perf(lua): optimize cache eviction logic in fifo_put, lfu_put, and rr_put

- Replace looping calls with batch ZPOPMIN in fifo_put and lfu_put
- Use batch SPOP in rr_put
- Improve performance by reducing the number of Redis calls

Author: tanbro

src/redis_func_cache/lua/fifo_put.lua

@@ -58,13 +58,15 @@ else
     if maxsize > 0 then
         local n = redis.call('ZCARD', zset_key) - maxsize
         if n >= 0 then
+            -- Use batch ZPOPMIN instead of looping calls
+            local popped_keys_data = redis.call('ZPOPMIN', zset_key, n + 1) -- evict oldest
+
+            -- Extract keys from returned data (ZPOPMIN returns [key,score,key,score,...] format)
             local popped_keys = {}
-            for i = 1, n + 1 do
-                local popped = redis.call('ZPOPMIN', zset_key) -- evict oldest
-                if popped[1] then
-                    table.insert(popped_keys, popped[1])
-                end
+            for i = 1, #popped_keys_data, 2 do
+                table.insert(popped_keys, popped_keys_data[i])
             end
+
             if #popped_keys > 0 then
                 redis.call('HDEL', hmap_key, unpack(popped_keys))
                 c = #popped_keys

src/redis_func_cache/lua/lfu_put.lua

@@ -58,13 +58,15 @@ else
     if maxsize > 0 then
         local n = redis.call('ZCARD', zset_key) - maxsize
         if n >= 0 then
+            -- Use batch ZPOPMIN instead of looping calls
+            local popped_keys_data = redis.call('ZPOPMIN', zset_key, n + 1) -- evict least frequently used
+
+            -- Extract keys from returned data (ZPOPMIN returns [key,score,key,score,...] format)
             local popped_keys = {}
-            for i = 1, n + 1 do
-                local popped = redis.call('ZPOPMIN', zset_key) -- evict least frequently used
-                if popped[1] then
-                    table.insert(popped_keys, popped[1])
-                end
+            for i = 1, #popped_keys_data, 2 do
+                table.insert(popped_keys, popped_keys_data[i])
             end
+
             if #popped_keys > 0 then
                 redis.call('HDEL', hmap_key, unpack(popped_keys))
                 c = #popped_keys

src/redis_func_cache/lua/rr_put.lua

@@ -58,14 +58,15 @@ else
     if maxsize > 0 then
         local n = redis.call('SCARD', set_key) - maxsize
         if n >= 0 then
-            local popped_keys = {}
-            for i = 1, n + 1 do
-                local popped = redis.call('SPOP', set_key) -- evict random member
-                if popped then
-                    table.insert(popped_keys, popped)
-                end
-            end
-            if #popped_keys > 0 then
+            -- SPOP: Removes and returns one or more random members from the set value store at key
+            local popped_keys = redis.call('SPOP', set_key, n + 1) -- evict random members
+
+            if type(popped_keys) == "string" then
+                -- What returned by SPOP is a string when only one element is popped
+                redis.call('HDEL', hmap_key, popped_keys)
+                c = 1
+            elseif type(popped_keys) == "table" and #popped_keys > 0 then
+                -- what returned by SPOP is a table when multiple elements are popped
                 redis.call('HDEL', hmap_key, unpack(popped_keys))
                 c = #popped_keys
             end