Class: ActiveSupport::Cache::Store

Inherits:
Object
  • Object
show all
Defined in:
lib/fetch_process_multi/active_support.rb

Instance Method Summary collapse

Instance Method Details

#fetch_and_process_multi(ids_to_keys, options = {}) ⇒ Object

Fetches data from the cache, using the given ids and ids_to_keys_proc. If there is data in the cache with the given keys, then that data is returned. Otherwise, the supplied block is called for ids for which there was no data, and the result will be written to the cache and returned as ids -> values hash. Ids can be any even composite identifiers.

Options are passed to the underlying cache implementation.

Returns hash of id -> value of passed ids. For example:

def ids_to_keys(ids)
  ids.each_with_object({}) do |id, memo|
    memo[id] = "key_base/id_#{id}"
  end
end
cache.write("key_for_1", "value_for_1")
cache.fetch_and_process_multi(ids_to_keys([1, 2]) do |uncached_ids|
  uncached_ids.each_with_object({}) do |id, memo|
    memo[id] = "fallback_value_for_#{id}"
  end
end
# => { 1 => "value_for_1", 2 => "fallback_value_for_2" }



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# File 'lib/fetch_process_multi/active_support.rb', line 29

def fetch_and_process_multi(ids_to_keys, options = {})
  options = merged_options(options)
  return {} if ids_to_keys.blank?

  keys_to_ids = ids_to_keys.invert

  cached_keys_to_values = read_multi(*keys_to_ids.keys, options)
  cached_ids_to_values =
    cached_keys_to_values.each_with_object({}) do |(key, value), memo|
      memo[keys_to_ids[key]] = value
    end

  if cached_ids_to_values.size == ids_to_keys.size
    return cached_ids_to_values
  end

  uncached_ids = ids_to_keys.keys - cached_ids_to_values.keys
  uncached_ids_to_values = yield(uncached_ids)
  uncached_ids_to_values.each do |id, value|
    write(ids_to_keys[id], value, options)
  end

  cached_ids_to_values.merge!(uncached_ids_to_values)
end