Class: Heathrow::EventBus

Inherits:
Object
  • Object
show all
Defined in:
lib/heathrow/event_bus.rb

Overview

EventBus - Simple pub/sub system for inter-component communication

Usage:

bus = EventBus.instance

# Subscribe to events
bus.subscribe('message.new') { |data| puts "New message: #{data}" }

# Publish events
bus.publish('message.new', message_data)

# Unsubscribe
handler_id = bus.subscribe('message.new') { |data| ... }
bus.unsubscribe('message.new', handler_id)

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(logger = nil) ⇒ EventBus

Returns a new instance of EventBus.



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# File 'lib/heathrow/event_bus.rb', line 22

def initialize(logger = nil)
  @subscribers = Hash.new { |h, k| h[k] = {} }
  @event_log = []
  @mutex = Mutex.new
  @logger = logger
  @next_id = 0
end

Instance Attribute Details

#event_log ⇒ Object (readonly)

Returns the value of attribute event_log.



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# File 'lib/heathrow/event_bus.rb', line 20

def event_log
  @event_log
end

#subscribers ⇒ Object (readonly)

Returns the value of attribute subscribers.



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# File 'lib/heathrow/event_bus.rb', line 20

def subscribers
  @subscribers
end

Class Method Details

.instance ⇒ Object 



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# File 'lib/heathrow/event_bus.rb', line 166

def instance
  @instance ||= new
end

.reset_instance! ⇒ Object 



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# File 'lib/heathrow/event_bus.rb', line 170

def reset_instance!
  @instance = nil
end

Instance Method Details

#clear ⇒ Object

Clear all subscribers (useful for testing)



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# File 'lib/heathrow/event_bus.rb', line 120

def clear
  @mutex.synchronize do
    @subscribers.clear
    @logger&.debug("EventBus: Cleared all subscribers")
  end
end

#event_names ⇒ Object

Get all event names that have subscribers



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# File 'lib/heathrow/event_bus.rb', line 106

def event_names
  @mutex.synchronize do
    @subscribers.keys.reject { |k| @subscribers[k].empty? }
  end
end

#log_events=(enabled) ⇒ Object

Enable/disable event logging



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# File 'lib/heathrow/event_bus.rb', line 135

def log_events=(enabled)
  @log_events = enabled
end

#log_events? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/heathrow/event_bus.rb', line 139

def log_events?
  @log_events != false  # Default to true
end

#publish(event_name, data = nil) ⇒ Object

Publish an event



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# File 'lib/heathrow/event_bus.rb', line 64

def publish(event_name, data = nil)
  handlers = nil

  @mutex.synchronize do
    handlers = @subscribers[event_name].values.dup
    log_event(event_name, data)
  end

  @logger&.debug("EventBus: Publishing '#{event_name}' to #{handlers.size} handler(s)")

  # Execute handlers outside the mutex to avoid deadlocks
  handlers.each do |handler|
    begin
      handler.call(data)
    rescue => e
      @logger&.error("EventBus: Error in handler for '#{event_name}': #{e.message}")
      @logger&.error(e.backtrace.join("\n")) if @logger
    end
  end

  handlers.size
end

#publish_async(event_name, data = nil) ⇒ Object

Publish event asynchronously (returns immediately)



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# File 'lib/heathrow/event_bus.rb', line 88

def publish_async(event_name, data = nil)
  Thread.new do
    begin
      publish(event_name, data)
    rescue => e
      @logger&.error("EventBus: Error in async publish of '#{event_name}': #{e.message}")
    end
  end
end

#recent_events(count = 10) ⇒ Object

Get event log (last N events)



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# File 'lib/heathrow/event_bus.rb', line 128

def recent_events(count = 10)
  @mutex.synchronize do
    @event_log.last(count)
  end
end

#subscribe(event_name, &block) ⇒ Object

Subscribe to an event Returns handler ID for later unsubscribing



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# File 'lib/heathrow/event_bus.rb', line 32

def subscribe(event_name, &block)
  @mutex.synchronize do
    handler_id = generate_handler_id
    @subscribers[event_name][handler_id] = block
    @logger&.debug("EventBus: Subscribed to '#{event_name}' (handler #{handler_id})")
    handler_id
  end
end

#subscriber_count(event_name) ⇒ Object

Get count of subscribers for an event



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# File 'lib/heathrow/event_bus.rb', line 113

def subscriber_count(event_name)
  @mutex.synchronize do
    @subscribers[event_name].size
  end
end

#subscribers_for(event_name) ⇒ Object

Get all subscribers for an event



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# File 'lib/heathrow/event_bus.rb', line 99

def subscribers_for(event_name)
  @mutex.synchronize do
    @subscribers[event_name].keys
  end
end

#unsubscribe(event_name, handler_id) ⇒ Object

Unsubscribe from an event



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# File 'lib/heathrow/event_bus.rb', line 42

def unsubscribe(event_name, handler_id)
  @mutex.synchronize do
    if @subscribers[event_name].delete(handler_id)
      @logger&.debug("EventBus: Unsubscribed from '#{event_name}' (handler #{handler_id})")
      true
    else
      false
    end
  end
end

#unsubscribe_all(event_name) ⇒ Object

Unsubscribe all handlers for an event



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# File 'lib/heathrow/event_bus.rb', line 54

def unsubscribe_all(event_name)
  @mutex.synchronize do
    count = @subscribers[event_name].size
    @subscribers.delete(event_name)
    @logger&.debug("EventBus: Unsubscribed all #{count} handlers from '#{event_name}'")
    count
  end
end