/
file.go
135 lines (120 loc) · 2.19 KB
/
file.go
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package filecache
import (
"errors"
"math"
"os"
"sync"
"time"
"github.com/anacrolix/missinggo/pproffd"
)
type File struct {
mu sync.Mutex
c *Cache
path string
f pproffd.OSFile
gone bool
}
func (me *File) Remove() (err error) {
return me.c.Remove(me.path)
}
func (me *File) Seek(offset int64, whence int) (ret int64, err error) {
ret, err = me.f.Seek(offset, whence)
return
}
func (me *File) maxWrite() (max int64, err error) {
if me.c.capacity < 0 {
max = math.MaxInt64
return
}
pos, err := me.Seek(0, os.SEEK_CUR)
if err != nil {
return
}
max = me.c.capacity - pos
if max < 0 {
max = 0
}
return
}
var (
ErrFileTooLarge = errors.New("file too large for cache")
ErrFileDisappeared = errors.New("file disappeared")
)
func (me *File) checkGone() {
if me.gone {
return
}
ffi, _ := me.Stat()
fsfi, _ := os.Stat(me.c.realpath(me.path))
me.gone = !os.SameFile(ffi, fsfi)
}
func (me *File) goneErr() error {
me.mu.Lock()
defer me.mu.Unlock()
me.checkGone()
if me.gone {
me.f.Close()
return ErrFileDisappeared
}
return nil
}
func (me *File) Write(b []byte) (n int, err error) {
err = me.goneErr()
if err != nil {
return
}
n, err = me.f.Write(b)
me.c.mu.Lock()
me.c.statItem(me.path, time.Now())
me.c.trimToCapacity()
me.c.mu.Unlock()
if err == nil {
err = me.goneErr()
}
return
}
func (me *File) WriteAt(b []byte, off int64) (n int, err error) {
err = me.goneErr()
if err != nil {
return
}
n, err = me.f.WriteAt(b, off)
me.c.mu.Lock()
me.c.statItem(me.path, time.Now())
me.c.trimToCapacity()
me.c.mu.Unlock()
if err == nil {
err = me.goneErr()
}
return
}
func (me *File) Close() error {
return me.f.Close()
}
func (me *File) Stat() (os.FileInfo, error) {
return me.f.Stat()
}
func (me *File) Read(b []byte) (n int, err error) {
err = me.goneErr()
if err != nil {
return
}
defer func() {
me.c.mu.Lock()
defer me.c.mu.Unlock()
me.c.statItem(me.path, time.Now())
}()
return me.f.Read(b)
}
func (me *File) ReadAt(b []byte, off int64) (n int, err error) {
err = me.goneErr()
if err != nil {
return
}
defer func() {
me.c.mu.Lock()
defer me.c.mu.Unlock()
me.c.statItem(me.path, time.Now())
}()
return me.f.ReadAt(b, off)
}