Class: Pvectl::Commands::Get::WatchLoop

Inherits:
Object
  • Object
show all
Defined in:
lib/pvectl/commands/get/watch_loop.rb,
sig/pvectl/commands/get/watch_loop.rbs

Overview

Handles continuous watch mode for the get command.

Repeatedly executes a block at specified intervals, clearing the screen between iterations when running in a TTY. Handles SIGINT for graceful termination.

Examples:

Basic usage

loop = WatchLoop.new(interval: 5)
loop.run { puts Time.now }

With custom interval (clamped to minimum)

loop = WatchLoop.new(interval: 0.5)  # Will be clamped to 1 second

Constant Summary collapse

DEFAULT_INTERVAL =

Default refresh interval in seconds.

2
MIN_INTERVAL =

Minimum allowed refresh interval in seconds.

1

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(interval: DEFAULT_INTERVAL, output: $stdout) ⇒ WatchLoop

Creates a new WatchLoop.



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# File 'lib/pvectl/commands/get/watch_loop.rb', line 34

def initialize(interval: DEFAULT_INTERVAL, output: $stdout)
  @interval = [interval.to_i, MIN_INTERVAL].max
  @output = output
  @running = false
end

Instance Attribute Details

#interval ⇒ Integer (readonly) 



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# File 'lib/pvectl/commands/get/watch_loop.rb', line 27

def interval
  @interval
end

Instance Method Details

#clear_screen ⇒ void

This method returns an undefined value.

Clears the terminal screen using ANSI escape codes.



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# File 'lib/pvectl/commands/get/watch_loop.rb', line 81

def clear_screen
  @output.print "\e[H\e[2J"
end

#print_header ⇒ void

This method returns an undefined value.

Prints the watch mode header with timestamp.



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# File 'lib/pvectl/commands/get/watch_loop.rb', line 88

def print_header
  timestamp = Time.now.strftime("%Y-%m-%d %H:%M:%S")
  @output.puts "Every #{@interval}s: #{timestamp}"
  @output.puts
end

#run { ... } ⇒ void

This method returns an undefined value.

Runs the watch loop, executing the block repeatedly.

Examples:

loop.run do
  models = handler.list
  puts format(models)
end

Yields:

  • Block to execute on each iteration

Yield Returns:

  • (void) 


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# File 'lib/pvectl/commands/get/watch_loop.rb', line 50

def run
  @running = true
  setup_signal_handler

  while @running
    clear_screen if tty?
    print_header if tty?
    yield
    sleep_interruptible(@interval)
  end
end

#running? ⇒ Boolean

Checks if the loop is currently running.



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# File 'lib/pvectl/commands/get/watch_loop.rb', line 72

def running?
  @running
end

#setup_signal_handler ⇒ void

This method returns an undefined value.

Sets up SIGINT handler for graceful termination.



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# File 'lib/pvectl/commands/get/watch_loop.rb', line 104

def setup_signal_handler
  @previous_handler = trap("INT") do
    stop
    # Don't print newline in non-TTY mode to avoid extra output
    @output.puts if tty?
  end
end

#sleep_interruptible(duration) ⇒ void

This method returns an undefined value.

Sleeps for the specified duration, allowing interruption.

Uses small sleep intervals to allow quick response to stop signal.



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# File 'lib/pvectl/commands/get/watch_loop.rb', line 118

def sleep_interruptible(duration)
  remaining = duration
  while remaining > 0 && @running
    chunk = [remaining, 0.1].min
    sleep(chunk)
    remaining -= chunk
  end
end

#stop ⇒ void

This method returns an undefined value.

Stops the watch loop.



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# File 'lib/pvectl/commands/get/watch_loop.rb', line 65

def stop
  @running = false
end

#tty? ⇒ Boolean

Checks if output is a TTY.



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# File 'lib/pvectl/commands/get/watch_loop.rb', line 97

def tty?
  @output.tty?
end