counter will lazily fetch the value, and only update it if increment
     # or decrement is called.  This forces a network call to redis-server

lib/redis/objects/counters.rb

@@ -79,6 +79,13 @@ def reset_counter(name, id=nil, to=nil)
           redis.set(redis_field_key(name, id), to.to_i)
           true
         end
+
+        # Set a counter to its starting value and return the old value.
+        def getset_counter(name, id=nil, to=nil)
+          verify_counter_defined!(name, id)
+          to = @redis_objects[name][:start] if to.nil?
+          redis.getset(redis_field_key(name, id), to.to_i).to_i
+        end
 
         private
 

spec/redis_objects_active_record_spec.rb

@@ -81,6 +81,10 @@ class Post < ActiveRecord::Base
       @ar2.total.decrement.should == 1
       @ar2.total.reset
       @ar2.total.should == 0
+      @ar2.total.reset(55)
+      @ar2.total.should == 55
+      @ar2.total.getset(12).should == 55
+      @ar2.total.should == 12
       @ar2.destroy
     end
 

spec/redis_objects_instance_spec.rb

@@ -266,6 +266,8 @@
     @counter.should == 0
     @counter.reset(15).should.be.true
     @counter.should == 15
+    @counter.getset(111).should == 15
+    @counter.should == 111
   end
 
   after do

spec/redis_objects_model_spec.rb

@@ -193,6 +193,8 @@ class CustomMethodRoster < MethodRoster
     Roster.decrement_counter(:available_slots, @roster.id).should == 11
     Roster.reset_counter(:available_slots, @roster.id).should == true
     Roster.get_counter(:available_slots, @roster.id).should == 10
+    Roster.getset_counter(:available_slots, @roster.id, 555).should == 10
+    Roster.get_counter(:available_slots, @roster.id).should == 555
   end
 
   it "should support class-level increment/decrement of global counters" do
@@ -211,6 +213,8 @@ class CustomMethodRoster < MethodRoster
     Roster.decrement_counter(:total_players_online).should == 1
     Roster.reset_counter(:total_players_online).should == true
     Roster.get_counter(:total_players_online).should == 0
+    Roster.getset_counter(:total_players_online, nil, 111).should == 0
+    Roster.get_counter(:total_players_online).should == 111
   end
 
   it "should take an atomic block for increment/decrement" do