/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* 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
*
* $FreeBSD$
*/
#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);
void 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 */
