Class: Caddy::Cache

Inherits:
Object
  • Object
show all
Defined in:
lib/caddy/cache.rb

Constant Summary collapse

DEFAULT_REFRESH_INTERVAL = 
60
REFRESH_INTERVAL_JITTER_PCT = 
0.15

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(key) ⇒ Cache

Returns a new instance of Cache.



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# File 'lib/caddy/cache.rb', line 9

def initialize(key)
  @task = nil
  @refresh_interval = DEFAULT_REFRESH_INTERVAL
  @cache = nil
  @key = key
end

Instance Attribute Details

#error_handler ⇒ Object

Returns the value of attribute error_handler.



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# File 'lib/caddy/cache.rb', line 7

def error_handler
  @error_handler
end

#refresh_interval ⇒ Object

Returns the value of attribute refresh_interval.



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# File 'lib/caddy/cache.rb', line 7

def refresh_interval
  @refresh_interval
end

#refresher ⇒ Object

Returns the value of attribute refresher.



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# File 'lib/caddy/cache.rb', line 7

def refresher
  @refresher
end

Instance Method Details

#[](k) ⇒ Object 



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# File 'lib/caddy/cache.rb', line 16

def [](k)
  cache[k]
end

#cache ⇒ Object 



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# File 'lib/caddy/cache.rb', line 20

def cache
  raise "Please run `Caddy.start` before attempting to access the cache" unless @task && @task.running?
  raise "Caddy cache access of :#{@key} before initial load; allow some more time for your app to start up" unless @cache

  @cache
end

#start ⇒ Object 



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# File 'lib/caddy/cache.rb', line 27

def start
  unless refresher && refresher.respond_to?(:call)
    raise "Please set your cache refresher via `Caddy[:#{@key}].refresher = -> { <code that returns a value> }`"
  end

  raise "`Caddy[:#{@key}].refresh_interval` must be > 0" unless refresh_interval > 0

  jitter_amount = [0.1, refresh_interval * REFRESH_INTERVAL_JITTER_PCT].max
  interval = refresh_interval + rand(-jitter_amount...jitter_amount)
  timeout_interval = [interval - 1, 0.1].max

  stop # stop any existing task from running

  @task = Concurrent::TimerTask.new(
    run_now: true,
    execution_interval: interval,
    timeout_interval: timeout_interval
  ) do
    @cache = refresher.call.freeze
    nil # no need to save the value internally to TimerTask
  end

  @task.add_observer(Caddy::TaskObserver.new(error_handler, @key))
  @task.execute

  @task.running?
end

#stop ⇒ Object 



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# File 'lib/caddy/cache.rb', line 55

def stop
  @task.shutdown if @task && @task.running?
end