use different redis keys for production / staging

This also replaces the `REDIS_MOVIE_SCORE_PREFIX` that was used to have
a specific key prefix for the tests. We now use
`KeyValueStore::KEY_PREFIX` that handles giving out a specific key for
test, production and staging.

Author: koffeinfrei

www/.env.test

@@ -1,5 +1,5 @@
 module MovieScore
-  KEY_PREFIX = ENV.fetch("REDIS_MOVIE_SCORE_PREFIX", "siwt_movie")
+  KEY_PREFIX = "#{KeyValueStore::KEY_PREFIX}:score:"
   STD_TTL = 3.days
 
   def self.get(wiki_id)
@@ -29,11 +29,11 @@ def self.get_local(wiki_id)
   end
 
   def self.save(wiki_id, scores, trailer_url, ttl: STD_TTL)
-    REDIS.set(key(wiki_id), Oj.dump([scores, trailer_url]), ex: ttl)
+    KeyValueStore.client.set(key(wiki_id), Oj.dump([scores, trailer_url]), ex: ttl)
   end
 
   def self.load(wiki_id)
-    value = REDIS.get(key(wiki_id))
+    value = KeyValueStore.client.get(key(wiki_id))
     if value
       Oj.load(value)
     end
@@ -47,12 +47,12 @@ def self.fetch(wiki_id)
   end
 
   def self.key(wiki_id)
-    "#{KEY_PREFIX}_#{wiki_id}"
+    "#{KEY_PREFIX}#{wiki_id}"
   end
 
   def self.delete_all
-    REDIS.scan_each(match: "#{KEY_PREFIX}_*") do |key|
-      REDIS.del(key)
+    KeyValueStore.client.scan_each(match: "#{KEY_PREFIX}:*") do |key|
+      KeyValueStore.client.del(key)
     end
   end
 end

www/app/models/movie_score.rb

@@ -1,28 +1,26 @@
 module SimpleStore
-  KEY_PREFIX = "siwt"
-
   def self.fetch(key)
     key = self.key(key)
 
-    value = REDIS.get(key)
+    value = KeyValueStore.client.get(key)
     return value if value
 
     new_value = yield
 
     # Only one thread should compute + set
-    REDIS.set(key, new_value, nx: true)
+    KeyValueStore.client.set(key, new_value, nx: true)
 
     # Return whichever value ended up stored
-    REDIS.get(key)
+    KeyValueStore.client.get(key)
   end
 
   def self.delete(key)
     key = self.key(key)
 
-    REDIS.del(key)
+    KeyValueStore.client.del(key)
   end
 
   def self.key(key)
-    "#{KEY_PREFIX}_#{key}"
+    "#{KeyValueStore::KEY_PREFIX}:#{key}"
   end
 end

www/app/models/simple_store.rb

@@ -1,5 +1,14 @@
-REDIS = Redis.new(
-  url:  ENV["REDIS_URL"],
-  port: ENV["REDIS_PORT"],
-  db:   ENV["REDIS_DB"]
-)
+module KeyValueStore
+  KEY_PREFIX =
+    begin
+      prefix = ENV.fetch("APPLICATION_NAME").parameterize.underscore
+      if Rails.env.test?
+        prefix += "_test"
+      end
+      prefix
+    end
+
+  def self.client
+    @client ||= Redis.new
+  end
+end