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/*
* lib/cache_mngt.c Cache Management
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation version 2.1
* of the License.
*
* Copyright (c) 2003-2008 Thomas Graf <tgraf@suug.ch>
*/
/**
* @ingroup core
* @defgroup cache_mngt Caching
* @{
*/
#include <netlink-local.h>
#include <netlink/netlink.h>
#include <netlink/cache.h>
#include <netlink/utils.h>
static struct nl_cache_ops *cache_ops;
/**
* @name Cache Operations Sets
* @{
*/
/**
* Lookup the set cache operations of a certain cache type
* @arg name name of the cache type
*
* @return The cache operations or NULL if no operations
* have been registered under the specified name.
*/
struct nl_cache_ops *nl_cache_ops_lookup(const char *name)
{
struct nl_cache_ops *ops;
for (ops = cache_ops; ops; ops = ops->co_next)
if (!strcmp(ops->co_name, name))
return ops;
return NULL;
}
/**
* Associate a message type to a set of cache operations
* @arg protocol netlink protocol
* @arg msgtype netlink message type
*
* Associates the specified netlink message type with
* a registered set of cache operations.
*
* @return The cache operations or NULL if no association
* could be made.
*/
struct nl_cache_ops *nl_cache_ops_associate(int protocol, int msgtype)
{
int i;
struct nl_cache_ops *ops;
for (ops = cache_ops; ops; ops = ops->co_next) {
if (ops->co_protocol != protocol)
continue;
for (i = 0; ops->co_msgtypes[i].mt_id >= 0; i++)
if (ops->co_msgtypes[i].mt_id == msgtype)
return ops;
}
return NULL;
}
/**
* Lookup message type cache association
* @arg ops cache operations
* @arg msgtype netlink message type
*
* Searches for a matching message type association ing the specified
* cache operations.
*
* @return A message type association or NULL.
*/
struct nl_msgtype *nl_msgtype_lookup(struct nl_cache_ops *ops, int msgtype)
{
int i;
for (i = 0; ops->co_msgtypes[i].mt_id >= 0; i++)
if (ops->co_msgtypes[i].mt_id == msgtype)
return &ops->co_msgtypes[i];
return NULL;
}
static struct nl_cache_ops *cache_ops_lookup_for_obj(struct nl_object_ops *obj_ops)
{
struct nl_cache_ops *ops;
for (ops = cache_ops; ops; ops = ops->co_next)
if (ops->co_obj_ops == obj_ops)
return ops;
return NULL;
}
/**
* Call a function for each registered cache operation
* @arg cb Callback function to be called
* @arg arg User specific argument.
*/
void nl_cache_ops_foreach(void (*cb)(struct nl_cache_ops *, void *), void *arg)
{
struct nl_cache_ops *ops;
for (ops = cache_ops; ops; ops = ops->co_next)
cb(ops, arg);
}
/**
* Register a set of cache operations
* @arg ops cache operations
*
* Called by users of caches to announce the avaibility of
* a certain cache type.
*
* @return 0 on success or a negative error code.
*/
int nl_cache_mngt_register(struct nl_cache_ops *ops)
{
if (!ops->co_name || !ops->co_obj_ops)
return -NLE_INVAL;
if (nl_cache_ops_lookup(ops->co_name))
return -NLE_EXIST;
ops->co_next = cache_ops;
cache_ops = ops;
NL_DBG(1, "Registered cache operations %s\n", ops->co_name);
return 0;
}
/**
* Unregister a set of cache operations
* @arg ops cache operations
*
* Called by users of caches to announce a set of
* cache operations is no longer available. The
* specified cache operations must have been registered
* previously using nl_cache_mngt_register()
*
* @return 0 on success or a negative error code
*/
int nl_cache_mngt_unregister(struct nl_cache_ops *ops)
{
struct nl_cache_ops *t, **tp;
for (tp = &cache_ops; (t=*tp) != NULL; tp = &t->co_next)
if (t == ops)
break;
if (!t)
return -NLE_NOCACHE;
NL_DBG(1, "Unregistered cache operations %s\n", ops->co_name);
*tp = t->co_next;
return 0;
}
/** @} */
/**
* @name Global Cache Provisioning/Requiring
* @{
*/
/**
* Provide a cache for global use
* @arg cache cache to provide
*
* Offers the specified cache to be used by other modules.
* Only one cache per type may be shared at a time,
* a previsouly provided caches will be overwritten.
*/
void nl_cache_mngt_provide(struct nl_cache *cache)
{
struct nl_cache_ops *ops;
ops = cache_ops_lookup_for_obj(cache->c_ops->co_obj_ops);
if (!ops)
BUG();
else
ops->co_major_cache = cache;
}
/**
* Unprovide a cache for global use
* @arg cache cache to unprovide
*
* Cancels the offer to use a cache globally. The
* cache will no longer be returned via lookups but
* may still be in use.
*/
void nl_cache_mngt_unprovide(struct nl_cache *cache)
{
struct nl_cache_ops *ops;
ops = cache_ops_lookup_for_obj(cache->c_ops->co_obj_ops);
if (!ops)
BUG();
else if (ops->co_major_cache == cache)
ops->co_major_cache = NULL;
}
/**
* Demand the use of a global cache
* @arg name name of the required object type
*
* Trys to find a cache of the specified type for global
* use.
*
* @return A cache provided by another subsystem of the
* specified type marked to be available.
*/
struct nl_cache *nl_cache_mngt_require(const char *name)
{
struct nl_cache_ops *ops;
ops = nl_cache_ops_lookup(name);
if (!ops || !ops->co_major_cache) {
fprintf(stderr, "Application BUG: Your application must "
"call nl_cache_mngt_provide() and\nprovide a valid "
"%s cache to be used for internal lookups.\nSee the "
" API documentation for more details.\n", name);
return NULL;
}
return ops->co_major_cache;
}
/** @} */
/** @} */
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