Class: Karafka::Core::Configurable::Node

Inherits:
Object
  • Object
show all
Defined in:
lib/karafka/core/configurable/node.rb

Overview

Single non-leaf node This is a core component for the configurable settings

The idea here is simple: we collect settings (leafs) and children (nodes) information and we only compile/initialize the values prior to user running the ‘#configure` API. This API needs to run prior to using the result stuff even if there is nothing to configure

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(node_name, nestings = ->(_) {}, evaluate: true) ⇒ Node

Returns a new instance of Node.

Parameters:

  • node_name (Symbol) —

    node name

  • nestings (Proc) (defaults to: ->(_) {}) —

    block for nested settings

  • evaluate (Boolean) (defaults to: true) —

    when false, skip evaluating the nestings block. Used by deep_dup to avoid re-creating children that will be overwritten immediately.



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# File 'lib/karafka/core/configurable/node.rb', line 22

def initialize(node_name, nestings = ->(_) {}, evaluate: true)
  @node_name = node_name
  @children = []
  @nestings = nestings
  @compiled = false
  @configs_refs = {}
  @local_defs = {}
  instance_eval(&nestings) if evaluate
end

Instance Attribute Details

#children ⇒ Object

We need to be able to redefine children for deep copy



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# File 'lib/karafka/core/configurable/node.rb', line 16

def children
  @children
end

#nestings ⇒ Object (readonly)

Returns the value of attribute nestings.



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# File 'lib/karafka/core/configurable/node.rb', line 13

def nestings
  @nestings
end

#node_name ⇒ Object (readonly)

Returns the value of attribute node_name.



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# File 'lib/karafka/core/configurable/node.rb', line 13

def node_name
  @node_name
end

Instance Method Details

#compile ⇒ Object

Note:

It runs once, after things are compiled, they will not be recompiled again

Converts the settings definitions into end children



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# File 'lib/karafka/core/configurable/node.rb', line 133

def compile
  @children.each do |value|
    # Do not redefine something that was already set during compilation
    # This will allow us to reconfigure things and skip override with defaults
    skippable = @configs_refs.key?(value.node_name) || (value.is_a?(Leaf) && value.compiled?)
    lazy_leaf = value.is_a?(Leaf) && value.lazy?

    # Do not create accessor for leafs that are lazy as they will get a custom method
    # created instead
    build_accessors(value) unless lazy_leaf

    next if skippable

    initialized = if value.is_a?(Leaf)
      value.compiled = true

      if value.constructor && value.lazy?
        false
      elsif value.constructor
        call_constructor(value)
      else
        value.default
      end
    else
      value.compile
      value
    end

    if lazy_leaf && !initialized
      build_dynamic_accessor(value)
    else
      @configs_refs[value.node_name] = initialized
    end
  end

  @compiled = true
end

#configure {|_self| ... } ⇒ Node

Allows for the configuration and setup of the settings

Compile settings, allow for overrides via yielding

Yields:

  • (_self)

Yield Parameters:

Returns:

  • (Node) —

    returns self after configuration



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# File 'lib/karafka/core/configurable/node.rb', line 53

def configure
  compile if !@compiled || node_name == :root
  yield(self) if block_given?
  self
end

#deep_dup ⇒ Node

Deep copies all the children nodes to allow us for templates building on a class level and non-side-effect usage on an instance/inherited.

Returns:

  • (Node) —

    duplicated node



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# File 'lib/karafka/core/configurable/node.rb', line 87

def deep_dup
  dupped = Node.new(node_name, nestings, evaluate: false)

  children.each do |value|
    dupped.children << if value.is_a?(Leaf)
      # After inheritance we need to reload the state so the leafs are recompiled again
      value = value.dup
      value.compiled = false
      value
    else
      value.deep_dup
    end
  end

  dupped
end

#register(name, value) ⇒ Object

Registers a key-value pair as a setting on an already-compiled node without going through the static ‘setting` DSL. Useful for dynamic registries (e.g. named clusters) where the keys are not known at class-load time.

Unlike ‘setting`, which is designed to be called at class-definition time, `register` is safe to call at runtime because it:

- appends a pre-compiled Leaf so `deep_dup` and `to_h` include it
- sets `@configs_refs` directly so the reader accessor returns the value immediately
- builds reader/writer accessors via the same `build_accessors` path

Raises ‘ArgumentError` if the name is already registered to prevent silent overwrites.

Parameters:

  • name (Symbol, String) —

    setting name

  • value (Object) —

    the setting value assigned immediately; also used as the default when the node is deep-duped and recompiled on a new instance

Raises:

  • (ArgumentError) —

    when the name is already taken



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# File 'lib/karafka/core/configurable/node.rb', line 120

def register(name, value)
  name = name.to_sym

  raise ArgumentError, "#{name} is already registered" if @configs_refs.key?(name)

  leaf = Leaf.new(name, value, nil, true, false)
  @children << leaf
  build_accessors(leaf)
  @configs_refs[name] = value
end

#setting(node_name, default: nil, constructor: nil, lazy: false, &block) ⇒ Object

Allows for a single leaf or nested node definition

Parameters:

  • node_name (Symbol) —

    setting or nested node name

  • default (Object) (defaults to: nil) —

    default value

  • constructor (#call, nil) (defaults to: nil) —

    callable or nil

  • lazy (Boolean) (defaults to: false) —

    is this a lazy leaf

  • block (Proc) —

    block for nested settings



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# File 'lib/karafka/core/configurable/node.rb', line 39

def setting(node_name, default: nil, constructor: nil, lazy: false, &block)
  @children << if block
    Node.new(node_name, block)
  else
    Leaf.new(node_name, default, constructor, false, lazy)
  end

  compile
end

#to_h ⇒ Hash

Returns frozen config hash representation.

Returns:

  • (Hash) —

    frozen config hash representation



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# File 'lib/karafka/core/configurable/node.rb', line 60

def to_h
  config = {}

  @children.each do |value|
    config[value.node_name] = if value.is_a?(Leaf)
      result = if @configs_refs.key?(value.node_name)
        @configs_refs[value.node_name]
      elsif value.constructor
        value.constructor.call
      elsif value.default
        value.default
      end

      # We need to check if value is not a result node for cases
      # where we merge additional config
      result.is_a?(Node) ? result.to_h : result
    else
      value.to_h
    end
  end

  config.freeze
end