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filecache.go
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filecache.go
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//Copyright 2014 Mahendra Kathirvel. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package filecache
import (
"bytes"
"encoding/gob"
"errors"
"io"
"log"
"os"
"path/filepath"
"regexp"
"strconv"
"strings"
"sync"
"time"
)
const (
cache_dir = "/tmp" // Cache directory
expire = 8 * time.Hour // Hours to keep the cache
)
func Set(key string, data interface{}) error {
t1 := time.Now()
key = regexp.MustCompile("[^a-zA-Z0-9_-]").ReplaceAllLiteralString(key, "")
clean(key)
file := "filecache." + key + "." + strconv.FormatInt(time.Now().Add(expire).Unix(), 10)
fpath := filepath.Join(cache_dir, file)
serialized, err := serialize(data)
if err != nil {
return err
}
var fmutex sync.RWMutex
fmutex.Lock()
fp, err := os.OpenFile(fpath, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0600)
if err != nil {
return err
}
defer fp.Close()
if _, err = fp.Write(serialized); err != nil {
return err
}
defer fmutex.Unlock()
t2 := time.Now()
log.Println("Set filecache: ", key, " : ", t2.Sub(t1))
return nil
}
func Get(key string, dst interface{}) error {
t:= time.Now()
key = regexp.MustCompile("[^a-zA-Z0-9_-]").ReplaceAllLiteralString(key, "")
pattern := filepath.Join(cache_dir, "filecache."+key+".*")
files, err := filepath.Glob(pattern)
if len(files) < 1 || err != nil {
return errors.New("filecache: no cache file found")
}
if _, err = os.Stat(files[0]); err != nil {
return err
}
fp, err := os.OpenFile(files[0], os.O_RDONLY, 0400)
if err != nil {
return err
}
defer fp.Close()
var serialized []byte
buf := make([]byte, 1024)
for {
var n int
n, err = fp.Read(buf)
serialized = append(serialized, buf[0:n]...)
if err != nil || err == io.EOF {
break
}
}
if err = deserialize(serialized, dst); err != nil {
return err
}
for _, file := range files {
exptime, err := strconv.ParseInt(strings.Split(file, ".")[2], 10, 64)
if err != nil {
return err
}
if exptime < time.Now().Unix() {
if _, err = os.Stat(file); err == nil {
os.Remove(file)
}
}
}
log.Println("Get filecache: ", key, " : ", time.Since(t))
return nil
}
func clean(key string) {
pattern := filepath.Join(cache_dir, "filecache."+key+".*")
files, _ := filepath.Glob(pattern)
for _, file := range files {
if _, err := os.Stat(file); err == nil {
os.Remove(file)
}
}
}
// serialize encodes a value using binary.
func serialize(src interface{}) ([]byte, error) {
buf := new(bytes.Buffer)
if err := gob.NewEncoder(buf).Encode(src); err != nil {
return nil, err
}
return buf.Bytes(), nil
}
// deserialize decodes a value using binary.
func deserialize(src []byte, dst interface{}) error {
buf := bytes.NewReader(src)
if err := gob.NewDecoder(buf).Decode(dst); err != nil {
log.Println(dst)
return err
}
return nil
}