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diff --git a/app/models/concerns/reactive_caching.rb b/app/models/concerns/reactive_caching.rb
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+++ b/app/models/concerns/reactive_caching.rb
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+# The ReactiveCaching concern is used to fetch some data in the background and
+# store it in the Rails cache, keeping it up-to-date for as long as it is being
+# requested.  If the data hasn't been requested for +reactive_cache_lifetime+,
+# it stop being refreshed, and then be removed.
+#
+# Example of use:
+#
+#    class Foo < ActiveRecord::Base
+#      include ReactiveCaching
+#
+#      self.reactive_cache_key = ->(thing) { ["foo", thing.id] }
+#
+#      after_save :clear_reactive_cache!
+#
+#      def calculate_reactive_cache
+#        # Expensive operation here. The return value of this method is cached
+#      end
+#
+#      def result
+#        with_reactive_cache do |data|
+#          # ...
+#        end
+#      end
+#    end
+#
+# In this example, the first time `#result` is called, it will return `nil`.
+# However, it will enqueue a background worker to call `#calculate_reactive_cache`
+# and set an initial cache lifetime of ten minutes.
+#
+# Each time the background job completes, it stores the return value of
+# `#calculate_reactive_cache`. It is also re-enqueued to run again after
+# `reactive_cache_refresh_interval`, so keeping the stored value up to date.
+# Calculations are never run concurrently.
+#
+# Calling `#result` while a value is in the cache will call the block given to
+# `#with_reactive_cache`, yielding the cached value. It will also extend the
+# lifetime by `reactive_cache_lifetime`.
+#
+# Once the lifetime has expired, no more background jobs will be enqueued and
+# calling `#result` will again return `nil` - starting the process all over
+# again
+module ReactiveCaching
+  extend ActiveSupport::Concern
+
+  included do
+    class_attribute :reactive_cache_lease_timeout
+
+    class_attribute :reactive_cache_key
+    class_attribute :reactive_cache_lifetime
+    class_attribute :reactive_cache_refresh_interval
+
+    # defaults
+    self.reactive_cache_lease_timeout = 2.minutes
+
+    self.reactive_cache_refresh_interval = 1.minute
+    self.reactive_cache_lifetime = 10.minutes
+
+    def calculate_reactive_cache
+      raise NotImplementedError
+    end
+
+    def with_reactive_cache(&blk)
+      within_reactive_cache_lifetime do
+        data = Rails.cache.read(full_reactive_cache_key)
+        yield data if data.present?
+      end
+    ensure
+      Rails.cache.write(full_reactive_cache_key('alive'), true, expires_in: self.class.reactive_cache_lifetime)
+      ReactiveCachingWorker.perform_async(self.class, id)
+    end
+
+    def clear_reactive_cache!
+      Rails.cache.delete(full_reactive_cache_key)
+    end
+
+    def exclusively_update_reactive_cache!
+      locking_reactive_cache do
+        within_reactive_cache_lifetime do
+          enqueuing_update do
+            value = calculate_reactive_cache
+            Rails.cache.write(full_reactive_cache_key, value)
+          end
+        end
+      end
+    end
+
+    private
+
+    def full_reactive_cache_key(*qualifiers)
+      prefix = self.class.reactive_cache_key
+      prefix = prefix.call(self) if prefix.respond_to?(:call)
+
+      ([prefix].flatten + qualifiers).join(':')
+    end
+
+    def locking_reactive_cache
+      lease = Gitlab::ExclusiveLease.new(full_reactive_cache_key, timeout: reactive_cache_lease_timeout)
+      uuid = lease.try_obtain
+      yield if uuid
+    ensure
+      Gitlab::ExclusiveLease.cancel(full_reactive_cache_key, uuid)
+    end
+
+    def within_reactive_cache_lifetime
+      yield if Rails.cache.read(full_reactive_cache_key('alive'))
+    end
+
+    def enqueuing_update
+      yield
+    ensure
+      ReactiveCachingWorker.perform_in(self.class.reactive_cache_refresh_interval, self.class, id)
+    end
+  end
+end