managed_object_pool.h

/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#ifndef AGS_ENGINE_AC_DYNOBJ_CC_MANAGED_OBJECT_POOL_H
#define AGS_ENGINE_AC_DYNOBJ_CC_MANAGED_OBJECT_POOL_H

#include "common/std/vector.h"
#include "common/std/queue.h"
#include "common/std/map.h"

#include "ags/shared/core/platform.h"
#include "ags/engine/script/runtime_script_value.h"
#include "ags/engine/ac/dynobj/cc_script_object.h"   // IScriptObject

namespace AGS3 {

namespace AGS {
namespace Shared {
class Stream;
} // namespace Shared
} // namespace AGS

using namespace AGS; // FIXME later

struct Pointer_Hash {
    uint operator()(void *v) const {
        return static_cast<uint>(reinterpret_cast<uintptr>(v));
    }
};


struct ManagedObjectPool final {
private:
    // TODO: find out if we can make handle size_t
    struct ManagedObject {
        ScriptValueType obj_type;
        int32_t handle;
        void *addr;
        IScriptObject *callback;
        int refCount;

        bool isUsed() const {
            return obj_type != kScValUndefined;
        }

        ManagedObject() : obj_type(kScValUndefined), handle(0), addr(nullptr),
            callback(nullptr), refCount(0) {}
        ManagedObject(ScriptValueType theType, int32_t theHandle,
                      void *theAddr, IScriptObject *theCallback)
            : obj_type(theType), handle(theHandle), addr(theAddr),
              callback(theCallback), refCount(0) {
        }
    };

    int objectCreationCounter;  // used to do garbage collection every so often

    int32_t nextHandle{}; // TODO: manage nextHandle's going over INT32_MAX !
    std::queue<int32_t> available_ids;
    std::vector<ManagedObject> objects;
    std::unordered_map<void *, int32_t, Pointer_Hash> handleByAddress;

    int Add(int handle, void *address, IScriptObject *callback, ScriptValueType obj_type);
    int Remove(ManagedObject &o, bool force = false);
    void RunGarbageCollection();

public:

    int32_t AddRef(int32_t handle);
    int CheckDispose(int32_t handle);
    int32_t SubRef(int32_t handle);
    int32_t AddressToHandle(void *addr);
    void *HandleToAddress(int32_t handle);
    ScriptValueType HandleToAddressAndManager(int32_t handle, void *&object, IScriptObject *&manager);
    int RemoveObject(void *address);
    void RunGarbageCollectionIfAppropriate();
    int AddObject(void *address, IScriptObject *callback, ScriptValueType obj_type);
    int AddUnserializedObject(void *address, IScriptObject *callback, ScriptValueType obj_type, int handle);
    void WriteToDisk(Shared::Stream *out);
    int ReadFromDisk(Shared::Stream *in, ICCObjectCollectionReader *reader);
    void reset();
    ManagedObjectPool();

    void *disableDisposeForObject{ nullptr };
};

// Extreme(!!) verbosity managed memory pool log
#if DEBUG_MANAGED_OBJECTS
#define ManagedObjectLog(...) Debug::Printf(kDbgGroup_ManObj, kDbgMsg_Debug, __VA_ARGS__)
#else
#define ManagedObjectLog(...)
#endif

} // namespace AGS3

#endif