Refactor for cleaner caching in dashboards

Opts to cache a full list of cached dashboards
to better manage removing items from the cache.
This also allows dashboards to be stored in the
cache that don't necessarily correspond to a
single dashboard yml.

app/controllers/projects/environments_controller.rb

@@ -164,7 +164,7 @@ class Projects::EnvironmentsController < Projects::ApplicationController
     if Feature.enabled?(:environment_metrics_show_multiple_dashboards, project)
       result = dashboard_finder.find(project, current_user, environment, params[:dashboard])
 
-      result[:all_dashboards] = project.repository.metrics_dashboard_paths
+      result[:all_dashboards] = dashboard_finder.find_all_paths(project)
     else
       result = dashboard_finder.find(project, current_user, environment)
     end

lib/gitlab/metrics/dashboard/base_service.rb

@@ -7,18 +7,19 @@ module Gitlab
     module Dashboard
       class BaseService < ::BaseService
         PROCESSING_ERROR = Gitlab::Metrics::Dashboard::Stages::BaseStage::DashboardProcessingError
+        NOT_FOUND_ERROR = Gitlab::Template::Finders::RepoTemplateFinder::FileNotFoundError
 
         def get_dashboard
-          return error("#{dashboard_path} could not be found.", :not_found) unless path_available?
-
           success(dashboard: process_dashboard)
+        rescue NOT_FOUND_ERROR
+          error("#{dashboard_path} could not be found.", :not_found)
         rescue PROCESSING_ERROR => e
           error(e.message, :unprocessable_entity)
         end
 
         # Summary of all known dashboards for the service.
         # @return [Array<Hash>] ex) [{ path: String, default: Boolean }]
-        def all_dashboard_paths(_project)
+        def self.all_dashboard_paths(_project)
           raise NotImplementedError
         end
 
@@ -38,7 +39,7 @@ module Gitlab
 
         # Returns an un-processed dashboard from the cache.
         def raw_dashboard
-          Rails.cache.fetch(cache_key) { get_raw_dashboard }
+          Gitlab::Metrics::Dashboard::Cache.fetch(cache_key) { get_raw_dashboard }
         end
 
         # @return [Hash] an unmodified dashboard
@@ -56,17 +57,6 @@ module Gitlab
         def insert_project_metrics?
           false
         end
-
-        # Checks if dashboard path exists or should be rejected
-        # as a result of file-changes to the project repository.
-        # @return [Boolean]
-        def path_available?
-          available_paths = Gitlab::Metrics::Dashboard::Finder.find_all_paths(project)
-
-          available_paths.any? do |path_params|
-            path_params[:path] == dashboard_path
-          end
-        end
       end
     end
   end

lib/gitlab/metrics/dashboard/cache.rb

+# frozen_string_literal: true
+
+require 'set'
+
+module Gitlab
+  module Metrics
+    module Dashboard
+      class Cache
+        CACHE_KEYS = 'all_cached_metric_dashboards'
+
+        class << self
+          # Stores a dashboard in the cache, documenting the key
+          # so the cached can be cleared in bulk at another time.
+          def fetch(key)
+            register_key(key)
+
+            Rails.cache.fetch(key) { yield }
+          end
+
+          # Resets all dashboard caches, such that all
+          # dashboard content will be loaded from source on
+          # subsequent dashboard calls.
+          def delete_all!
+            all_keys.each { |key| Rails.cache.delete(key) }
+
+            Rails.cache.delete(CACHE_KEYS)
+          end
+
+          private
+
+          def register_key(key)
+            new_keys = all_keys.add(key).to_a.join('|')
+
+            Rails.cache.write(CACHE_KEYS, new_keys)
+          end
+
+          def all_keys
+            Set.new(Rails.cache.read(CACHE_KEYS)&.split('|'))
+          end
+        end
+      end
+    end
+  end
+end

lib/gitlab/metrics/dashboard/finder.rb

@@ -27,6 +27,8 @@ module Gitlab
           # Summary of all known dashboards. Used to populate repo cache.
           # Prefer #find_all_paths.
           def find_all_paths_from_source(project)
+            Gitlab::Metrics::Dashboard::Cache.delete_all!
+
             system_service.all_dashboard_paths(project)
             .+ project_service.all_dashboard_paths(project)
           end

lib/gitlab/metrics/dashboard/project_dashboard_service.rb

@@ -13,20 +13,12 @@ module Gitlab
           def all_dashboard_paths(project)
             file_finder(project)
               .list_files_for(DASHBOARD_ROOT)
-              .map do |filepath|
-                Rails.cache.delete(cache_key(project.id, filepath))
-
-                { path: filepath, default: false }
-              end
+              .map { |filepath| { path: filepath, default: false } }
           end
 
           def file_finder(project)
             Gitlab::Template::Finders::RepoTemplateFinder.new(project, DASHBOARD_ROOT, '.yml')
           end
-
-          def cache_key(id, dashboard_path)
-            "project_#{id}_metrics_dashboard_#{dashboard_path}"
-          end
         end
 
         private
@@ -39,7 +31,7 @@ module Gitlab
         end
 
         def cache_key
-          self.class.cache_key(project.id, dashboard_path)
+          "project_#{project.id}_metrics_dashboard_#{dashboard_path}"
         end
       end
     end