Issue #4692 - Rewrite `SetTimeout` facility to avoid `JsValuePtr` and `JsValueList`

src/JsEngineInternal.h

Index: src/JsEngineInternal.h
===================================================================
new file mode 100644
--- /dev/null
+++ b/src/JsEngineInternal.h
@@ -0,0 +1,171 @@
+
+#if !defined(ADBLOCK_PLUS_JS_ENGINE_INTERNAL_H)
+#define ADBLOCK_PLUS_JS_ENGINE_INTERNAL_H
+
+#include <AdblockPlus/JsEngine.h>
+#include <v8.h>
+#include <array>
+#include "AllocatedArray.h"
+#include "V8Upgrade.h"
+
+class PersistentValueArray
+  : public AllocatedArray<V8PersistentNG<v8::Value>>
+{
+  typedef AllocatedArray<V8PersistentNG<v8::Value>> Base;
+  /**
+   * Copy constructor deleted. Allocation is unique to single object.
+   */
+  PersistentValueArray(const PersistentValueArray&); // = delete;
+  /**
+   * Copy assignment deleted. Allocation is unique to single object.
+   */
+  PersistentValueArray operator=(const PersistentValueArray&); // = delete;
+
+public:
+  PersistentValueArray()
+    : Base()
+  {}
+
+  PersistentValueArray(size_t n)
+    : Base(n)
+  {}
+
+  /**
+   * As-if-default move constructor
+   */
+  PersistentValueArray(PersistentValueArray&& x) // = default;
+    : Base(std::move(x))
+  {}
+  /**
+   * As-if-default move assignment
+   */
+  PersistentValueArray& operator=(PersistentValueArray&& x) // = default;
+  {
+    Base::operator=(std::move(x));
+    return *this;
+  }
+
+  /**
+   * Convert our array from `Persistent` to `Local`.
+   */
+  AllocatedArray<v8::Local<v8::Value>> GetAsLocal(v8::Isolate* isolate)
+  {
+    const auto length = Base::Size();
+    AllocatedArray<v8::Local<v8::Value>> locals(length);
+    for (size_t i = 0; i < length; ++i)
+    {
+      locals[i] = (*this)[i].Get(isolate);
+    }
+    return std::move(locals);
+  }
+};
+
+/**
+ * \par Implementation Notes
+ */
+class JsEngineInternal
+  : public AdblockPlus::JsEngine
+{
+  /**
+   * Unique context associated with this isolate.
+   */
+  v8::Persistent<v8::Context> context;
+
+public:
+  JsEngineInternal(const AdblockPlus::ScopedV8IsolatePtr& isolate);
+
+  /**
+   * Retrieve our persistent v8 context as a local handle.
+   */
+  v8::Local<v8::Context> GetContextAsLocal() const;
+
+  /**
+   * Retrieve the global object of our context.
+   */
+  v8::Local<v8::Object> GetGlobalObject();
+
+  /**
+   * Create a JavaScript function that binds to a C++ callback.
+   *
+   * We save a copy of a pointer to the present instance when we
+   *   create the JS function inside the v8 isolate.
+   * This pointer is accessible through the `v8::Arguments` class,
+   *   which is the argument of the callback function.
+   * The isolate pointer is already available;
+   *   the engine pointer is available if its services are needed.
+   *
+   * @param callback C++ callback to invoke.
+   * @return handle function instance within our isolate
+   *
+   * \par Precondition
+   *   - Single-threading has been ensured
+   *   - A v8::Context has been entered.
+   *   - A handle context already exists
+   */
+  v8::Local<v8::Function> MakeCallback(v8::InvocationCallback callback);
+
+  /**
+   * Extract the engine from the arguments to a function created by `MakeCallback`
+   *
+   * @param [v8::Arguments]
+   *   Arguments object pass as the argument to a callback function
+   * @return
+   *   Pointer to engine instance within the arguments.
+   *
+   * \par Precondition
+   */
+  static JsEngineInternal* ExtractEngine(const v8::Arguments& arguments);
+
+  /**
+   * Call a function with the global object as "this"
+   */
+  v8::Local<v8::Value> ApplyFunction(
+    v8::Local<v8::Function> func, 
+    AllocatedArray<v8::Local<v8::Value>> args);
+
+  /**
+   * Call a function with an arbitrary object as "this"
+   *
+   * Defined as a member of the engine class as part of v8 upgrade path.
+   * Newer versions of v8 require a context argument for `v8::Function::Call()`.
+   */
+  v8::Local<v8::Value> ApplyFunction(
+    v8::Local<v8::Object> thisObject,
+    v8::Local<v8::Function> func,
+    AllocatedArray<v8::Local<v8::Value>> args);
+};
+
+/**
+ * Sentry class setting up a multi-threaded v8 usage environment.
+ *
+ * The engine has the responsibility for maintaining an isolate and a context.
+ * This class maintains the following:
+ * - v8 lock to ensure single-threaded JS evaluation.
+ * - v8 scopes for isolate, handle, and scope.
+ * - shared_ptr to engine
+ */
+class V8ExecutionScope
+{
+  /**
+   * Multithread lock for v8.
+   * Declared first to ensure acquiring a lock before anything else happens.
+   */
+  const v8::Locker lock;
+  /**
+   * Isolate scope required for Isolate::GetCurrent() to work.
+   * Probably not needed as we upgrade our v8 version.
+   */
+  const v8::Isolate::Scope isolateScope;
+  /**
+   * Handle scope must be declared before any member that uses handles.
+   * Required to obtain the local context handle to initialize context scope.
+   */
+  const v8::HandleScope handleScope;
+  const v8::Context::Scope contextScope;
+public:
+  V8ExecutionScope(JsEngineInternal* engine);
+};
+
+
+
+#endif