Class: DispatchPolicy::Pipeline

Inherits:
Object
  • Object
show all
Defined in:
lib/dispatch_policy/pipeline.rb

Overview

Composes a sequence of gates into a single admission decision for one partition. Returns a value object describing how many jobs may be admitted right now and which gate-state patches to persist.

Defined Under Namespace

Classes: Result

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(policy) ⇒ Pipeline

Returns a new instance of Pipeline.



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# File 'lib/dispatch_policy/pipeline.rb', line 10

def initialize(policy)
  @policy = policy
end

Class Method Details

.settle(decisions, admitted_count) ⇒ Object

Computes the gate_state patch to persist once the REAL admitted count is known (after the staging DELETE). Each gate’s #consume settles its state against the actual number of jobs claimed — the throttle deducts that many tokens rather than the optimistic ‘allowed` it returned at evaluate time. Gates that keep no gate_state (concurrency, adaptive_concurrency — their state lives in their own tables) return nil from #consume and contribute nothing here.

‘decisions` is the [gate, decision] list carried on the Result.



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# File 'lib/dispatch_policy/pipeline.rb', line 23

def self.settle(decisions, admitted_count)
  patch = {}
  decisions.each do |gate, decision|
    sub = gate.consume(decision, admitted_count)
    patch.merge!(sub) if sub
  end
  patch
end

Instance Method Details

#call(ctx, partition, max_budget) ⇒ Object 



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# File 'lib/dispatch_policy/pipeline.rb', line 32

def call(ctx, partition, max_budget)
  budget          = max_budget
  retry_after     = nil
  patch           = {}
  reasons         = []
  decisions       = []

  @policy.gates.each do |gate|
    decision = gate.evaluate(ctx, partition, budget)
    decisions << [gate, decision]
    budget   = decision.allowed.finite? ? [budget, decision.allowed].min : budget
    if decision.retry_after
      retry_after = retry_after.nil? ? decision.retry_after : [retry_after, decision.retry_after].min
    end
    reasons << "#{gate.name}:#{decision.reason}" if decision.reason
    break if budget.zero?
  end

  admit_count = budget.finite? ? budget : max_budget
  admit_count = 0 if admit_count.negative?

  decisions.each do |_, decision|
    next unless decision.gate_state_patch
    patch.merge!(decision.gate_state_patch)
  end

  Result.new(
    admit_count:       admit_count,
    retry_after:       retry_after,
    gate_state_patch:  patch,
    reasons:           reasons,
    decisions:         decisions
  )
end