--- /dev/null
+/*-
+ * 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: head/sys/netinet/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 */
git://git.onelab.eu / ipfw.git / blobdiff