libnl 3.5.0

Macros
Cache
Core Library (libnl) » Caching System

## Macros
#define | NL_CACHE_AF_ITER 0x0001
| Explicitely iterate over all address families when updating the cache.

## Access Functions
int | nl_cache_nitems (struct nl_cache *cache)
| Return the number of items in the cache. More...
int | nl_cache_nitems_filter (struct nl_cache *cache, struct nl_object *filter)
| Return the number of items matching a filter in the cache. More...
int | nl_cache_is_empty (struct nl_cache *cache)
| Returns true if the cache is empty. More...
struct nl_cache_ops * | nl_cache_get_ops (struct nl_cache *cache)
| Return the operations set of the cache. More...
struct nl_object * | nl_cache_get_first (struct nl_cache *cache)
| Return the first element in the cache. More...
struct nl_object * | nl_cache_get_last (struct nl_cache *cache)
| Return the last element in the cache. More...
struct nl_object * | nl_cache_get_next (struct nl_object *obj)
| Return the next element in the cache. More...
struct nl_object * | nl_cache_get_prev (struct nl_object *obj)
| Return the previous element in the cache. More...

## Cache Allocation/Deletion
struct nl_cache * | nl_cache_alloc (struct nl_cache_ops *ops)
| Allocate new cache. More...
int | nl_cache_alloc_and_fill (struct nl_cache_ops *ops, struct nl_sock *sock, struct nl_cache **result)
| Allocate new cache and fill it. More...
int | nl_cache_alloc_name (const char *kind, struct nl_cache **result)
| Allocate new cache based on type name. More...
struct nl_cache * | nl_cache_subset (struct nl_cache *orig, struct nl_object *filter)
| Allocate new cache containing a subset of an existing cache. More...
struct nl_cache * | nl_cache_clone (struct nl_cache *cache)
| Allocate new cache and copy the contents of an existing cache. More...
void | nl_cache_clear (struct nl_cache *cache)
| Remove all objects of a cache. More...
void | nl_cache_get (struct nl_cache *cache)
| Increase reference counter of cache. More...
void | nl_cache_free (struct nl_cache *cache)
| Free a cache. More...
void | nl_cache_put (struct nl_cache *cache)

## Cache Modifications
int | nl_cache_add (struct nl_cache *cache, struct nl_object *obj)
| Add object to cache. More...
int | nl_cache_move (struct nl_cache *cache, struct nl_object *obj)
| Move object from one cache to another. More...
void | nl_cache_remove (struct nl_object *obj)
| Remove object from cache. More...

## Synchronization
void | nl_cache_set_arg1 (struct nl_cache *cache, int arg)
| Set synchronization arg1 of cache. More...
void | nl_cache_set_arg2 (struct nl_cache *cache, int arg)
| Set synchronization arg2 of cache. More...
void | nl_cache_set_flags (struct nl_cache *cache, unsigned int flags)
| Set cache flags. More...
int | nl_cache_pickup_checkdup (struct nl_sock *sk, struct nl_cache *cache)
| Pickup a netlink dump response and put it into a cache. More...
int | nl_cache_pickup (struct nl_sock *sk, struct nl_cache *cache)
| Pickup a netlink dump response and put it into a cache. More...
int | nl_cache_include (struct nl_cache *cache, struct nl_object *obj, change_func_t change_cb, void *data)
int | nl_cache_include_v2 (struct nl_cache *cache, struct nl_object *obj, change_func_v2_t change_cb, void *data)
int | nl_cache_resync (struct nl_sock *sk, struct nl_cache *cache, change_func_t change_cb, void *data)

## Parsing
int | nl_cache_parse_and_add (struct nl_cache *cache, struct nl_msg *msg)
| Parse a netlink message and add it to the cache. More...
int | nl_cache_refill (struct nl_sock *sk, struct nl_cache *cache)
| (Re)fill a cache with the contents in the kernel. More...

## Utillities
struct nl_object * | nl_cache_search (struct nl_cache *cache, struct nl_object *needle)
| Search object in cache. More...
struct nl_object * | nl_cache_find (struct nl_cache *cache, struct nl_object *filter)
| Find object in cache. More...
void | nl_cache_mark_all (struct nl_cache *cache)
| Mark all objects of a cache. More...

## Dumping
void | nl_cache_dump (struct nl_cache *cache, struct nl_dump_params *params)
| Dump all elements of a cache. More...
void | nl_cache_dump_filter (struct nl_cache *cache, struct nl_dump_params *params, struct nl_object *filter)
| Dump all elements of a cache (filtered). More...

