Class: Async::Container::Controller

Inherits:
Object
  • Object
show all
Defined in:
lib/async/container/controller.rb

Overview

Manages the life-cycle of a container.

Constant Summary collapse

SIGHUP = 
Signal.list["HUP"]
SIGINT = 
Signal.list["INT"]
SIGTERM = 
Signal.list["TERM"]
SIGUSR1 = 
Signal.list["USR1"]
SIGUSR2 = 
Signal.list["USR2"]

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(notify: Notify.open!) ⇒ Controller

Returns a new instance of Controller.



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# File 'lib/async/container/controller.rb', line 49

def initialize(notify: Notify.open!)
  @container = nil
  
  if @notify = notify
    @notify.status!("Initializing...")
  end
  
  @signals = {}
  
  trap(SIGHUP, &self.method(:restart))
end

Instance Attribute Details

#container ⇒ Object (readonly)

Returns the value of attribute container.



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# File 'lib/async/container/controller.rb', line 77

def container
  @container
end

Instance Method Details

#create_container ⇒ Object 



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# File 'lib/async/container/controller.rb', line 79

def create_container
  Container.new
end

#reload ⇒ Object 



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# File 'lib/async/container/controller.rb', line 150

def reload
  @notify&.reloading!
  
  Async.logger.info(self) {"Reloading container: #{@container}..."}
  
  begin
    self.setup(@container)
  rescue
    raise InitializationError, container
  end
  
  # Wait for all child processes to enter the ready state.
  Async.logger.debug(self, "Waiting for startup...")
  @container.wait_until_ready
  Async.logger.debug(self, "Finished startup.")
  
  if @container.failed?
    @notify.error!("Container failed!")
    
    raise InitializationError, @container
  else
    @notify&.ready!
  end
end

#restart ⇒ Object 



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# File 'lib/async/container/controller.rb', line 105

def restart
  if @container
    @notify&.restarting!
    
    Async.logger.debug(self) {"Restarting container..."}
  else
    Async.logger.debug(self) {"Starting container..."}
  end
  
  container = self.create_container
  
  begin
    self.setup(container)
  rescue
    @notify&.error!($!.to_s)
    
    raise InitializationError, container
  end
  
  # Wait for all child processes to enter the ready state.
  Async.logger.debug(self, "Waiting for startup...")
  container.wait_until_ready
  Async.logger.debug(self, "Finished startup.")
  
  if container.failed?
    @notify&.error!($!.to_s)
    
    container.stop
    
    raise InitializationError, container
  end
  
  # Make this swap as atomic as possible:
  old_container = @container
  @container = container
  
  old_container&.stop
  @notify&.ready!
rescue
  # If we are leaving this function with an exception, try to kill the container:
  container&.stop(false)
  
  raise
end

#run ⇒ Object 



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# File 'lib/async/container/controller.rb', line 175

def run
  # I thought this was the default... but it doesn't always raise an exception unless you do this explicitly.
  interrupt_action = Signal.trap(:INT) do
    raise Interrupt
  end
  
  terminate_action = Signal.trap(:TERM) do
    raise Terminate
  end
  
  self.start
  
  while @container&.running?
    begin
      @container.wait
    rescue SignalException => exception
      if handler = @signals[exception.signo]
        begin
          handler.call
        rescue InitializationError => error
          Async.logger.error(self) {error}
        end
      else
        raise
      end
    end
  end
rescue Interrupt
  self.stop(true)
rescue Terminate
  self.stop(false)
ensure
  self.stop(true)
  
  # Restore the interrupt handler:
  Signal.trap(:INT, interrupt_action)
  Signal.trap(:TERM, terminate_action)
end

#running? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/async/container/controller.rb', line 83

def running?
  !!@container
end

#setup(container) ⇒ Object 



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# File 'lib/async/container/controller.rb', line 91

def setup(container)
  # Don't do this, otherwise calling super is risky for sub-classes:
  # raise NotImplementedError, "Container setup is must be implemented in derived class!"
end

#start ⇒ Object 



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# File 'lib/async/container/controller.rb', line 96

def start
  self.restart unless @container
end

#state_string ⇒ Object 



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# File 'lib/async/container/controller.rb', line 61

def state_string
  if running?
    "running"
  else
    "stopped"
  end
end

#stop(graceful = true) ⇒ Object 



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# File 'lib/async/container/controller.rb', line 100

def stop(graceful = true)
  @container&.stop(graceful)
  @container = nil
end

#to_s ⇒ Object 



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# File 'lib/async/container/controller.rb', line 69

def to_s
  "#{self.class} #{state_string}"
end

#trap(signal, &block) ⇒ Object 



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# File 'lib/async/container/controller.rb', line 73

def trap(signal, &block)
  @signals[signal] = block
end

#wait ⇒ Object 



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# File 'lib/async/container/controller.rb', line 87

def wait
  @container&.wait
end