fe267a5590
Mainly focus on files that use BSD 2-Clause license, however the tool I was using misidentified many licenses so this was mostly a manual - error prone - task. The Software Package Data Exchange (SPDX) group provides a specification to make it easier for automated tools to detect and summarize well known opensource licenses. We are gradually adopting the specification, noting that the tags are considered only advisory and do not, in any way, superceed or replace the license texts. No functional change intended.
194 lines
7.5 KiB
C
194 lines
7.5 KiB
C
/*-
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* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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*
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* Copyright (c) 1998-2010 Luigi Rizzo, Universita` di Pisa
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* All rights reserved
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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* Binary heap and hash tables, header file
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*
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* $FreeBSD$
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*/
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#ifndef _IP_DN_HEAP_H
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#define _IP_DN_HEAP_H
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#define DN_KEY_LT(a,b) ((int64_t)((a)-(b)) < 0)
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#define DN_KEY_LEQ(a,b) ((int64_t)((a)-(b)) <= 0)
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/*
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* This module implements a binary heap supporting random extraction.
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*
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* A heap entry contains an uint64_t key and a pointer to object.
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* DN_KEY_LT(a,b) returns true if key 'a' is smaller than 'b'
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*
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* The heap is a struct dn_heap plus a dynamically allocated
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* array of dn_heap_entry entries. 'size' represents the size of
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* the array, 'elements' count entries in use. The topmost
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* element has the smallest key.
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* The heap supports ordered insert, and extract from the top.
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* To extract an object from the middle of the heap, we the object
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* must reserve an 'int32_t' to store the position of the object
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* in the heap itself, and the location of this field must be
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* passed as an argument to heap_init() -- use -1 if the feature
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* is not used.
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*/
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struct dn_heap_entry {
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uint64_t key; /* sorting key, smallest comes first */
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void *object; /* object pointer */
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};
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struct dn_heap {
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int size; /* the size of the array */
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int elements; /* elements in use */
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int ofs; /* offset in the object of heap index */
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struct dn_heap_entry *p; /* array of "size" entries */
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};
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enum {
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HEAP_SCAN_DEL = 1,
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HEAP_SCAN_END = 2,
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};
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/*
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* heap_init() reinitializes the heap setting the size and the offset
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* of the index for random extraction (use -1 if not used).
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* The 'elements' counter is set to 0.
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*
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* SET_HEAP_OFS() indicates where, in the object, is stored the index
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* for random extractions from the heap.
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*
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* heap_free() frees the memory associated to a heap.
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*
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* heap_insert() adds a key-pointer pair to the heap
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*
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* HEAP_TOP() returns a pointer to the top element of the heap,
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* but makes no checks on its existence (XXX should we change ?)
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*
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* heap_extract() removes the entry at the top, returning the pointer.
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* (the key should have been read before).
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*
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* heap_scan() invokes a callback on each entry of the heap.
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* The callback can return a combination of HEAP_SCAN_DEL and
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* HEAP_SCAN_END. HEAP_SCAN_DEL means the current element must
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* be removed, and HEAP_SCAN_END means to terminate the scan.
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* heap_scan() returns the number of elements removed.
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* Because the order is not guaranteed, we should use heap_scan()
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* only as a last resort mechanism.
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*/
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#define HEAP_TOP(h) ((h)->p)
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#define SET_HEAP_OFS(h, n) do { (h)->ofs = n; } while (0)
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int heap_init(struct dn_heap *h, int size, int ofs);
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int heap_insert(struct dn_heap *h, uint64_t key1, void *p);
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void heap_extract(struct dn_heap *h, void *obj);
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void heap_free(struct dn_heap *h);
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int heap_scan(struct dn_heap *, int (*)(void *, uintptr_t), uintptr_t);
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/*------------------------------------------------------
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* This module implements a generic hash table with support for
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* running callbacks on the entire table. To avoid allocating
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* memory during hash table operations, objects must reserve
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* space for a link field. XXX if the heap is moderately full,
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* an SLIST suffices, and we can tolerate the cost of a hash
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* computation on each removal.
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*
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* dn_ht_init() initializes the table, setting the number of
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* buckets, the offset of the link field, the main callbacks.
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* Callbacks are:
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*
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* hash(key, flags, arg) called to return a bucket index.
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* match(obj, key, flags, arg) called to determine if key
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* matches the current 'obj' in the heap
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* newh(key, flags, arg) optional, used to allocate a new
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* object during insertions.
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*
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* dn_ht_free() frees the heap or unlink elements.
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* DNHT_REMOVE unlink elements, 0 frees the heap.
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* You need two calls to do both.
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*
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* dn_ht_find() is the main lookup function, which can also be
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* used to insert or delete elements in the hash table.
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* The final 'arg' is passed to all callbacks.
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*
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* dn_ht_scan() is used to invoke a callback on all entries of
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* the heap, or possibly on just one bucket. The callback
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* is invoked with a pointer to the object, and must return
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* one of DNHT_SCAN_DEL or DNHT_SCAN_END to request the
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* removal of the object from the heap and the end of the
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* scan, respectively.
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*
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* dn_ht_scan_bucket() is similar to dn_ht_scan(), except that it scans
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* only the specific bucket of the table. The bucket is a in-out
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* parameter and return a valid bucket number if the original
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* is invalid.
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*
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* A combination of flags can be used to modify the operation
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* of the dn_ht_find(), and of the callbacks:
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*
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* DNHT_KEY_IS_OBJ means the key is the object pointer.
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* It is usually of interest for the hash and match functions.
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*
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* DNHT_MATCH_PTR during a lookup, match pointers instead
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* of calling match(). Normally used when removing specific
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* entries. Does not imply KEY_IS_OBJ as the latter _is_ used
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* by the match function.
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*
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* DNHT_INSERT insert the element if not found.
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* Calls new() to allocates a new object unless
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* DNHT_KEY_IS_OBJ is set.
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*
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* DNHT_UNIQUE only insert if object not found.
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* XXX should it imply DNHT_INSERT ?
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*
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* DNHT_REMOVE remove objects if we find them.
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*/
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struct dn_ht; /* should be opaque */
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struct dn_ht *dn_ht_init(struct dn_ht *, int buckets, int ofs,
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uint32_t (*hash)(uintptr_t, int, void *),
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int (*match)(void *, uintptr_t, int, void *),
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void *(*newh)(uintptr_t, int, void *));
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void dn_ht_free(struct dn_ht *, int flags);
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void *dn_ht_find(struct dn_ht *, uintptr_t, int, void *);
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int dn_ht_scan(struct dn_ht *, int (*)(void *, void *), void *);
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int dn_ht_scan_bucket(struct dn_ht *, int * , int (*)(void *, void *), void *);
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int dn_ht_entries(struct dn_ht *);
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enum { /* flags values.
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* first two are returned by the scan callback to indicate
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* to delete the matching element or to end the scan
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*/
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DNHT_SCAN_DEL = 0x0001,
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DNHT_SCAN_END = 0x0002,
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DNHT_KEY_IS_OBJ = 0x0004, /* key is the obj pointer */
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DNHT_MATCH_PTR = 0x0008, /* match by pointer, not match() */
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DNHT_INSERT = 0x0010, /* insert if not found */
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DNHT_UNIQUE = 0x0020, /* report error if already there */
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DNHT_REMOVE = 0x0040, /* remove on find or dn_ht_free */
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};
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#endif /* _IP_DN_HEAP_H */
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