Use JsonCache only for the persistent cache

These changes use the Gitlab::SafeRequestStore without
Gitlab::JsonCache, but still use the Gitlab::JsonCache
for the persistent storage.

ee/lib/gitlab/geo.rb

@@ -86,24 +86,24 @@ module Gitlab
     end
 
     def self.request_store_cache
-      @request_store_cache ||= Gitlab::JsonCache.new(namespace: :geo, backend: Gitlab::SafeRequestStore)
+      Gitlab::SafeRequestStore
     end
 
-    def self.cache_value(key, as: nil, &block)
+    def self.cache_value(raw_key, as: nil, &block)
       return yield unless request_store_cache.active?
 
-      request_store_cache.fetch(key, as: as) do
+      request_store_cache.fetch(cache.cache_key(raw_key)) do
         # We need a short expire time as we can't manually expire on a secondary node
-        cache.fetch(key, as: as, expires_in: 15.seconds) { yield }
+        cache.fetch(raw_key, as: as, expires_in: 15.seconds) { yield }
       end
     end
 
     def self.expire_cache!
       return true unless request_store_cache.active?
 
-      CACHE_KEYS.each do |key|
-        cache.expire(key)
-        request_store_cache.expire(key)
+      CACHE_KEYS.each do |raw_key|
+        cache.expire(raw_key)
+        request_store_cache.delete(cache.cache_key(raw_key))
       end
 
       true

ee/spec/lib/gitlab/geo_spec.rb

@@ -9,8 +9,12 @@ describe Gitlab::Geo, :geo, :request_store do
 
   shared_examples 'a Geo cached value' do |method, key|
     it 'includes GitLab version and Rails.version in the cache key' do
+      expanded_key = "geo:#{key}:#{Gitlab::VERSION}:#{Rails.version}"
+
+      expect(Gitlab::SafeRequestStore).to receive(:fetch)
+        .with(expanded_key).and_call_original
       expect(Rails.cache).to receive(:write)
-        .with("geo:#{key}:#{Gitlab::VERSION}:#{Rails.version}", an_instance_of(String), expires_in: 15.seconds)
+        .with(expanded_key, an_instance_of(String), expires_in: 15.seconds)
 
       described_class.public_send(method)
     end
@@ -171,7 +175,10 @@ describe Gitlab::Geo, :geo, :request_store do
   describe '.expire_cache!' do
     it 'clears the Geo cache keys', :request_store do
       described_class::CACHE_KEYS.each do |raw_key|
-        expect(Rails.cache).to receive(:delete).with("geo:#{raw_key}:#{Gitlab::VERSION}:#{Rails.version}")
+        expanded_key = "geo:#{raw_key}:#{Gitlab::VERSION}:#{Rails.version}"
+
+        expect(Rails.cache).to receive(:delete).with(expanded_key)
+        expect(Gitlab::SafeRequestStore).to receive(:delete).with(expanded_key)
       end
 
       described_class.expire_cache!