View Source Reactor (reactor v0.7.0)

Reactor is a dynamic, concurrent, dependency resolving saga orchestrator.

Usage

You can construct a reactor using the Reactor Spark DSL:

defmodule HelloWorldReactor do
  @moduledoc false
  use Reactor

  input :whom

  step :greet, Greeter do
    argument :whom, input(:whom)
  end

  return :greet
end
iex> Reactor.run(HelloWorldReactor, %{whom: "Dear Reader"})
{:ok, "Hello, Dear Reader!"}

or you can build it programmatically:

iex> reactor = Builder.new()
...> {:ok, reactor} = Builder.add_input(reactor, :whom)
...> {:ok, reactor} = Builder.add_step(reactor, :greet, Greeter, whom: {:input, :whom})
...> {:ok, reactor} = Builder.return(reactor, :greet)
...> Reactor.run(reactor, %{whom: nil})
{:ok, "Hello, World!"}

Summary

Types

When set to false forces the Reactor to run every step synchronously, regardless of the step configuration.

Use a Reactor.Executor.ConcurrencyTracker.pool_key to allow this Reactor to share it's concurrency pool with other Reactor instances.

How long to wait for asynchronous steps to complete when halting.

Specify the maximum number of asynchronous steps which can be run in parallel.

The maximum number of iterations which after which the Reactor will halt.

t()

Specify the amount of execution time after which to halt processing.

Types

@type async_option() :: {:async?, boolean()}

When set to false forces the Reactor to run every step synchronously, regardless of the step configuration.

Defaults to true.

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concurrency_key_option()

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@type concurrency_key_option() :: {:concurrency_key, reference()}

Use a Reactor.Executor.ConcurrencyTracker.pool_key to allow this Reactor to share it's concurrency pool with other Reactor instances.

If you do not specify one then the Reactor will initialise a new pool and place it in it's context for any child Reactors to re-use.

Only used if async? is set to true.

@type context() :: %{optional(atom()) => any()}
@type context_arg() :: Enumerable.t({atom(), any()})
@type halt_timeout_option() :: {:halt_timeout, pos_integer() | :infinity}

How long to wait for asynchronous steps to complete when halting.

Defaults to 5000ms.

@type inputs() :: %{optional(atom()) => any()}
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max_concurrency_option()

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@type max_concurrency_option() :: {:max_concurrency, pos_integer()}

Specify the maximum number of asynchronous steps which can be run in parallel.

Defaults to the result of System.schedulers_online/0. Only used if async? is set to true.

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max_iterations_option()

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@type max_iterations_option() :: {:max_iterations, pos_integer() | :infinity}

The maximum number of iterations which after which the Reactor will halt.

Defaults to :infinity.

@type state() :: :pending | :executing | :halted | :failed | :successful
@type t() :: %Reactor{
  context: context(),
  id: any(),
  inputs: [atom()],
  intermediate_results: %{required(any()) => any()},
  middleware: [Reactor.Middleware.t()],
  plan: nil | Graph.t(),
  return: any(),
  state: state(),
  steps: [Reactor.Step.t()],
  undo: [{Reactor.Step.t(), any()}]
}
@type timeout_option() :: {:timeout, pos_integer() | :infinity}

Specify the amount of execution time after which to halt processing.

Note that this is not a hard limit. The Reactor will stop when the first step completes after the timeout has expired.

Defaults to :infinity.

Functions

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run(reactor, inputs \\ %{}, context \\ %{}, options \\ [])

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@spec run(t() | module(), inputs(), context_arg(), options()) ::
  {:ok, any()} | {:error, any()} | {:halted, t()}

Run a reactor.