Type Definition paho_mqtt3as_sys::Persistence_keys

type Persistence_keys = Option<unsafe extern "C" fn(_: *mut c_void, _: *mut *mut *mut c_char, _: *mut c_int) -> c_int>;

@brief Returns the keys in this persistent data store.

@param handle The handle pointer from a successful call to Persistence_open(). @param keys The address of a pointer to pointers to strings. Assuming successful execution, this function allocates memory to hold the returned keys (strings used to store the data with Persistence_put()). It also allocates memory to hold an array of pointers to these strings. keys is set to point to the array of pointers to strings. @param nkeys A pointer to the number of keys in this persistent data store. This function sets the number of keys, if successful. @return Return 0 if the function completes successfully, otherwise return ::MQTTCLIENT_PERSISTENCE_ERROR.