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Contents
# frozen_string_literal: true
module Hyrax
##
# constructs IIIF Manifests and holds them in the Rails cache,
# this approach avoids long manifest build times for some kinds of requests,
# at the cost of introducing cache invalidation issues.
class CachingIiifManifestBuilder < ManifestBuilderService
KEY_PREFIX = 'iiif-cache-v1'
attr_accessor :expires_in
##
# @api public
#
# @param iiif_manifest_factory [Class] a class that initializes with presenter
# object and returns an object that responds to `#to_h`
# @param expires_in [Integer] the number of seconds until the cache expires
# @see Hyrax::Configuration#iiif_manifest_cache_duration
def initialize(iiif_manifest_factory: ::IIIFManifest::ManifestFactory, expires_in: Hyrax.config.iiif_manifest_cache_duration)
self.expires_in = expires_in
super(iiif_manifest_factory: iiif_manifest_factory)
end
##
# @see ManifestBuilderService#as_json
def manifest_for(presenter:)
Rails.cache.fetch(manifest_cache_key(presenter: presenter), expires_in: expires_in) do
super
end
end
private
##
# @note adding a version_for suffix helps us manage cache expiration,
# reducing false cache hits
#
# @param presenter [Hyrax::IiifManifestPresenter]
#
# @return [String]
def manifest_cache_key(presenter:)
"#{KEY_PREFIX}_#{presenter.id}/#{version_for(presenter)}"
end
##
# @note `etag` is a better option than the solr document `_version_`; the
# latter isn't always available, depending on how the presenter was
# built!
#
# @return [String]
def version_for(presenter)
presenter.version
end
end
end
Version data entries
25 entries across 25 versions & 1 rubygems