add back-reference for protected resource object to circuit breaker

examples/dual_circuit_breaker_demo.rb

@@ -0,0 +1,174 @@
+#!/usr/bin/env ruby
+# frozen_string_literal: true
+
+require "bundler/setup"
+require "semian"
+
+# Example: Dual Circuit Breaker Demo
+# This demonstrates how to use both legacy and adaptive circuit breakers
+# simultaneously, switching between them at runtime based on a callable.
+
+# Simulate a feature flag that can be toggled
+module ExperimentFlags
+  @enabled = false
+
+  def self.enable_adaptive!
+    @enabled = true
+  end
+
+  def self.disable_adaptive!
+    @enabled = false
+  end
+
+  def self.use_adaptive_circuit_breaker?
+    @enabled
+  end
+end
+
+# Helper function to print state of all Semian objects between each phase
+def print_semian_state
+  puts "\n=== Semian Resources State ===\n"
+  Semian.resources.values.each do |resource|
+    puts "Resource: #{resource.name}"
+
+    # Bulkhead info
+    if resource.bulkhead
+      puts "  Bulkhead: tickets=#{resource.tickets}, count=#{resource.count}"
+    else
+      puts "  Bulkhead: disabled"
+    end
+
+    # Circuit breaker info
+    cb = resource.circuit_breaker
+    if cb.nil?
+      puts "  Circuit Breaker: disabled"
+    elsif cb.is_a?(Semian::DualCircuitBreaker)
+      puts "  Circuit Breaker: DualCircuitBreaker"
+      metrics = cb.metrics
+      puts "    Active: #{metrics[:active]}"
+      puts "    Classic: state=#{metrics[:classic][:state]}, open=#{metrics[:classic][:open]}, half_open=#{metrics[:classic][:half_open]}"
+      puts "    Adaptive: rejection_rate=#{metrics[:adaptive][:rejection_rate]}, error_rate=#{metrics[:adaptive][:error_rate]}"
+    elsif cb.is_a?(Semian::AdaptiveCircuitBreaker)
+      puts "  Circuit Breaker: AdaptiveCircuitBreaker"
+      puts "    open=#{cb.open?}, closed=#{cb.closed?}, half_open=#{cb.half_open?}"
+    else
+      puts "  Circuit Breaker: Legacy"
+      puts "    state=#{cb.state&.value}, open=#{cb.open?}, closed=#{cb.closed?}, half_open=#{cb.half_open?}"
+      puts "    last_error=#{cb.last_error&.class}"
+    end
+    puts ""
+  end
+  puts "=== END STATE OUTPUT ===\n\n"
+end
+
+# Register a resource with dual circuit breaker mode
+resource = Semian.register(
+  :my_service,
+  # Enable dual circuit breaker mode
+  dual_circuit_breaker: true,
+
+  # Legacy circuit breaker parameters (required)
+  success_threshold: 2,
+  error_threshold: 3,
+  error_timeout: 10,
+
+  # Adaptive circuit breaker parameters (optional, has defaults)
+  seed_error_rate: 0.01,
+
+  # Common parameters
+  tickets: 5,
+  timeout: 0.5,
+  exceptions: [RuntimeError],
+)
+
+Semian::DualCircuitBreaker.adaptive_circuit_breaker_selector(->(_resource) { ExperimentFlags.use_adaptive_circuit_breaker? })
+
+puts "=== Dual Circuit Breaker Demo ===\n\n"
+
+# Helper to simulate service calls
+def simulate_call(success: true)
+  if success
+    "Success!"
+  else
+    raise "Service error"
+  end
+end
+
+# Test with legacy circuit breaker (use_adaptive returns false)
+puts "Phase 1: Using LEGACY circuit breaker (use_adaptive=false)"
+puts "The first 3 requests will succeed, the rest will fail."
+puts "-" * 50
+
+ExperimentFlags.disable_adaptive!