## Iterators
void | nl_cache_foreach (struct nl_cache *cache, void(*cb)(struct nl_object *, void *), void *arg)
| Call a callback on each element of the cache. More...
void | nl_cache_foreach_filter (struct nl_cache *cache, struct nl_object *filter, void(*cb)(struct nl_object *, void *), void *arg)
| Call a callback on each element of the cache (filtered). More...

## Detailed Description

Cache Management | | Type Specific Cache Operations
| | +----------------+ +------------+
| request update | | msg_parser |
| | +----------------+ +------------+
+- - - - -^- - - - - - - -^- -|- - - -
nl_cache_update: | | | |
1) --------- co_request_update ------+ | |
| | |
2) destroy old cache +----------- pp_cb ---------|---+
| | |
3) ---------- nl_recvmsgs ----------+ +- cb_valid -+
+--------------+ | | | |
| nl_cache_add |<-----+ + - - -v- -|- - - - - - - - - - -
+--------------+ | | +-------------+
| nl_recvmsgs |
| | +-----|-^-----+
+---v-|---+
| | | nl_recv |
+---------+
| | Core Netlink

Related sections in the development guide:

- Caching System (Netlink Core Library Development Guide)

## Header

#include <netlink/cache.h>

## Function Documentation

## ◆ nl_cache_nitems()

int nl_cache_nitems | ( | struct nl_cache * | cache | ) |

Return the number of items in the cache.

Parameters

  cache | cache handle

Definition at line 69 of file cache.c.

## ◆ nl_cache_nitems_filter()

int nl_cache_nitems_filter | ( | struct nl_cache * | cache,
|  | struct nl_object * | filter
| ) |  |

Return the number of items matching a filter in the cache.

Parameters

  cache | Cache object.
  filter | Filter object.

Definition at line 79 of file cache.c.

References nl_object_match_filter().

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## ◆ nl_cache_is_empty()

int nl_cache_is_empty | ( | struct nl_cache * | cache | ) |

Returns true if the cache is empty.

Parameters

  cache | Cache to check

Returns
  true if the cache is empty, otherwise false is returned.

Definition at line 102 of file cache.c.

## ◆ nl_cache_get_ops()

struct nl_cache_ops* nl_cache_get_ops | ( | struct nl_cache * | cache | ) |

Return the operations set of the cache.

Parameters

  cache | cache handle

Definition at line 111 of file cache.c.

Referenced by nl_cache_clone().

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## ◆ nl_cache_get_first()

struct nl_object* nl_cache_get_first | ( | struct nl_cache * | cache | ) |

Return the first element in the cache.

Parameters

  cache | cache handle

Definition at line 120 of file cache.c.

## ◆ nl_cache_get_last()

struct nl_object* nl_cache_get_last | ( | struct nl_cache * | cache | ) |

Return the last element in the cache.

Parameters

  cache | cache handle

Definition at line 133 of file cache.c.

## ◆ nl_cache_get_next()

struct nl_object* nl_cache_get_next | ( | struct nl_object * | obj | ) |

Return the next element in the cache.

Parameters

  obj | current object

Definition at line 146 of file cache.c.

## ◆ nl_cache_get_prev()

struct nl_object* nl_cache_get_prev | ( | struct nl_object * | obj | ) |

Return the previous element in the cache.

Parameters

  obj | current object

Definition at line 159 of file cache.c.

## ◆ nl_cache_alloc()

struct nl_cache* nl_cache_alloc | ( | struct nl_cache_ops * | ops | ) |

Allocate new cache.

Parameters

  ops | Cache operations

Allocate and initialize a new cache based on the cache operations provided.

Returns
  Allocated cache or NULL if allocation failed.

Definition at line 184 of file cache.c.

References nl_hash_table_alloc().

Referenced by flnl_result_alloc_cache(), idiagnl_msg_alloc_cache(), nl_cache_alloc_and_fill(), nl_cache_alloc_name(), nl_cache_clone(), nl_cache_mngr_add(), nl_cache_subset(), rtnl_class_alloc_cache(), rtnl_cls_alloc_cache(), rtnl_link_alloc_cache_flags(), rtnl_neigh_alloc_cache_flags(), rtnl_route_alloc_cache(), and rtnl_rule_alloc_cache().

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## ◆ nl_cache_alloc_and_fill()

int nl_cache_alloc_and_fill | ( | struct nl_cache_ops * | ops,
|  | struct nl_sock * | sock,
|  | struct nl_cache ** | result
| ) |  |

Allocate new cache and fill it.

