Issue #4826 - Use latch to replace thread-sleeping in tests

test/JsLatch.cpp

+/*
+ * This file is part of Adblock Plus <https://adblockplus.org/>,
+ * Copyright (C) 2006-2016 Eyeo GmbH
+ *
+ * Adblock Plus is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 3 as
+ * published by the Free Software Foundation.
+ *
+ * Adblock Plus is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "JsLatch.h"
+
+namespace
+{
+  /**
+   * Implementation of JS function "Arrive()" on latch objects.
+   */
+  v8::Handle<v8::Value> ArriveCallback(const v8::Arguments& arguments)
+  {
+    auto self = static_cast<JsTestingLatch *>(
+      v8::Local<v8::External>::Cast(arguments.Holder()->GetInternalField(0))->Value());
+    if (self)
+    {
+      self->GetLatch().Arrive();
+    }
+    return v8::Undefined();
+  }
+}
+
+/**
+ * \par Implementation Notes
+ *    Internal field 0 of the JS object contains a copy of \c this.
+ */
+V8PersistentNG<v8::Object> JsTestingLatch::JsObjectInitializer(const std::string& propertyName)
+{
+  /*
+   * N.B. Member order ensures that \c engine has been initialized before this function runs.
+   */
+  V8ExecutionScope context(engine);
+  // Object template
+  auto jsObjectTemplate = v8::ObjectTemplate::New();
+  jsObjectTemplate->SetInternalFieldCount(1);
+  jsObjectTemplate->Set(engine->ToV8String("Arrive"), v8::FunctionTemplate::New(ArriveCallback));
+  // Object
+  auto localJsObject = jsObjectTemplate->NewInstance();
+  localJsObject->SetInternalField(0, v8::External::New(this));
+  // Property on global
+  engine->GetGlobalObject()->Set(engine->ToV8String(propertyName), localJsObject);
+  // Persistent
+  return V8PersistentNG<v8::Object>(engine->GetIsolate(), localJsObject);
+}
+
+JsTestingLatch::JsTestingLatch(JsEngineInternal* engine, const std::string& propertyName, int count)
+  : engine(engine), latch(count), jsObject(JsObjectInitializer(propertyName))
+{}
+
+JsTestingLatch::~JsTestingLatch()
+{
+  V8ExecutionScope context(engine);
+  auto obj = jsObject.Get(engine->GetIsolate());
+  // ensure object still exists
+  if (obj->IsObject())
+  {
+    obj->SetInternalField(0, v8::External::New(nullptr));
+  }
+  // Rather than changing the "Arrive" property, we handle a null pointer in the callback for it.
+}