Class: LcpRuby::ModelFactory::SequenceApplicator

Inherits:
Object
  • Object
show all
Defined in:
lib/lcp_ruby/model_factory/sequence_applicator.rb

Constant Summary collapse

VIRTUAL_SCOPE_KEYS = 
%w[_year _month _day].freeze
VALID_ASSIGN_ON = 
%w[create always].freeze

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(model_class, model_definition) ⇒ SequenceApplicator

Returns a new instance of SequenceApplicator.



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# File 'lib/lcp_ruby/model_factory/sequence_applicator.rb', line 7

def initialize(model_class, model_definition)
  @model_class = model_class
  @model_definition = model_definition
end

Class Method Details

.assign_next!(record, model_name, field_name, config) ⇒ Object

Atomically get the next counter value, format it, and return the formatted string.



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# File 'lib/lcp_ruby/model_factory/sequence_applicator.rb', line 45

def self.assign_next!(record, model_name, field_name, config)
  scope_values = resolve_scope_values(record, config)
  scope_key = Sequences.build_scope_key(scope_values)
  start = config["start"]
  step = config["step"]

  counter_value = next_value!(model_name, field_name, scope_key, start, step)

  format_template = config["format"]
  if format_template
    format_value(counter_value, format_template, record, scope_values)
  else
    counter_value
  end
end

.format_value(counter, format_template, record, scope_values) ⇒ Object

Format the counter value using the template.



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# File 'lib/lcp_ruby/model_factory/sequence_applicator.rb', line 114

def self.format_value(counter, format_template, record, scope_values)
  result = format_template.dup

  # Handle %{sequence:Nd} (zero-padded) — must be processed before %{sequence}
  result.gsub!(/\%\{sequence:(\d+)d\}/) { counter.to_s.rjust(Regexp.last_match(1).to_i, "0") }
  # Handle %{sequence} (raw)
  result.gsub!("%{sequence}", counter.to_s)

  # Handle scope values and field references in a single pass
  result.gsub(/\%\{(\w+)\}/) do
    key = Regexp.last_match(1)
    if scope_values.key?(key)
      scope_values[key].to_s
    elsif record.respond_to?(key)
      record.send(key).to_s
    else
      ""
    end
  end
end

.next_value!(model_name, field_name, scope_key, start, step) ⇒ Object

Atomically increment the counter and return the new value. Wrapped in its own transaction to ensure the UPDATE row lock and subsequent SELECT are atomic, even if called outside an AR save callback.



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# File 'lib/lcp_ruby/model_factory/sequence_applicator.rb', line 64

def self.next_value!(model_name, field_name, scope_key, start, step)
  counter_model = LcpRuby.registry.model_for("gapfree_sequence")

  # The unique index on (seq_model, seq_field, scope_key) prevents duplicates.
  # Retry on conflict handles the race where two threads both try to INSERT.
  attrs = { seq_model: model_name, seq_field: field_name, scope_key: scope_key }

  counter_model.transaction do
    # Try atomic increment first (most common path for existing counters).
    # The UPDATE acquires an implicit row lock held until transaction commit,
    # so the subsequent SELECT is safe from concurrent increments.
    updated = counter_model.where(attrs).update_all(
      [ "current_value = current_value + ?, updated_at = ?", step, Time.current ]
    )

    if updated == 0
      # New scope — insert with start value, retry increment on unique constraint violation
      begin
        counter_model.create!(attrs.merge(current_value: start))
        next start
      rescue ActiveRecord::RecordNotUnique
        # Another thread beat us to the INSERT — increment the row they created.
        # The losing thread gets start + step (the winner got start).
        retried = counter_model.where(attrs).update_all(
          [ "current_value = current_value + ?, updated_at = ?", step, Time.current ]
        )
        raise "Sequence counter row vanished for #{attrs.inspect}" if retried == 0
      end
    end

    counter_model.where(attrs).pick(:current_value)
  end
end

.resolve_scope_values(record, config) ⇒ Object

Resolve scope values from the record.



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# File 'lib/lcp_ruby/model_factory/sequence_applicator.rb', line 99

def self.resolve_scope_values(record, config)
  scope = config.fetch("scope", [])
  time = resolve_time(record)

  scope.each_with_object({}) do |key, values|
    values[key] = case key
    when "_year"  then time.strftime("%Y")
    when "_month" then time.strftime("%m")
    when "_day"   then time.strftime("%d")
    else record.send(key).to_s
    end
  end
end

.resolve_time(record) ⇒ Object 



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# File 'lib/lcp_ruby/model_factory/sequence_applicator.rb', line 164

def self.resolve_time(record)
  if record.respond_to?(:created_at) && record.created_at
    record.created_at
  else
    Time.current
  end
end

Instance Method Details

#apply! ⇒ Object 



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# File 'lib/lcp_ruby/model_factory/sequence_applicator.rb', line 12

def apply!
  sequence_fields = collect_sequence_fields
  return if sequence_fields.empty?

  model_name = @model_definition.name

  # before_create: assign sequence values for new records
  @model_class.before_create do |record|
    sequence_fields.each do |field_name, config|
      next unless record.has_attribute?(field_name)
      next if config["assign_on"] == "always" && record.send(field_name).present?

      value = SequenceApplicator.assign_next!(record, model_name, field_name, config)
      record.send("#{field_name}=", value)
    end
  end

  # before_update: fill blank values for assign_on: "always" fields
  always_fields = sequence_fields.select { |_, config| config["assign_on"] == "always" }
  return if always_fields.empty?

  @model_class.before_update do |record|
    always_fields.each do |field_name, config|
      next unless record.has_attribute?(field_name)
      next if record.send(field_name).present?

      value = SequenceApplicator.assign_next!(record, model_name, field_name, config)
      record.send("#{field_name}=", value)
    end
  end
end