Provided by: libpmemkv-dev_1.1-1_amd64 
NAME
pmemkv_config - Configuration API for libpmemkv
SYNOPSIS
#include <libpmemkv.h>
pmemkv_config *pmemkv_config_new(void);
void pmemkv_config_delete(pmemkv_config *config);
int pmemkv_config_put_data(pmemkv_config *config, const char *key, const void *value,
size_t value_size);
int pmemkv_config_put_object(pmemkv_config *config, const char *key, void *value,
void (*deleter)(void *));
int pmemkv_config_put_uint64(pmemkv_config *config, const char *key, uint64_t value);
int pmemkv_config_put_int64(pmemkv_config *config, const char *key, int64_t value);
int pmemkv_config_put_string(pmemkv_config *config, const char *key, const char *value);
int pmemkv_config_get_data(pmemkv_config *config, const char *key, const void **value,
size_t *value_size);
int pmemkv_config_get_object(pmemkv_config *config, const char *key, void **value);
int pmemkv_config_get_uint64(pmemkv_config *config, const char *key, uint64_t *value);
int pmemkv_config_get_int64(pmemkv_config *config, const char *key, int64_t *value);
int pmemkv_config_get_string(pmemkv_config *config, const char *key, const char **value);
For general description of pmemkv and available engines see libpmemkv(7). For description
of pmemkv core API see libpmemkv(3).
DESCRIPTION
pmemkv database is configured using pmemkv_config structure. It stores mappings of keys
(null-terminated strings) to values. A value can be:
• uint64_t
• int64_t
• c-style string
• binary data
• pointer to an object (with accompanying deleter function)
It also delivers methods to store and read configuration items provided by a user. Once
the configuration object is set (with all required parameters), it can be passed to
pmemkv_open() method.
List of options which are required by pmemkv database is specific to an engine. Every
engine has documented all supported config parameters (please see libpmemkv(7) for
details).
pmemkv_config *pmemkv_config_new(void);
Creates an instance of configuration for pmemkv database.
On failure, NULL is returned.
void pmemkv_config_delete(pmemkv_config *config);
Deletes pmemkv_config. Should be called ONLY for configs which were not passed to
pmemkv_open (as this function moves ownership of the config to the database).
int pmemkv_config_put_uint64(pmemkv_config *config, const char *key, uint64_t value);
Puts uint64_t value value to pmemkv_config at key key.
int pmemkv_config_put_int64(pmemkv_config *config, const char *key, int64_t value);
Puts int64_t value value to pmemkv_config at key key.
int pmemkv_config_put_string(pmemkv_config *config, const char *key, const char *value);
Puts null-terminated string to pmemkv_config. The string is copied to the config.
int pmemkv_config_put_data(pmemkv_config *config, const char *key, const void *value,
size_t value_size);
Puts copy of binary data pointed by value to pmemkv_config. value_size specifies
size of the data.
int pmemkv_config_put_object(pmemkv_config *config, const char *key, void *value, void
(*deleter)(void *));
Puts value to pmemkv_config. value can point to arbitrary object. deleter
parameter specifies function which will be called for value when the config is
destroyed (using pmemkv_config_delete).
int pmemkv_config_get_uint64(pmemkv_config *config, const char *key, uint64_t *value);
Gets value of a config item with key key. Value is copied to variable pointed by
value.
int pmemkv_config_get_int64(pmemkv_config *config, const char *key, int64_t *value);
Gets value of a config item with key key. Value is copied to variable pointed by
value.
int pmemkv_config_get_string(pmemkv_config *config, const char *key, const char **value);
Gets pointer to a null-terminated string. The string is not copied. After
successful call value points to string stored in pmemkv_config.
int pmemkv_config_get_data(pmemkv_config *config, const char *key, const void **value,
size_t *value_size);
Gets pointer to binary data. Data is not copied. After successful call *value
points to data stored in pmemkv_config and value_size holds size of the data.
int pmemkv_config_get_object(pmemkv_config *config, const char *key, const void **value);
Gets pointer to an object. After successful call, *value points to the object.