+
+10.times do |i|
+  result = Semian[:my_service].acquire do
+    simulate_call(success: i < 3) # First 3 succeed, rest fail
+  end
+  puts "  Request #{i + 1}: #{result}"
+rescue => e
+  puts "  Request #{i + 1}: Failed - #{e.class.name}: #{e.message}"
+end
+
+print_semian_state
+
+# Reset both circuit breakers
+puts "\n" + "=" * 50
+puts "Resetting circuit breakers..."
+resource.circuit_breaker.reset
+
+# Test with adaptive circuit breaker (use_adaptive returns true)
+puts "\nPhase 2: Using ADAPTIVE circuit breaker (use_adaptive=true)"
+puts "The first 3 requests will succeed, then the rest will be failures."
+puts "The adaptive circuit breaker is not expected to open yet."
+puts "-" * 50
+
+ExperimentFlags.enable_adaptive!
+
+10.times do |i|
+  begin
+    result = Semian[:my_service].acquire do
+      simulate_call(success: i < 3) # First 3 succeed, rest fail
+    end
+    puts "  Request #{i + 1}: #{result}"
+  rescue => e
+    puts "  Request #{i + 1}: Failed - #{e.class.name}: #{e.message}"
+  end
+  sleep 0.05 # Small delay to see adaptive behavior
+end
+
+print_semian_state
+
+# Demonstrate dynamic switching
+puts "\n" + "=" * 50
+puts "Phase 3: Dynamic switching between circuit breakers"
+puts "-" * 50
+
+5.times do |i|
+  # Toggle every 2 requests
+  if i.even?
+    ExperimentFlags.disable_adaptive!
+    puts "  Switched to LEGACY"
+  else
+    ExperimentFlags.enable_adaptive!
+    puts "  Switched to ADAPTIVE"
+  end
+
+  begin
+    result = Semian[:my_service].acquire do
+      simulate_call(success: true)
+    end
+    puts "    Request #{i + 1}: #{result}"
+  rescue => e
+    puts "    Request #{i + 1}: Failed - #{e.class.name}"
+  end
+end
+
+puts "\n=== Demo Complete ===\n"
+puts "Both circuit breakers tracked all requests, but only the active one"
+puts "was used for decision-making based on the adaptive_circuit_breaker_selector callable."
+
+print_semian_state
+
+# Cleanup
+Semian.destroy(:my_service)

examples/net_http/08_dual_circuit_breaker.rb

@@ -0,0 +1,166 @@
+#!/usr/bin/env ruby
+# frozen_string_literal: true
+
+require "bundler/setup"
+require "semian"
+require "semian/net_http"
+require "net/http"
+
+# Example: Dual Circuit Breaker with Net::HTTP
+# This shows how to run both legacy and adaptive circuit breakers in parallel
+# and switch between them at runtime using a callable that determines which to use.
+
+# Simulate a feature flag system (in production, this would be your actual feature flag service)
+module ExperimentFlags
+  @enabled = false
+
+  def self.enable_adaptive!
+    @enabled = true
+  end
+
+  def self.disable_adaptive!
+    @enabled = false
+  end
+
+  def self.use_adaptive_circuit_breaker?
+    @enabled
+  end
+end
+
+# Helper function to print state of all Semian objects between each phase
+def print_semian_state
+  puts "\n=== Semian Resources State ===\n"
+  Semian.resources.values.each do |resource|
+    puts "Resource: #{resource.name}"
+
+    # Bulkhead info
+    if resource.bulkhead
+      puts "  Bulkhead: tickets=#{resource.tickets}, count=#{resource.count}"
+    else
+      puts "  Bulkhead: disabled"
+    end
+
+    # Circuit breaker info
+    cb = resource.circuit_breaker
+    if cb.nil?
