From 798b8444cf1cecee7a4e278a1520700d3648cadc Mon Sep 17 00:00:00 2001
From: Sam <sam.saffron@gmail.com>
Date: Mon, 17 Mar 2014 15:22:11 +1100
Subject: [PATCH] BUGFIX: work correctly if process forks

---
 lib/scheduler/defer.rb                  | 26 ++++++++++++++++++++-----
 spec/components/scheduler/defer_spec.rb | 20 +++++++++++++++++++
 2 files changed, 41 insertions(+), 5 deletions(-)

diff --git a/lib/scheduler/defer.rb b/lib/scheduler/defer.rb
index 46b94ee50..5c27c56b5 100644
--- a/lib/scheduler/defer.rb
+++ b/lib/scheduler/defer.rb
@@ -3,11 +3,10 @@ module Scheduler
     def initialize
       @async = Rails.env != "test"
       @queue = Queue.new
-      @thread = Thread.new {
-        while true
-          do_work
-        end
-      }
+      @mutex = Mutex.new
+      @thread = nil
+      start_thread
+
     end
 
     # for test
@@ -17,6 +16,7 @@ module Scheduler
 
     def later(&blk)
       if @async
+        start_thread unless @thread.alive?
         @queue << [RailsMultisite::ConnectionManagement.current_db, blk]
       else
         blk.call
@@ -27,8 +27,24 @@ module Scheduler
       @thread.kill
     end
 
+    # test only
+    def stopped?
+      !@thread.alive?
+    end
+
     private
 
+    def start_thread
+      @mutex.synchronize do
+        return if @thread && @thread.alive?
+        @thread = Thread.new {
+          while true
+            do_work
+          end
+        }
+      end
+    end
+
     def do_work
       db, job = @queue.deq
       RailsMultisite::ConnectionManagement.establish_connection(db: db)
diff --git a/spec/components/scheduler/defer_spec.rb b/spec/components/scheduler/defer_spec.rb
index b27c36c3a..f564e94a0 100644
--- a/spec/components/scheduler/defer_spec.rb
+++ b/spec/components/scheduler/defer_spec.rb
@@ -23,6 +23,26 @@ describe Scheduler::Defer do
     @defer.stop!
   end
 
+  it "recovers from a crash / fork" do
+    s = nil
+    @defer.stop!
+    wait_for(10) do
+      @defer.stopped?
+    end
+    # hack allow thread to die
+    sleep 0.005
+
+    @defer.later do
+      s = "good"
+    end
+
+    wait_for(10) do
+      s == "good"
+    end
+
+    s.should == "good"
+  end
+
   it "can queue jobs properly" do
     s = nil