From 5d92c1dbae1397ee138d4cd678bb427465a9566b Mon Sep 17 00:00:00 2001
From: Jim Myhrberg <contact@jimeh.me>
Date: Fri, 15 Apr 2011 14:03:26 +0100
Subject: [PATCH] created Redistat::Synchronize mixin to help with
 thread-safety

---
 lib/redistat.rb             | 10 ++++++
 lib/redistat/synchronize.rb | 51 +++++++++++++++++++++++++++++
 spec/synchronize_spec.rb    | 64 +++++++++++++++++++++++++++++++++++++
 3 files changed, 125 insertions(+)
 create mode 100644 lib/redistat/synchronize.rb
 create mode 100644 spec/synchronize_spec.rb

diff --git a/lib/redistat.rb b/lib/redistat.rb
index 11d63db..a2505bd 100644
--- a/lib/redistat.rb
+++ b/lib/redistat.rb
@@ -3,6 +3,7 @@ require 'rubygems'
 require 'date'
 require 'time'
 require 'digest/sha1'
+require 'monitor'
 
 # Active Support 2.x or 3.x
 require 'active_support'
@@ -16,6 +17,7 @@ require 'redis'
 require 'json'
 
 require 'redistat/options'
+require 'redistat/synchronize'
 require 'redistat/connection'
 require 'redistat/database'
 require 'redistat/collection'
@@ -47,6 +49,14 @@ module Redistat
   
   class << self
     
+    def thread_safe
+      Synchronize.thread_safe
+    end
+    
+    def thread_safe=(value)
+      Synchronize.thread_safe = value
+    end
+    
     def connection(ref = nil)
       Connection.get(ref)
     end
diff --git a/lib/redistat/synchronize.rb b/lib/redistat/synchronize.rb
new file mode 100644
index 0000000..2d20b89
--- /dev/null
+++ b/lib/redistat/synchronize.rb
@@ -0,0 +1,51 @@
+require 'monitor'
+
+module Redistat
+  module Synchronize
+    
+    class << self
+      def included(base)
+        base.send(:include, InstanceMethods)
+      end
+      
+      def monitor
+        @monitor ||= Monitor.new
+      end
+      
+      def thread_safe
+        monitor.synchronize do
+          @thread_safe ||= false
+        end
+      end
+      
+      def thread_safe=(value)
+        monitor.synchronize do
+          @thread_safe = value
+        end
+      end
+    end # << self
+    
+    module InstanceMethods
+      def thread_safe
+        Synchronize.thread_safe
+      end
+      
+      def thread_safe=(value)
+        Synchronize.thread_safe = value
+      end
+      
+      def monitor
+        Synchronize.monitor
+      end
+      
+      def synchronize(&block)
+        if thread_safe
+          monitor.synchronize(&block)
+        else
+          block.call
+        end
+      end
+    end # InstanceMethods
+    
+  end
+end
\ No newline at end of file
diff --git a/spec/synchronize_spec.rb b/spec/synchronize_spec.rb
new file mode 100644
index 0000000..56e8f26
--- /dev/null
+++ b/spec/synchronize_spec.rb
@@ -0,0 +1,64 @@
+require "spec_helper"
+
+describe Redistat::Synchronize do
+  it { should respond_to(:monitor) }
+  it { should respond_to(:thread_safe) }
+  it { should respond_to(:thread_safe=) }
+  
+  describe "instanciated class with Redistat::Synchronize included" do
+    subject { SynchronizeSpecHelper.new }
+    it { should respond_to(:monitor) }
+    it { should respond_to(:thread_safe) }
+    it { should respond_to(:thread_safe=) }
+    it { should respond_to(:synchronize) }
+    
+  end
+  
+  describe "#synchronize method" do
+    
+    before(:each) do
+      Redistat::Synchronize.instance_variable_set("@thread_safe", nil)
+      @obj = SynchronizeSpecHelper.new
+    end
+    
+    it "should share single Monitor object across all objects" do
+      @obj.monitor.should == Redistat::Synchronize.monitor
+    end
+    
+    it "should share thread_safe option across all objects" do
+      obj2 = SynchronizeSpecHelper.new
+      Redistat::Synchronize.thread_safe.should be_false
+      @obj.thread_safe.should be_false
+      obj2.thread_safe.should be_false
+      @obj.thread_safe = true
+      Redistat::Synchronize.thread_safe.should be_true
+      @obj.thread_safe.should be_true
+      obj2.thread_safe.should be_true
+    end
+    
+    it "should not synchronize when thread_safe is disabled" do
+      # monitor receives :synchronize twice cause #thread_safe is _always_ synchronized
+      Redistat::Synchronize.monitor.should_receive(:synchronize).twice
+      @obj.thread_safe.should be_false # first #synchronize call
+      @obj.synchronize { 'foo' } # one #synchronize call while checking #thread_safe
+    end
+    
+    it "should synchronize when thread_safe is enabled" do
+      Monitor.class_eval {
+        # we're stubbing synchronize to ensure it's being called correctly, but still need it :P
+        alias :real_synchronize :synchronize
+      }
+      Redistat::Synchronize.monitor.should_receive(:synchronize).with.exactly(4).times.and_return { |block|
+        Redistat::Synchronize.monitor.real_synchronize(&block)
+      }
+      @obj.thread_safe.should be_false # first synchronize call
+      Redistat::Synchronize.thread_safe = true # second synchronize call
+      @obj.synchronize { 'foo' } # two synchronize calls, once while checking thread_safe, once to call black
+    end
+  end
+  
+end
+
+class SynchronizeSpecHelper
+  include Redistat::Synchronize
+end