michael@0: /*
michael@0:  * Copyright (c) 2007-2012 Niels Provos and Nick Mathewson
michael@0:  *
michael@0:  * Copyright (c) 2006 Maxim Yegorushkin <maxim.yegorushkin@gmail.com>
michael@0:  *
michael@0:  * Redistribution and use in source and binary forms, with or without
michael@0:  * modification, are permitted provided that the following conditions
michael@0:  * are met:
michael@0:  * 1. Redistributions of source code must retain the above copyright
michael@0:  *    notice, this list of conditions and the following disclaimer.
michael@0:  * 2. Redistributions in binary form must reproduce the above copyright
michael@0:  *    notice, this list of conditions and the following disclaimer in the
michael@0:  *    documentation and/or other materials provided with the distribution.
michael@0:  * 3. The name of the author may not be used to endorse or promote products
michael@0:  *    derived from this software without specific prior written permission.
michael@0:  *
michael@0:  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
michael@0:  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
michael@0:  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
michael@0:  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
michael@0:  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
michael@0:  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
michael@0:  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
michael@0:  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
michael@0:  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
michael@0:  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
michael@0:  */
michael@0: #ifndef _MIN_HEAP_H_
michael@0: #define _MIN_HEAP_H_
michael@0: 
michael@0: #include "event2/event-config.h"
michael@0: #include "event2/event.h"
michael@0: #include "event2/event_struct.h"
michael@0: #include "event2/util.h"
michael@0: #include "util-internal.h"
michael@0: #include "mm-internal.h"
michael@0: 
michael@0: typedef struct min_heap
michael@0: {
michael@0: 	struct event** p;
michael@0: 	unsigned n, a;
michael@0: } min_heap_t;
michael@0: 
michael@0: static inline void	     min_heap_ctor(min_heap_t* s);
michael@0: static inline void	     min_heap_dtor(min_heap_t* s);
michael@0: static inline void	     min_heap_elem_init(struct event* e);
michael@0: static inline int	     min_heap_elt_is_top(const struct event *e);
michael@0: static inline int	     min_heap_elem_greater(struct event *a, struct event *b);
michael@0: static inline int	     min_heap_empty(min_heap_t* s);
michael@0: static inline unsigned	     min_heap_size(min_heap_t* s);
michael@0: static inline struct event*  min_heap_top(min_heap_t* s);
michael@0: static inline int	     min_heap_reserve(min_heap_t* s, unsigned n);
michael@0: static inline int	     min_heap_push(min_heap_t* s, struct event* e);
michael@0: static inline struct event*  min_heap_pop(min_heap_t* s);
michael@0: static inline int	     min_heap_erase(min_heap_t* s, struct event* e);
michael@0: static inline void	     min_heap_shift_up_(min_heap_t* s, unsigned hole_index, struct event* e);
michael@0: static inline void	     min_heap_shift_down_(min_heap_t* s, unsigned hole_index, struct event* e);
michael@0: 
michael@0: int min_heap_elem_greater(struct event *a, struct event *b)
michael@0: {
michael@0: 	return evutil_timercmp(&a->ev_timeout, &b->ev_timeout, >);
michael@0: }
michael@0: 
michael@0: void min_heap_ctor(min_heap_t* s) { s->p = 0; s->n = 0; s->a = 0; }
michael@0: void min_heap_dtor(min_heap_t* s) { if (s->p) mm_free(s->p); }
michael@0: void min_heap_elem_init(struct event* e) { e->ev_timeout_pos.min_heap_idx = -1; }
