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