Parameters

  ops | Cache operations
  sock | Netlink socket
  result | Result pointer

Allocate new cache and fill it. Equivalent to calling:

cache = nl_cache_alloc(ops);
nl_cache_refill(sock, cache);

See also
  nl_cache_alloc

Returns
  0 on success or a negative error code.

Definition at line 234 of file cache.c.

References nl_cache_alloc(), nl_cache_free(), and nl_cache_refill().

Referenced by genl_ctrl_alloc_cache(), nfnl_ct_alloc_cache(), nfnl_exp_alloc_cache(), rtnl_neigh_alloc_cache(), rtnl_neightbl_alloc_cache(), and rtnl_qdisc_alloc_cache().

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## ◆ nl_cache_alloc_name()

int nl_cache_alloc_name | ( | const char * | kind,
|  | struct nl_cache ** | result
| ) |  |

Allocate new cache based on type name.

Parameters

  kind | Name of cache type
  result | Result pointer

Lookup cache ops via nl_cache_ops_lookup() and allocate the cache by calling nl_cache_alloc(). Stores the allocated cache in the result pointer provided.

See also
  nl_cache_alloc

Returns
  0 on success or a negative error code.

Definition at line 265 of file cache.c.

References nl_cache_alloc(), nl_cache_ops_lookup_safe(), and nl_cache_ops_put().

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## ◆ nl_cache_subset()

struct nl_cache* nl_cache_subset | ( | struct nl_cache * | orig,
|  | struct nl_object * | filter
| ) |  |

Allocate new cache containing a subset of an existing cache.

Parameters

  orig | Original cache to base new cache on
  filter | Filter defining the subset to be filled into the new cache

Allocates a new cache matching the type of the cache specified by `orig`. Iterates over the `orig` cache applying the specified `filter` and copies all objects that match to the new cache.

The copied objects are clones but do not contain a reference to each other. Later modifications to objects in the original cache will not affect objects in the new cache.

Returns
  A newly allocated cache or NULL.

Definition at line 298 of file cache.c.

References nl_cache_add(), nl_cache_alloc(), and nl_object_match_filter().

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## ◆ nl_cache_clone()

struct nl_cache* nl_cache_clone | ( | struct nl_cache * | cache | ) |

Allocate new cache and copy the contents of an existing cache.

Parameters

  cache | Original cache to base new cache on

Allocates a new cache matching the type of the cache specified by `cache`. Iterates over the `cache` cache and copies all objects to the new cache.

The copied objects are clones but do not contain a reference to each other. Later modifications to objects in the original cache will not affect objects in the new cache.

Returns
  A newly allocated cache or NULL.

Definition at line 338 of file cache.c.

References nl_cache_add(), nl_cache_alloc(), and nl_cache_get_ops().

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## ◆ nl_cache_clear()

void nl_cache_clear | ( | struct nl_cache * | cache | ) |

Remove all objects of a cache.

Parameters

  cache | Cache to clear

The objects are unliked/removed from the cache by calling nl_cache_remove() on each object in the cache. If any of the objects to not contain any further references to them, those objects will be freed.

Unlike with nl_cache_free(), the cache is not freed just emptied.

Definition at line 367 of file cache.c.

References nl_cache_remove().

Referenced by nl_cache_refill().

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## ◆ nl_cache_get()

void nl_cache_get | ( | struct nl_cache * | cache | ) |

Increase reference counter of cache.

Parameters

  cache | Cache

Definition at line 392 of file cache.c.

Referenced by nl_cache_mngt_require_safe().

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## ◆ nl_cache_free()

void nl_cache_free | ( | struct nl_cache * | cache | ) |

Free a cache.

Parameters

  cache | Cache to free.

Calls nl_cache_clear() to remove all objects associated with the cache and frees the cache afterwards.

See also
  nl_cache_clear()

Definition at line 409 of file cache.c.

Referenced by genl_mngt_resolve(), genl_ops_resolve(), nl_cache_alloc_and_fill(), nl_cache_mngr_add(), and nl_cache_mngr_free().

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## ◆ nl_cache_add()

int nl_cache_add | ( | struct nl_cache * | cache,
|  | struct nl_object * | obj
| ) |  |

Add object to cache.