+      puts "  Circuit Breaker: disabled"
+    elsif cb.is_a?(Semian::DualCircuitBreaker)
+      puts "  Circuit Breaker: DualCircuitBreaker"
+      metrics = cb.metrics
+      puts "    Active: #{metrics[:active]}"
+      puts "    Classic: state=#{metrics[:classic][:state]}, open=#{metrics[:classic][:open]}, half_open=#{metrics[:classic][:half_open]}"
+      puts "    Adaptive: rejection_rate=#{metrics[:adaptive][:rejection_rate]}, error_rate=#{metrics[:adaptive][:error_rate]}"
+    elsif cb.is_a?(Semian::AdaptiveCircuitBreaker)
+      puts "  Circuit Breaker: AdaptiveCircuitBreaker"
+      puts "    open=#{cb.open?}, closed=#{cb.closed?}, half_open=#{cb.half_open?}"
+    else
+      puts "  Circuit Breaker: Legacy"
+      puts "    state=#{cb.state&.value}, open=#{cb.open?}, closed=#{cb.closed?}, half_open=#{cb.half_open?}"
+      puts "    last_error=#{cb.last_error&.class}"
+    end
+    puts ""
+  end
+  puts "=== END STATE OUTPUT ===\n\n"
+end
+
+Semian::DualCircuitBreaker.adaptive_circuit_breaker_selector(->(_resource) { ExperimentFlags.use_adaptive_circuit_breaker? })
+
+# Configure Semian with dual circuit breaker
+Semian::NetHTTP.semian_configuration = proc do |host, port|
+  # Example: only enable for specific host
+  if host == "shopify-debug.com"
+    {
+      # Enable dual circuit breaker mode
+      dual_circuit_breaker: true,
+
+      # Legacy circuit breaker settings (required)
+      success_threshold: 2,
+      error_threshold: 3,
+      error_timeout: 5,
+
+      # Adaptive circuit breaker settings (uses defaults if not specified)
+      seed_error_rate: 0.01,
+
+      # Bulkhead settings
+      tickets: 3,
+      timeout: 1,
+
+      # Exceptions to track
+      exceptions: [Net::HTTPServerException],
+    }
+  end
+end
+
+puts "=== Dual Circuit Breaker with Net::HTTP ===\n\n"
+
+# Helper to make HTTP requests
+def make_request(uri_str)
+  uri = URI(uri_str)
+  Net::HTTP.start(uri.host, uri.port) do |http|
+    request = Net::HTTP::Get.new(uri)
+    response = http.request(request)
+    response.code
+  end
+rescue => e
+  e.class.name
+end
+
+print_semian_state
+
+# Phase 1: Use legacy circuit breaker
+puts "Phase 1: Using LEGACY circuit breaker"
+puts "-" * 50
+ExperimentFlags.disable_adaptive!
+
+3.times do |i|
+  puts "Request #{i + 1} (using legacy)..."
+  result = make_request("http://shopify-debug.com/")
+  puts "  Result: #{result}\n\n"
+  sleep 3
+end
+
+print_semian_state
+
+# Phase 2: Switch to adaptive circuit breaker
+puts "Phase 2: Switching to ADAPTIVE circuit breaker"
+puts "-" * 50
+ExperimentFlags.enable_adaptive!
+
+3.times do |i|
+  puts "Request #{i + 1} (using adaptive)..."
+  result = make_request("http://shopify-debug.com/")
+  puts "  Result: #{result}\n\n"
+  sleep 3
+end
+
+print_semian_state
+
+# Phase 3: Demonstrate dynamic switching
+puts "Phase 3: Dynamic switching during runtime"
+puts "-" * 50
+
+5.times do |i|
+  # Toggle between legacy and adaptive
+  if i.even?
+    ExperimentFlags.disable_adaptive!
+    active = "LEGACY"
+  else
+    ExperimentFlags.enable_adaptive!
+    active = "ADAPTIVE"
+  end
+
+  puts "Request #{i + 1} (using #{active})..."
+  result = make_request("http://shopify-debug.com/")
+  puts "  Result: #{result}\n\n"
+  sleep 3
+end
+
+print_semian_state
+
+puts "=== Demo Complete ===\n\n"
+puts "Key Benefits of Dual Circuit Breaker:"
+puts "  1. Both breakers track all requests independently"
+puts "  2. Can switch between breakers without losing state"
+puts "  3. Can compare behavior of both approaches with same traffic"
+puts "  4. Enables gradual rollout with instant rollback capability"
+puts "  5. Perfect for A/B testing circuit breaker strategies"