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nagios4/pqueue.h

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+/*
+ * Copyright 2010 Volkan Yazıcı <volkan.yazici@gmail.com>
+ * Copyright 2006-2010 The Apache Software Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+#ifndef LIBNAGIOS_pqueue_h__
+#define LIBNAGIOS_pqueue_h__
+#include <stdio.h>
+
+/**
+ * @file  pqueue.h
+ * @brief Priority Queue function declarations
+ *
+ * This priority queue library was originally written by Volkan Yazici
+ * <volkan.yazici@gmail.com>. It was lated adapted for Nagios by
+ * Andreas Ericsson <ae@op5.se>. Changes compared to the original
+ * version are pretty much limited to changing pqueue_pri_t to be
+ * an unsigned long long instead of a double, since ULL comparisons
+ * are 107 times faster on my 64-bit laptop.
+ *
+ * @{
+ */
+
+
+/** priority data type (used to be double, but ull is 107 times faster) */
+typedef unsigned long long pqueue_pri_t;
+
+/** callback functions to get/set/compare the priority of an element */
+typedef pqueue_pri_t (*pqueue_get_pri_f)(void *a);
+typedef void (*pqueue_set_pri_f)(void *a, pqueue_pri_t pri);
+typedef int (*pqueue_cmp_pri_f)(pqueue_pri_t next, pqueue_pri_t curr);
+
+
+/** callback functions to get/set the position of an element */
+typedef unsigned int (*pqueue_get_pos_f)(void *a);
+typedef void (*pqueue_set_pos_f)(void *a, unsigned int pos);
+
+
+/** debug callback function to print a entry */
+typedef void (*pqueue_print_entry_f)(FILE *out, void *a);
+
+
+/** the priority queue handle */
+typedef struct pqueue_t
+{
+    unsigned int size;       /**< number of elements in this queue */
+    unsigned int avail;      /**< slots available in this queue */
+    unsigned int step;       /**< growth stepping setting */
+    pqueue_cmp_pri_f cmppri; /**< callback to compare nodes */
+    pqueue_get_pri_f getpri; /**< callback to get priority of a node */
+    pqueue_set_pri_f setpri; /**< callback to set priority of a node */
+    pqueue_get_pos_f getpos; /**< callback to get position of a node */
+    pqueue_set_pos_f setpos; /**< callback to set position of a node */
+    void **d;                /**< The actualy queue in binary heap form */
+} pqueue_t;
+
+
+/**
+ * initialize the queue
+ *
+ * @param n the initial estimate of the number of queue items for which memory
+ *          should be preallocated
+ * @param cmppri The callback function to run to compare two elements
+ *    This callback should return 0 for 'lower' and non-zero
+ *    for 'higher', or vice versa if reverse priority is desired
+ * @param setpri the callback function to run to assign a score to an element
+ * @param getpri the callback function to run to set a score to an element
+ * @param getpos the callback function to get the current element's position
+ * @param setpos the callback function to set the current element's position
+ *
+ * @return the handle or NULL for insufficent memory
+ */
+pqueue_t *
+pqueue_init(unsigned int n,
+            pqueue_cmp_pri_f cmppri,
+            pqueue_get_pri_f getpri,
+            pqueue_set_pri_f setpri,
+            pqueue_get_pos_f getpos,
+            pqueue_set_pos_f setpos);
+
+
+/**
+ * free all memory used by the queue
+ * @param q the queue
+ */
+void pqueue_free(pqueue_t *q);
+
+
+/**
+ * return the size of the queue.
+ * @param q the queue
+ */
+unsigned int pqueue_size(pqueue_t *q);
+
+
+/**
+ * insert an item into the queue.
+ * @param q the queue
+ * @param d the item
+ * @return 0 on success
+ */
+int pqueue_insert(pqueue_t *q, void *d);
+
+
+/**
+ * move an existing entry to a different priority
+ * @param q the queue
+ * @param new_pri the new priority
+ * @param d the entry
+ */
+void
+pqueue_change_priority(pqueue_t *q,
+                       pqueue_pri_t new_pri,
+                       void *d);
+
+
+/**
+ * pop the highest-ranking item from the queue.
+ * @param q the queue
+ * @return NULL on error, otherwise the entry
+ */
+void *pqueue_pop(pqueue_t *q);
+
+
+/**
+ * remove an item from the queue.
+ * @param q the queue
+ * @param d the entry
+ * @return 0 on success
+ */
+int pqueue_remove(pqueue_t *q, void *d);
+
+
+/**
+ * access highest-ranking item without removing it.
+ * @param q the queue
+ * @return NULL on error, otherwise the entry
+ */
+void *pqueue_peek(pqueue_t *q);
+
+
+/**
+ * print the queue
+ * @internal
+ * DEBUG function only
+ * @param q the queue
+ * @param out the output handle
+ * @param the callback function to print the entry
+ */
+void
+pqueue_print(pqueue_t *q, FILE *out, pqueue_print_entry_f print);
+
+
+/**
+ * dump the queue and it's internal structure
+ * @internal
+ * debug function only
+ * @param q the queue
+ * @param out the output handle
+ * @param the callback function to print the entry
+ */
+void pqueue_dump(pqueue_t *q, FILE *out, pqueue_print_entry_f print);
+
+
+/**
+ * checks that the pq is in the right order, etc
+ * @internal
+ * debug function only
+ * @param q the queue
+ */
+int pqueue_is_valid(pqueue_t *q);
+
+#endif
+/** @} */