minio/cmd/disk-cache-utils.go

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/*
* MinIO Cloud Storage, (C) 2019 MinIO, Inc.
*
* 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 cmd
import (
"io"
"os"
"strconv"
"strings"
"time"
"github.com/minio/minio/cmd/crypto"
)
type cacheControl struct {
expiry time.Time
maxAge int
sMaxAge int
minFresh int
maxStale int
}
func (c cacheControl) isEmpty() bool {
return c == cacheControl{}
}
func (c cacheControl) isStale(modTime time.Time) bool {
if c.isEmpty() {
return false
}
now := time.Now()
if c.sMaxAge > 0 && c.sMaxAge < int(now.Sub(modTime).Seconds()) {
return true
}
if c.maxAge > 0 && c.maxAge < int(now.Sub(modTime).Seconds()) {
return true
}
if !c.expiry.Equal(time.Time{}) && c.expiry.Before(time.Now().Add(time.Duration(c.maxStale))) {
return true
}
if c.minFresh > 0 && c.minFresh <= int(now.Sub(modTime).Seconds()) {
return true
}
return false
}
// returns struct with cache-control settings from user metadata.
func cacheControlOpts(o ObjectInfo) (c cacheControl) {
m := o.UserDefined
if o.Expires != timeSentinel {
c.expiry = o.Expires
}
var headerVal string
for k, v := range m {
if strings.ToLower(k) == "cache-control" {
headerVal = v
}
}
if headerVal == "" {
return
}
headerVal = strings.ToLower(headerVal)
headerVal = strings.TrimSpace(headerVal)
vals := strings.Split(headerVal, ",")
for _, val := range vals {
val = strings.TrimSpace(val)
p := strings.Split(val, "=")
if len(p) != 2 {
continue
}
if p[0] == "max-age" ||
p[0] == "s-maxage" ||
p[0] == "min-fresh" ||
p[0] == "max-stale" {
i, err := strconv.Atoi(p[1])
if err != nil {
return cacheControl{}
}
if p[0] == "max-age" {
c.maxAge = i
}
if p[0] == "s-maxage" {
c.sMaxAge = i
}
if p[0] == "min-fresh" {
c.minFresh = i
}
if p[0] == "max-stale" {
c.maxStale = i
}
}
}
return c
}
// backendDownError returns true if err is due to backend failure or faulty disk if in server mode
func backendDownError(err error) bool {
_, backendDown := err.(BackendDown)
return backendDown || IsErr(err, baseErrs...)
}
// IsCacheable returns if the object should be saved in the cache.
func (o ObjectInfo) IsCacheable() bool {
return !crypto.IsEncrypted(o.UserDefined)
}
// reads file cached on disk from offset upto length
func readCacheFileStream(filePath string, offset, length int64) (io.ReadCloser, error) {
if filePath == "" || offset < 0 {
return nil, errInvalidArgument
}
if err := checkPathLength(filePath); err != nil {
return nil, err
}
fr, err := os.Open(filePath)
if err != nil {
return nil, osErrToFSFileErr(err)
}
// Stat to get the size of the file at path.
st, err := fr.Stat()
if err != nil {
err = osErrToFSFileErr(err)
return nil, err
}
// Verify if its not a regular file, since subsequent Seek is undefined.
if !st.Mode().IsRegular() {
return nil, errIsNotRegular
}
if err = os.Chtimes(filePath, time.Now(), st.ModTime()); err != nil {
return nil, err
}
// Seek to the requested offset.
if offset > 0 {
_, err = fr.Seek(offset, io.SeekStart)
if err != nil {
return nil, err
}
}
return struct {
io.Reader
io.Closer
}{Reader: io.LimitReader(fr, length), Closer: fr}, nil
}