Class: OnlineMigrations::BackgroundDataMigrations::Ticker

Inherits:
Object
  • Object
show all
Defined in:
lib/online_migrations/background_data_migrations/ticker.rb

Overview

This class encapsulates the logic behind updating the tick counter.

It’s initialized with a duration for the throttle, and a block to persist the number of ticks to increment.

When tick is called, the block will be called with the increment, provided the duration since the last update (or initialization) has been long enough.

To not lose any increments, persist should be used, which may call the block with any leftover ticks.

Instance Method Summary collapse

Constructor Details

#initialize(interval) {|ticks| ... } ⇒ Ticker

Creates a Ticker that will call the block each time tick is called, unless the tick is being throttled.

Parameters:

  • interval (ActiveSupport::Duration, Numeric) —

    Duration since initialization or last call that will cause a throttle.

Yield Parameters:

  • ticks (Integer) —

    the increment in ticks to be persisted.



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# File 'lib/online_migrations/background_data_migrations/ticker.rb', line 26

def initialize(interval, &block)
  @interval = interval
  @block = block
  @last_persisted_at = Time.current
  @ticks_recorded = 0
end

Instance Method Details

#persist ⇒ Object

Persists the tick increments by calling the block passed to the initializer. This is idempotent in the sense that calling it twice in a row will call the block at most once (if it had been throttled).



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# File 'lib/online_migrations/background_data_migrations/ticker.rb', line 46

def persist
  return if @ticks_recorded == 0

  now = Time.current
  duration = now - @last_persisted_at
  @last_persisted_at = now
  @block.call(@ticks_recorded, duration)
  @ticks_recorded = 0
end

#tick ⇒ Object

Increments the tick count by one, and may persist the new value if the threshold duration has passed since initialization or the tick count was last persisted.



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# File 'lib/online_migrations/background_data_migrations/ticker.rb', line 37

def tick
  @ticks_recorded += 1
  persist if persist?
end