View Source Retry.DelayStreams (retry v0.17.0)

This module provide a set of helper functions that produce delay streams for use with retry.

Link to this section Summary

Functions

Returns a stream that is the same as delays except that the delays never exceed max. This allow capping the delay between attempts to some max value.

Returns a constant stream of delays.

Returns a delay stream that is the same as delays except it limits the total life span of the stream to time_budget. This calculation takes the execution time of the block being retried into account.

Returns a stream of delays that increase exponentially.

Returns a stream in which each element of delays is randomly adjusted to a number between 1 and the original delay.

Returns a stream of delays that increase linearly.

Returns a stream in which each element of delays is randomly adjusted no more than proportion of the delay.

Link to this section Functions

@spec cap(Enumerable.t(), pos_integer()) :: Enumerable.t()

Returns a stream that is the same as delays except that the delays never exceed max. This allow capping the delay between attempts to some max value.

Example

retry with: exponential_backoff() |> cap(10_000) do
  # ...
end

Produces an exponentially increasing delay stream until the delay reaches 10 seconds at which point it stops increasing

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constant_backoff(delay \\ 100)

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@spec constant_backoff(pos_integer()) :: Enumerable.t()

Returns a constant stream of delays.

Example

retry with: constant_backoff(50) do
  # ...
end
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expiry(delays, time_budget, min_delay \\ 100)

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@spec expiry(Enumerable.t(), pos_integer(), pos_integer()) :: Enumerable.t()

Returns a delay stream that is the same as delays except it limits the total life span of the stream to time_budget. This calculation takes the execution time of the block being retried into account.

The execution of the code within the block will not be interrupted, so the total time of execution may run over the time_budget depending on how long a single try will take.

Optionally, you can specify a minimum delay so the smallest value doesn't go below the threshold.

Example

retry with: exponential_backoff() |> expiry(1_000) do
  # ...
end

Produces a delay stream that ends after 1 second has elapsed since its creation.

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exponential_backoff(initial_delay \\ 10, factor \\ 2)

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@spec exponential_backoff(pos_integer(), pos_integer()) :: Enumerable.t()

Returns a stream of delays that increase exponentially.

Example

retry with: exponential_backoff do
  # ...
end
@spec jitter(Enumerable.t()) :: Enumerable.t()

Returns a stream in which each element of delays is randomly adjusted to a number between 1 and the original delay.

Example

retry with: exponential_backoff() |> jitter() do
  # ...
end
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linear_backoff(initial_delay, factor)

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@spec linear_backoff(pos_integer(), pos_integer()) :: Enumerable.t()

Returns a stream of delays that increase linearly.

Example

retry with: linear_backoff(50, 2) do
  # ...
end
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randomize(delays, proportion \\ 0.1)

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@spec randomize(Enumerable.t(), float()) :: Enumerable.t()

Returns a stream in which each element of delays is randomly adjusted no more than proportion of the delay.

Example

retry with: exponential_backoff() |> randomize do
  # ...
end

Produces an exponentially increasing delay stream where each delay is randomly adjusted to be within 10 percent of the original value