Backoff strategy implementations for retry delays.
Supports fixed, linear, and exponential strategies with optional jitter.
Strategies
:fixed-- constant delay between attempts.:linear-- delay increases linearly:base * attempt.:exponential-- delay doubles each attempt:base * 2^(attempt - 1).
Jitter
Jitter adds randomness to avoid thundering herd effects. When enabled, the actual delay is a random value between 0 and the computed delay.
Examples
iex> ExResilience.Backoff.delay(:fixed, 100, 1)
100
iex> ExResilience.Backoff.delay(:fixed, 100, 5)
100
iex> ExResilience.Backoff.delay(:linear, 100, 3)
300
iex> ExResilience.Backoff.delay(:exponential, 100, 1)
100
iex> ExResilience.Backoff.delay(:exponential, 100, 4)
800Summary
Functions
Computes the delay in milliseconds for the given strategy and attempt number.
Computes delay with an optional max cap.
Computes delay with jitter applied.
Types
@type milliseconds() :: non_neg_integer()
@type strategy() :: :fixed | :linear | :exponential
Functions
@spec delay(strategy(), milliseconds(), pos_integer()) :: milliseconds()
Computes the delay in milliseconds for the given strategy and attempt number.
attempt is 1-based.
Examples
iex> ExResilience.Backoff.delay(:exponential, 50, 3)
200@spec delay_capped(strategy(), milliseconds(), pos_integer(), milliseconds()) :: milliseconds()
Computes delay with an optional max cap.
The delay is clamped to max_ms if it would exceed it.
Examples
iex> ExResilience.Backoff.delay_capped(:exponential, 100, 10, 5_000)
5000@spec delay_with_jitter(strategy(), milliseconds(), pos_integer()) :: milliseconds()
Computes delay with jitter applied.
Returns a random value in [0, delay]. Uses :rand.uniform/1 internally,
so seed your PRNG if you need deterministic results.
Examples
iex> delay = ExResilience.Backoff.delay_with_jitter(:fixed, 100, 1)
iex> delay >= 0 and delay <= 100
true