Adding upstream version 8.4.4.upstream/8.4.4upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 337 insertions, 0 deletions

diff --git a/lib/hash.h b/lib/hash.h
new file mode 100644
index 0000000..91770d1
--- /dev/null
+++ b/lib/hash.h
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+/* Hash routine.
+ * Copyright (C) 1998 Kunihiro Ishiguro
+ *
+ * This file is part of GNU Zebra.
+ *
+ * GNU Zebra is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published
+ * by the Free Software Foundation; either version 2, or (at your
+ * option) any later version.
+ *
+ * GNU Zebra is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; see the file COPYING; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef _ZEBRA_HASH_H
+#define _ZEBRA_HASH_H
+
+#include "memory.h"
+#include "frratomic.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* Default hash table size.  */
+#define HASH_INITIAL_SIZE 256
+/* Expansion threshold */
+#define HASH_THRESHOLD(used, size) ((used) > (size))
+
+#define HASHWALK_CONTINUE 0
+#define HASHWALK_ABORT -1
+
+struct hash_bucket {
+	/*
+	 * if this bucket is the head of the linked listed, len denotes the
+	 * number of elements in the list
+	 */
+	int len;
+
+	/* Linked list.  */
+	struct hash_bucket *next;
+
+	/* Hash key. */
+	unsigned int key;
+
+	/* Data.  */
+	void *data;
+};
+
+struct hashstats {
+	/* number of empty hash buckets */
+	atomic_uint_fast32_t empty;
+	/* sum of squares of bucket length */
+	atomic_uint_fast32_t ssq;
+};
+
+struct hash {
+	/* Hash bucket. */
+	struct hash_bucket **index;
+
+	/* Hash table size. Must be power of 2 */
+	unsigned int size;
+
+	/* If max_size is 0 there is no limit */
+	unsigned int max_size;
+
+	/* Key make function. */
+	unsigned int (*hash_key)(const void *);
+
+	/* Data compare function. */
+	bool (*hash_cmp)(const void *, const void *);
+
+	/* Bucket alloc. */
+	unsigned long count;
+
+	struct hashstats stats;
+
+	/* hash name */
+	char *name;
+};
+
+#define hashcount(X) ((X)->count)
+
+/*
+ * Create a hash table.
+ *
+ * The created hash table uses chaining and a user-provided comparator function
+ * to resolve collisions. For best performance use a perfect hash function.
+ * Worst case lookup time is O(N) when using a constant hash function. Best
+ * case lookup time is O(1) when using a perfect hash function.
+ *
+ * The initial size of the created hash table is HASH_INITIAL_SIZE.
+ *
+ * hash_key
+ *    hash function to use; should return a unique unsigned integer when called
+ *    with a data item. Collisions are acceptable.
+ *
+ * hash_cmp
+ *    comparison function used for resolving collisions; when called with two
+ *    data items, should return true if the two items are equal and false
+ *    otherwise
+ *
+ * name
+ *    optional name for the hashtable; this is used when displaying global
+ *    hashtable statistics. If this parameter is NULL the hash's name will be
+ *    set to NULL and the default name will be displayed when showing
+ *    statistics.
+ *
+ * Returns:
+ *    a new hash table
+ */
+extern struct hash *hash_create(unsigned int (*hash_key)(const void *),
+				bool (*hash_cmp)(const void *, const void *),
+				const char *name);
+
+/*
+ * Create a hash table.
+ *
+ * The created hash table uses chaining and a user-provided comparator function
+ * to resolve collisions. For best performance use a perfect hash function.
+ * Worst case lookup time is O(N) when using a constant hash function. Best
+ * case lookup time is O(1) when using a perfect hash function.
+ *
+ * size
+ *    initial number of hash buckets to allocate; must be a power of 2 or the
+ *    program will assert
+ *
+ * hash_key
+ *    hash function to use; should return a unique unsigned integer when called
+ *    with a data item. Collisions are acceptable.
+ *
+ * hash_cmp
+ *    comparison function used for resolving collisions; when called with two
+ *    data items, should return true if the two items are equal and false
+ *    otherwise
+ *
+ * name
+ *    optional name for the hashtable; this is used when displaying global
+ *    hashtable statistics. If this parameter is NULL the hash's name will be
+ *    set to NULL and the default name will be displayed when showing
+ *    statistics.
+ *
+ * Returns:
+ *    a new hash table
+ */
+extern struct hash *
+hash_create_size(unsigned int size, unsigned int (*hash_key)(const void *),
+		 bool (*hash_cmp)(const void *, const void *),
+		 const char *name);
+
+/*
+ * Retrieve or insert data from / into a hash table.
+ *
+ * This function is somewhat counterintuitive in its usage. In order to look up
+ * an element from its key, you must provide the data item itself, with the
+ * portions used in the hash function set to the same values as the data item
+ * to retrieve. To insert a data element, either provide the key as just
+ * described and provide alloc_func as described below to allocate the full
+ * data element, or provide the full data element and pass 'hash_alloc_intern'
+ * to alloc_func.
