Class: Async::Container::Controller
- Inherits:
-
Object
- Object
- Async::Container::Controller
- Defined in:
- lib/async/container/controller.rb
Overview
Manages the life-cycle of one or more containers in order to support a persistent system. e.g. a web server, job server or some other long running system.
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
-
#container ⇒ Object
readonly
The current container being managed by the controller.
Instance Method Summary collapse
-
#create_container ⇒ Object
Create a container for the controller.
-
#initialize(notify: Notify.open!) ⇒ Controller
constructor
Initialize the controller.
-
#reload ⇒ Object
Reload the existing container.
-
#restart ⇒ Object
Restart the container.
-
#run ⇒ Object
Enter the controller run loop, trapping ‘SIGINT` and `SIGTERM`.
-
#running? ⇒ Boolean
Whether the controller has a running container.
-
#setup(container) ⇒ Object
Spawn container instances into the given container.
-
#start ⇒ Object
Start the container unless it’s already running.
-
#state_string ⇒ Object
The state of the controller.
-
#stop(graceful = true) ⇒ Object
Stop the container if it’s running.
-
#to_s ⇒ Object
A human readable representation of the controller.
-
#trap(signal, &block) ⇒ Object
Trap the specified signal.
-
#wait ⇒ Object
Wait for the underlying container to start.
Constructor Details
#initialize(notify: Notify.open!) ⇒ Controller
Initialize the controller.
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# File 'lib/async/container/controller.rb', line 42 def initialize(notify: Notify.open!) @container = nil if @notify = notify @notify.status!("Initializing...") end @signals = {} trap(SIGHUP) do self.restart end end |
Instance Attribute Details
#container ⇒ Object (readonly)
The current container being managed by the controller.
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# File 'lib/async/container/controller.rb', line 80 def container @container end |
Instance Method Details
#create_container ⇒ Object
Create a container for the controller. Can be overridden by a sub-class.
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# File 'lib/async/container/controller.rb', line 85 def create_container Container.new end |
#reload ⇒ Object
Reload the existing container. Children instances will be reloaded using ‘SIGHUP`.
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# File 'lib/async/container/controller.rb', line 168 def reload @notify&.reloading! Console.logger.info(self) {"Reloading container: #{@container}..."} begin self.setup(@container) rescue raise SetupError, container end # Wait for all child processes to enter the ready state. Console.logger.debug(self, "Waiting for startup...") @container.wait_until_ready Console.logger.debug(self, "Finished startup.") if @container.failed? @notify.error!("Container failed!") raise SetupError, @container else @notify&.ready! end end |
#restart ⇒ Object
Restart the container. A new container is created, and if successful, any old container is terminated gracefully.
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# File 'lib/async/container/controller.rb', line 121 def restart if @container @notify&.restarting! Console.logger.debug(self) {"Restarting container..."} else Console.logger.debug(self) {"Starting container..."} end container = self.create_container begin self.setup(container) rescue @notify&.error!($!.to_s) raise SetupError, container end # Wait for all child processes to enter the ready state. Console.logger.debug(self, "Waiting for startup...") container.wait_until_ready Console.logger.debug(self, "Finished startup.") if container.failed? @notify&.error!($!.to_s) container.stop raise SetupError, container end # Make this swap as atomic as possible: old_container = @container @container = container Console.logger.debug(self, "Stopping old 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
Enter the controller run loop, trapping ‘SIGINT` and `SIGTERM`.
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# File 'lib/async/container/controller.rb', line 194 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 hangup_action = Signal.trap(:HUP) do raise Hangup end self.start while @container&.running? begin @container.wait rescue SignalException => exception if handler = @signals[exception.signo] begin handler.call rescue SetupError => error Console.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) Signal.trap(:HUP, hangup_action) end |
#running? ⇒ Boolean
Whether the controller has a running container.
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# File 'lib/async/container/controller.rb', line 91 def running? !!@container end |
#setup(container) ⇒ Object
Spawn container instances into the given container. Should be overridden by a sub-class.
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# File 'lib/async/container/controller.rb', line 103 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
Start the container unless it’s already running.
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# File 'lib/async/container/controller.rb', line 109 def start self.restart unless @container end |
#state_string ⇒ Object
The state of the controller.
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# File 'lib/async/container/controller.rb', line 58 def state_string if running? "running" else "stopped" end end |
#stop(graceful = true) ⇒ Object
Stop the container if it’s running.
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# File 'lib/async/container/controller.rb', line 115 def stop(graceful = true) @container&.stop(graceful) @container = nil end |
#to_s ⇒ Object
A human readable representation of the controller.
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# File 'lib/async/container/controller.rb', line 68 def to_s "#{self.class} #{state_string}" end |
#trap(signal, &block) ⇒ Object
Trap the specified signal.
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# File 'lib/async/container/controller.rb', line 75 def trap(signal, &block) @signals[signal] = block end |
#wait ⇒ Object
Wait for the underlying container to start.
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# File 'lib/async/container/controller.rb', line 96 def wait @container&.wait end |