Repo created

TMessagesProj/jni/voip/webrtc/third_party/libevent/min_heap.h

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+/*
+ * 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"
+
+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) free(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**)realloc(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_ */