Class: Xeno::Dedup

Inherits:
ApplicationRecord show all
Defined in:
app/models/xeno/dedup.rb

Overview

The at-least-once dedup ledger. Redelivered work (a cron tick fired twice, a Slack retry storm) claims its (scope, key) once; every other delivery loses the unique-index race and can read what the winner recorded in metadata.

Class Method Summary collapse

Class Method Details

.claim(scope, key, metadata: {}) ⇒ Object

Returns the freshly claimed row, or nil when the key was already claimed. Safe inside enclosing transactions (savepoint), safe under concurrency (the unique index decides).



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# File 'app/models/xeno/dedup.rb', line 12

def self.claim(scope, key, metadata: {})
  transaction(requires_new: true) do
    create!(scope: scope, key: key, metadata: metadata)
  end
rescue ActiveRecord::RecordNotUnique
  nil
end

.existing(scope, key) ⇒ Object 



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# File 'app/models/xeno/dedup.rb', line 20

def self.existing(scope, key)
  find_by(scope: scope, key: key)
end