RUBY-184 Connection#locked?

lib/mongo/connection.rb

@@ -222,6 +222,13 @@ module Mongo
       self['admin'].command(cmd)
     end
 
+    # Is this database locked against writes?
+    #
+    # @return [Boolean]
+    def locked?
+      self['admin']['$cmd.sys.inprog'].find_one['fsyncLock'] == 1
+    end
+
     # Unlock a previously fsync-locked mongod process.
     #
     # @return [BSON::OrderedHash] command response

test/connection_test.rb

@@ -144,7 +144,9 @@ class TestConnection < Test::Unit::TestCase
   end
 
   def test_fsync_lock
+    assert !@mongo.locked?
     @mongo.lock!
+    assert @mongo.locked?
     assert_equal 1, @mongo['admin']['$cmd.sys.inprog'].find_one['fsyncLock'], "Not fsync-locked"
     assert_equal "unlock requested", @mongo.unlock!['info']
     unlocked = false
@@ -158,6 +160,7 @@ class TestConnection < Test::Unit::TestCase
         counter += 1
       end
     end
+    assert !@mongo.locked?
     assert unlocked, "mongod failed to unlock"
   end