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cached.go
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cached.go
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/*
Copyright 2024 The GoPlus Authors (goplus.org)
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package cached
import (
"crypto/md5"
"encoding/base64"
"fmt"
"io"
"io/fs"
"net/url"
"os"
"path"
"github.com/goplus/hdq/stream"
"github.com/goplus/hdq/stream/http"
)
// -------------------------------------------------------------------------------------
var (
cacheDir = getCacheDir()
)
func getCacheDir() string {
root, err := os.UserCacheDir()
if err != nil {
panic(err)
}
dir := root + "/hdq/http/"
os.MkdirAll(dir, 0755)
return dir
}
// -------------------------------------------------------------------------------------
// TODO(xsw): add checksum to cache file
func WriteCache(cacheFile string, url string) (err error) {
resp, err := http.Get(url)
if err != nil {
return
}
defer resp.Body.Close()
f, err := os.Create(cacheFile)
if err != nil {
return
}
defer f.Close()
_, err = io.Copy(f, resp.Body)
return
}
func ReadCache(cacheFile string, fi fs.FileInfo) (ret io.ReadCloser, err error) {
return os.Open(cacheFile)
}
// -------------------------------------------------------------------------------------
// Open opens a http file object.
func Open(url_ string) (ret io.ReadCloser, err error) {
u, err := url.Parse(url_)
if err != nil {
return
}
fname := path.Base(u.Path)
ext := path.Ext(fname)
hash := md5.Sum([]byte(url_))
hashstr := base64.RawURLEncoding.EncodeToString(hash[:])
fname = fmt.Sprintf("%s-%s%s", fname[:len(fname)-len(ext)], hashstr, ext)
file := cacheDir + fname
if fi, e := os.Stat(file); e == nil {
if ret, err = ReadCache(file, fi); err == nil { // cache hit
return
}
}
if err = WriteCache(file, url_); err != nil {
return // write cache failed
}
return ReadCache(file, nil)
}
func init() {
stream.Register("http", Open)
stream.Register("https", Open)
}
// -------------------------------------------------------------------------------------