/*- * SPDX-License-Identifier: BSD-2-Clause * * Copyright (c) 1998-2010 Luigi Rizzo, Universita` di Pisa * All rights reserved * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ /* * Binary heap and hash tables, header file */ #ifndef _IP_DN_HEAP_H #define _IP_DN_HEAP_H #define DN_KEY_LT(a,b) ((int64_t)((a)-(b)) < 0) #define DN_KEY_LEQ(a,b) ((int64_t)((a)-(b)) <= 0) /* * This module implements a binary heap supporting random extraction. * * A heap entry contains an uint64_t key and a pointer to object. * DN_KEY_LT(a,b) returns true if key 'a' is smaller than 'b' * * The heap is a struct dn_heap plus a dynamically allocated * array of dn_heap_entry entries. 'size' represents the size of * the array, 'elements' count entries in use. The topmost * element has the smallest key. * The heap supports ordered insert, and extract from the top. * To extract an object from the middle of the heap, we the object * must reserve an 'int32_t' to store the position of the object * in the heap itself, and the location of this field must be * passed as an argument to heap_init() -- use -1 if the feature * is not used. */ struct dn_heap_entry { uint64_t key; /* sorting key, smallest comes first */ void *object; /* object pointer */ }; struct dn_heap { int size; /* the size of the array */ int elements; /* elements in use */ int ofs; /* offset in the object of heap index */ struct dn_heap_entry *p; /* array of "size" entries */ }; enum { HEAP_SCAN_DEL = 1, HEAP_SCAN_END = 2, }; /* * heap_init() reinitializes the heap setting the size and the offset * of the index for random extraction (use -1 if not used). * The 'elements' counter is set to 0. * * SET_HEAP_OFS() indicates where, in the object, is stored the index * for random extractions from the heap. * * heap_free() frees the memory associated to a heap. * * heap_insert() adds a key-pointer pair to the heap * * HEAP_TOP() returns a pointer to the top element of the heap, * but makes no checks on its existence (XXX should we change ?) * * heap_extract() removes the entry at the top, returning the pointer. * (the key should have been read before). * * heap_scan() invokes a callback on each entry of the heap. * The callback can return a combination of HEAP_SCAN_DEL and * HEAP_SCAN_END. HEAP_SCAN_DEL means the current element must * be removed, and HEAP_SCAN_END means to terminate the scan. * heap_scan() returns the number of elements removed. * Because the order is not guaranteed, we should use heap_scan() * only as a last resort mechanism. */ #define HEAP_TOP(h) ((h)->p) #define SET_HEAP_OFS(h, n) do { (h)->ofs = n; } while (0) int heap_init(struct dn_heap *h, int size, int ofs); int heap_insert(struct dn_heap *h, uint64_t key1, void *p); bool heap_extract(struct dn_heap *h, void *obj); void heap_free(struct dn_heap *h); int heap_scan(struct dn_heap *, int (*)(void *, uintptr_t), uintptr_t); /*------------------------------------------------------ * This module implements a generic hash table with support for * running callbacks on the entire table. To avoid allocating * memory during hash table operations, objects must reserve * space for a link field. XXX if the heap is moderately full, * an SLIST suffices, and we can tolerate the cost of a hash * computation on each removal. * * dn_ht_init() initializes the table, setting the number of * buckets, the offset of the link field, the main callbacks. * Callbacks are: * * hash(key, flags, arg) called to return a bucket index. * match(obj, key, flags, arg) called to determine if key * matches the current 'obj' in the heap * newh(key, flags, arg) optional, used to allocate a new * object during insertions. * * dn_ht_free() frees the heap or unlink elements. * DNHT_REMOVE unlink elements, 0 frees the heap. * You need two calls to do both. * * dn_ht_find() is the main lookup function, which can also be * used to insert or delete elements in the hash table. * The final 'arg' is passed to all callbacks. * * dn_ht_scan() is used to invoke a callback on all entries of * the heap, or possibly on just one bucket. The callback * is invoked with a pointer to the object, and must return * one of DNHT_SCAN_DEL or DNHT_SCAN_END to request the * removal of the object from the heap and the end of the * scan, respectively. * * dn_ht_scan_bucket() is similar to dn_ht_scan(), except that it scans * only the specific bucket of the table. The bucket is a in-out * parameter and return a valid bucket number if the original * is invalid. * * A combination of flags can be used to modify the operation * of the dn_ht_find(), and of the callbacks: * * DNHT_KEY_IS_OBJ means the key is the object pointer. * It is usually of interest for the hash and match functions. * * DNHT_MATCH_PTR during a lookup, match pointers instead * of calling match(). Normally used when removing specific * entries. Does not imply KEY_IS_OBJ as the latter _is_ used * by the match function. * * DNHT_INSERT insert the element if not found. * Calls new() to allocates a new object unless * DNHT_KEY_IS_OBJ is set. * * DNHT_UNIQUE only insert if object not found. * XXX should it imply DNHT_INSERT ? * * DNHT_REMOVE remove objects if we find them. */ struct dn_ht; /* should be opaque */ struct dn_ht *dn_ht_init(struct dn_ht *, int buckets, int ofs, uint32_t (*hash)(uintptr_t, int, void *), int (*match)(void *, uintptr_t, int, void *), void *(*newh)(uintptr_t, int, void *)); void dn_ht_free(struct dn_ht *, int flags); void *dn_ht_find(struct dn_ht *, uintptr_t, int, void *); int dn_ht_scan(struct dn_ht *, int (*)(void *, void *), void *); int dn_ht_scan_bucket(struct dn_ht *, int * , int (*)(void *, void *), void *); int dn_ht_entries(struct dn_ht *); enum { /* flags values. * first two are returned by the scan callback to indicate * to delete the matching element or to end the scan */ DNHT_SCAN_DEL = 0x0001, DNHT_SCAN_END = 0x0002, DNHT_KEY_IS_OBJ = 0x0004, /* key is the obj pointer */ DNHT_MATCH_PTR = 0x0008, /* match by pointer, not match() */ DNHT_INSERT = 0x0010, /* insert if not found */ DNHT_UNIQUE = 0x0020, /* report error if already there */ DNHT_REMOVE = 0x0040, /* remove on find or dn_ht_free */ }; #endif /* _IP_DN_HEAP_H */
