FreeBSD/Linux Kernel Cross Reference
sys/netpfil/ipfw/dn_heap.h

     /*-
      * 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: releng/10.1/sys/netpfil/ipfw/dn_heap.h 204865 2010-03-08 11:27:08Z luigi $
     */
    
    #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 existance (XXX should we change ?)
     *
     * heap_extract() removes the entry at the top, returing 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 usally 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 */

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