NAME

       memcached_auto - Incrementing and Decrementing Values

SYNOPSIS

       #include <libmemcached/memcached.h>
              Compile and link with -lmemcached

       memcached_return_t   memcached_increment(memcached_st   *ptr,   const  char  *key,  size_t
       key_length, uint32_t offset, uint64_t *value)

       memcached_return_t  memcached_decrement(memcached_st  *ptr,  const   char   *key,   size_t
       key_length, uint32_t offset, uint64_t *value)

       memcached_return_t  memcached_increment_with_initial(memcached_st  *ptr,  const char *key,
       size_t key_length, uint64_t offset, uint64_t initial, time_t expiration, uint64_t *value)

       memcached_return_t memcached_decrement_with_initial(memcached_st *ptr,  const  char  *key,
       size_t key_length, uint64_t offset, uint64_t initial, time_t expiration, uint64_t *value)

       memcached_return_t  memcached_increment_by_key(memcached_st  *ptr,  const char *group_key,
       size_t group_key_length, const char *key, size_t  key_length,  uint32_t  offset,  uint64_t
       *value)

       memcached_return_t  memcached_decrement_by_key(memcached_st  *ptr,  const char *group_key,
       size_t group_key_length, const char *key, size_t  key_length,  uint32_t  offset,  uint64_t
       *value)

       memcached_return_t  memcached_increment_with_initial_by_key(memcached_st  *ptr, const char
       *group_key, size_t group_key_length, const char *key, size_t key_length, uint64_t  offset,
       uint64_t initial, time_t expiration, uint64_t *value)

       memcached_return_t  memcached_decrement_with_initial_by_key(memcached_st  *ptr, const char
       *group_key, size_t group_key_length, const char *key, size_t key_length, uint64_t  offset,
       uint64_t initial, time_t expiration, uint64_t *value)

              Parameters

                     • ptr -- pointer to an initialized memcached_st struct

                     • group_key -- key namespace

                     • group_key_length  --  length  of the key namespace without any terminating
                       zero

                     • key -- the key

                     • key_length -- length of the key without any terminating zero

                     • offset -- offset to increment/decrement

                     • initial -- initial value if key does  not  exist  and  expiration  is  not
                       MEMCACHED_EXPIRATION_NOT_ADD

                     • expiration  --  expiration  as  a unix timestamp or as relative expiration
                       time in seconds

                     • value -- the resulting value after initialization/increment/decrement

              Returns
                     memcached_return_t indicating success

DESCRIPTION

       memcached(1) servers have the ability  to  increment  and  decrement  keys  (overflow  and
       underflow  are  not  detected).  This  gives  you the ability to use memcached to generate
       shared sequences of values.

       memcached_increment() takes a key and key_length and increments the value  by  the  offset
       passed to it. The value is then returned via the uint32_t value pointer you pass to it.

       memcached_decrement()  takes  a  key and key_length and decrements the value by the offset
       passed to it. The value is then returned via the uint32_t value pointer you pass to it.

       memcached_increment_with_initial() takes a key and key_length and increments the value  by
       the  offset passed to it. If the object specified by key does not exist, one of two things
       may happen: If the expiration value is MEMCACHED_EXPIRATION_NOT_ADD,  the  operation  will
       fail. For all other expiration values, the operation will succeed by seeding the value for
       that key with a initial value to expire with the provided expiration time.  The flags will
       be  set to zero. The value is then returned via the uint32_t value pointer you pass to it.
       memcached_increment_with_initial is only available when using the binary protocol.

       memcached_decrement_with_initial() takes a key and key_length and decrements the value  by
       the  offset passed to it. If the object specified by key does not exist, one of two things
       may happen: If the expiration value is MEMCACHED_EXPIRATION_NOT_ADD,  the  operation  will
       fail. For all other expiration values, the operation will succeed by seeding the value for
       that key with a initial value to expire with the provided expiration time.  The flags will
       be  set to zero. The value is then returned via the uint32_t value pointer you pass to it.
       memcached_decrement_with_initial() is only available when using the binary protocol.

       memcached_increment_by_key(),                                memcached_decrement_by_key(),
       memcached_increment_with_initial_by_key(),  and  memcached_decrement_with_initial_by_key()
       are master key equivalents of the above.

RETURN VALUE

       A value  of  type  memcached_return_t   is  returned.   On  success  that  value  will  be
       MEMCACHED_SUCCESS.   Use  memcached_strerror()  to  translate  this  value  to a printable
       string.

SEE ALSO

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