1 /*- 2 * Copyright (c) 1998-2010 Luigi Rizzo, Universita` di Pisa 3 * All rights reserved 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27 /* 28 * Binary heap and hash tables, header file 29 * 30 * $FreeBSD$ 31 */ 32 33 #ifndef _IP_DN_HEAP_H 34 #define _IP_DN_HEAP_H 35 36 #define DN_KEY_LT(a,b) ((int64_t)((a)-(b)) < 0) 37 #define DN_KEY_LEQ(a,b) ((int64_t)((a)-(b)) <= 0) 38 39 /* 40 * This module implements a binary heap supporting random extraction. 41 * 42 * A heap entry contains an uint64_t key and a pointer to object. 43 * DN_KEY_LT(a,b) returns true if key 'a' is smaller than 'b' 44 * 45 * The heap is a struct dn_heap plus a dynamically allocated 46 * array of dn_heap_entry entries. 'size' represents the size of 47 * the array, 'elements' count entries in use. The topmost 48 * element has the smallest key. 49 * The heap supports ordered insert, and extract from the top. 50 * To extract an object from the middle of the heap, we the object 51 * must reserve an 'int32_t' to store the position of the object 52 * in the heap itself, and the location of this field must be 53 * passed as an argument to heap_init() -- use -1 if the feature 54 * is not used. 55 */ 56 struct dn_heap_entry { 57 uint64_t key; /* sorting key, smallest comes first */ 58 void *object; /* object pointer */ 59 }; 60 61 struct dn_heap { 62 int size; /* the size of the array */ 63 int elements; /* elements in use */ 64 int ofs; /* offset in the object of heap index */ 65 struct dn_heap_entry *p; /* array of "size" entries */ 66 }; 67 68 enum { 69 HEAP_SCAN_DEL = 1, 70 HEAP_SCAN_END = 2, 71 }; 72 73 /* 74 * heap_init() reinitializes the heap setting the size and the offset 75 * of the index for random extraction (use -1 if not used). 76 * The 'elements' counter is set to 0. 77 * 78 * SET_HEAP_OFS() indicates where, in the object, is stored the index 79 * for random extractions from the heap. 80 * 81 * heap_free() frees the memory associated to a heap. 82 * 83 * heap_insert() adds a key-pointer pair to the heap 84 * 85 * HEAP_TOP() returns a pointer to the top element of the heap, 86 * but makes no checks on its existance (XXX should we change ?) 87 * 88 * heap_extract() removes the entry at the top, returing the pointer. 89 * (the key should have been read before). 90 * 91 * heap_scan() invokes a callback on each entry of the heap. 92 * The callback can return a combination of HEAP_SCAN_DEL and 93 * HEAP_SCAN_END. HEAP_SCAN_DEL means the current element must 94 * be removed, and HEAP_SCAN_END means to terminate the scan. 95 * heap_scan() returns the number of elements removed. 96 * Because the order is not guaranteed, we should use heap_scan() 97 * only as a last resort mechanism. 98 */ 99 #define HEAP_TOP(h) ((h)->p) 100 #define SET_HEAP_OFS(h, n) do { (h)->ofs = n; } while (0) 101 int heap_init(struct dn_heap *h, int size, int ofs); 102 int heap_insert(struct dn_heap *h, uint64_t key1, void *p); 103 void heap_extract(struct dn_heap *h, void *obj); 104 void heap_free(struct dn_heap *h); 105 int heap_scan(struct dn_heap *, int (*)(void *, uintptr_t), uintptr_t); 106 107 /*------------------------------------------------------ 108 * This module implements a generic hash table with support for 109 * running callbacks on the entire table. To avoid allocating 110 * memory during hash table operations, objects must reserve 111 * space for a link field. XXX if the heap is moderately full, 112 * an SLIST suffices, and we can tolerate the cost of a hash 113 * computation on each removal. 114 * 115 * dn_ht_init() initializes the table, setting the number of 116 * buckets, the offset of the link field, the main callbacks. 117 * Callbacks are: 118 * 119 * hash(key, flags, arg) called to return a bucket index. 120 * match(obj, key, flags, arg) called to determine if key 121 * matches the current 'obj' in the heap 122 * newh(key, flags, arg) optional, used to allocate a new 123 * object during insertions. 124 * 125 * dn_ht_free() frees the heap or unlink elements. 126 * DNHT_REMOVE unlink elements, 0 frees the heap. 127 * You need two calls to do both. 128 * 129 * dn_ht_find() is the main lookup function, which can also be 130 * used to insert or delete elements in the hash table. 131 * The final 'arg' is passed to all callbacks. 132 * 133 * dn_ht_scan() is used to invoke a callback on all entries of 134 * the heap, or possibly on just one bucket. The callback 135 * is invoked with a pointer to the object, and must return 136 * one of DNHT_SCAN_DEL or DNHT_SCAN_END to request the 137 * removal of the object from the heap and the end of the 138 * scan, respectively. 139 * 140 * dn_ht_scan_bucket() is similar to dn_ht_scan(), except that it scans 141 * only the specific bucket of the table. The bucket is a in-out 142 * parameter and return a valid bucket number if the original 143 * is invalid. 144 * 145 * A combination of flags can be used to modify the operation 146 * of the dn_ht_find(), and of the callbacks: 147 * 148 * DNHT_KEY_IS_OBJ means the key is the object pointer. 149 * It is usally of interest for the hash and match functions. 150 * 151 * DNHT_MATCH_PTR during a lookup, match pointers instead 152 * of calling match(). Normally used when removing specific 153 * entries. Does not imply KEY_IS_OBJ as the latter _is_ used 154 * by the match function. 155 * 156 * DNHT_INSERT insert the element if not found. 157 * Calls new() to allocates a new object unless 158 * DNHT_KEY_IS_OBJ is set. 159 * 160 * DNHT_UNIQUE only insert if object not found. 161 * XXX should it imply DNHT_INSERT ? 162 * 163 * DNHT_REMOVE remove objects if we find them. 164 */ 165 struct dn_ht; /* should be opaque */ 166 167 struct dn_ht *dn_ht_init(struct dn_ht *, int buckets, int ofs, 168 uint32_t (*hash)(uintptr_t, int, void *), 169 int (*match)(void *, uintptr_t, int, void *), 170 void *(*newh)(uintptr_t, int, void *)); 171 void dn_ht_free(struct dn_ht *, int flags); 172 173 void *dn_ht_find(struct dn_ht *, uintptr_t, int, void *); 174 int dn_ht_scan(struct dn_ht *, int (*)(void *, void *), void *); 175 int dn_ht_scan_bucket(struct dn_ht *, int * , int (*)(void *, void *), void *); 176 int dn_ht_entries(struct dn_ht *); 177 178 enum { /* flags values. 179 * first two are returned by the scan callback to indicate 180 * to delete the matching element or to end the scan 181 */ 182 DNHT_SCAN_DEL = 0x0001, 183 DNHT_SCAN_END = 0x0002, 184 DNHT_KEY_IS_OBJ = 0x0004, /* key is the obj pointer */ 185 DNHT_MATCH_PTR = 0x0008, /* match by pointer, not match() */ 186 DNHT_INSERT = 0x0010, /* insert if not found */ 187 DNHT_UNIQUE = 0x0020, /* report error if already there */ 188 DNHT_REMOVE = 0x0040, /* remove on find or dn_ht_free */ 189 }; 190 191 #endif /* _IP_DN_HEAP_H */ 192