Add ability to see a pre_fork hook that will be called once before each worker forks for the first time.

Author: scotttam

README.markdown

@@ -648,6 +648,11 @@ this way we can tell our Sinatra app about the config file:
 
 Now everyone is on the same page.
 
+If you wish to have a Proc called before the worker forks for the first time, you
+can add it in the initializer like so:
+
+    Resque.before_fork = Proc.new { puts "CALL ME ONCE BEFORE THE WORKER FORKS THE FIRST TIME" }
+
 
 Namespaces
 ----------

lib/resque.rb

@@ -48,6 +48,16 @@ def redis
     self.redis
   end
 
+  #Set a proc that will be called once before the worker forks
+  def before_fork=(before_fork)
+    @before_fork = before_fork
+  end
+
+  #Returns the before_fork proc
+  def before_fork
+    @before_fork
+  end
+
   def to_s
     "Resque Client connected to #{redis.server}"
   end

lib/resque/worker.rb

@@ -61,6 +61,11 @@ def self.exists?(worker_id)
       redis.sismember(:workers, worker_id)
     end
 
+    #Sets the before_hook proc
+    def self.before_fork=(before_fork)
+      @@before_fork = before_fork
+    end
+
     # Workers should be initialized with an array of string queue
     # names. The order is important: a Worker will check the first
     # queue given for a job. If none is found, it will check the
@@ -202,6 +207,7 @@ def startup
       enable_gc_optimizations
       register_signal_handlers
       prune_dead_workers
+      before_fork
       register_worker
     end
 
@@ -306,6 +312,11 @@ def register_worker
       started!
     end
 
+    #Call any before_fork procs, if any
+    def before_fork
+      @@before_fork.call if Worker.class_variable_defined?(:@@before_fork)
+    end
+
     # Unregisters ourself as a worker. Useful when shutting down.
     def unregister_worker
       redis.srem(:workers, self)

test/worker_test.rb

@@ -240,4 +240,21 @@
     @worker.work(0)
     assert_equal 1, Resque.info[:processed]
   end
+
+  test "Will call a pre-fork proc when the worker starts if set in the initializer only once" do
+    $BEFORE_FORK_CALLED = false
+    Resque.before_fork = Proc.new { $BEFORE_FORK_CALLED = true }
+    Resque::Worker.before_fork = Resque.before_fork
+    workerA = Resque::Worker.new(:jobs)
+    Resque::Job.create(:jobs, SomeJob, 20, '/tmp')
+    
+    assert !$BEFORE_FORK_CALLED
+    workerA.work(0)
+    assert $BEFORE_FORK_CALLED
+    
+    $BEFORE_FORK_CALLED = false
+    Resque::Job.create(:jobs, SomeJob, 20, '/tmp')
+    assert !$BEFORE_FORK_CALLED
+    Resque::Worker.send(:remove_class_variable, :@@before_fork)
+  end
 end