int aeron_feedback_delay_state_init(
aeron_feedback_delay_generator_state_t *state,
aeron_feedback_delay_generator_func_t delay_generator,
int64_t delay_ns,
size_t multicast_group_size,
bool should_immediate_feedback)
{
static bool is_seeded = false;
double lambda = log((double)multicast_group_size) + 1;
double max_backoff_T = (double)delay_ns;
state->static_delay.delay_ns = delay_ns;
state->optimal_delay.rand_max = lambda / max_backoff_T;
state->optimal_delay.base_x = lambda / (max_backoff_T * (exp(lambda) - 1));
state->optimal_delay.constant_t = max_backoff_T / lambda;
state->optimal_delay.factor_t = (exp(lambda) - 1) * (max_backoff_T / lambda);
if (!is_seeded)
{
aeron_srand48(aeron_nano_clock());
is_seeded = true;
}
state->should_immediate_feedback = should_immediate_feedback;
state->delay_generator = delay_generator;
return 0;
}
int64_t aeron_loss_detector_nak_multicast_delay_generator()
{
static bool initialized = false;
static double lambda;
static double rand_max;
static double base_x;
static double constant_t;
static double factor_t;
if (!initialized)
{
lambda = log(AERON_LOSS_DETECTOR_NAK_MULTICAST_GROUPSIZE) + 1;
rand_max = lambda / AERON_LOSS_DETECTOR_NAK_MULTICAST_MAX_BACKOFF;
base_x = lambda / (AERON_LOSS_DETECTOR_NAK_MULTICAST_MAX_BACKOFF * (exp(lambda) - 1));
constant_t = AERON_LOSS_DETECTOR_NAK_MULTICAST_MAX_BACKOFF / lambda;
factor_t = (exp(lambda) - 1) * constant_t;
srand48(aeron_nano_clock());
initialized = true;
}
const double x = (drand48() * rand_max) + base_x;
return (int64_t)(constant_t * log(x * factor_t));
}