jabberd2
2.2.16
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00001 /* 00002 * jabberd - Jabber Open Source Server 00003 * Copyright (c) 2002 Jeremie Miller, Thomas Muldowney, 00004 * Ryan Eatmon, Robert Norris 00005 * 00006 * This program is free software; you can redistribute it and/or modify 00007 * it under the terms of the GNU General Public License as published by 00008 * the Free Software Foundation; either version 2 of the License, or 00009 * (at your option) any later version. 00010 * 00011 * This program is distributed in the hope that it will be useful, 00012 * but WITHOUT ANY WARRANTY; without even the implied warranty of 00013 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.See the 00014 * GNU General Public License for more details. 00015 * 00016 * You should have received a copy of the GNU General Public License 00017 * along with this program; if not, write to the Free Software 00018 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA02111-1307USA 00019 */ 00020 00021 /* priority queues */ 00022 00023 #include "pqueue.h" 00024 00025 #include "pool.h" 00026 00027 #include <stdio.h> /* to get NULL */ 00028 #include <assert.h> 00029 00030 typedef struct _pqueue_node_st *_pqueue_node_t; 00031 struct _pqueue_node_st { 00032 void *data; 00033 00034 int priority; 00035 00036 _pqueue_node_t next; 00037 _pqueue_node_t prev; 00038 }; 00039 00040 struct _pqueue_st { 00041 pool_t p; 00042 _pqueue_node_t cache; 00043 00044 _pqueue_node_t front; 00045 _pqueue_node_t back; 00046 00047 int size; 00048 }; 00049 00050 pqueue_t pqueue_new(pool_t p) { 00051 pqueue_t q; 00052 00053 q = (pqueue_t) pmalloco(p, sizeof(struct _pqueue_st)); 00054 00055 q->p = p; 00056 00057 return q; 00058 } 00059 00060 void pqueue_push(pqueue_t q, void *data, int priority) { 00061 _pqueue_node_t qn, scan; 00062 00063 assert((q != NULL)); 00064 00065 q->size++; 00066 00067 /* node from the cache, or make a new one */ 00068 qn = q->cache; 00069 if(qn != NULL) 00070 q->cache = qn->next; 00071 else 00072 qn = (_pqueue_node_t) pmalloc(q->p, sizeof(struct _pqueue_node_st)); 00073 00074 qn->data = data; 00075 qn->priority = priority; 00076 00077 qn->next = NULL; 00078 qn->prev = NULL; 00079 00080 /* first one */ 00081 if(q->back == NULL && q->front == NULL) { 00082 q->back = qn; 00083 q->front = qn; 00084 00085 return; 00086 } 00087 00088 /* find the first node with priority <= to us */ 00089 for(scan = q->back; scan != NULL && scan->priority > priority; scan = scan->next); 00090 00091 /* didn't find one, so we have top priority - push us on the front */ 00092 if(scan == NULL) { 00093 qn->prev = q->front; 00094 qn->prev->next = qn; 00095 q->front = qn; 00096 00097 return; 00098 } 00099 00100 /* push us in front of scan */ 00101 qn->next = scan; 00102 qn->prev = scan->prev; 00103 00104 if(scan->prev != NULL) 00105 scan->prev->next = qn; 00106 else 00107 q->back = qn; 00108 00109 scan->prev = qn; 00110 } 00111 00112 void *pqueue_pull(pqueue_t q) { 00113 void *data; 00114 _pqueue_node_t qn; 00115 00116 assert((q != NULL)); 00117 00118 if(q->front == NULL) 00119 return NULL; 00120 00121 data = q->front->data; 00122 00123 qn = q->front; 00124 00125 if(qn->prev != NULL) 00126 qn->prev->next = NULL; 00127 00128 q->front = qn->prev; 00129 00130 /* node to cache for later reuse */ 00131 qn->next = q->cache; 00132 q->cache = qn; 00133 00134 if(q->front == NULL) 00135 q->back = NULL; 00136 00137 q->size--; 00138 00139 return data; 00140 } 00141 00142 int pqueue_size(pqueue_t q) { 00143 return q->size; 00144 }