src/plugin.c: Use a heap to schedule reads.

[collectd.git] / src / utils_heap.h

diff --git a/src/utils_heap.h b/src/utils_heap.h
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+/**
+ * collectd - src/utils_heap.h
+ * Copyright (C) 2009  Florian octo Forster
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+ *
+ * Authors:
+ *   Florian octo Forster <octo at verplant.org>
+ **/
+
+#ifndef UTILS_HEAP_H
+#define UTILS_HEAP_H 1
+
+struct c_heap_s;
+typedef struct c_heap_s c_heap_t;
+
+/*
+ * NAME
+ *   c_heap_create
+ *
+ * DESCRIPTION
+ *   Allocates a new heap.
+ *
+ * PARAMETERS
+ *   `compare'  The function-pointer `compare' is used to compare two keys. It
+ *              has to return less than zero if it's first argument is smaller
+ *              then the second argument, more than zero if the first argument
+ *              is bigger than the second argument and zero if they are equal.
+ *              If your keys are char-pointers, you can use the `strcmp'
+ *              function from the libc here.
+ *
+ * RETURN VALUE
+ *   A c_heap_t-pointer upon success or NULL upon failure.
+ */
+c_heap_t *c_heap_create (int (*compare) (const void *, const void *));
+
+/*
+ * NAME
+ *   c_heap_destroy
+ *
+ * DESCRIPTION
+ *   Deallocates a heap. Stored value- and key-pointer are lost, but of course
+ *   not freed.
+ */
+void c_heap_destroy (c_heap_t *h);
+
+/*
+ * NAME
+ *   c_heap_insert
+ *
+ * DESCRIPTION
+ *   Stores the key-value-pair in the heap pointed to by `h'.
+ *
+ * PARAMETERS
+ *   `h'        Heap to store the data in.
+ *   `ptr'      Value to be stored. This is typically a pointer to a data
+ *              structure. The data structure is of course *not* copied and may
+ *              not be free'd before the pointer has been removed from the heap
+ *              again.
+ *
+ * RETURN VALUE
+ *   Zero upon success, non-zero otherwise. It's less than zero if an error
+ *   occurred or greater than zero if the key is already stored in the tree.
+ */
+int c_heap_insert (c_heap_t *h, void *ptr);
+
+/*
+ * NAME
+ *   c_head_get_root
+ *
+ * DESCRIPTION
+ *   Removes the value at the root of the heap and returns both, key and value.
+ *
+ * PARAMETERS
+ *   `h'           Heap to remove key-value-pair from.
+ *
+ * RETURN VALUE
+ *   The pointer passed to `c_heap_insert' or NULL if there are no more
+ *   elements in the heap (or an error occurred).
+ */
+void *c_head_get_root (c_heap_t *h);
+
+#endif /* UTILS_HEAP_H */
+/* vim: set sw=2 sts=2 et : */