Class: SagaForge::CompositeRetryPolicy

Inherits:
Object
  • Object
show all
Defined in:
lib/saga_forge/composite_retry_policy.rb

Overview

An ordered list of RetryPolicy objects, each scoped to an error type via its retry_on. On failure the first policy whose retry_on matches the raised error (by is_a?) is applied, giving each error type its own independent attempt budget and backoff curve. Put specific policies first and a catch-all (retry_on: nil) last; an unmatched error is not retried.

Pure: it never reads storage. The per-error count is supplied by the caller through the block passed to #retry_backoff, keyed by the matched policy's budget_key (its declared errors) — the caller is expected to persist counts per budget_key, e.g. in Event#retry_budgets.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(policies) ⇒ CompositeRetryPolicy

Returns a new instance of CompositeRetryPolicy.



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# File 'lib/saga_forge/composite_retry_policy.rb', line 17

def initialize(policies)
  @policies = Array(policies)
  if @policies.empty?
    raise ArgumentError, "composite retry policy needs at least one policy"
  end
end

Instance Attribute Details

#policies ⇒ Object (readonly)

Returns the value of attribute policies.



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# File 'lib/saga_forge/composite_retry_policy.rb', line 15

def policies
  @policies
end

Instance Method Details

#max_attempts ⇒ Object

Coarsest attempt bound across sub-policies, for a safety-net guard. nil (unbounded) if any sub-policy is unbounded.



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# File 'lib/saga_forge/composite_retry_policy.rb', line 43

def max_attempts
  caps = @policies.map(&:max_attempts)
  caps.include?(nil) ? nil : caps.max
end

#policy_for(error) ⇒ Object

First sub-policy whose retry_on matches the error, or nil.



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# File 'lib/saga_forge/composite_retry_policy.rb', line 25

def policy_for(error)
  @policies.find { |p| p.matches?(error) }
end

#retry_backoff(error, attempts:) ⇒ Object

Routes on the live error and delegates the decision to the matched sub-policy. When a block is given it is called with the matched policy's budget_key and must return that policy's running attempt count (1-based, including the current failure); otherwise attempts is used.



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# File 'lib/saga_forge/composite_retry_policy.rb', line 33

def retry_backoff(error, attempts:)
  sub = policy_for(error)
  return nil if sub.nil?

  count = block_given? ? yield(sub.budget_key) : attempts
  sub.retryable?(error, count) ? sub.backoff_for(count) : nil
end