Only check for solr alias changes on a timer

Gemfile

@@ -21,6 +21,7 @@ gem "aws-sdk-s3", "~> 1.160"
 gem "content_disposition", "~> 1.0"
 gem "uppy-s3_multipart", "~> 1.2"
 
+gem "concurrent-ruby"
 
 #####################################
 # Try to work around brokenness on

Gemfile.lock

@@ -453,6 +453,7 @@ DEPENDENCIES
   bundler (~> 2.4.22)
   canister
   coffee-rails (~> 4.2)
+  concurrent-ruby
   content_disposition (~> 1.0)
   date_named_file
   debase

app/views/shared/_footer.html.erb

@@ -39,7 +39,7 @@
       Data last refreshed <%= if Dromedary::Services[:looks_like_first_upload]
                                 "never"
                               else
-                                Dromedary.collection_creation_date.strftime("%A, %B %-e, %Y")
+                                Dromedary.collection_creation_date_string
                               end
     %>.
     </p>

config/initializers/solr_admin_cache.rb

@@ -0,0 +1,37 @@
+S = Dromedary::Services
+
+# Set up some places to work
+S.register(:hyp_to_bibid) { Concurrent::Atom.new(:no_hyp_to_bib_id_yet) }
+S.register(:collection_creation_date) { Concurrent::Atom.new(:no_creation_date_yet) }
+S.register(:underlying_collection_name) {Concurrent::Atom.new(:no_underlying_name_yet) }
+
+
+# Update the underlying concurrent variables.
+# If the collection name underlying the (presumed) alias we're working with changes,
+# update the collection-specific data and reset our understanding of the
+# current collection name.
+def update_timeout_variables
+  Rails.logger.warn "################# CHECK FOR UPDATE ########################"
+  collection = S[:solr_current_collection]
+  # Bail if there's no current collection
+  return unless collection
+  actual_current_underlying_collection_name = collection.collection.name
+  expected_underlying_collection_name = S[:underlying_collection_name].value
+  if actual_current_underlying_collection_name != expected_underlying_collection_name
+    Rails.logger.warn "################# PERFORMING UPDATE ########################"
+    S[:hyp_to_bibid].reset MedInstaller::HypToBibId.get_from_solr(collection: collection)
+    S[:collection_creation_date].reset Dromedary.compute_collection_creation_date(actual_current_underlying_collection_name)
+    S[:underlying_collection_name].reset actual_current_underlying_collection_name
+  end
+end
+
+# The timer, with `run_now`, is supposed to run immediately, but I keep getting not-set-yet
+# errors, so we'll run it once manually on startup.
+update_timeout_variables
+
+# Run the update method ever 20 seconds
+collection_timer = Concurrent::TimerTask.new(execution_interval: 20, run_now: true) do
+  update_timeout_variables
+end
+# Need to call #execute to actually fire up the timer
+collection_timer.execute

config/load_local_config.rb

@@ -7,7 +7,7 @@
 module Dromedary
   class << self
     def logger
-      MedInstaller::Logger::LOGGER
+      Rails.logger || MedInstaller::Logger::LOGGER
     end
 
     # For whatever historical reasons, this uses the Ettin gem to load
@@ -26,34 +26,23 @@ def config
         ENV["RAILS_ENV"]
       else
         "development"
-      end
+            end
       @config = Dromedary::Services
     end
 
-    def hyp_to_bibid(collection: Dromedary::Services[:solr_current_collection])
-      logger.info "Trying to get hyp_to_bibid for collection #{collection}"
-      current_real_collection_name = underlying_real_collection_name(coll: collection)
-      logger.info "Real collection name identified as #{current_real_collection_name}"
-      if @recorded_real_collection_name != current_real_collection_name
-        @hyp_to_bibid = MedInstaller::HypToBibId.get_from_solr(collection: collection)
-        @recorded_real_collection_name = current_real_collection_name
-        @collection_creation_date = nil
-      end
-      @hyp_to_bibid
 
-    end
 
-    # @param coll [SolrCloud::Alias]
-    def underlying_real_collection_name(coll:  Dromedary::Services[:solr_current_collection])
-      return coll.name unless coll.alias?
-      underlying_real_collection_name(coll: coll.collection)
+    def hyp_to_bibid
+      Dromedary::Services[:hyp_to_bibid].value
     end
 
-    def collection_creation_date(coll:  Dromedary::Services[:solr_current_collection])
-      return @collection_creation_date if defined?(@collection_creation_date) && !@collection_creation_date.nil?
 
-      real_collection_name = underlying_real_collection_name(coll: coll)
-      @collection_creation_date = compute_collection_creation_date(real_collection_name)
+    def collection_creation_date
+      Dromedary::Services[:collection_creation_date].value
+    end
+
+    def collection_creation_date_string
+      collection_creation_date.strftime("%A, %B %-e, %Y at %H:%M:%S")
     end
 
     def compute_collection_creation_date(coll)

indexer/main_indexing_rules.rb

@@ -19,7 +19,7 @@
   provide "solr_writer.basic_auth_password", Dromedary::Services[:solr_password]
 end
 
-hyp_to_bibid = Dromedary.hyp_to_bibid(collection: Dromedary::Services[:solr_collection_to_index_into])
+hyp_to_bibid = MedInstaller::HypToBibId.get_from_solr(collection:  Dromedary::Services[:solr_collection_to_index_into])
 bibset = MiddleEnglishDictionary::Collection::BibSet.new(filename: settings["bibfile"])
 
 # Do a terrible disservice to traject and monkeypatch it to take