Class: Whodunit::Chronicles::Chronicler

Inherits:
CDC::Core::Processor
  • Object
show all
Defined in:
lib/whodunit/chronicles/chronicler.rb,
sig/whodunit/chronicles/chronicler.rbs

Overview

Minimal CDC::Core processor that records change events into a ledger.

Chronicler is intentionally small. It consumes a CDC::Core::ChangeEvent, converts it into an immutable LedgerEntry, and appends that entry into the provided ledger. Scheduling, retries, backpressure, worker pools, and orchestration belong to CDC runtimes outside this gem.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(ledger:, prepare: true, ensure_indexes: true, clock: Time) ⇒ Chronicler

Create a chronicler.

Parameters:

  • ledger (#append) —

    ledger-like object

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

    whether to call ledger.prepare! during initialization

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

    whether to call ledger.ensure_indexes! during initialization

  • clock (#now) (defaults to: Time) —

    clock used when creating ledger entries

  • ledger: (Object)
  • prepare: (Boolean) (defaults to: true)
  • ensure_indexes: (Boolean) (defaults to: true)
  • clock: (Object) (defaults to: Time) 


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# File 'lib/whodunit/chronicles/chronicler.rb', line 25

def initialize(ledger:, prepare: true, ensure_indexes: true, clock: Time)
  @ledger = ledger
  @clock = clock
  @ledger.prepare! if prepare && @ledger.respond_to?(:prepare!)
  @ledger.ensure_indexes! if ensure_indexes && @ledger.respond_to?(:ensure_indexes!)
end

Instance Attribute Details

#ledger ⇒ Object (readonly)

Returns ledger receiving immutable entries.

Returns:

  • (Object) —

    ledger receiving immutable entries



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# File 'lib/whodunit/chronicles/chronicler.rb', line 17

def ledger
  @ledger
end

Instance Method Details

#partition_for(entry) ⇒ Object

Resolve the ledger partition for an entry.

Parameters:

Returns:

  • (Object) —

    ledger-like target



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# File 'lib/whodunit/chronicles/chronicler.rb', line 55

def partition_for(entry)
  return @ledger.partition_for(entry) if @ledger.respond_to?(:partition_for)

  @ledger
end

#process(event) ⇒ CDC::Core::ProcessorResult

Process one CDC change event and append one ledger entry.

Parameters:

  • event (CDC::Core::ChangeEvent) —

    normalized CDC event

Returns:

  • (CDC::Core::ProcessorResult) —

    standardized processor result



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# File 'lib/whodunit/chronicles/chronicler.rb', line 36

def process(event)
  entry = LedgerEntry.from_change_event(event, clock: @clock)
  partition_for(entry).append(entry)
  CDC::Core::ProcessorResult.success(event)
rescue StandardError => e
  CDC::Core::ProcessorResult.failure(
    e,
    event: event,
    processor: self.class.name,
    retryable: true
  )
end