Class: AsyncCache::Store

Inherits:
Object
  • Object
show all
Defined in:
lib/async_cache/store.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(opts = {}) ⇒ Store

Returns a new instance of Store.

Parameters:

  • opts (Hash) (defaults to: {}) —

    Initialization options

  • ops (Hash) —

    a customizable set of options

Options Hash (opts):

  • :backend (Object) —

    The backend that it will read/write entries to/from

  • :worker (Symbol) —

    Shorthand symbol for the worker to use, options are :active_job and :sidekiq.



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# File 'lib/async_cache/store.rb', line 11

def initialize(opts = {})
  @worker_klass =
    if opts[:worker_klass]
      opts[:worker_klass]
    elsif opts[:worker]
      AsyncCache::Workers.worker_for_name opts[:worker]
    else
      raise ArgumentError, 'Must have a :worker_klass or :worker option'
    end

  @backend = opts[:backend] || AsyncCache.backend
end

Instance Attribute Details

#backend ⇒ Object

Returns the value of attribute backend.



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# File 'lib/async_cache/store.rb', line 3

def backend
  @backend
end

#worker_klass ⇒ Object

Returns the value of attribute worker_klass.



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# File 'lib/async_cache/store.rb', line 3

def worker_klass
  @worker_klass
end

Instance Method Details

#check_arguments(arguments) ⇒ Object (private)

Ensures the arguments are primitives.



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# File 'lib/async_cache/store.rb', line 117

def check_arguments arguments
  arguments.each_with_index do |argument, index|
    next if argument.is_a? Numeric
    next if argument.is_a? String
    next if argument.is_a? Symbol
    next if argument.is_a? Hash
    next if argument.is_a? NilClass
    next if argument.is_a? TrueClass
    next if argument.is_a? FalseClass

    raise ArgumentError, "Cannot send complex data for block argument #{index + 1}: #{argument.class.name}"
  end

  arguments
end

#determine_strategy(has_cached_data:, needs_regen:, synchronous_regen:) ⇒ Object 



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# File 'lib/async_cache/store.rb', line 69

def determine_strategy(has_cached_data:, needs_regen:, synchronous_regen:)
  case
  when !has_cached_data
    # Not present at all
    :generate
  when needs_regen && synchronous_regen
    # Caller has indicated we should synchronously regenerate
    :generate
  when needs_regen && !worker_klass.has_workers?
    # No workers available to regnerate, so do it ourselves; we'll log a
    # warning message that we can alert on
    AsyncCache.logger.warn "No workers running to handle AsyncCache jobs"
    :generate
  when needs_regen
    :enqueue
  else
    :current
  end
end

#enqueue_generation(key:, version:, expires_in:, block:, arguments:) ⇒ Object 



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# File 'lib/async_cache/store.rb', line 104

def enqueue_generation(key:, version:, expires_in:, block:, arguments:)
  worker_klass.enqueue_async_job(
    key:        key,
    version:    version,
    expires_in: expires_in,
    block:      block.to_source,
    arguments:  arguments
  )
end

#fetch(locator, version, options = {}) {|*arguments in options[:arguments]| ... } ⇒ Object

Parameters:

  • locator (String) —

    The constant locator for the entry in the cache

  • version (Fixnum) —

    Version of the value identified by that locator

  • options (Hash) (defaults to: {})

Yields:

  • (*arguments in options[:arguments]) —

    Called if entry out-of-date



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# File 'lib/async_cache/store.rb', line 28

def fetch(locator, version, options = {}, &block)
  options = options.dup  # Duplicate to avoid side effects
  version = version.to_i # Versions must *always* be convertible to integers

  # Expires-in must be an integer if present, nil if not
  expires_in = options[:expires_in] ? options[:expires_in].to_i : nil

  block_arguments = check_arguments(options.delete(:arguments) || [])

  # Serialize arguments into the full cache key
  key = ActiveSupport::Cache.expand_cache_key Array.wrap(locator) + block_arguments

  cached_data, cached_version = @backend.read key

  strategy = determine_strategy(
    :has_cached_data   => !!cached_data,
    :needs_regen       => version > (cached_version || 0),
    :synchronous_regen => options[:synchronous_regen]
  )

  context = {
    :key        => key,
    :version    => version,
    :expires_in => expires_in,
    :block      => block,
    :arguments  => block_arguments
  }

  case strategy
  when :generate
    return generate_and_cache context

  when :enqueue
    enqueue_generation context
    return cached_data

  when :current
    return cached_data
  end
end

#generate_and_cache(key:, version:, expires_in:, block:, arguments:) ⇒ Object 



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# File 'lib/async_cache/store.rb', line 89

def generate_and_cache(key:, version:, expires_in:, block:, arguments:)
  block_source = block.to_source

  # Mimic the destruction-of-scope behavior of the worker in development
  # so it will *fail* for developers if they try to depend upon scope
  block = eval(block_source)

  data = block.call(*arguments)

  entry = [data, version]
  @backend.write key, entry, :expires_in => expires_in

  return data
end