Type Definition paho_mqtt_sys::Persistence_get

type Persistence_get = Option<unsafe extern "C" fn(handle: *mut c_void, key: *mut c_char, buffer: *mut *mut c_char, buflen: *mut c_int) -> c_int>;

@brief Retrieve the specified data from the persistent store.

@param handle The handle pointer from a successful call to Persistence_open(). @param key A string that is the key for the data to be retrieved. This is the same key used to save the data to the store with Persistence_put(). @param buffer The address of a pointer to a buffer. This function sets the pointer to point at the retrieved data, if successful. @param buflen The address of an int that is set to the length of buffer by this function if successful. @return Return 0 if the function completes successfully, otherwise return ::MQTTCLIENT_PERSISTENCE_ERROR.