Parameters

  cache | Cache
  obj | Object to be added to the cache

Adds the object `obj` to the specified `cache`. In case the object is already associated with another cache, the object is cloned before adding it to the cache. In this case, the sole reference to the object will be the one of the cache. Therefore clearing/freeing the cache will result in the object being freed again.

If the object has not been associated with a cache yet, the reference counter of the object is incremented to account for the additional reference.

The type of the object and cache must match, otherwise an error is returned (-NLE_OBJ_MISMATCH).

See also
  nl_cache_move()

Returns
  0 or a negative error code.

Definition at line 480 of file cache.c.

References nl_object_clone(), and nl_object_get().

Referenced by nl_cache_clone(), and nl_cache_subset().

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## ◆ nl_cache_move()

int nl_cache_move | ( | struct nl_cache * | cache,
|  | struct nl_object * | obj
| ) |  |

Move object from one cache to another.

Parameters

  cache | Cache to move object to.
  obj | Object subject to be moved

Removes the the specified object `obj` from its associated cache and moves it to another cache.

If the object is not associated with a cache, the function behaves just like nl_cache_add().

The type of the object and cache must match, otherwise an error is returned (-NLE_OBJ_MISMATCH).

See also
  nl_cache_add()

Returns
  0 on success or a negative error code.

Definition at line 524 of file cache.c.

References nl_cache_remove(), and nl_object_get().

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## ◆ nl_cache_remove()

void nl_cache_remove | ( | struct nl_object * | obj | ) |

Remove object from cache.

Parameters

  obj | Object to remove from cache

Removes the object `obj` from the cache it is associated with. The reference counter of the object will be decremented. If the reference to the object was the only one remaining, the object will be freed.

If no cache is associated with the object, this function is a NOP.

Definition at line 552 of file cache.c.

References nl_hash_table_del(), and nl_object_put().

Referenced by nl_cache_clear(), and nl_cache_move().

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## ◆ nl_cache_set_arg1()

void nl_cache_set_arg1 | ( | struct nl_cache * | cache,
|  | int | arg
| ) |  |

Set synchronization arg1 of cache.

Parameters

  cache | Cache
  arg | argument

Synchronization arguments are used to specify filters when requesting dumps from the kernel.

Definition at line 591 of file cache.c.

Referenced by nl_cache_refill().

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## ◆ nl_cache_set_arg2()

void nl_cache_set_arg2 | ( | struct nl_cache * | cache,
|  | int | arg
| ) |  |

Set synchronization arg2 of cache.

Parameters

  cache | Cache
  arg | argument

Synchronization arguments are used to specify filters when requesting dumps from the kernel.

Definition at line 604 of file cache.c.

## ◆ nl_cache_set_flags()

void nl_cache_set_flags | ( | struct nl_cache * | cache,
|  | unsigned int | flags
| ) |  |

Set cache flags.

Parameters

  cache | Cache
  flags | Flags

Definition at line 614 of file cache.c.

## ◆ nl_cache_pickup_checkdup()

int nl_cache_pickup_checkdup | ( | struct nl_sock * | sk,
|  | struct nl_cache * | cache
| ) |  |

Pickup a netlink dump response and put it into a cache.

Parameters

  sk | Netlink socket.
  cache | Cache to put items into.

Waits for netlink messages to arrive, parses them and puts them into the specified cache.

Returns
  0 on success or a negative error code.

Definition at line 764 of file cache.c.

Referenced by flnl_lookup().

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## ◆ nl_cache_pickup()

int nl_cache_pickup | ( | struct nl_sock * | sk,
|  | struct nl_cache * | cache
| ) |  |

Pickup a netlink dump response and put it into a cache.

Parameters

  sk | Netlink socket.
  cache | Cache to put items into.

Waits for netlink messages to arrive, parses them and puts them into the specified cache. If an old object with same key attributes is present in the cache, it is replaced with the new object. If the old object type supports an update operation, an update is attempted before a replace.

Returns
  0 on success or a negative error code.

Definition at line 782 of file cache.c.

## ◆ nl_cache_parse_and_add()

int nl_cache_parse_and_add | ( | struct nl_cache * | cache,
|  | struct nl_msg * | msg
| ) |  |

Parse a netlink message and add it to the cache.

Parameters

  cache | cache to add element to
  msg | netlink message

Parses a netlink message by calling the cache specific message parser and adds the new element to the cache. If an old object with same key attributes is present in the cache, it is replaced with the new object. If the old object type supports an update operation, an update is attempted before a replace.

Returns
  0 or a negative error code.

Definition at line 1021 of file cache.c.

