RUBY-133 maximum insert size

lib/mongo/collection.rb

@@ -670,6 +670,8 @@ module Mongo
       message = BSON::ByteBuffer.new([0, 0, 0, 0])
       BSON::BSON_RUBY.serialize_cstr(message, "#{@db.name}.#{collection_name}")
       documents.each { |doc| message.put_array(BSON::BSON_CODER.serialize(doc, check_keys, true).to_a) }
+      raise InvalidOperation, "Exceded maximum insert size of 16,000,000 bytes" if message.size > 16_000_000
+
       if safe
         @connection.send_message_with_safe_check(Mongo::Constants::OP_INSERT, message, @db.name,
           "#{@db.name}['#{collection_name}'].insert(#{documents.inspect})", safe)

test/collection_test.rb

@@ -115,6 +115,17 @@ class TestCollection < Test::Unit::TestCase
     end
   end
 
+  def test_maximum_insert_size
+    docs = []
+    16.times do
+      docs << {'foo' => 'a' * 1_000_000}
+    end
+
+    assert_raise InvalidOperation do
+      @@test.insert(docs)
+    end
+  end
+
   if @@version >= "1.5.1"
     def test_safe_mode_with_advanced_safe_with_invalid_options
       assert_raise_error ArgumentError, "Unknown key(s): wtime" do