X-Git-Url: http://git.onelab.eu/?p=libnl.git;a=blobdiff_plain;f=lib%2Fcache_mngt.c;fp=lib%2Fcache_mngt.c;h=98a26c10fcfb7e8e98a3692796be95ff495ff2ee;hp=0000000000000000000000000000000000000000;hb=4cee2ecb3b8afa0637e6f5fe4c57985a4bc740ff;hpb=2df2fbe518d5a221ce6e3ee88a3fb23fb1b94b27 diff --git a/lib/cache_mngt.c b/lib/cache_mngt.c new file mode 100644 index 0000000..98a26c1 --- /dev/null +++ b/lib/cache_mngt.c @@ -0,0 +1,254 @@ +/* + * 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) 2003-2006 Thomas Graf + */ + +/** + * @ingroup utils + * @defgroup cache_mngt Cache Management + * @{ + */ + +#include +#include +#include +#include + +/** + * @name Access Functions + * @{ + */ + +/** + * Return the cache type of the cache operations + * @arg ops cache operations + */ +char *nl_cache_ops_get_name(struct nl_cache_ops *ops) +{ + return ops->co_name; +} + +/** @} */ + +/** + * @name Message Type Association + * @{ + */ + +static struct nl_cache_ops *cache_ops; + +/** + * Associate a message type to a set of cache operations + * @arg protocol netlink protocol + * @arg message_type 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_mngt_associate(int protocol, int message_type) +{ + int i; + struct nl_cache_ops *ops; + + for (ops = cache_ops; ops; ops = ops->co_next) + for (i = 0; ops->co_msgtypes[i].mt_id >= 0; i++) + if (ops->co_msgtypes[i].mt_id == message_type && + ops->co_protocol == protocol) + return ops; + + return NULL; +} + +/** + * Convert message type to character string. + * @arg ops Cache operations. + * @arg msgtype Message type. + * @arg buf Destination buffer. + * @arg len Size of destination buffer. + * + * Converts a message type to a character string and stores it in the + * provided buffer. + * + * @return The destination buffer or the message type encoded in + * hexidecimal form if no match was found. + */ +char *nl_cache_mngt_type2name(struct nl_cache_ops *ops, int msgtype, + char *buf, size_t len) +{ + int i; + + for (i = 0; ops->co_msgtypes[i].mt_id >= 0; i++) { + if (ops->co_msgtypes[i].mt_id == msgtype) { + snprintf(buf, len, "%s::%s", + ops->co_name, + ops->co_msgtypes[i].mt_name); + return buf; + } + } + + snprintf(buf, len, "%s->0x%x()", ops->co_name, msgtype); + return buf; +} + +/** @} */ + +/** + * @name Cache Type Management + * @{ + */ + +/** + * 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_mngt_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; +} + +/** + * 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) + return nl_error(EINVAL, "No cache name specified"); + + if (nl_cache_mngt_lookup(ops->co_name)) + return nl_error(EEXIST, "Cache operations already 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 nl_error(ENOENT, "No such cache operations"); + + 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 = nl_cache_mngt_lookup(cache->c_ops->co_name); + 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 = nl_cache_mngt_lookup(cache->c_ops->co_name); + 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 cache 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_mngt_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; +} + +/** @} */ + +/** @} */