filecache

README

A simple LRU FileCache with file freshness monitor.

FileCache accepts a max size and age, and will remove items if they become too old or at end of the LRU list.

Documentation

Index

• Variables
• type CacheEntry
  • func (e *CacheEntry) Bytes() []byte
  • func (e *CacheEntry) Reader() io.Reader
  • func (e *CacheEntry) Release()
• type Config
• type File
• type FileCache
  • func New(cfg *Config) *FileCache
  • func (fc *FileCache) Get(path string) (*CacheEntry, error)
  • func (fc *FileCache) Put(path string, file File) error
  • func (fc *FileCache) Remove(path string)

Variables

var (
	ErrNotFound      = errors.Define("filecache: file not found")
	ErrAlreadyExists = errors.Define("filecache: file at path already exists")
	ErrFailedRefresh = errors.Define("filecache: failed refreshing cache entry")
	ErrFileTooLarge  = errors.Define("filecache: file too large")
	ErrClosed        = errors.Define("filecache: closed")
)

var DefaultConfig = Config{
	RefreshFreq:      time.Minute,
	Size:             100,
	MaxSize:          int64(1024 * 1000 * 5),
	MaxAge:           time.Minute * 30,
	EvictionCallback: func(path string, file File) { log.Printf("FileCache evicted '%s'", path) },
	ErrorEvictionCallback: func(path string, file File, err error) {
		log.Printf("FileCache evicted '%s' due to error: %v", path, err)
	},
}

Types

type CacheEntry

type CacheEntry struct {
	// contains filtered or unexported fields
}

func (*CacheEntry) Bytes

func (e *CacheEntry) Bytes() []byte

func (*CacheEntry) Reader

func (e *CacheEntry) Reader() io.Reader

func (*CacheEntry) Release

func (e *CacheEntry) Release()

type Config

type Config struct {
	// RefreshFreq is the frequency at which the refresh routines operates
	RefreshFreq time.Duration

	// Size is the fixed size of the FileCache
	Size int

	// MaxSize is the maximum size of files permitted in the cache
	MaxSize int64

	// MaxAge is the maximum time entries can go unused in
	// the cache before being marked for eviction. The minimum age
	// (and granularity) is 1 second
	MaxAge time.Duration

	// AllowOverwrites signifies whether to overwrite existing
	// files of the same path when passed to .Put()
	AllowOverwrites bool

	// EvictionCallback is called when a file is evicted from the FileCache
	EvictionCallback func(path string, file File)

	// ErrorEvictionCallback is called when a file is evicted from the FileCache
	// due to an error, e.g. cannot stat, file too large, etc
	ErrorEvictionCallback func(path string, file File, err error)
}

type File

type File interface {
	Open() (io.ReadCloser, error)
	Stat() (os.FileInfo, error)
}

type FileCache

type FileCache struct {
	// contains filtered or unexported fields
}

FileCache is an LRU cache with filesystem monitoring. UpgradeableMutex is built-in to the FileCache and CachedFile objects it manages for multi-threading

func New

func New(cfg *Config) *FileCache

NewFileCache returns a new FileCache object of size, and max file age

func (*FileCache) Get

func (fc *FileCache) Get(path string) (*CacheEntry, error)

func (*FileCache) Put

func (fc *FileCache) Put(path string, file File) error

Put places a CachedFile object in the FileCache.

func (*FileCache) Remove

func (fc *FileCache) Remove(path string)