citra/src/core/hle/kernel/object.h
Lioncash c47e1db46d kernel/object: Tighten object against data races
Despite being covered by a global mutex, we should still ensure that the
class handles its reference counts properly. This avoids potential
shenanigans when it comes to data races.

Given this is the root object that drives quite a bit of the kernel
object hierarchy, ensuring we always have the correct behavior (and no
races) is a good thing.
2018-08-31 00:14:48 +02:00

107 lines
2.4 KiB
C++

// Copyright 2018 Citra Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.
#pragma once
#include <atomic>
#include <string>
#include <utility>
#include <boost/smart_ptr/intrusive_ptr.hpp>
#include "common/common_types.h"
namespace Kernel {
using Handle = u32;
enum class HandleType : u32 {
Unknown,
Event,
Mutex,
SharedMemory,
Thread,
Process,
AddressArbiter,
Semaphore,
Timer,
ResourceLimit,
CodeSet,
ClientPort,
ServerPort,
ClientSession,
ServerSession,
};
enum {
DEFAULT_STACK_SIZE = 0x4000,
};
enum class ResetType {
OneShot,
Sticky,
Pulse,
};
class Object : NonCopyable {
public:
virtual ~Object();
/// Returns a unique identifier for the object. For debugging purposes only.
u32 GetObjectId() const {
return object_id.load(std::memory_order_relaxed);
}
virtual std::string GetTypeName() const {
return "[BAD KERNEL OBJECT TYPE]";
}
virtual std::string GetName() const {
return "[UNKNOWN KERNEL OBJECT]";
}
virtual HandleType GetHandleType() const = 0;
/**
* Check if a thread can wait on the object
* @return True if a thread can wait on the object, otherwise false
*/
bool IsWaitable() const;
public:
static std::atomic<u32> next_object_id;
private:
friend void intrusive_ptr_add_ref(Object*);
friend void intrusive_ptr_release(Object*);
std::atomic<u32> ref_count{0};
std::atomic<u32> object_id{next_object_id++};
};
// Special functions used by boost::instrusive_ptr to do automatic ref-counting
inline void intrusive_ptr_add_ref(Object* object) {
object->ref_count.fetch_add(1, std::memory_order_relaxed);
}
inline void intrusive_ptr_release(Object* object) {
if (object->ref_count.fetch_sub(1, std::memory_order_acq_rel) == 1) {
delete object;
}
}
template <typename T>
using SharedPtr = boost::intrusive_ptr<T>;
/**
* Attempts to downcast the given Object pointer to a pointer to T.
* @return Derived pointer to the object, or `nullptr` if `object` isn't of type T.
*/
template <typename T>
inline SharedPtr<T> DynamicObjectCast(SharedPtr<Object> object) {
if (object != nullptr && object->GetHandleType() == T::HANDLE_TYPE) {
return boost::static_pointer_cast<T>(std::move(object));
}
return nullptr;
}
} // namespace Kernel