NAME

       memcached_get, memcached_mget, memcached_fetch, memcached_mget_execute, memcached_mget_execute_by_key -
       Get a value

LIBRARY

       C Client Library for memcached (libmemcached, -lmemcached)

SYNOPSIS

         #include <memcached.h>

         memcached_result_st *
           memcached_fetch_result (memcached_st *ptr,
                                   memcached_result_st *result,
                                   memcached_return_t *error);

         char *
           memcached_get (memcached_st *ptr,
                          const char *key, size_t key_length,
                          size_t *value_length,
                          uint32_t *flags,
                          memcached_return_t *error);

         memcached_return_t
           memcached_mget (memcached_st *ptr,
                         const char * const *keys,
                         const size_t *key_length,
                         size_t number_of_keys);
         char *
           memcached_get_by_key (memcached_st *ptr,
                                 const char *master_key, size_t master_key_length,
                                 const char *key, size_t key_length,
                                 size_t *value_length,
                                 uint32_t *flags,
                                 memcached_return_t *error);

         memcached_return_t
           memcached_mget_by_key (memcached_st *ptr,
                                  const char *master_key, size_t master_key_length,
                                  const char * const *keys,
                                  const size_t *key_length,
                                  size_t number_of_keys);

         char *
           memcached_fetch (memcached_st *ptr,
                            char *key, size_t *key_length,
                            size_t *value_length,
                            uint32_t *flags,
                            memcached_return_t *error);

         memcached_return_t
           memcached_fetch_execute (memcached_st *ptr,
                                    memcached_execute_fn *callback,
                                    void *context,
                                    uint32_t number_of_callbacks);

         memcached_return_t
           memcached_mget_execute (memcached_st *ptr,
                                   const char * const *keys,
                                   const size_t *key_length,
                                   size_t number_of_keys,
                                   memcached_execute_fn *callback,
                                   void *context,
                                   uint32_t number_of_callbacks);

         memcached_return_t
           memcached_mget_execute_by_key (memcached_st *ptr,
                                          const char *master_key,
                                          size_t master_key_length,
                                          const char * const *keys,
                                          const size_t *key_length,
                                          size_t number_of_keys,
                                          memcached_execute_fn *callback,
                                          void *context,
                                          uint32_t number_of_callbacks);

DESCRIPTION

       memcached_get() is used to fetch an individual value from the server. You must pass in a key and its
       length to fetch the object. You must supply three pointer variables which will give you the state of the
       returned object.  A uint32_t pointer to contain whatever flags you stored with the value, a size_t
       pointer which will be filled with size of of the object, and a memcached_return_t pointer to hold any
       error. The object will be returned upon success and NULL will be returned on failure. Any object returned
       by memcached_get() must be released by the caller application.

       memcached_mget() is used to select multiple keys at once. For multiple key operations it is always faster
       to use this function. This function always works asynchronously. memcached_fetch() is then used to
       retrieve any keys found. No error is given on keys that are not found. You must call either
       memcached_fetch() or memcached_fetch_result() after a successful call to memcached_mget(). You should
       continue to call these functions until they return NULL (aka no more values). If you need to quit in the
       middle of a memcached_get() call, execute a memcached_quit(). After you do this, you can issue new
       queries against the server.

       memcached_fetch() is used to fetch an individual value from the server.  memcached_mget() must always be
       called before using this method.  You must pass in a key and its length to fetch the object. You must
       supply three pointer variables which will give you the state of the returned object.  A uint32_t pointer
       to contain whatever flags you stored with the value, a size_t pointer which will be filled with size of
       of the object, and a memcached_return_t pointer to hold any error. The object will be returned upon
       success and NULL will be returned on failure. MEMCACHD_END is returned by the *error value when all
       objects that have been found are returned.  The final value upon MEMCACHED_END is null. Values returned
       by memcached_fetch() musted be free'ed by the caller. memcached_fetch() will be DEPRECATED in the near
       future, memcached_fetch_result() should be used instead.

       memcached_fetch_result() is used to return a memcached_result_st(3) structure from a memcached server.
       The result object is forward compatible with changes to the server. For more information please refer to
       the memcached_result_st(3) help. This function will dynamically allocate a result structure for you if
       you do not pass one to the function.

       memcached_fetch_execute() is a callback function for result sets. Instead of returning the results to you
       for processing, it passes each of the result sets to the list of functions you provide. It passes to the
       function a memcached_st that can be cloned for use in the called function (it can not be used directly).
       It also passes a result set which does not need to be freed.  Finally it passes a "context". This is just
       a pointer to a memory reference you supply the calling function. Currently only one value is being passed
       to each function call. In the future there will be an option to allow this to be an array.

       memcached_mget_execute() and memcached_mget_execute_by_key() is similar to memcached_mget(), but it may
       trigger the supplied callbacks with result sets while sending out the queries. If you try to perform a
       really large multiget with memcached_mget() you may encounter a deadlock in the OS kernel (we fail to
       write data to the socket because the input buffer is full). memcached_mget_execute() solves this problem
       by processing some of the results before continuing sending out requests. Please note that this function
       is only available in the binary protocol.

       memcached_get_by_key() and memcached_mget_by_key() behave in a similar nature as memcached_get() and
       memcached_mget(). The difference is that they take a master key that is used for determining which server
       an object was stored if key partitioning was used for storage.

       All of the above functions are not supported when the "MEMCACHED_BEHAVIOR_USE_UDP" has been set.
       Executing any of these functions with this behavior on will result in "MEMCACHED_NOT_SUPPORTED" being
       returned or, for those functions which do not return a "memcached_return_t", the error function parameter
       will be set to "MEMCACHED_NOT_SUPPORTED".

RETURN

       All objects returned must be freed by the calling application.  memcached_get() and memcached_fetch()
       will return NULL on error. You must look at the value of error to determine what the actual error was.

       MEMCACHED_KEY_TOO_BIG is set to error whenever memcached_fetch() was used and the key was set larger then
       MEMCACHED_MAX_KEY, which was the largest key allowed for the original memcached ascii server.

HOME

       To find out more information please check: <https://launchpad.net/libmemcached>

AUTHOR

       Brian Aker, <brian@tangent.org>

SEE ALSO

       memcached(1) libmemcached(3) memcached_strerror(3)