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dobjgc.h
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dobjgc.h
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#pragma once
#include <stdint.h>
#include "tarray.h"
class DObject;
class FSerializer;
enum EObjectFlags
{
// GC flags
OF_White0 = 1 << 0, // Object is white (type 0)
OF_White1 = 1 << 1, // Object is white (type 1)
OF_Black = 1 << 2, // Object is black
OF_Fixed = 1 << 3, // Object is fixed (should not be collected)
OF_Rooted = 1 << 4, // Object is soft-rooted
OF_EuthanizeMe = 1 << 5, // Object wants to die
OF_Cleanup = 1 << 6, // Object is now being deleted by the collector
OF_YesReallyDelete = 1 << 7, // Object is being deleted outside the collector, and this is okay, so don't print a warning
OF_WhiteBits = OF_White0 | OF_White1,
OF_MarkBits = OF_WhiteBits | OF_Black,
// Other flags
OF_JustSpawned = 1 << 8, // Thinker was spawned this tic
OF_SerialSuccess = 1 << 9, // For debugging Serialize() calls
OF_Sentinel = 1 << 10, // Object is serving as the sentinel in a ring list
OF_Transient = 1 << 11, // Object should not be archived (references to it will be nulled on disk)
OF_Spawned = 1 << 12, // Thinker was spawned at all (some thinkers get deleted before spawning)
OF_Released = 1 << 13, // Object was released from the GC system and should not be processed by GC function
};
template<class T> class TObjPtr;
namespace GC
{
enum EGCState
{
GCS_Pause,
GCS_Propagate,
GCS_Sweep,
GCS_Finalize
};
// Number of bytes currently allocated through M_Malloc/M_Realloc.
extern size_t AllocBytes;
// Number of allocated objects since last CheckGC call.
extern size_t AllocCount;
// Amount of memory to allocate before triggering a collection.
extern size_t Threshold;
// List of gray objects.
extern DObject *Gray;
// List of every object.
extern DObject *Root;
// Current white value for potentially-live objects.
extern uint32_t CurrentWhite;
// Current collector state.
extern EGCState State;
// Position of GC sweep in the list of objects.
extern DObject **SweepPos;
// Size of GC pause.
extern int Pause;
// Size of GC steps.
extern int StepMul;
// Is this the final collection just before exit?
extern bool FinalGC;
// Counts the number of times CheckGC has been called.
extern int CheckTime;
// Current white value for known-dead objects.
static inline uint32_t OtherWhite()
{
return CurrentWhite ^ OF_WhiteBits;
}
// Frees all objects, whether they're dead or not.
void FreeAll();
// Does one collection step.
void Step();
// Does a complete collection.
void FullGC();
// Handles the grunt work for a write barrier.
void Barrier(DObject *pointing, DObject *pointed);
// Handles a write barrier.
static inline void WriteBarrier(DObject *pointing, DObject *pointed);
// Handles a write barrier for a pointer that isn't inside an object.
static inline void WriteBarrier(DObject *pointed);
// Handles a read barrier.
template<class T> inline T *ReadBarrier(T *&obj)
{
if (obj == NULL || !(obj->ObjectFlags & OF_EuthanizeMe))
{
return obj;
}
return obj = NULL;
}
// Check if it's time to collect, and do a collection step if it is.
static inline bool CheckGC()
{
AllocCount = 0;
CheckTime++;
if (AllocBytes >= Threshold)
{
Step();
return true;
}
return false;
}
// Forces a collection to start now.
static inline void StartCollection()
{
Threshold = AllocBytes;
}
// Marks a white object gray. If the object wants to die, the pointer
// is NULLed instead.
void Mark(DObject **obj);
// Marks an array of objects.
void MarkArray(DObject **objs, size_t count);
// For cleanup
void DelSoftRootHead();
// Soft-roots an object.
void AddSoftRoot(DObject *obj);
// Unroots an object.
void DelSoftRoot(DObject *obj);
template<class T> void Mark(T *&obj)
{
union
{
T *t;
DObject *o;
};
o = obj;
Mark(&o);
obj = t;
}
template<class T> void Mark(TObjPtr<T> &obj);
template<class T> void MarkArray(T **obj, size_t count)
{
MarkArray((DObject **)(obj), count);
}
template<class T> void MarkArray(TObjPtr<T>* obj, size_t count)
{
MarkArray((DObject**)(obj), count);
}
template<class T> void MarkArray(TArray<T> &arr)
{
MarkArray(&arr[0], arr.Size());
}
using GCMarkerFunc = void(*)();
void AddMarkerFunc(GCMarkerFunc func);
}
// A template class to help with handling read barriers. It does not
// handle write barriers, because those can be handled more efficiently
// with knowledge of the object that holds the pointer.
template<class T>
class TObjPtr
{
union
{
T pp;
DObject *o;
};
public:
TObjPtr() = default;
TObjPtr(const TObjPtr<T> &q) = default;
TObjPtr(T q) noexcept
: pp(q)
{
}
T operator=(T q)
{
pp = q;
return *this;
}
T operator=(std::nullptr_t nul)
{
o = nullptr;
return *this;
}
// To allow NULL, too.
T operator=(const int val)
{
assert(val == 0);
o = nullptr;
return *this;
}
// To allow NULL, too. In Clang NULL is a long.
T operator=(const long val)
{
assert(val == 0);
o = nullptr;
return *this;
}
T Get() noexcept
{
return GC::ReadBarrier(pp);
}
T ForceGet() noexcept //for situations where the read barrier needs to be skipped.
{
return pp;
}
operator T() noexcept
{
return GC::ReadBarrier(pp);
}
T &operator*() noexcept
{
T q = GC::ReadBarrier(pp);
assert(q != NULL);
return *q;
}
T operator->() noexcept
{
return GC::ReadBarrier(pp);
}
bool operator!=(T u) noexcept
{
return GC::ReadBarrier(o) != u;
}
bool operator==(T u) noexcept
{
return GC::ReadBarrier(o) == u;
}
template<class U> friend inline void GC::Mark(TObjPtr<U> &obj);
template<class U> friend FSerializer &Serialize(FSerializer &arc, const char *key, TObjPtr<U> &value, TObjPtr<U> *);
template<class U> friend FSerializer &Serialize(FSerializer &arc, const char *key, TObjPtr<U> &value, U *);
friend class DObject;
};
// Use barrier_cast instead of static_cast when you need to cast
// the contents of a TObjPtr to a related type.
template<class T,class U> inline T barrier_cast(TObjPtr<U> &o)
{
return static_cast<T>(static_cast<U>(o));
}
namespace GC
{
template<class T> inline void Mark(TObjPtr<T> &obj)
{
GC::Mark(&obj.o);
}
}