+ *
+ * hash
+ *    hash table to operate on
+ *
+ * data
+ *    data to insert or retrieve - A hash bucket will not be created if
+ *    the alloc_func returns a NULL pointer and nothing will be added to
+ *    the hash.  As such bucket->data will always be non-NULL.
+ *
+ * alloc_func
+ *    function to call if the item is not found in the hash table. This
+ *    function is called with the value of 'data' and should create the data
+ *    item to insert and return a pointer to it. If the data has already been
+ *    completely created and provided in the 'data' parameter, passing
+ *    'hash_alloc_intern' to this parameter will cause 'data' to be inserted.
+ *    If this parameter is NULL, then this call to hash_get is equivalent to
+ *    hash_lookup.
+ *
+ * Returns:
+ *    the data item found or inserted, or NULL if alloc_func is NULL and the
+ *    data is not found
+ */
+extern void *hash_get(struct hash *hash, void *data,
+		      void *(*alloc_func)(void *));
+
+/*
+ * Dummy element allocation function.
+ *
+ * See hash_get for details.
+ *
+ * data
+ *    data to insert into the hash table
+ *
+ * Returns:
+ *    data
+ */
+extern void *hash_alloc_intern(void *data);
+
+/*
+ * Retrieve an item from a hash table.
+ *
+ * This function is equivalent to calling hash_get with alloc_func set to NULL.
+ *
+ * hash
+ *    hash table to operate on
+ *
+ * data
+ *    data element with values used for key computation set
+ *
+ * Returns:
+ *    the data element if found, or NULL if not found
+ */
+extern void *hash_lookup(struct hash *hash, void *data);
+
+/*
+ * Remove an element from a hash table.
+ *
+ * hash
+ *    hash table to operate on
+ *
+ * data
+ *    data element to remove with values used for key computation set
+ *
+ * Returns:
+ *    the removed element if found, or NULL if not found
+ */
+extern void *hash_release(struct hash *hash, void *data);
+
+/*
+ * Iterate over the elements in a hash table.
+ *
+ * The passed in arg to the handler function is the only safe
+ * item to delete from the hash.
+ *
+ * Please note that adding entries to the hash
+ * during the walk will cause undefined behavior in that some new entries
+ * will be walked and some will not.  So do not do this.
+ *
+ * The bucket passed to func will have a non-NULL data pointer.
+ *
+ * hash
+ *    hash table to operate on
+ *
+ * func
+ *    function to call with each data item
+ *
+ * arg
+ *    arbitrary argument passed as the second parameter in each call to 'func'
+ */
+extern void hash_iterate(struct hash *hash,
+			 void (*func)(struct hash_bucket *, void *), void *arg);
+
+/*
+ * Iterate over the elements in a hash table, stopping on condition.
+ *
+ * The passed in arg to the handler function is the only safe item
+ * to delete from the hash.
+ *
+ * Please note that adding entries to the hash
+ * during the walk will cause undefined behavior in that some new entries
+ * will be walked and some will not.  So do not do this.
+ *
+ * The bucket passed to func will have a non-NULL data pointer.
+ *
+ * hash
+ *    hash table to operate on
+ *
+ * func
+ *    function to call with each data item. If this function returns
+ *    HASHWALK_ABORT then the iteration stops.
+ *
+ * arg
+ *    arbitrary argument passed as the second parameter in each call to 'func'
+ */
+extern void hash_walk(struct hash *hash,
+		      int (*func)(struct hash_bucket *, void *), void *arg);
+
+/*
+ * Remove all elements from a hash table.
+ *
+ * hash
+ *    hash table to operate on
+ *
+ * free_func
+ *    function to call with each removed item; intended to free the data
+ */
+extern void hash_clean(struct hash *hash, void (*free_func)(void *));
+
+/*
+ * Delete a hash table.
+ *
+ * This function assumes the table is empty. Call hash_clean to delete the
+ * hashtable contents if necessary.
+ *
+ * hash
+ *    hash table to delete
+ */
+extern void hash_free(struct hash *hash);
+
+/*
+ * Converts a hash table to an unsorted linked list.
+ * Does not modify the hash table in any way.
+ *
+ * hash
+ *    hash table to convert
+ */
+extern struct list *hash_to_list(struct hash *hash);
+
+/*
+ * Hash a string using the modified Bernstein hash.
+ *
+ * This is not a perfect hash function.
+ *
+ * str
+ *    string to hash
+ *
+ * Returns:
+ *    modified Bernstein hash of the string
+ */
+extern unsigned int string_hash_make(const char *);
+
+/*
+ * Install CLI commands for viewing global hash table statistics.
+ */
+extern void hash_cmd_init(void);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _ZEBRA_HASH_H */