`class Supervisor`

Implements a host supervisor which can restart the host services and provide various metrics about the running processes.

Definitions

`def initialize(...)`

Initialize the supervisor using the given environment.

Signature

parameter　environment　Build::Environment

Implementation

def initialize(...)
	super
	
	@bound_endpoint = nil
end

`def endpoint`

The endpoint which the supervisor will bind to. Typically a unix pipe in the same directory as the host.

Implementation

def endpoint
	@evaluator.endpoint
end

`def do_restart(message)`

Restart the process group that the supervisor belongs to.

Implementation

def do_restart(message)
	# Tell the parent of this process group to spin up a new process group/container.
	# Wait for that to start accepting new connections.
	# Stop accepting connections.
	# Wait for existing connnections to drain.
	# Terminate this process group.
	signal = message[:signal] || :INT
	
	Process.kill(signal, Process.ppid)
end

`def do_metrics(message)`

Capture process metrics relating to the process group that the supervisor belongs to.

Implementation

def do_metrics(message)
	Process::Metrics::General.capture(pid: Process.ppid, ppid: Process.ppid)
end

`def handle(message)`

Handle an incoming request.

Signature

parameter　message　Hash: The decoded message.

Implementation

def handle(message)
	case message[:please]
	when "restart"
		self.do_restart(message)
	when "metrics"
		self.do_metrics(message)
	end
end

`def start`

Bind the supervisor to the specified endpoint.

Implementation

def start
	Console.logger.info(self) {"Binding to #{self.endpoint}..."}
	
	@bound_endpoint = Sync{self.endpoint.bound}
	
	super
end

`def setup(container)`

Start the supervisor process which accepts connections from the bound endpoint and processes JSON formatted messages.

Signature

parameter　container　Async::Container::Generic

Implementation

def setup(container)
	container.run(name: self.name, restart: true, count: 1) do |instance|
		Async do
			@bound_endpoint.accept do |peer|
				stream = ::IO::Stream(peer)
				
				while message = stream.read_until("\0")
					response = handle(JSON.parse(message, symbolize_names: true))
					stream.puts(response.to_json, separator: "\0")
				end
			end
			
			instance.ready!
		end
	end
	
	super
end

`def stop`

Release the bound endpoint.

Implementation

def stop
	@bound_endpoint&.close
	@bound_endpoint = nil
	
	super
end