Working with result sets

SYNOPSIS

#include <libmemcached/memcached.h>
Compile and link with -lmemcachedutil -lmemcached
typedef struct memcached_result_st memcached_result_st
memcached_result_st *memcached_result_create(memcached_st *ptr, memcached_result_st *result)
Parameters:
  • ptr -- pointer to initialized memcached_st struct
  • result -- pointer to an memcached_result_st instance to initialize or nullptr to allocate a new instance
Returns:

pointer to initialized memcached_result_st instance
void memcached_result_free(memcached_result_st *result)
Parameters:result -- pointer to initialized memcached_result_st struct
const char *memcached_result_key_value(memcached_result_st *result)
Parameters:result -- pointer to initialized memcached_result_st struct
Returns:the key value associated with the current result object
size_t memcached_result_key_length(const memcached_result_st *result)
Parameters:result -- pointer to initialized memcached_result_st struct
Returns:the key length associated with the current result object
const char *memcached_result_value(memcached_result_st *result)
Parameters:result -- pointer to initialized memcached_result_st struct
Returns:the result value associated with the current result object
char *memcached_result_take_value(memcached_result_st *result)
Parameters:result -- pointer to initialized memcached_result_st struct
Returns:the result value associated with the current result object
size_t memcached_result_length(const memcached_result_st *result)
Parameters:result -- pointer to initialized memcached_result_st struct
Returns:the result length associated with the current result object
uint32_t memcached_result_flags(const memcached_result_st *result)
Parameters:result -- pointer to initialized memcached_result_st struct
Returns:the flags associated with the current result object
uint64_t memcached_result_cas(const memcached_result_st *result)
Parameters:result -- pointer to initialized memcached_result_st struct
Returns:the cas associated with the current result object
memcached_return_t memcached_result_set_value(memcached_result_st *result, const char *value, size_t length)
Parameters:
  • result -- pointer to initialized memcached_result_st struct
  • value -- byte array to set the value of the current result object to
  • length -- the length of value wothout any terminating zero
Returns:

memcached_return_t indicating success
void memcached_result_set_flags(memcached_result_st *result, uint32_t flags)
Parameters:
  • result -- pointer to initialized memcached_result_st struct
  • flags -- a new value for the flags field
void memcached_result_set_expiration(memcached_result_st *result, time_t expiration)
Parameters:
  • result -- pointer to initialized memcached_result_st struct
  • expiration -- a new value for the expiration field

DESCRIPTION

libmemcached can optionally return a memcached_result_st which acts as a result object. The result objects have added benefits over the character pointer return values, in that they are forward compatible with new return items that future memcached servers may implement (the best current example of this is the CAS return item). The structures can also be reused, which will save on calls to malloc(3). It is suggested that you use result objects over char * return functions.

The structure of memcached_result_st has been encapsulated, you should not write code directly accessing members of the structure.

memcached_result_create() will either allocate memory for a memcached_result_st or will initialize a structure passed to it.

memcached_result_free() will deallocate any memory attached to the structure. If the structure was also allocated, it will deallocate it.

memcached_result_key_value() returns the key value associated with the current result object.

memcached_result_key_length() returns the key length associated with the current result object.

memcached_result_value() returns the result value associated with the current result object.

memcached_result_take_value() returns and hands over the result value associated with the current result object. You must call free(3) to release this value, unless you have made use of a custom allocator. Use of a custom allocator requires that you create your own custom free() to release it.

memcached_result_length() returns the result length associated with the current result object.

memcached_result_flags() returns the flags associated with the current result object.

memcached_result_cas() returns the cas associated with the current result object. This value will only be available if the server tests it.

memcached_result_set_value() takes a byte array and a size and sets the result to this value. This function is used for trigger responses.

memcached_result_set_flags() takes a result structure and stores a new value for the flags field.

memcached_result_set_expiration() takes a result structure and stores a new value for the expiration field (this is only used by read through triggers).

RETURN VALUE

Varies, see particular functions. All structures must have memcached_result_free() called on them for cleanup purposes. Failure to do this will result in leaked memory.