refactor(cache)!: extract hybrid_cache package (#2477)

* refactor(HybridCache)!: extract hybrid_cache package and rename cache_threshold to auto_memory_limit

* split HybridCache and stores into internal/hybrid_cache package
* introduce BackingStore abstraction with BufferStore and FileStore
* rename CacheThreshold to AutoMemoryLimit in config/env/bootstrap
* update stream/request integration and related tests

* rename singleFileCache and MultiFileCache to singleFileStore and MultiFileStore

* refactor(HybridCache): improve memory management strategies in NewHybridCache

* rename

* alias hybrid_cache to hcache

* omments

internal/conf/config.go

@@ -120,9 +120,9 @@ type Config struct {
 	DistDir               string      `json:"dist_dir"`
 	Log                   LogConfig   `json:"log" envPrefix:"LOG_"`
 	DelayedStart          int         `json:"delayed_start" env:"DELAYED_START"`
+	AutoMemoryLimit       int         `json:"auto_memory_limit" env:"AUTO_MEMORY_LIMIT"`
 	MinFreeMemory         int         `json:"min_free_memory" env:"MIN_FREE_MEMORY"`
 	MaxBlockLimit         int         `json:"max_block_limit" env:"MAX_BLOCK_LIMIT"`
-	CacheThreshold        int         `json:"cache_threshold" env:"CACHE_THRESHOLD"`
 	MaxConnections        int         `json:"max_connections" env:"MAX_CONNECTIONS"`
 	MaxConcurrency        int         `json:"max_concurrency" env:"MAX_CONCURRENCY"`
 	TlsInsecureSkipVerify bool        `json:"tls_insecure_skip_verify" env:"TLS_INSECURE_SKIP_VERIFY"`
@@ -179,7 +179,7 @@ func DefaultConfig(dataDir string) *Config {
 				},
 			},
 		},
-		CacheThreshold:        4,
+		AutoMemoryLimit:       4,
 		MaxConnections:        0,
 		MaxConcurrency:        64,
 		TlsInsecureSkipVerify: false,

internal/conf/var.go

@@ -25,16 +25,16 @@ var FilenameCharMap = make(map[string]string)
 var PrivacyReg []*regexp.Regexp
 
 var (
-	// 限制单次内存的扩容大小，超过该阈值将分多次扩容。
-	// CacheThreshold大于0时，也限制 Downloader 的PartSize
-	MaxBlockLimit uint64 = 16 * 1024 * 1024
-	// 大于该阈值的数据流将使用HybridCache，可主动释放内存。
-	// 否则使用Go的内存分配，直到GC回收。
-	CacheThreshold uint64 = 4 * 1024 * 1024
+	// 在HybridCache中使用[]byte缓存数据流的限制，内存为Go自动管理，直到GC
+	AutoMemoryLimit uint64 = 4 * 1024 * 1024
 	// 最小空闲内存，当内存不足时，HybridCache会回退到文件缓存。
 	// 如果为0，HybridCache会使用文件缓存，不占用内存。
 	MinFreeMemory uint64 = 16 * 1024 * 1024
+	// 限制HybridCache手动管理内存单次的扩容大小，超过该阈值将分多次扩容。
+	// MinFreeMemory大于0时，也限制 Downloader 的PartSize
+	MaxBlockLimit uint64 = 16 * 1024 * 1024
 )
+
 var (
 	RawIndexHtml string
 	ManageHtml   string