Class: CacheIfSlow

Inherits:
Object
  • Object
show all
Defined in:
lib/cache_if_slow.rb,
lib/cache_if_slow/version.rb

Constant Summary collapse

VERSION = 
"0.0.2"

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(cache: Rails.cache, expiry_lookup: nil, logger: Rails.logger) ⇒ CacheIfSlow

Returns a new instance of CacheIfSlow.



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# File 'lib/cache_if_slow.rb', line 8

def initialize(cache: Rails.cache, expiry_lookup: nil, logger: Rails.logger)
  @cache = cache
  @logger = logger
  if expiry_lookup.present?
    expiry_lookup.each do |v|
      raise ArgumentError, "`slower_than` if required for all entries in `expiry_lookup`" if v[:slower_than].blank?
      raise ArgumentError, "`expires_in` if required for all entries in `expiry_lookup`" if v[:expires_in].blank?
    end
    @expiry_lookup = expiry_lookup.sort_by { |v| -v[:slower_than] }
  end
end

Instance Attribute Details

#logger ⇒ Object

Returns the value of attribute logger.



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# File 'lib/cache_if_slow.rb', line 7

def logger
  @logger
end

Class Method Details

.fetch(name, max_seconds:, **options, &block) ⇒ Object 



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# File 'lib/cache_if_slow.rb', line 47

def fetch(name, max_seconds:, **options, &block)
  new.fetch(name, max_seconds: max_seconds, **options, &block)
end

Instance Method Details

#fetch(name, max_seconds: nil, **options) ⇒ Object 



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# File 'lib/cache_if_slow.rb', line 20

def fetch(name, max_seconds: nil, **options)
  unless block_given?
    raise ArgumentError, "Missing block: Calling `CacheIfSlow#fetch` requires a block."
  end

  if @expiry_lookup.blank? && max_seconds.nil?
    raise ArgumentError, "`max_seconds` is required if `expiry_lookup` is not present."
  end
  max_seconds = @expiry_lookup[-1][:slower_than] if max_seconds.nil? || @expiry_lookup[-1][:slower_than] < max_seconds

  value = @cache.read(name, options)
  return value unless value.nil?

  start = Time.now
  value = yield(name)
  total_time = Time.now - start

  if total_time > max_seconds && @cache.read(name, options).nil?
    expires_in = lookup_expiry(total_time, options)
    options[:expires_in] = expires_in
    @logger.info "CacheIfSlow :: Storing '#{name}' as #{total_time} > #{max_seconds} expires_in: #{expires_in}"
    @cache.write(name, value, options)
  end
  value
end