[fix] conj keys always have -1 as expiration in redis 7

Author: shubhamagrawal1906

cacheops/lua/cache_thing.lua

@@ -47,11 +47,19 @@ for db_table, disj in pairs(dnfs) do
         redis.call('sadd', conj_key, key)
         -- NOTE: an invalidator should live longer than any key it references.
         --       So we update its ttl on every key if needed.
+        local conj_ttl = redis.call('ttl', conj_key)
         -- REDIS_7
-        redis.call('expire', conj_key, timeout, 'gt')
+        -- Removing `redis.call('expire', conj_key, timeout, 'gt')` as ttl is not setting up when its value is -1
+        -- Refer - https://redis.io/docs/latest/commands/expire/
+        if conj_ttl == -1 then
+            -- Use NX when no expiry is present i.e. ttl = -1
+            redis.call('expire', conj_key, timeout, 'nx')
+        elseif conj_ttl < timeout then
+            -- Use XX when current expiration time is less than timeout
+            redis.call('expire', conj_key, timeout, 'xx')
+        end
         -- /REDIS_7
         -- REDIS_4
-        local conj_ttl = redis.call('ttl', conj_key)
         if conj_ttl < timeout then
             -- We set conj_key life with a margin over key life to call expire rarer
             -- And add few extra seconds to be extra safe

cacheops/lua/cache_thing_insideout.lua

@@ -28,11 +28,19 @@ for _, conj_key in ipairs(conj_keys) do
     table.insert(stamps, stamp)
     -- NOTE: an invalidator should live longer than any key it references.
     --       So we update its ttl on every key if needed.
+    local conj_ttl = redis.call('ttl', conj_key)
     -- REDIS_7
-    redis.call('expire', conj_key, timeout, 'gt')
+    -- Removing `redis.call('expire', conj_key, timeout, 'gt')` as ttl is not setting up when its value is -1
+    -- Refer - https://redis.io/docs/latest/commands/expire/
+    if conj_ttl == -1 then
+        -- Use NX when no expiry is present i.e. ttl = -1
+        redis.call('expire', conj_key, timeout, 'nx')
+    elseif conj_ttl < timeout then
+        -- Use XX when current expiration time is less than timeout
+        redis.call('expire', conj_key, timeout, 'xx')
+    end
     -- /REDIS_7
     -- REDIS_4
-    local conj_ttl = redis.call('ttl', conj_key)
     if conj_ttl < timeout then
         -- We set conj_key life with a margin over key life to call expire rarer
         -- And add few extra seconds to be extra safe