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arangodb/lib/V8/v8-wrapper.h

280 lines
10 KiB
C++

////////////////////////////////////////////////////////////////////////////////
/// @brief V8 wrapper for external structures
///
/// @file
///
/// DISCLAIMER
///
/// Copyright 2014 ArangoDB GmbH, Cologne, Germany
/// Copyright 2004-2014 triAGENS GmbH, Cologne, Germany
///
/// Licensed under the Apache License, Version 2.0 (the "License");
/// you may not use this file except in compliance with the License.
/// You may obtain a copy of the License at
///
/// http://www.apache.org/licenses/LICENSE-2.0
///
/// Unless required by applicable law or agreed to in writing, software
/// distributed under the License is distributed on an "AS IS" BASIS,
/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
/// See the License for the specific language governing permissions and
/// limitations under the License.
///
/// Copyright holder is ArangoDB GmbH, Cologne, Germany
///
/// @author Dr. Frank Celler
/// @author Copyright 2014, ArangoDB GmbH, Cologne, Germany
/// @author Copyright 2013, triAGENS GmbH, Cologne, Germany
///
/// Parts of the code are based on:
///
/// Copyright Joyent, Inc. and other Node contributors.
///
/// Permission is hereby granted, free of charge, to any person obtaining a
/// copy of this software and associated documentation files (the
/// "Software"), to deal in the Software without restriction, including
/// without limitation the rights to use, copy, modify, merge, publish,
/// distribute, sublicense, and/or sell copies of the Software, and to permit
/// persons to whom the Software is furnished to do so, subject to the
/// following conditions:
///
/// The above copyright notice and this permission notice shall be included
/// in all copies or substantial portions of the Software.
///
/// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
/// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
/// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
/// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
/// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
/// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
/// USE OR OTHER DEALINGS IN THE SOFTWARE.
////////////////////////////////////////////////////////////////////////////////
#ifndef ARANGODB_V8_V8__WRAPPER_H
#define ARANGODB_V8_V8__WRAPPER_H 1
#include "Basics/Common.h"
#include <v8.h>
// -----------------------------------------------------------------------------
// --SECTION-- class V8Wrapper
// -----------------------------------------------------------------------------
////////////////////////////////////////////////////////////////////////////////
/// @brief V8 wrapper helper
////////////////////////////////////////////////////////////////////////////////
template<typename STRUCT, uint16_t CID>
class V8Wrapper {
// -----------------------------------------------------------------------------
// --SECTION-- constructors and destructors
// -----------------------------------------------------------------------------
public:
////////////////////////////////////////////////////////////////////////////////
/// @brief constructor
////////////////////////////////////////////////////////////////////////////////
V8Wrapper (v8::Isolate* isolate,
STRUCT* object,
void (*free)(STRUCT* object),
v8::Handle<v8::Object> result)
: _refs(0),
_object(object),
_free(free),
_isolate(isolate) {
// sanity checks
TRI_ASSERT(_handle.IsEmpty());
TRI_ASSERT(result->InternalFieldCount() > 0);
// create a new persistent handle
result->SetAlignedPointerInInternalField(0, this);
_handle.Reset(_isolate, result);
_handle.SetWrapperClassId(CID);
// and make it weak, so that we can garbage collect
makeWeak();
}
////////////////////////////////////////////////////////////////////////////////
/// @brief destructor
////////////////////////////////////////////////////////////////////////////////
virtual ~V8Wrapper () {
if (! _handle.IsEmpty()) {
TRI_ASSERT(_handle.IsNearDeath());
_handle.ClearWeak();
v8::Local<v8::Object> data = v8::Local<v8::Object>::New(_isolate, _handle);
data->SetInternalField(0, v8::Undefined(_isolate));
_handle.Reset();
if (_free != nullptr) {
_free(_object);
}
}
}
// -----------------------------------------------------------------------------
// --SECTION-- static public methods
// -----------------------------------------------------------------------------
public:
////////////////////////////////////////////////////////////////////////////////
/// @brief unwraps a structure
////////////////////////////////////////////////////////////////////////////////
static STRUCT* unwrap (v8::Handle<v8::Object> handle) {
TRI_ASSERT(handle->InternalFieldCount() > 0);
return static_cast<V8Wrapper*>(handle->GetAlignedPointerFromInternalField(0))->_object;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief deletes a structure
////////////////////////////////////////////////////////////////////////////////
static void deleteObject (STRUCT* object) {
delete object;
}
// -----------------------------------------------------------------------------
// --SECTION-- public methods
// -----------------------------------------------------------------------------
public:
////////////////////////////////////////////////////////////////////////////////
/// @brief increases reference count
///
/// Marks the object as being attached to an external entity. Refed objects
/// will not be garbage collected, even if all references are lost.
