refactor: move go-chi/cache into Gitea (#39530)

The `gitea.com/go-chi/cache` package only exists for Gitea, so it moves
into `modules/cache`.

- `ITEM_TTL = -1` disables caching as documented
- Sub-second TTLs round up instead of never expiring
- The Redis adapter no longer grows a `MacaronCache` hash
- Use two-queue cache for in-memory cache

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

modules/setting/cache.go

@@ -4,6 +4,7 @@
 package setting
 
 import (
+	"math"
 	"time"
 
 	"gitea.dev/modules/log"
@@ -37,9 +38,6 @@ var CacheService = struct {
 	},
 }
 
-// MemcacheMaxTTL represents the maximum memcache TTL
-const MemcacheMaxTTL = 30 * 24 * time.Hour
-
 func loadCacheFrom(rootCfg ConfigProvider) {
 	sec := rootCfg.Section("cache")
 	if err := sec.MapTo(&CacheService); err != nil {
@@ -60,18 +58,19 @@ func loadCacheFrom(rootCfg ConfigProvider) {
 	}
 }
 
-// TTLSeconds returns the TTLSeconds or unix timestamp for memcache
+// TTLSeconds returns the item TTL in seconds, negative when ITEM_TTL disables caching
 func (c Cache) TTLSeconds() int64 {
-	if c.Adapter == "memcache" && c.TTL > MemcacheMaxTTL {
-		return time.Now().Add(c.TTL).Unix()
-	}
-	return int64(c.TTL.Seconds())
+	return ttlSeconds(c.TTL)
 }
 
-// LastCommitCacheTTLSeconds returns the TTLSeconds or unix timestamp for memcache
+// LastCommitCacheTTLSeconds returns the last commit item TTL in seconds, negative when ITEM_TTL disables caching
 func LastCommitCacheTTLSeconds() int64 {
-	if CacheService.Adapter == "memcache" && CacheService.LastCommit.TTL > MemcacheMaxTTL {
-		return time.Now().Add(CacheService.LastCommit.TTL).Unix()
-	}
-	return int64(CacheService.LastCommit.TTL.Seconds())
+	return ttlSeconds(CacheService.LastCommit.TTL)
+}
+
+func ttlSeconds(ttl time.Duration) int64 {
+	if ttl < 0 {
+		return -1
+	}
+	return int64(math.Ceil(ttl.Seconds()))
 }

modules/setting/cache_test.go

@@ -69,3 +69,14 @@ ADAPTER = memcache
 		})
 	}
 }
+
+func TestCacheItemTTLSeconds(t *testing.T) {
+	defer test.MockVariableValue(&CacheService)()
+	for ttl, want := range map[string]int64{"-1": -1, "500ms": 1} {
+		cfg, err := NewConfigProviderFromData("[cache]\nITEM_TTL = " + ttl + "\n[cache.last_commit]\nITEM_TTL = " + ttl)
+		assert.NoError(t, err)
+		loadCacheFrom(cfg)
+		assert.Equal(t, want, CacheService.TTLSeconds())
+		assert.Equal(t, want, LastCommitCacheTTLSeconds())
+	}
+}