Cizen.Saga behaviour (Cizen v0.18.1) View Source

The saga behaviour

Example

defmodule SomeSaga do
  use Cizen.Saga
  defstruct []

  @impl true
  def on_start(%__MODULE__{}) do
    saga
  end

  @impl true
  def handle_event(_event, state) do
    state
  end
end

Link to this section Summary

Types

lifetime()

start_option()

state()

t()

Functions

call(id, message)

cast(id, message)

exit(id, reason, trace)

get_pid(saga_id)

Returns the pid for the given saga ID.

get_saga(saga_id)

Returns the saga struct for the given saga ID.

lazy_init()

module(saga)

Returns the module for a saga.

reply(from, reply)

resume(id, saga, state, opts \\ [])

Resumes a saga with the given state.

self()

send_to(id, message)

start(saga, opts \\ [])

Starts a saga.

start_link(saga, opts \\ [])

Starts a saga linked to the current process.

stop(id)

Callbacks

handle_call(message, from, state)

The handler for Saga.call/2.

handle_cast(message, state)

The handler for Saga.cast/2.

handle_event(arg1, state)

Invoked when the saga receives an event.

on_resume(t, state)

Invoked when the saga is resumed.

on_start(t)

Invoked when the saga is started. Saga.Started event will be dispatched after this callback.

Link to this section Types

lifetime()

Specs

lifetime() :: pid() | {atom(), node()} | atom() | nil

start_option()

Specs

start_option() ::
  {:saga_id, Cizen.SagaID.t()}
  | {:lifetime, pid() | Cizen.SagaID.t() | nil}
  | {:return, :pid | :saga_id}
  | {:resume, term()}

state()

Specs

state() :: any()

t()

Specs

t() :: struct()

Link to this section Functions

call(id, message)

cast(id, message)

exit(id, reason, trace)

get_pid(saga_id)

Specs

get_pid(Cizen.SagaID.t()) :: {:ok, pid()} | :error

Returns the pid for the given saga ID.

get_saga(saga_id)

Specs

get_saga(Cizen.SagaID.t()) :: {:ok, t()} | :error

Returns the saga struct for the given saga ID.

lazy_init()

module(saga)

Specs

module(t()) :: module()

Returns the module for a saga.

reply(from, reply)

resume(id, saga, state, opts \\ [])

Specs

resume(Cizen.SagaID.t(), t(), state(), [start_option()]) :: GenServer.on_start()

Resumes a saga with the given state.

Options:

{:lifetime, lifetime_saga_or_pid} the lifetime saga ID or pid. (Default: the saga lives forever)
{:return, return_type} when :saga_id, {:ok, saga_id} is returned. (Default: :pid)

self()

send_to(id, message)

start(saga, opts \\ [])

Specs

start(t(), opts :: [start_option()]) :: GenServer.on_start()

Starts a saga.

Options:

{:saga_id, saga_id} starts with the specified saga ID. (Default: randomly generated)
{:lifetime, lifetime_saga_or_pid} the lifetime saga ID or pid. (Default: the saga lives forever)
{:return, return_type} when :saga_id, {:ok, saga_id} is returned. (Default: :pid)
{:resume, state} when given, resumes the saga with the specified state.

start_link(saga, opts \\ [])

Specs

start_link(t(), opts :: [start_option()]) :: GenServer.on_start()

Starts a saga linked to the current process.

See Saga.start/2 for details.

stop(id)

Specs

stop(Cizen.SagaID.t()) :: :ok

Link to this section Callbacks

handle_call(message, from, state)

Specs

handle_call(message :: term(), from :: GenServer.from(), state()) :: state()

The handler for Saga.call/2.

You should call Saga.reply/2 with from, otherwise the call will be timeout. You can reply from any process, at any time.

handle_cast(message, state)

Specs

handle_cast(message :: term(), state()) :: state()

The handler for Saga.cast/2.

handle_event(arg1, state)

Specs

handle_event(Cizen.Event.t(), state()) :: state()

Invoked when the saga receives an event.

Returned value will be used as the next state to pass handle_event/2 callback.

on_resume(t, state)

Specs

on_resume(t(), state()) :: state()

Invoked when the saga is resumed.

Returned value will be used as the next state to pass handle_event/2 callback.

This callback is predefined. The default implementation is here:

def on_resume(saga, state) do
  on_start(saga)
  state
end

on_start(t)

Specs

on_start(t()) :: state()

Invoked when the saga is started. Saga.Started event will be dispatched after this callback.

Returned value will be used as the next state to pass handle_event/2 callback.