git.m6w6.name Git - awesomized/libmemcached/blob - docs/memcached_get.pod

   1 =head1 NAME
   2
   3 memcached_get, memcached_mget, memcached_fetch
   4
   5 =head1 LIBRARY
   6
   7 C Client Library for memcached (libmemcached, -lmemcached)
   8
   9 =head1 SYNOPSIS
  10
  11   #include <memcached.h>
  12
  13   memcached_result_st *
  14   memcached_fetch_result(memcached_st *ptr,
  15                        memcached_result_st *result,
  16                        memcached_return *error);
  17
  18   char *memcached_get (memcached_st *ptr,
  19                        char *key, size_t key_length,
  20                        size_t *value_length,
  21                        uint16_t *flags,
  22                        memcached_return *error);
  23
  24   memcached_return
  25   memcached_mget (memcached_st *ptr,
  26                   char **keys, size_t *key_length,
  27                   unsigned int number_of_keys);
  28   char *
  29   memcached_get_by_key(memcached_st *ptr,
  30                        char *master_key, size_t master_key_length,
  31                        char *key, size_t key_length,
  32                        size_t *value_length,
  33                        uint16_t *flags,
  34                        memcached_return *error);
  35
  36   memcached_return
  37   memcached_mget_by_key(memcached_st *ptr,
  38                         char *master_key, size_t master_key_length,
  39                         char **keys, size_t *key_length,
  40                         unsigned int number_of_keys);
  41
  42   char *memcached_fetch (memcached_st *ptr,
  43                          char *key, size_t *key_length,
  44                          size_t *value_length,
  45                          uint16_t *flags,
  46                          memcached_return *error);
  47   memcached_return
  48   memcached_fetch_execute(memcached_st *ptr,
  49                           unsigned int (*callback[])(memcached_st *ptr, memcached_result_st *result, void *context),
  50                           void *context,
  51                           unsigned int number_of_callbacks
  52                          )
  53
  54 =head1 DESCRIPTION
  55
  56 memcached_get() is used to fetch an individual value from the server. You
  57 must pass in a key and its length to fetch the object. You must supply
  58 three pointer variables which will give you the state of the returned
  59 object.  A uint16_t pointer to contain whatever flags you stored with the value,
  60 a size_t pointer which will be filled with size of of the object, and a
  61 memcached_return pointer to hold any error. The object will be returned
  62 upon success and NULL will be returned on failure.
  63
  64 memcached_mget() is used to select multiple keys at once. For multiple key
  65 operations it is always faster to use this function. This function always
  66 works asynchronously. memcached_fetch() is then used to retrieve any keys
  67 found. No error is given on keys that are not found. You must call either
  68 memcached_fetch() or memcached_fetch_result() after a successful call to
  69 memcached_mget(). You should continue to call these functions until they
  70 return NULL (aka no more values). If you need to quit in the middle of a
  71 memcached_get() call, execute a memcached_quit(). After you do this, you can
  72 issue new queries against the server.
  73
  74 memcached_fetch() is used to fetch an individual value from the server.
  75 memcached_mget() must always be called before using this method.  You
  76 must pass in a key and its length to fetch the object. You must supply
  77 three pointer variables which will give you the state of the returned
  78 object.  A uint16_t pointer to contain whatever flags you stored with the value,
  79 a size_t pointer which will be filled with size of of the object, and a
  80 memcached_return pointer to hold any error. The object will be returned
  81 upon success and NULL will be returned on failure.
  82
  83 memcached_fetch_result() is used to return a memcached_result_st(3) structure
  84 from a memcached server. The result object is forward compatible with changes
  85 to the server. For more information please refer to the memcached_result_st(3)
  86 help. This function will dynamically allocate a result structure for you
  87 if you do not pass one to the function.
  88
  89 memcached_fetch_execute() is a callback function for result sets. Instead
  90 of returning the results to you for processing, it passes each of the
  91 result sets to the list of functions you provide. It passes to the function
  92 a memcached_st that can be cloned for use in called the cluster (it can not
  93 be used directly). It also passed a result set which does not need to be freed.
  94 Finally it passes a "context". This is just a pointer to a memory reference
  95 you supply the calling function. Currently only one value is being passed
  96 to each function call. In the future there will be an option to allow this
  97 to be an array.
  98
  99 memcached_get_by_key() and memcached_mget_by_key() behave in a similar nature
 100 as memcached_get() and memcached_mget(). The difference is that they take
 101 a master key that is used for determining which server an object was stored
 102 if key partitioning was used for storage.
 103
 104 =head1 RETURN
 105
 106 All objects returned must be freed by the calling application.
 107 memcached_get() and memcached_fetch() will return NULL on error. You must
 108 look at the value of error to determine what the actual error was.
 109
 110 =head1 HOME
 111
 112 To find out more information please check:
 113 L<http://tangent.org/552/libmemcached.html>
 114
 115 =head1 AUTHOR
 116
 117 Brian Aker, E<lt>brian@tangent.orgE<gt>
 118
 119 =head1 SEE ALSO
 120
 121 memcached(1) libmemcached(3) memcached_strerror(3)
 122
 123 =cut
 124