View Source Skitter.Strategy.Component behaviour (Skitter v0.5.3)

Component strategy behaviour.

This module defines and documents the various hooks a Skitter.Strategy for a component should implement, along with the functions it can use to access the runtime system.

Link to this section Summary

Callbacks

Accept data sent to the component and send it to a worker.

Deploy a component over the cluster.

Handle a message received by a worker.

Functions

Emit values.

Emit values with a custom invocation.

Link to this section Callbacks

Link to this callback

deliver(context, data, port)

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Specs

deliver(
  context :: Skitter.Strategy.context(),
  data :: any(),
  port :: Skitter.Port.index()
) ::
  any()

Accept data sent to the component and send it to a worker.

This hook is called by the runtime system when data needs to be sent to a given component (i.e. when a predecessor of the component emits data). It receives the data to be sent along with the index of the port to which the data should be sent.

The result of this hook is ignored. Instead, this hook should use Skitter.Worker.send/3 to transfer the received data to a worker.

Context

All context data (component, strategy, deployment data and the invocation) is available when this hook is called.

Specs

Deploy a component over the cluster.

This hook is called by the runtime system when a component has to be distributed over the cluster. Any data returned by this hook is made available to other hooks through the deployment field in Skitter.Strategy.context/0.

Context

When this hook is called, only the current strategy, component and arguments are available in the context.

Link to this callback

process( context, message, state, tag )

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Specs

process(
  context :: Skitter.Strategy.context(),
  message :: any(),
  state :: Skitter.Worker.state(),
  tag :: Skitter.Worker.tag()
) :: Skitter.Worker.state()

Handle a message received by a worker.

This hook is called by the runtime when a worker process receives a message. It is called with the received message, the data of the worker that received the message and its tag. This hook should return the new state of the worker that received the message.

Context

All context data (component, strategy, deployment data and the invocation) is available when this hook is called.

When the received message was not sent by Skitter (i.e. when the worker process received a regular message), the invocation is set to :external. This can be used by e.g. sources to respond to external data.

Link to this section Functions

Specs

Emit values.

This function causes the current component to emit data. In other words, the provided data will be sent to the components connected to the out ports of the current component. This function accepts a keyword list of {out_port, enum} pairs. Each element in enum will be sent to the in ports of the components connected to out_port.

The values are emitted with the invocation of the passed context, use emit/3 if you need to modify the invocation of the data to emit.

Note that data is emitted from the current worker. This may cause issues when infinite streams of data are emitted.

Link to this function

emit(context, enum, invocation)

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Specs

Emit values with a custom invocation.

This function emits values, like emit/2. Unlike emit/2, this function allows you to specify the invocation of the emitted data. An invocation or a 0-arity function which returns an invocation should be passed as an invocation to this function. If an invocation is passed, it will be used as the invocation for every data element to publish. If a function is passed, it will be called once for every data element to publish. The returned invocation will be used as the invocation for the data element.