source: src/Common/GC.h@ bd06384

//
// Cforall Version 1.0.0 Copyright (C) 2015 University of Waterloo
//
// The contents of this file are covered under the licence agreement in the
// file "LICENCE" distributed with Cforall.
//
// GC.h --
//
// Author           : Aaron B. Moss
// Created On       : Thu Mar 15 14:47:00 2018
// Last Modified By : Aaron B. Moss
// Last Modified On : Thu Mar 15 14:47:00 2018
// Update Count     : 1
//

#pragma once

#include <vector>

class GC_Traceable;
class GC_Object;
class BaseSyntaxNode;

/// Manually traced and called garbage collector
class GC {
        friend class GcTracer;
public:
        /// Gets singleton GC instance
        static GC& get();

        /// Traces a traceable object
        const GC& operator<< (const GC_Traceable*) const;

        /// Adds a new object to garbage collection
        void register_object(GC_Object*);

        /// Adds an object to the set of static roots
        void register_static_root(BaseSyntaxNode*);

        /// Use young generation for subsequent new objects
        void new_generation();

        /// Traces all static roots
        void trace_static_roots();

        /// Collects the young generation, placing survivors in old generation.
        /// Old generation is used for subsequent new objects.
        void collect_young();

        /// Collects all memory; use old generation afterward.
        void collect();

        /// Collects all contained objects
        ~GC();

private:
        GC();

        bool mark;                 ///< The current collection's mark bit
        bool using_young;          ///< Is the young generation in use?

        using Generation = std::vector<GC_Object*>;
        Generation old;            ///< Old generation
        Generation young;          ///< Young generation

        using StaticRoots = std::vector<BaseSyntaxNode*>;
        StaticRoots static_roots;  ///< Set of static-lifetime roots
};

/// Use young generation until next collection
inline void new_generation() { GC::get().new_generation(); }

/// no-op default trace
template<typename T>
inline const GC& operator<< (const GC& gc, const T& x) { return gc; }

inline void traceAll(const GC&) {}

/// Marks all arguments as live in current generation
template<typename T, typename... Args>
inline void traceAll(const GC& gc, T& x, Args&... xs) {
        gc << x;
        traceAll(gc, xs...);
}

/// Traces young-generation roots and does a young collection
template<typename... Args>
inline void collect_young(Args&... roots) {
        GC& gc = GC::get();
        traceAll(gc, roots...);
        gc.trace_static_roots();
        gc.collect_young();
}

/// Traces roots and collects other elements
template<typename... Args>
inline void collect(Args&... roots) {
        GC& gc = GC::get();
        traceAll(gc, roots...);
        gc.trace_static_roots();
        gc.collect();
}

/// Makes a new expression as a static root
template<typename T, typename... Args>
inline T* new_static_root( Args&&... args ) {
        T* root = new T( std::forward<Args>(args)... );
        GC::get().register_static_root( root );
        return root;
}

/// Class that is traced by the GC, but not managed by it
class GC_Traceable {
        friend class GC;
protected:
        mutable bool mark;

        /// override to trace any child objects
        virtual void trace(const GC&) const {}
};

/// Class that is managed by the GC
class GC_Object : public GC_Traceable {
        friend class GC;
protected:
        virtual ~GC_Object() {}
public:
        GC_Object();
};

// Local Variables: //
// tab-width: 4 //
// mode: c++ //
// compile-command: "make install" //
// End: //