Bring Gitlab::ShardHealthCache to CE

It already existed in EE in the Geo namespace. This change brings it
to CE.

1 files changed, 41 insertions, 0 deletions

diff --git a/lib/gitlab/shard_health_cache.rb b/lib/gitlab/shard_health_cache.rb
new file mode 100644
index 00000000000..3f03f46d4b1
--- /dev/null
+++ b/lib/gitlab/shard_health_cache.rb
@@ -0,0 +1,41 @@
+module Gitlab
+  class ShardHealthCache
+    HEALTHY_SHARDS_KEY = 'gitlab-healthy-shards'.freeze
+    HEALTHY_SHARDS_TIMEOUT = 300
+
+    # Clears the Redis set storing the list of healthy shards
+    def self.clear
+      Gitlab::Redis::Cache.with { |redis| redis.del(HEALTHY_SHARDS_KEY) }
+    end
+
+    # Updates the list of healthy shards using a Redis set
+    #
+    # shards - An array of shard names to store
+    def self.update(shards)
+      Gitlab::Redis::Cache.with do |redis|
+        redis.multi do |m|
+          m.del(HEALTHY_SHARDS_KEY)
+          shards.each { |shard_name| m.sadd(HEALTHY_SHARDS_KEY, shard_name) }
+          m.expire(HEALTHY_SHARDS_KEY, HEALTHY_SHARDS_TIMEOUT)
+        end
+      end
+    end
+
+    # Returns an array of strings of healthy shards
+    def self.cached_healthy_shards
+      Gitlab::Redis::Cache.with { |redis| redis.smembers(HEALTHY_SHARDS_KEY) }
+    end
+
+    # Checks whether the given shard name is in the list of healthy shards.
+    #
+    # shard_name - The string to check
+    def self.healthy_shard?(shard_name)
+      Gitlab::Redis::Cache.with { |redis| redis.sismember(HEALTHY_SHARDS_KEY, shard_name) }
+    end
+
+    # Returns the number of healthy shards in the Redis set
+    def self.healthy_shard_count
+      Gitlab::Redis::Cache.with { |redis| redis.scard(HEALTHY_SHARDS_KEY) }
+    end
+  end
+end