Extract scheduler cross-process locking into DistributedMutex.

spec/components/distributed_mutex_spec.rb

@@ -0,0 +1,36 @@
+require 'spec_helper'
+require_dependency 'distributed_mutex'
+
+describe DistributedMutex do
+  it "allows only one mutex object to have the lock at a time" do
+    m1 = DistributedMutex.new("test_mutex_key")
+    m2 = DistributedMutex.new("test_mutex_key")
+
+    m1.get_lock
+    m2.got_lock.should be_false
+
+    t = Thread.new do
+      m2.get_lock
+    end
+
+    m1.release_lock
+    t.join
+    m2.got_lock.should == true
+  end
+
+  it "synchronizes correctly" do
+    array = []
+    t = Thread.new do
+      DistributedMutex.new("correct_sync").synchronize do
+        sleep 0.01
+        array.push 1
+      end
+    end
+    sleep 0.005
+    DistributedMutex.new("correct_sync").synchronize do
+      array.push 2
+    end
+    t.join
+    array.should == [1, 2]
+  end
+end