--- /dev/null
+/**
+ * collectd - src/utils_heap.c
+ * Copyright (C) 2009 Florian octo Forster
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ *
+ * Authors:
+ * Florian octo Forster <octo at collectd.org>
+ **/
+
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <assert.h>
+#include <pthread.h>
+
+#include "utils_heap.h"
+
+struct c_heap_s
+{
+ pthread_mutex_t lock;
+ int (*compare) (const void *, const void *);
+
+ void **list;
+ size_t list_len; /* # entries used */
+ size_t list_size; /* # entries allocated */
+};
+
+enum reheap_direction
+{
+ DIR_UP,
+ DIR_DOWN
+};
+
+static void reheap (c_heap_t *h, size_t root, enum reheap_direction dir)
+{
+ size_t left;
+ size_t right;
+ size_t min;
+ int status;
+
+ /* Calculate the positions of the children */
+ left = (2 * root) + 1;
+ if (left >= h->list_len)
+ left = 0;
+
+ right = (2 * root) + 2;
+ if (right >= h->list_len)
+ right = 0;
+
+ /* Check which one of the children is smaller. */
+ if ((left == 0) && (right == 0))
+ return;
+ else if (left == 0)
+ min = right;
+ else if (right == 0)
+ min = left;
+ else
+ {
+ status = h->compare (h->list[left], h->list[right]);
+ if (status > 0)
+ min = right;
+ else
+ min = left;
+ }
+
+ status = h->compare (h->list[root], h->list[min]);
+ if (status <= 0)
+ {
+ /* We didn't need to change anything, so the rest of the tree should be
+ * okay now. */
+ return;
+ }
+ else /* if (status > 0) */
+ {
+ void *tmp;
+
+ tmp = h->list[root];
+ h->list[root] = h->list[min];
+ h->list[min] = tmp;
+ }
+
+ if ((dir == DIR_UP) && (root == 0))
+ return;
+
+ if (dir == DIR_UP)
+ reheap (h, (root - 1) / 2, dir);
+ else if (dir == DIR_DOWN)
+ reheap (h, min, dir);
+} /* void reheap */
+
+c_heap_t *c_heap_create (int (*compare) (const void *, const void *))
+{
+ c_heap_t *h;
+
+ if (compare == NULL)
+ return (NULL);
+
+ h = malloc (sizeof (*h));
+ if (h == NULL)
+ return (NULL);
+
+ memset (h, 0, sizeof (*h));
+ pthread_mutex_init (&h->lock, /* attr = */ NULL);
+ h->compare = compare;
+
+ h->list = NULL;
+ h->list_len = 0;
+ h->list_size = 0;
+
+ return (h);
+} /* c_heap_t *c_heap_create */
+
+void c_heap_destroy (c_heap_t *h)
+{
+ if (h == NULL)
+ return;
+
+ h->list_len = 0;
+ h->list_size = 0;
+ free (h->list);
+ h->list = NULL;
+
+ pthread_mutex_destroy (&h->lock);
+
+ free (h);
+} /* void c_heap_destroy */
+
+int c_heap_insert (c_heap_t *h, void *ptr)
+{
+ size_t index;
+
+ if ((h == NULL) || (ptr == NULL))
+ return (-EINVAL);
+
+ pthread_mutex_lock (&h->lock);
+
+ assert (h->list_len <= h->list_size);
+ if (h->list_len == h->list_size)
+ {
+ void **tmp;
+
+ tmp = realloc (h->list, (h->list_size + 16) * sizeof (*h->list));
+ if (tmp == NULL)
+ {
+ pthread_mutex_unlock (&h->lock);
+ return (-ENOMEM);
+ }
+
+ h->list = tmp;
+ h->list_size += 16;
+ }
+
+ /* Insert the new node as a leaf. */
+ index = h->list_len;
+ h->list[index] = ptr;
+ h->list_len++;
+
+ /* Reorganize the heap from bottom up. */
+ reheap (h, /* parent of this node = */ (index - 1) / 2, DIR_UP);
+
+ pthread_mutex_unlock (&h->lock);
+ return (0);
+} /* int c_heap_insert */
+
+void *c_heap_get_root (c_heap_t *h)
+{
+ void *ret = NULL;
+
+ if (h == NULL)
+ return (NULL);
+
+ pthread_mutex_lock (&h->lock);
+
+ if (h->list_len == 0)
+ {
+ pthread_mutex_unlock (&h->lock);
+ return (NULL);
+ }
+ else if (h->list_len == 1)
+ {
+ ret = h->list[0];
+ h->list[0] = NULL;
+ h->list_len = 0;
+ }
+ else /* if (h->list_len > 1) */
+ {
+ ret = h->list[0];
+ h->list[0] = h->list[h->list_len - 1];
+ h->list[h->list_len - 1] = NULL;
+ h->list_len--;
+
+ reheap (h, /* root = */ 0, DIR_DOWN);
+ }
+
+ /* free some memory */
+ if ((h->list_len + 32) < h->list_size)
+ {
+ void **tmp;
+
+ tmp = realloc (h->list, (h->list_len + 16) * sizeof (*h->list));
+ if (tmp != NULL)
+ {
+ h->list = tmp;
+ h->list_size = h->list_len + 16;
+ }
+ }
+
+ pthread_mutex_unlock (&h->lock);
+
+ return (ret);
+} /* void *c_heap_get_root */
+
+/* vim: set sw=2 sts=2 et fdm=marker : */
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