RUBY-193 don't create gridfs indexes when slave_ok

lib/mongo/gridfs/grid.rb

@@ -38,8 +38,11 @@ module Mongo
       @chunks  = @db["#{fs_name}.chunks"]
       @fs_name = fs_name
 
+      # Ensure indexes only if not connected to slave.
+      unless db.connection.slave_ok?
         @chunks.create_index([['files_id', Mongo::ASCENDING], ['n', Mongo::ASCENDING]], :unique => true)
       end
+    end
 
     # Store a file in the file store. This method is designed only for writing new files;
     # if you need to update a given file, first delete it using #Grid#delete.

lib/mongo/gridfs/grid_file_system.rb

@@ -39,9 +39,12 @@ module Mongo
 
       @default_query_opts = {:sort => [['filename', 1], ['uploadDate', -1]], :limit => 1}
 
+      # Ensure indexes only if not connected to slave.
+      unless db.connection.slave_ok?
         @files.create_index([['filename', 1], ['uploadDate', -1]])
         @chunks.create_index([['files_id', Mongo::ASCENDING], ['n', Mongo::ASCENDING]], :unique => true)
       end
+    end
 
     # Open a file for reading or writing. Note that the options for this method only apply
     # when opening in 'w' mode.

test/unit/grid_test.rb

@@ -0,0 +1,47 @@
+require './test/test_helper'
+
+class GridTest < Test::Unit::TestCase
+
+  context "GridFS: " do
+    setup do
+      @conn   = stub()
+      @db     = DB.new("testing", @conn)
+      @files  = mock()
+      @chunks = mock()
+
+      @db.expects(:[]).with('fs.files').returns(@files)
+      @db.expects(:[]).with('fs.chunks').returns(@chunks)
+    end
+
+    context "Grid classe with standard connections" do
+      setup do
+        @conn.expects(:slave_ok?).returns(false)
+      end
+
+      should "create indexes for Grid" do
+        @chunks.expects(:create_index)
+        Grid.new(@db)
+      end
+
+      should "create indexes for GridFileSystem" do
+        @files.expects(:create_index)
+        @chunks.expects(:create_index)
+        GridFileSystem.new(@db)
+      end
+    end
+
+    context "Grid classes with slave connection" do
+      setup do
+        @conn.expects(:slave_ok?).returns(true)
+      end
+
+      should "not create indexes for Grid" do
+        Grid.new(@db)
+      end
+
+      should "not create indexes for GridFileSystem" do
+        GridFileSystem.new(@db)
+      end
+    end
+  end
+end