cobalt / cobalt / b95ea55ccebda33f820d043e4b4dc85c10d7584d / . / base / third_party / libevent / min_heap.h

/* | |

* Copyright (c) 2006 Maxim Yegorushkin <maxim.yegorushkin@gmail.com> | |

* All rights reserved. | |

* | |

* 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 _MIN_HEAP_H_ | |

#define _MIN_HEAP_H_ | |

#include "event.h" | |

#include "evutil.h" | |

#include "starboard/memory.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_elem_greater(struct event *a, struct event *b); | |

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_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_down_(min_heap_t* s, unsigned hole_index, struct event* e); | |

int min_heap_elem_greater(struct event *a, struct event *b) | |

{ | |

return 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) | |

SbMemoryDeallocate(s->p); | |

} | |

void min_heap_elem_init(struct event* e) { e->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(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->min_heap_idx = -1; | |

return e; | |

} | |

return 0; | |

} | |

int min_heap_erase(min_heap_t* s, struct event* e) | |

{ | |

if(((unsigned int)-1) != e->min_heap_idx) | |

{ | |

struct event *last = s->p[--s->n]; | |

unsigned parent = (e->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->min_heap_idx > 0 && min_heap_elem_greater(s->p[parent], last)) | |

min_heap_shift_up_(s, e->min_heap_idx, last); | |

else | |

min_heap_shift_down_(s, e->min_heap_idx, last); | |

e->min_heap_idx = -1; | |

return 0; | |

} | |

return -1; | |

} | |

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 (!(p = (struct event**)SbMemoryReallocate(s->p, a * sizeof *p))) | |

return -1; | |

s->p = p; | |

s->a = a; | |

} | |

return 0; | |

} | |

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])->min_heap_idx = hole_index; | |

hole_index = parent; | |

parent = (hole_index - 1) / 2; | |

} | |

(s->p[hole_index] = e)->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])->min_heap_idx = hole_index; | |

hole_index = min_child; | |

min_child = 2 * (hole_index + 1); | |

} | |

min_heap_shift_up_(s, hole_index, e); | |

} | |

#endif /* _MIN_HEAP_H_ */ |