//
// 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.cc --
//
// 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
//

#include "GC.h"

#include "Common/PassVisitor.h"

#include "SynTree/GcTracer.h"

#include <algorithm>
#include <cassert>

// #include <csignal>

GC& GC::get() {
	static GC gc;
	return gc;
}

GC::GC() : mark(false), using_young(false), old(), young(), static_roots() {
	old.reserve(70000);
}

GC::~GC() {
	for ( GC_Object* o : young ) {
		delete o;
	}

	for ( GC_Object* o : old ) {
		delete o;
	}
}

const GC& GC::operator<< (const GC_Traceable* obj) const {
	if( obj )
	{
		bool isMarked = obj->mark == this->mark;
		if( !isMarked ) {
			obj->mark = this->mark;
			obj->trace( *this );
		}
	}
	return *this;
}

void GC::register_object(GC_Object* obj) {
	// if ( obj == (GC_Object*)0x60f00000e410ul ) std::raise( SIGTRAP );
	(using_young ? young : old).push_back(obj);
	obj->mark = ! this->mark;  // initialize as un-marked
}

void GC::register_static_root(BaseSyntaxNode* root) {
	static_roots.push_back(root);
}

void GC::new_generation() {
	using_young = true;
}

void GC::trace_static_roots() {
	PassVisitor<GcTracer> tracer{ *this };
	for ( BaseSyntaxNode* root : static_roots ) {
		root->accept( tracer );
	}
}

void GC::collect_young() {
	// check young generation, just reset mark if not using
	if ( ! using_young ) {
		mark = !mark;
		return;
	}

	// collect young gen
	for ( GC_Object*& obj : young ) {
		if ( obj->mark != mark ) {
			delete obj;
			obj = nullptr;
		}
	}
	
	// move uncollected elements into old gen
	auto end_live = std::remove( young.begin(), young.end(), nullptr );
	old.insert( old.end(), young.begin(), end_live );
	
	// clear young gen
	using_young = false;
	young.clear();

	// reset mark for next collection
	mark = !mark;
}

void GC::collect() {
	// collect old gen
	for ( GC_Object*& obj : old ) {
		if ( obj->mark != mark ) {
			// if ( obj == (GC_Object*)0x60f00000e410ul ) std::raise( SIGTRAP );
			delete obj;
			obj = nullptr;
		}
	}

	// clear collected elements
	old.erase( std::remove( old.begin(), old.end(), nullptr ), old.end() );

	// collect young gen (also resets mark)
	collect_young();
}

GC_Object::GC_Object() {
	GC::get().register_object( this );
}

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