/*
 * MARS Long Distance Replication Software
 *
 * This file is part of MARS project: http://schoebel.github.io/mars/
 *
 * Copyright (C) 2010-2014 Thomas Schoebel-Theuer
 * Copyright (C) 2011-2014 1&1 Internet AG
 *
 * 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 2 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, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */


#ifndef LIB_QUEUE_H
#define LIB_QUEUE_H

#define QUEUE_ANCHOR(PREFIX,KEYTYPE,HEAPTYPE)				\
	/* parameters */						\
	/* readonly from outside */					\
	int q_queued;							\
	atomic_t q_flying;						\
	/* tunables */							\
	int q_batchlen;							\
	int q_io_prio;							\
	bool q_ordering;						\
	/* private */							\
	wait_queue_head_t *q_event;					\
	spinlock_t q_lock;						\
	struct list_head q_anchor;					\
	struct pairing_heap_##HEAPTYPE *heap_high;			\
	struct pairing_heap_##HEAPTYPE *heap_low;			\
	long long q_last_insert; /* jiffies */				\
	KEYTYPE heap_margin;						\
	KEYTYPE last_pos;						\

#define QUEUE_FUNCTIONS(PREFIX,ELEM_TYPE,HEAD,KEYFN,KEYCMP,HEAPTYPE)	\
									\
static inline							        \
void q_##PREFIX##_trigger(struct PREFIX##_queue *q)			\
{									\
	if (q->q_event) {						\
		wake_up_interruptible(q->q_event);			\
	}								\
}									\
									\
static inline							        \
void q_##PREFIX##_init(struct PREFIX##_queue *q)			\
{									\
	INIT_LIST_HEAD(&q->q_anchor);					\
	q->heap_low = NULL;						\
	q->heap_high = NULL;						\
	spin_lock_init(&q->q_lock);					\
	q->q_queued = 0;						\
	atomic_set(&q->q_flying, 0);					\
}									\
									\
static inline							        \
void q_##PREFIX##_insert(struct PREFIX##_queue *q, ELEM_TYPE *elem)	\
{									\
	unsigned long flags;						\
									\
	traced_lock(&q->q_lock, flags);					\
									\
	if (q->q_ordering) {						\
		struct pairing_heap_##HEAPTYPE **use = &q->heap_high;	\
		if (KEYCMP(KEYFN(elem), &q->heap_margin) <= 0) {	\
			use = &q->heap_low;				\
		}							\
		ph_insert_##HEAPTYPE(use, &elem->ph);			\
	} else {							\
		list_add_tail(&elem->HEAD, &q->q_anchor);		\
	}								\
	q->q_queued++;							\
	q->q_last_insert = jiffies;					\
									\
	traced_unlock(&q->q_lock, flags);				\
									\
	q_##PREFIX##_trigger(q);					\
}									\
									\
static inline							        \
void q_##PREFIX##_pushback(struct PREFIX##_queue *q, ELEM_TYPE *elem)	\
{									\
	unsigned long flags;						\
									\
	if (q->q_ordering) {						\
		q_##PREFIX##_insert(q, elem);				\
		return;							\
	}								\
									\
	traced_lock(&q->q_lock, flags);					\
									\
	list_add(&elem->HEAD, &q->q_anchor);				\
	q->q_queued++;							\
									\
	traced_unlock(&q->q_lock, flags);				\
}									\
									\
static inline							        \
ELEM_TYPE *q_##PREFIX##_fetch(struct PREFIX##_queue *q)			\
{									\
	ELEM_TYPE *elem = NULL;						\
	unsigned long flags;						\
									\
	traced_lock(&q->q_lock, flags);					\
									\
	if (q->q_ordering) {						\
		if (!q->heap_high) {					\
			q->heap_high = q->heap_low;			\
			q->heap_low = NULL;				\
			q->heap_margin = 0;				\
			q->last_pos = 0;				\
		}							\
		if (q->heap_high) {					\
			elem = container_of(q->heap_high, ELEM_TYPE, ph); \
									\
			if (unlikely(KEYCMP(KEYFN(elem), &q->last_pos) < 0)) { \
				MARS_ERR("backskip pos %lld -> %lld\n", (long long)q->last_pos, (long long)KEYFN(elem)); \
			}						\
			memcpy(&q->last_pos, KEYFN(elem), sizeof(q->last_pos));	\
									\
			if (KEYCMP(KEYFN(elem), &q->heap_margin) > 0) {	\
				memcpy(&q->heap_margin, KEYFN(elem), sizeof(q->heap_margin)); \
			}						\
			ph_delete_min_##HEAPTYPE(&q->heap_high);	\
			q->q_queued--;					\
		}							\
	} else if (!list_empty(&q->q_anchor)) {				\
		struct list_head *next = q->q_anchor.next;		\
		list_del_init(next);					\
		q->q_queued--;						\
		elem = container_of(next, ELEM_TYPE, HEAD);		\
	}								\
									\
	traced_unlock(&q->q_lock, flags);				\
									\
	q_##PREFIX##_trigger(q);					\
									\
	return elem;							\
}									\
									\
static inline							        \
void q_##PREFIX##_inc_flying(struct PREFIX##_queue *q)			\
{									\
	atomic_inc(&q->q_flying);					\
	q_##PREFIX##_trigger(q);					\
}									\
									\
static inline							        \
void q_##PREFIX##_dec_flying(struct PREFIX##_queue *q)			\
{									\
	atomic_dec(&q->q_flying);					\
	q_##PREFIX##_trigger(q);					\
}									\
									\


#endif