Config items stored in pmemkv_config, which were put using a specific function can be
obtained only using corresponding pmemkv_config_get_ function (for example, config items
put using pmemkv_config_put_object can only be obtained using pmemkv_config_get_object).
Exception from this rule are functions for uint64 and int64. If value put by
pmemkv_config_put_int64 is in uint64_t range it can be obtained using
pmemkv_config_get_uint64 and vice versa.
ERRORS
Each function, except for pmemkv_config_new() and pmemkv_config_delete(), returns status.
Possible return values are:
• PMEMKV_STATUS_OK – no error
• PMEMKV_STATUS_UNKNOWN_ERROR – unknown error
• PMEMKV_STATUS_NOT_FOUND – record (or config item) not found
• PMEMKV_STATUS_CONFIG_PARSING_ERROR – parsing data to config failed
• PMEMKV_STATUS_CONFIG_TYPE_ERROR – config item has different type than expected
EXAMPLE
The following example is taken from examples/pmemkv_config_c/pmemkv_config.c.
#include <assert.h>
#include <libpmemkv.h>
#include <libpmemkv_json_config.h>
#include <stdlib.h>
#include <string.h>
/* deleter for int pointer */
void free_int_ptr(void *ptr)
{
free(ptr);
}
int main()
{
pmemkv_config *config = pmemkv_config_new();
assert(config != NULL);
/* Put int64_t value */
int status = pmemkv_config_put_int64(config, "size", 1073741824);
assert(status == PMEMKV_STATUS_OK);
char buffer[] = "ABC";
/* Put binary data stored in buffer */
status = pmemkv_config_put_data(config, "binary", buffer, 3);
assert(status == PMEMKV_STATUS_OK);
const void *data;
size_t data_size;
/* Get pointer to binary data stored in config */
status = pmemkv_config_get_data(config, "binary", &data, &data_size);
assert(status == PMEMKV_STATUS_OK);
assert(data_size == 3);
assert(((const char *)data)[0] == 'A');
int *int_ptr = malloc(sizeof(int));
assert(int_ptr != NULL);
*int_ptr = 10;
/* Put pointer to dynamically allocated object, free_int_ptr is called on
* pmemkv_config_delete */
status = pmemkv_config_put_object(config, "int_ptr", int_ptr, &free_int_ptr);
assert(status == PMEMKV_STATUS_OK);
int *get_int_ptr;
/* Get pointer to object stored in config */
status = pmemkv_config_get_object(config, "int_ptr", (void **)&get_int_ptr);
assert(status == PMEMKV_STATUS_OK);
assert(*get_int_ptr == 10);
pmemkv_config_delete(config);
pmemkv_config *config_from_json = pmemkv_config_new();
assert(config_from_json != NULL);
/* Parse JSON and put all items found into config_from_json */
status = pmemkv_config_from_json(config_from_json, "{\"path\":\"/dev/shm\",\
\"size\":1073741824,\
\"subconfig\":{\
\"size\":1073741824\
}\
}");
assert(status == PMEMKV_STATUS_OK);
const char *path;
status = pmemkv_config_get_string(config_from_json, "path", &path);
assert(status == PMEMKV_STATUS_OK);
assert(strcmp(path, "/dev/shm") == 0);
pmemkv_config *subconfig;
/* Get pointer to nested configuration "subconfig" */
status = pmemkv_config_get_object(config_from_json, "subconfig",
(void **)&subconfig);
assert(status == PMEMKV_STATUS_OK);
size_t sub_size;
status = pmemkv_config_get_uint64(subconfig, "size", &sub_size);
assert(status == PMEMKV_STATUS_OK);
assert(sub_size == 1073741824);
pmemkv_config_delete(config_from_json);
return 0;
}
SEE ALSO
libpmemkv(7), libpmemkv(3) , libpmemkv_json_config(3) and <https://pmem.io>