## ◆ nl_cache_refill()

int nl_cache_refill | ( | struct nl_sock * | sk,
|  | struct nl_cache * | cache
| ) |  |

(Re)fill a cache with the contents in the kernel.

Parameters

  sk | Netlink socket.
  cache | cache to update

Clears the specified cache and fills it with the current state in the kernel.

Returns
  0 or a negative error code.

Definition at line 1041 of file cache.c.

References NL_CACHE_AF_ITER, nl_cache_clear(), and nl_cache_set_arg1().

Referenced by nl_cache_alloc_and_fill().

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## ◆ nl_cache_search()

struct nl_object* nl_cache_search | ( | struct nl_cache * | cache,
|  | struct nl_object * | needle
| ) |  |

Search object in cache.

Parameters

  cache | Cache
  needle | Object to look for.

Searches the cache for an object which matches the object `needle`. The function nl_object_identical() is used to determine if the objects match. If a matching object is found, the reference counter is incremented and the object is returned.

Therefore, if an object is returned, the reference to the object must be returned by calling nl_object_put() after usage.

Returns
  Reference to object or NULL if not found.

Definition at line 1114 of file cache.c.

## ◆ nl_cache_find()

struct nl_object* nl_cache_find | ( | struct nl_cache * | cache,
|  | struct nl_object * | filter
| ) |  |

Find object in cache.

Parameters

  cache | Cache
  filter | object acting as a filter

Searches the cache for an object which matches the object filter. If the filter attributes matches the object type id attributes, and the cache supports hash lookups, a faster hashtable lookup is used to return the object. Else, function nl_object_match_filter() is used to determine if the objects match. If a matching object is found, the reference counter is incremented and the object is returned.

Therefore, if an object is returned, the reference to the object must be returned by calling nl_object_put() after usage.

Returns
  Reference to object or NULL if not found.

Definition at line 1149 of file cache.c.

References nl_object_get_id_attrs().

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## ◆ nl_cache_mark_all()

void nl_cache_mark_all | ( | struct nl_cache * | cache | ) |

Mark all objects of a cache.

Parameters

  cache | Cache

Marks all objects of a cache by calling nl_object_mark() on each object associated with the cache.

Definition at line 1178 of file cache.c.

References nl_object_mark().

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## ◆ nl_cache_dump()

void nl_cache_dump | ( | struct nl_cache * | cache,
|  | struct nl_dump_params * | params
| ) |  |

Dump all elements of a cache.

Parameters

  cache | cache to dump
  params | dumping parameters

Dumps all elements of the cache to the file descriptor fd.

Definition at line 1203 of file cache.c.

References nl_cache_dump_filter().

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## ◆ nl_cache_dump_filter()

void nl_cache_dump_filter | ( | struct nl_cache * | cache,
|  | struct nl_dump_params * | params,
|  | struct nl_object * | filter
| ) |  |

Dump all elements of a cache (filtered).

Parameters

  cache | cache to dump
  params | dumping parameters (optional)
  filter | filter object

Dumps all elements of the cache to the file descriptor fd given they match the given filter filter.

Definition at line 1217 of file cache.c.

References nl_dump_params::dp_buf, nl_dump_params::dp_buflen, nl_dump_params::dp_type, NL_DUMP_DETAILS, and nl_object_match_filter().

Referenced by nl_cache_dump().

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## ◆ nl_cache_foreach()

void nl_cache_foreach | ( | struct nl_cache * | cache,
|  | void(*)(struct nl_object *, void *) | cb,
|  | void * | arg
| ) |  |

Call a callback on each element of the cache.

Parameters

  cache | cache to iterate on
  cb | callback function
  arg | argument passed to callback function

Calls a callback function cb on each element of the cache. The argument arg is passed on the callback function.

Definition at line 1266 of file cache.c.

References nl_cache_foreach_filter().

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## ◆ nl_cache_foreach_filter()

void nl_cache_foreach_filter | ( | struct nl_cache * | cache,
|  | struct nl_object * | filter,
|  | void(*)(struct nl_object *, void *) | cb,
|  | void * | arg
| ) |  |

Call a callback on each element of the cache (filtered).

Parameters

  cache | cache to iterate on
  filter | filter object
  cb | callback function
  arg | argument passed to callback function

Calls a callback function cb on each element of the cache that matches the filter. The argument arg is passed on to the callback function.

Definition at line 1283 of file cache.c.

References nl_object_get(), nl_object_match_filter(), and nl_object_put().

Referenced by nl_cache_foreach().

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