add locking for concurrent access

ext/mini_racer_extension/extconf.rb

@@ -34,8 +34,8 @@ LIBV8_COMPATIBILITY = '~> 5.0.71.35.0'
 #
 # Libv8.configure_makefile
 
-NODE_PATH = "/home/sam/Source/libv8"
-#NODE_PATH = "/Users/sam/Source/libv8"
+#NODE_PATH = "/home/sam/Source/libv8"
+NODE_PATH = "/Users/sam/Source/libv8"
 #
 NODE_LIBS = NODE_PATH + "/vendor/v8/out/x64.release"
 NODE_INCLUDE = NODE_PATH + "/vendor/v8/include"

ext/mini_racer_extension/mini_racer_extension.cc

@@ -178,7 +178,7 @@ static Handle<Value> convert_ruby_to_v8(Isolate* isolate, VALUE value) {
 
 }
 
-static VALUE rb_context_eval(VALUE self, VALUE str) {
+static VALUE rb_context_eval_unsafe(VALUE self, VALUE str) {
 
     EvalParams eval_params;
     EvalResult eval_result;
@@ -408,10 +408,10 @@ extern "C" {
 	VALUE rb_mMiniRacer = rb_define_module("MiniRacer");
 	VALUE rb_cContext = rb_define_class_under(rb_mMiniRacer, "Context", rb_cObject);
 	VALUE rb_cExternalFunction = rb_define_class_under(rb_cContext, "ExternalFunction", rb_cObject);
-	rb_define_method(rb_cContext, "eval",(VALUE(*)(...))&rb_context_eval, 1);
 	rb_define_method(rb_cContext, "stop", (VALUE(*)(...))&rb_context_stop, 0);
 	rb_define_alloc_func(rb_cContext, allocate);
 
+	rb_define_private_method(rb_cContext, "eval_unsafe",(VALUE(*)(...))&rb_context_eval_unsafe, 1);
 	rb_define_private_method(rb_cExternalFunction, "notify_v8", (VALUE(*)(...))&rb_external_function_notify_v8, 0);
 	rb_define_alloc_func(rb_cExternalFunction, allocate_external_function);
     }

lib/mini_racer.rb

@@ -1,5 +1,6 @@
 require "mini_racer/version"
 require "mini_racer_extension"
+require "thread"
 
 module MiniRacer
   class JavaScriptError < StandardError; end
@@ -18,14 +19,23 @@ module MiniRacer
 
     def initialize(options = nil)
       @functions = {}
+      @lock = Mutex.new
       if options
         @timeout = options[:timeout]
       end
     end
 
+    def eval(str)
+      @lock.synchronize do
+        eval_unsafe(str)
+      end
+    end
+
     def attach(name, callback)
-      external = ExternalFunction.new(name, callback, self)
-      @functions[name.to_s] = external
+      @lock.synchronize do
+        external = ExternalFunction.new(name, callback, self)
+        @functions[name.to_s] = external
+      end
     end
 
   end

test/mini_racer_test.rb

@@ -73,14 +73,25 @@ class MiniRacerTest < Minitest::Test
     assert_equal 42, context.eval('adder=(x,y)=>x+y; adder(21,21);')
   end
 
-  def test_attached_exceptions
+  def test_concurrent_access
+    context = MiniRacer::Context.new
+    context.eval('counter=0; plus=()=>counter++;')
 
+    (1..10).map do
+      Thread.new {
+        context.eval("plus()")
+      }
+    end.each(&:join)
+
+    assert_equal 10, context.eval("counter")
+  end
+
+  def test_attached_exceptions
     context = MiniRacer::Context.new
     context.attach("adder", proc{raise StandardError})
     assert_raises do
       context.eval('adder(1,2,3)')
     end
-
   end
 
 end