diff options
Diffstat (limited to 'libevent/minheap-internal.h')
| -rw-r--r-- | libevent/minheap-internal.h | 192 |
1 files changed, 192 insertions, 0 deletions
diff --git a/libevent/minheap-internal.h b/libevent/minheap-internal.h new file mode 100644 index 0000000..b3a0eb1 --- /dev/null +++ b/libevent/minheap-internal.h @@ -0,0 +1,192 @@ +/* + * Copyright (c) 2007-2012 Niels Provos and Nick Mathewson + * + * Copyright (c) 2006 Maxim Yegorushkin <maxim.yegorushkin@gmail.com> + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. The name of the author may not be used to endorse or promote products + * derived from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ +#ifndef MINHEAP_INTERNAL_H_INCLUDED_ +#define MINHEAP_INTERNAL_H_INCLUDED_ + +#include "event2/event-config.h" +#include "evconfig-private.h" +#include "event2/event.h" +#include "event2/event_struct.h" +#include "event2/util.h" +#include "util-internal.h" +#include "mm-internal.h" + +typedef struct min_heap +{ + struct event** p; + unsigned n, a; +} min_heap_t; + +static inline void min_heap_ctor_(min_heap_t* s); +static inline void min_heap_dtor_(min_heap_t* s); +static inline void min_heap_elem_init_(struct event* e); +static inline int min_heap_elt_is_top_(const struct event *e); +static inline int min_heap_empty_(min_heap_t* s); +static inline unsigned min_heap_size_(min_heap_t* s); +static inline struct event* min_heap_top_(min_heap_t* s); +static inline int min_heap_reserve_(min_heap_t* s, unsigned n); +static inline int min_heap_push_(min_heap_t* s, struct event* e); +static inline struct event* min_heap_pop_(min_heap_t* s); +static inline int min_heap_adjust_(min_heap_t *s, struct event* e); +static inline int min_heap_erase_(min_heap_t* s, struct event* e); +static inline void min_heap_shift_up_(min_heap_t* s, unsigned hole_index, struct event* e); +static inline void min_heap_shift_up_unconditional_(min_heap_t* s, unsigned hole_index, struct event* e); +static inline void min_heap_shift_down_(min_heap_t* s, unsigned hole_index, struct event* e); + +#define min_heap_elem_greater(a, b) \ + (evutil_timercmp(&(a)->ev_timeout, &(b)->ev_timeout, >)) + +void min_heap_ctor_(min_heap_t* s) { s->p = 0; s->n = 0; s->a = 0; } +void min_heap_dtor_(min_heap_t* s) { if (s->p) mm_free(s->p); } +void min_heap_elem_init_(struct event* e) { e->ev_timeout_pos.min_heap_idx = -1; } +int min_heap_empty_(min_heap_t* s) { return 0u == s->n; } +unsigned min_heap_size_(min_heap_t* s) { return s->n; } +struct event* min_heap_top_(min_heap_t* s) { return s->n ? *s->p : 0; } + +int min_heap_push_(min_heap_t* s, struct event* e) +{ + if (s->n == UINT32_MAX || min_heap_reserve_(s, s->n + 1)) + return -1; + min_heap_shift_up_(s, s->n++, e); + return 0; +} + +struct event* min_heap_pop_(min_heap_t* s) +{ + if (s->n) + { + struct event* e = *s->p; + min_heap_shift_down_(s, 0u, s->p[--s->n]); + e->ev_timeout_pos.min_heap_idx = -1; + return e; + } + return 0; +} + +int min_heap_elt_is_top_(const struct event *e) +{ + return e->ev_timeout_pos.min_heap_idx == 0; +} + +int min_heap_erase_(min_heap_t* s, struct event* e) +{ + if (-1 != e->ev_timeout_pos.min_heap_idx) + { + struct event *last = s->p[--s->n]; + unsigned parent = (e->ev_timeout_pos.min_heap_idx - 1) / 2; + /* we replace e with the last element in the heap. We might need to + shift it upward if it is less than its parent, or downward if it is + greater than one or both its children. Since the children are known + to be less than the parent, it can't need to shift both up and + down. */ + if (e->ev_timeout_pos.min_heap_idx > 0 && min_heap_elem_greater(s->p[parent], last)) + min_heap_shift_up_unconditional_(s, e->ev_timeout_pos.min_heap_idx, last); + else + min_heap_shift_down_(s, e->ev_timeout_pos.min_heap_idx, last); + e->ev_timeout_pos.min_heap_idx = -1; + return 0; + } + return -1; +} + +int min_heap_adjust_(min_heap_t *s, struct event *e) +{ + if (-1 == e->ev_timeout_pos.min_heap_idx) { + return min_heap_push_(s, e); + } else { + unsigned parent = (e->ev_timeout_pos.min_heap_idx - 1) / 2; + /* The position of e has changed; we shift it up or down + * as needed. We can't need to do both. */ + if (e->ev_timeout_pos.min_heap_idx > 0 && min_heap_elem_greater(s->p[parent], e)) + min_heap_shift_up_unconditional_(s, e->ev_timeout_pos.min_heap_idx, e); + else + min_heap_shift_down_(s, e->ev_timeout_pos.min_heap_idx, e); + return 0; + } +} + +int min_heap_reserve_(min_heap_t* s, unsigned n) +{ + if (s->a < n) + { + struct event** p; + unsigned a = s->a ? s->a * 2 : 8; + if (a < n) + a = n; +#if (SIZE_MAX == UINT32_MAX) + if (a > SIZE_MAX / sizeof *p) + return -1; +#endif + if (!(p = (struct event**)mm_realloc(s->p, a * sizeof *p))) + return -1; + s->p = p; + s->a = a; + } + return 0; +} + +void min_heap_shift_up_unconditional_(min_heap_t* s, unsigned hole_index, struct event* e) +{ + unsigned parent = (hole_index - 1) / 2; + do + { + (s->p[hole_index] = s->p[parent])->ev_timeout_pos.min_heap_idx = hole_index; + hole_index = parent; + parent = (hole_index - 1) / 2; + } while (hole_index && min_heap_elem_greater(s->p[parent], e)); + (s->p[hole_index] = e)->ev_timeout_pos.min_heap_idx = hole_index; +} + +void min_heap_shift_up_(min_heap_t* s, unsigned hole_index, struct event* e) +{ + unsigned parent = (hole_index - 1) / 2; + while (hole_index && min_heap_elem_greater(s->p[parent], e)) + { + (s->p[hole_index] = s->p[parent])->ev_timeout_pos.min_heap_idx = hole_index; + hole_index = parent; + parent = (hole_index - 1) / 2; + } + (s->p[hole_index] = e)->ev_timeout_pos.min_heap_idx = hole_index; +} + +void min_heap_shift_down_(min_heap_t* s, unsigned hole_index, struct event* e) +{ + unsigned min_child = 2 * (hole_index + 1); + while (min_child <= s->n) + { + min_child -= min_child == s->n || min_heap_elem_greater(s->p[min_child], s->p[min_child - 1]); + if (!(min_heap_elem_greater(e, s->p[min_child]))) + break; + (s->p[hole_index] = s->p[min_child])->ev_timeout_pos.min_heap_idx = hole_index; + hole_index = min_child; + min_child = 2 * (hole_index + 1); + } + (s->p[hole_index] = e)->ev_timeout_pos.min_heap_idx = hole_index; +} + +#endif /* MINHEAP_INTERNAL_H_INCLUDED_ */ |