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/** @file
*
* Definitions for the Wireshark Memory Manager Hash Multimap
* Copyright 2021, John Thacker <johnthacker@gmail.com>
* Copyright 2014, Evan Huus <eapache@gmail.com>
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#ifndef __WMEM_MULTIMAP_H__
#define __WMEM_MULTIMAP_H__
#include <glib.h>
#include "wmem_core.h"
#include "wmem_list.h"
#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */
/** @addtogroup wmem
* @{
* @defgroup wmem-multimap Hash Multimap
*
* A hash multimap implementation on top of wmem_map and wmem_tree, storing
* multiple values at each hash key in a tree indexed by a 32 bit integer.
*
* The primary use case is a protocol with an ID used as the hash lookup
* key that can be reused in a capture, and the frame number used as the
* tree key. We often want to find the most recent frame that had a certain
* ID, e.g. for request/response matching, and wmem_multimap_lookup32_le()
* serves that purpose.
*
* Since the tree implementation is a self-balancing red-black tree, lookup
* time is still O(log(n)) even though elements with equivalent hash keys
* are usually added in increasing order of frame number.
*
* NOTE: The multimap does not yet support inserting items without
* specifying the tree key, because the total capacity of individual trees
* (including deleted nodes) is not tracked.
*
* @{
*/
typedef struct _wmem_multimap_t wmem_multimap_t;
/** Creates a multimap with the given allocator scope. When the scope is emptied,
* the map is fully destroyed. Items stored in it will not be freed unless they
* were allocated from the same scope.
*
* @param allocator The allocator scope with which to create the map.
* @param hash_func The hash function used to place inserted keys.
* @param eql_func The equality function used to compare inserted keys.
* @return The newly-allocated map.
*/
WS_DLL_PUBLIC
wmem_multimap_t *
wmem_multimap_new(wmem_allocator_t *allocator,
GHashFunc hash_func, GEqualFunc eql_func)
G_GNUC_MALLOC;
/** Creates a multimap with two allocator scopes. The base structure lives in the
* metadata scope, and the map data lives in the data scope. Every time free_all
* occurs in the data scope the map is transparently emptied without affecting
* the location of the base / metadata structure.
*
* WARNING: None of the map (even the part in the metadata scope) can be used
* after the data scope has been *destroyed*.
*
* The primary use for this function is to create maps that reset for each new
* capture file that is loaded. This can be done by specifying wmem_epan_scope()
* as the metadata scope and wmem_file_scope() as the data scope.
*/
WS_DLL_PUBLIC
wmem_multimap_t *
wmem_multimap_new_autoreset(wmem_allocator_t *metadata_scope, wmem_allocator_t *data_scope,
GHashFunc hash_func, GEqualFunc eql_func)
G_GNUC_MALLOC;
/** Retrieves a list of the keys inside the multimap
*
* @param list_allocator The allocator scope for the returned list.
* @param map The multimap to extract keys from
* @return list of keys in the multimap
*/
WS_DLL_PUBLIC
wmem_list_t*
wmem_multimap_get_keys(wmem_allocator_t *list_allocator, wmem_multimap_t *map);
/** Return the total number of elements in the multimap.
*
* @param map The multimap to use
* @return the number of elements
*/
WS_DLL_PUBLIC
unsigned
wmem_multimap_size(wmem_multimap_t *map);
/** Returns the number of values in the multimap with a certain hash key.
* (Note: This is the number of current elements, so this can only be used to
* safely generate unique tree keys prior to insertion if no values have been
* removed, due to how the tree implementation works.)
*
* @param map The multimap to search in.
* @param key The primary key to lookup in the map.
* @return The number of values in the tree stored at map key, or zero if no
* tree exists at that key.
*/
WS_DLL_PUBLIC
unsigned
wmem_multimap_count(wmem_multimap_t *map, const void *key);
/** Insert a value in the multimap.
*
* @param map The multimap to insert into.
* @param key The key to insert by in the map.
* @param frame_num The key to insert by in the tree.
* @param value The value to insert.
* @return true if there was already a tree mapped at key, in which case the
* caller may safely free key. (This is not necessary if key is allocated with
* a wmem pool.)
*
* Note: as with wmem_tree, if there is already a node with the same pair
* of keys, then the existing value will simply be overwritten. This is not
* a problem if the value is wmem allocated, but if it is manually managed,
* then you must ensure that the pair is unique or do a lookup before inserting.
*/
WS_DLL_PUBLIC
bool
wmem_multimap_insert32(wmem_multimap_t *map, const void *key, uint32_t frame_num, void *value);
/** Lookup a value in the multimap combination with an exact match.
*
* @param map The multimap to search in.
* @param key The primary key to lookup in the map.
* @param frame_num The secondary key to lookup in the tree.
* @return The value stored at the keys if any, or NULL.
*/
WS_DLL_PUBLIC
void *
wmem_multimap_lookup32(wmem_multimap_t *map, const void *key, const uint32_t frame_num);
/** Lookup a value in the multimap with an exact match for the map key
* and the largest value less than or equal to the tree key. This is
* useful for request/response matching where IDs can be reused.
*
* @param map The multimap to search in.
* @param key The primary key to lookup in the map.
* @param frame_num The secondary key to lookup in the tree.
* @return The value stored at the primary key in the map and with the largest
* key in the tree that is less than or equal to the second key if any, or NULL.
*/
WS_DLL_PUBLIC
void *
wmem_multimap_lookup32_le(wmem_multimap_t *map, const void *key, const uint32_t frame_num);
/** Remove a value from the multimap. If no value is stored at that key pair,
* nothing happens. As with wmem_tree, this is not really a remove, but the
* value is set to NULL so that wmem_multimap_lookup32 not will find it.
*
* @param map The multimap to remove from.
* @param key The map key of the value to remove.
* @param frame_num The tree key of the value to remove.
* @return The (removed) value stored at the key if any, or NULL.
*/
WS_DLL_PUBLIC
void *
wmem_multimap_remove32(wmem_multimap_t *map, const void *key, const uint32_t frame_num);
/** @}
* @} */
#ifdef __cplusplus
}
#endif /* __cplusplus */
#endif /* __WMEM_MULTIMAP_H__ */
/*
* Editor modelines - https://www.wireshark.org/tools/modelines.html
*
* Local variables:
* c-basic-offset: 4
* tab-width: 8
* indent-tabs-mode: nil
* End:
*
* vi: set shiftwidth=4 tabstop=8 expandtab:
* :indentSize=4:tabSize=8:noTabs=true:
*/
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