michael@0: int min_heap_empty(min_heap_t* s) { return 0u == s->n; }
michael@0: unsigned min_heap_size(min_heap_t* s) { return s->n; }
michael@0: struct event* min_heap_top(min_heap_t* s) { return s->n ? *s->p : 0; }
michael@0: 
michael@0: int min_heap_push(min_heap_t* s, struct event* e)
michael@0: {
michael@0: 	if (min_heap_reserve(s, s->n + 1))
michael@0: 		return -1;
michael@0: 	min_heap_shift_up_(s, s->n++, e);
michael@0: 	return 0;
michael@0: }
michael@0: 
michael@0: struct event* min_heap_pop(min_heap_t* s)
michael@0: {
michael@0: 	if (s->n)
michael@0: 	{
michael@0: 		struct event* e = *s->p;
michael@0: 		min_heap_shift_down_(s, 0u, s->p[--s->n]);
michael@0: 		e->ev_timeout_pos.min_heap_idx = -1;
michael@0: 		return e;
michael@0: 	}
michael@0: 	return 0;
michael@0: }
michael@0: 
michael@0: int min_heap_elt_is_top(const struct event *e)
michael@0: {
michael@0: 	return e->ev_timeout_pos.min_heap_idx == 0;
michael@0: }
michael@0: 
michael@0: int min_heap_erase(min_heap_t* s, struct event* e)
michael@0: {
michael@0: 	if (-1 != e->ev_timeout_pos.min_heap_idx)
michael@0: 	{
michael@0: 		struct event *last = s->p[--s->n];
michael@0: 		unsigned parent = (e->ev_timeout_pos.min_heap_idx - 1) / 2;
michael@0: 		/* we replace e with the last element in the heap.  We might need to
michael@0: 		   shift it upward if it is less than its parent, or downward if it is
michael@0: 		   greater than one or both its children. Since the children are known
michael@0: 		   to be less than the parent, it can't need to shift both up and
michael@0: 		   down. */
michael@0: 		if (e->ev_timeout_pos.min_heap_idx > 0 && min_heap_elem_greater(s->p[parent], last))
michael@0: 			min_heap_shift_up_(s, e->ev_timeout_pos.min_heap_idx, last);
michael@0: 		else
michael@0: 			min_heap_shift_down_(s, e->ev_timeout_pos.min_heap_idx, last);
michael@0: 		e->ev_timeout_pos.min_heap_idx = -1;
michael@0: 		return 0;
michael@0: 	}
michael@0: 	return -1;
michael@0: }
michael@0: 
michael@0: int min_heap_reserve(min_heap_t* s, unsigned n)
michael@0: {
michael@0: 	if (s->a < n)
michael@0: 	{
michael@0: 		struct event** p;
michael@0: 		unsigned a = s->a ? s->a * 2 : 8;
michael@0: 		if (a < n)
michael@0: 			a = n;
michael@0: 		if (!(p = (struct event**)mm_realloc(s->p, a * sizeof *p)))
michael@0: 			return -1;
michael@0: 		s->p = p;
michael@0: 		s->a = a;
michael@0: 	}
michael@0: 	return 0;
michael@0: }
michael@0: 
michael@0: void min_heap_shift_up_(min_heap_t* s, unsigned hole_index, struct event* e)
michael@0: {
michael@0:     unsigned parent = (hole_index - 1) / 2;
michael@0:     while (hole_index && min_heap_elem_greater(s->p[parent], e))
michael@0:     {
michael@0: 	(s->p[hole_index] = s->p[parent])->ev_timeout_pos.min_heap_idx = hole_index;
michael@0: 	hole_index = parent;
michael@0: 	parent = (hole_index - 1) / 2;
michael@0:     }
michael@0:     (s->p[hole_index] = e)->ev_timeout_pos.min_heap_idx = hole_index;
michael@0: }
michael@0: 
michael@0: void min_heap_shift_down_(min_heap_t* s, unsigned hole_index, struct event* e)
michael@0: {
michael@0:     unsigned min_child = 2 * (hole_index + 1);
michael@0:     while (min_child <= s->n)
michael@0: 	{
michael@0: 	min_child -= min_child == s->n || min_heap_elem_greater(s->p[min_child], s->p[min_child - 1]);
michael@0: 	if (!(min_heap_elem_greater(e, s->p[min_child])))
michael@0: 	    break;
michael@0: 	(s->p[hole_index] = s->p[min_child])->ev_timeout_pos.min_heap_idx = hole_index;
michael@0: 	hole_index = min_child;
michael@0: 	min_child = 2 * (hole_index + 1);
michael@0: 	}
michael@0:     (s->p[hole_index] = e)->ev_timeout_pos.min_heap_idx = hole_index;
michael@0: }
michael@0: 
michael@0: #endif /* _MIN_HEAP_H_ */