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Typedefs | Functions

Typedefs

typedef struct _wmem_multimap_t wmem_multimap_t
 

Functions

WS_DLL_PUBLIC wmem_multimap_twmem_multimap_new (wmem_allocator_t *allocator, GHashFunc hash_func, GEqualFunc eql_func) G_GNUC_MALLOC
 
WS_DLL_PUBLIC wmem_multimap_twmem_multimap_new_autoreset (wmem_allocator_t *metadata_scope, wmem_allocator_t *data_scope, GHashFunc hash_func, GEqualFunc eql_func) G_GNUC_MALLOC
 
WS_DLL_PUBLIC wmem_list_twmem_multimap_get_keys (wmem_allocator_t *list_allocator, wmem_multimap_t *map)
 
WS_DLL_PUBLIC unsigned wmem_multimap_size (wmem_multimap_t *map)
 
WS_DLL_PUBLIC unsigned wmem_multimap_count (wmem_multimap_t *map, const void *key)
 
WS_DLL_PUBLIC bool wmem_multimap_insert32 (wmem_multimap_t *map, const void *key, uint32_t frame_num, void *value)
 
WS_DLL_PUBLIC void * wmem_multimap_lookup32 (wmem_multimap_t *map, const void *key, const uint32_t frame_num)
 
WS_DLL_PUBLIC void * wmem_multimap_lookup32_le (wmem_multimap_t *map, const void *key, const uint32_t frame_num)
 
WS_DLL_PUBLIC void * wmem_multimap_remove32 (wmem_multimap_t *map, const void *key, const uint32_t frame_num)
 

Detailed Description

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.

Function Documentation

◆ wmem_multimap_count()

WS_DLL_PUBLIC unsigned wmem_multimap_count ( wmem_multimap_t map,
const void *  key 
)

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.)

Parameters
mapThe multimap to search in.
keyThe primary key to lookup in the map.
Returns
The number of values in the tree stored at map key, or zero if no tree exists at that key.

◆ wmem_multimap_get_keys()

WS_DLL_PUBLIC wmem_list_t * wmem_multimap_get_keys ( wmem_allocator_t list_allocator,
wmem_multimap_t map 
)

Retrieves a list of the keys inside the multimap

Parameters
list_allocatorThe allocator scope for the returned list.
mapThe multimap to extract keys from
Returns
list of keys in the multimap

◆ wmem_multimap_insert32()

WS_DLL_PUBLIC bool wmem_multimap_insert32 ( wmem_multimap_t map,
const void *  key,
uint32_t  frame_num,
void *  value 
)

Insert a value in the multimap.

Parameters
mapThe multimap to insert into.
keyThe key to insert by in the map.
frame_numThe key to insert by in the tree.
valueThe value to insert.
Returns
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.

◆ wmem_multimap_lookup32()

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 combination with an exact match.

Parameters
mapThe multimap to search in.
keyThe primary key to lookup in the map.
frame_numThe secondary key to lookup in the tree.
Returns
The value stored at the keys if any, or NULL.

◆ wmem_multimap_lookup32_le()

WS_DLL_PUBLIC void * wmem_multimap_lookup32_le ( 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.

Parameters
mapThe multimap to search in.
keyThe primary key to lookup in the map.
frame_numThe secondary key to lookup in the tree.
Returns
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.

◆ wmem_multimap_new()

WS_DLL_PUBLIC wmem_multimap_t * wmem_multimap_new ( wmem_allocator_t allocator,
GHashFunc  hash_func,
GEqualFunc  eql_func 
)

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.

Parameters
allocatorThe allocator scope with which to create the map.
hash_funcThe hash function used to place inserted keys.
eql_funcThe equality function used to compare inserted keys.
Returns
The newly-allocated map.

◆ wmem_multimap_new_autoreset()

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 
)

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.

◆ wmem_multimap_remove32()

WS_DLL_PUBLIC void * wmem_multimap_remove32 ( 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.

Parameters
mapThe multimap to remove from.
keyThe map key of the value to remove.
frame_numThe tree key of the value to remove.
Returns
The (removed) value stored at the key if any, or NULL.

◆ wmem_multimap_size()

WS_DLL_PUBLIC unsigned wmem_multimap_size ( wmem_multimap_t map)

Return the total number of elements in the multimap.

Parameters
mapThe multimap to use
Returns
the number of elements