/*
 * sgen-gray.h: Gray queue management.
 *
 * Copyright 2011 Xamarin Inc (http://www.xamarin.com)
 * Copyright (C) 2012 Xamarin Inc
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License 2.0 as published by the Free Software Foundation;
 *
 * This library 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
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License 2.0 along with this library; if not, write to the Free
 * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
#ifndef __MONO_SGEN_GRAY_H__
#define __MONO_SGEN_GRAY_H__

#define SGEN_GRAY_QUEUE_SECTION_SIZE	(128 - 3)

/*
 * This is a stack now instead of a queue, so the most recently added items are removed
 * first, improving cache locality, and keeping the stack size manageable.
 */
typedef struct _GrayQueueSection GrayQueueSection;
struct _GrayQueueSection {
	int end;
	GrayQueueSection *next;
	char *objects [SGEN_GRAY_QUEUE_SECTION_SIZE];
};

typedef struct _SgenGrayQueue SgenGrayQueue;

typedef void (*GrayQueueAllocPrepareFunc) (SgenGrayQueue*);
typedef void (*GrayQueueEnqueueCheckFunc) (SgenGrayQueue*, char*);

struct _SgenGrayQueue {
	GrayQueueSection *first;
	GrayQueueSection *free_list;
	int balance;
	GrayQueueAllocPrepareFunc alloc_prepare_func;
#ifdef SGEN_CHECK_GRAY_OBJECT_ENQUEUE
	GrayQueueEnqueueCheckFunc enqueue_check_func;
#endif
	void *alloc_prepare_data;
};

void sgen_gray_object_enqueue (SgenGrayQueue *queue, char *obj) MONO_INTERNAL;
char* sgen_gray_object_dequeue (SgenGrayQueue *queue) MONO_INTERNAL;
GrayQueueSection* sgen_gray_object_dequeue_section (SgenGrayQueue *queue) MONO_INTERNAL;
void sgen_gray_object_enqueue_section (SgenGrayQueue *queue, GrayQueueSection *section) MONO_INTERNAL;
void sgen_gray_object_queue_init (SgenGrayQueue *queue, GrayQueueEnqueueCheckFunc enqueue_check_func) MONO_INTERNAL;
void sgen_gray_object_queue_init_invalid (SgenGrayQueue *queue) MONO_INTERNAL;
void sgen_gray_object_queue_init_with_alloc_prepare (SgenGrayQueue *queue, GrayQueueEnqueueCheckFunc enqueue_check_func,
		GrayQueueAllocPrepareFunc func, void *data) MONO_INTERNAL;
void sgen_gray_object_alloc_queue_section (SgenGrayQueue *queue) MONO_INTERNAL;
void sgen_gray_object_free_queue_section (GrayQueueSection *section) MONO_INTERNAL;

static inline gboolean
sgen_gray_object_queue_is_empty (SgenGrayQueue *queue)
{
	return queue->first == NULL;
}

#endif