////////////////////////////////////////////////////////////////////////////////
virtual void ref () {
TRI_ASSERT(! _handle.IsEmpty());
++_refs;
_handle.ClearWeak();
}
////////////////////////////////////////////////////////////////////////////////
/// @brief decreases reference count
///
/// Marks an object as detached from the event loop. This is its default state.
/// When an object with a "weak" reference changes from attached to detached
/// state it will be freed. Be careful not to access the object after making
/// this call as it might be gone! (A "weak reference" means an object that
/// only has a persistant handle.)
///
/// DO NOT CALL THIS FROM DESTRUCTOR.
////////////////////////////////////////////////////////////////////////////////
virtual void unref () {
TRI_ASSERT(! _handle.IsEmpty());
TRI_ASSERT(! _handle.IsWeak());
TRI_ASSERT(_refs > 0);
if (--_refs == 0) {
makeWeak();
}
}
// -----------------------------------------------------------------------------
// --SECTION-- public variables
// -----------------------------------------------------------------------------
public:
////////////////////////////////////////////////////////////////////////////////
/// @brief persistent handle for V8 object
////////////////////////////////////////////////////////////////////////////////
v8::Persistent<v8::Object> _handle;
// -----------------------------------------------------------------------------
// --SECTION-- protected methods
// -----------------------------------------------------------------------------
private:
////////////////////////////////////////////////////////////////////////////////
/// @brief weak callback
////////////////////////////////////////////////////////////////////////////////
static void weakCallback (const v8::WeakCallbackData<v8::Object, v8::Persistent<v8::Object>>& data) {
auto isolate = data.GetIsolate();
auto persistent = data.GetParameter();
auto myPointer = v8::Local<v8::Object>::New(isolate, *persistent);
TRI_ASSERT(myPointer->InternalFieldCount() > 0);
auto obj = static_cast<V8Wrapper*>(myPointer->GetAlignedPointerFromInternalField(0))->_object;
TRI_ASSERT(persistent == &obj->_handle);
TRI_ASSERT(! obj->_refs);
TRI_ASSERT(persistent->IsNearDeath());
delete obj;
}
protected:
////////////////////////////////////////////////////////////////////////////////
/// @brief weakens the reference
////////////////////////////////////////////////////////////////////////////////
void makeWeak () {
_handle.SetWeak(&_handle, weakCallback);
}
// -----------------------------------------------------------------------------
// --SECTION-- protected variables
// -----------------------------------------------------------------------------
protected:
////////////////////////////////////////////////////////////////////////////////
/// @brief reference count
////////////////////////////////////////////////////////////////////////////////
ssize_t _refs;
////////////////////////////////////////////////////////////////////////////////
/// @brief stored structure
////////////////////////////////////////////////////////////////////////////////
STRUCT* _object;
////////////////////////////////////////////////////////////////////////////////
/// @brief free function for stored object
////////////////////////////////////////////////////////////////////////////////
void (*_free) (STRUCT* object);
public:
////////////////////////////////////////////////////////////////////////////////
/// @brief isolate
////////////////////////////////////////////////////////////////////////////////
v8::Isolate* _isolate;
// -----------------------------------------------------------------------------
// --SECTION-- static private methods
// -----------------------------------------------------------------------------
};
#endif
// -----------------------------------------------------------------------------
// --SECTION-- END-OF-FILE
// -----------------------------------------------------------------------------
// Local Variables:
// mode: outline-minor
// outline-regexp: "/// @brief\\|/// {@inheritDoc}\\|/// @page\\|// --SECTION--\\|/// @\\}"
// End: