Initial commit based on https://github.com/minio/minio/releases/tag/RELEASE.2020-07-02T00-15-09Z

cmd/disk-cache-utils.go

@@ -0,0 +1,455 @@
+/*
+ * 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 (
+	"container/list"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"io"
+	"math"
+	"os"
+	"path"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/minio/minio/cmd/crypto"
+)
+
+// CacheStatusType - whether the request was served from cache.
+type CacheStatusType string
+
+const (
+	// CacheHit - whether object was served from cache.
+	CacheHit CacheStatusType = "HIT"
+
+	// CacheMiss - object served from backend.
+	CacheMiss CacheStatusType = "MISS"
+)
+
+func (c CacheStatusType) String() string {
+	if c != "" {
+		return string(c)
+	}
+	return string(CacheMiss)
+}
+
+type cacheControl struct {
+	expiry       time.Time
+	maxAge       int
+	sMaxAge      int
+	minFresh     int
+	maxStale     int
+	noStore      bool
+	onlyIfCached bool
+	noCache      bool
+}
+
+func (c *cacheControl) isStale(modTime time.Time) bool {
+	if c == nil {
+		return false
+	}
+	// response will never be stale if only-if-cached is set
+	if c.onlyIfCached {
+		return false
+	}
+	// Cache-Control value no-store indicates never cache
+	if c.noStore {
+		return true
+	}
+	// Cache-Control value no-cache indicates cache entry needs to be revalidated before
+	// serving from cache
+	if c.noCache {
+		return true
+	}
+	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) *cacheControl {
+	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 nil
+	}
+	headerVal = strings.ToLower(headerVal)
+	headerVal = strings.TrimSpace(headerVal)
+
+	vals := strings.Split(headerVal, ",")
+	for _, val := range vals {
+		val = strings.TrimSpace(val)
+
+		if val == "no-store" {
+			c.noStore = true
+			continue
+		}
+		if val == "only-if-cached" {
+			c.onlyIfCached = true
+			continue
+		}
+		if val == "no-cache" {
+			c.noCache = true
+			continue
+		}
+		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 nil
+			}
+			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) || globalCacheKMS != nil
+}
+
+// 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
+	}
+
+	if err = os.Chtimes(filePath, time.Now(), st.ModTime()); err != nil {
+		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
+}
+
+func isCacheEncrypted(meta map[string]string) bool {
+	_, ok := meta[SSECacheEncrypted]
+	return ok
+}
+
+// decryptCacheObjectETag tries to decrypt the ETag saved in encrypted format using the cache KMS
+func decryptCacheObjectETag(info *ObjectInfo) error {
+	// Directories are never encrypted.
+	if info.IsDir {
+		return nil
+	}
+	encrypted := crypto.S3.IsEncrypted(info.UserDefined) && isCacheEncrypted(info.UserDefined)
+
+	switch {
+	case encrypted:
+		if globalCacheKMS == nil {
+			return errKMSNotConfigured
+		}
+		keyID, kmsKey, sealedKey, err := crypto.S3.ParseMetadata(info.UserDefined)
+
+		if err != nil {
+			return err
+		}
+		extKey, err := globalCacheKMS.UnsealKey(keyID, kmsKey, crypto.Context{info.Bucket: path.Join(info.Bucket, info.Name)})
+		if err != nil {
+			return err
+		}
+		var objectKey crypto.ObjectKey
+		if err = objectKey.Unseal(extKey, sealedKey, crypto.S3.String(), info.Bucket, info.Name); err != nil {
+			return err
+		}
+		etagStr := tryDecryptETag(objectKey[:], info.ETag, false)
+		// backend ETag was hex encoded before encrypting, so hex decode to get actual ETag
+		etag, err := hex.DecodeString(etagStr)
+		if err != nil {
+			return err
+		}
+		info.ETag = string(etag)
+		return nil
+	}
+
+	return nil
+}
+
+func isMetadataSame(m1, m2 map[string]string) bool {
+	if m1 == nil && m2 == nil {
+		return true
+	}
+	if (m1 == nil && m2 != nil) || (m2 == nil && m1 != nil) {
+		return false
+	}
+	if len(m1) != len(m2) {
+		return false
+	}
+	for k1, v1 := range m1 {
+		if v2, ok := m2[k1]; !ok || (v1 != v2) {
+			return false
+		}
+	}
+	return true
+}
+
+type fileScorer struct {
+	saveBytes uint64
+	now       int64
+	maxHits   int
+	// 1/size for consistent score.
+	sizeMult float64
+
+	// queue is a linked list of files we want to delete.
+	// The list is kept sorted according to score, highest at top, lowest at bottom.
+	queue       list.List
+	queuedBytes uint64
+}
+
+type queuedFile struct {
+	name  string
+	size  uint64
+	score float64
+}
+
+// newFileScorer allows to collect files to save a specific number of bytes.
+// Each file is assigned a score based on its age, size and number of hits.
+// A list of files is maintained
+func newFileScorer(saveBytes uint64, now int64, maxHits int) (*fileScorer, error) {
+	if saveBytes == 0 {
+		return nil, errors.New("newFileScorer: saveBytes = 0")
+	}
+	if now < 0 {
+		return nil, errors.New("newFileScorer: now < 0")
+	}
+	if maxHits <= 0 {
+		return nil, errors.New("newFileScorer: maxHits <= 0")
+	}
+	f := fileScorer{saveBytes: saveBytes, maxHits: maxHits, now: now, sizeMult: 1 / float64(saveBytes)}
+	f.queue.Init()
+	return &f, nil
+}
+
+func (f *fileScorer) addFile(name string, lastAccess time.Time, size int64, hits int) {
+	// Calculate how much we want to delete this object.
+	file := queuedFile{
+		name: name,
+		size: uint64(size),
+	}
+	score := float64(f.now - lastAccess.Unix())
+	// Size as fraction of how much we want to save, 0->1.
+	szWeight := math.Max(0, (math.Min(1, float64(size)*f.sizeMult)))
+	// 0 at f.maxHits, 1 at 0.
+	hitsWeight := (1.0 - math.Max(0, math.Min(1.0, float64(hits)/float64(f.maxHits))))
+	file.score = score * (1 + 0.25*szWeight + 0.25*hitsWeight)
+	// If we still haven't saved enough, just add the file
+	if f.queuedBytes < f.saveBytes {
+		f.insertFile(file)
+		f.trimQueue()
+		return
+	}
+	// If we score less than the worst, don't insert.
+	worstE := f.queue.Back()
+	if worstE != nil && file.score < worstE.Value.(queuedFile).score {
+		return
+	}
+	f.insertFile(file)
+	f.trimQueue()
+}
+
+// adjustSaveBytes allows to adjust the number of bytes to save.
+// This can be used to adjust the count on the fly.
+// Returns true if there still is a need to delete files (saveBytes >0),
+// false if no more bytes needs to be saved.
+func (f *fileScorer) adjustSaveBytes(n int64) bool {
+	if n < 0 {
+		f.saveBytes -= ^uint64(n - 1)
+	} else {
+		f.saveBytes += uint64(n)
+	}
+	if f.saveBytes == 0 {
+		f.queue.Init()
+		f.saveBytes = 0
+		return false
+	}
+	if n < 0 {
+		f.trimQueue()
+	}
+	return true
+}
+
+// insertFile will insert a file into the list, sorted by its score.
+func (f *fileScorer) insertFile(file queuedFile) {
+	e := f.queue.Front()
+	for e != nil {
+		v := e.Value.(queuedFile)
+		if v.score < file.score {
+			break
+		}
+		e = e.Next()
+	}
+	f.queuedBytes += file.size
+	// We reached the end.
+	if e == nil {
+		f.queue.PushBack(file)
+		return
+	}
+	f.queue.InsertBefore(file, e)
+}
+
+// trimQueue will trim the back of queue and still keep below wantSave.
+func (f *fileScorer) trimQueue() {
+	for {
+		e := f.queue.Back()
+		if e == nil {
+			return
+		}
+		v := e.Value.(queuedFile)
+		if f.queuedBytes-v.size < f.saveBytes {
+			return
+		}
+		f.queue.Remove(e)
+		f.queuedBytes -= v.size
+	}
+}
+
+func (f *fileScorer) purgeFunc(p func(qfile queuedFile)) {
+	e := f.queue.Front()
+	for e != nil {
+		p(e.Value.(queuedFile))
+		e = e.Next()
+	}
+}
+
+// fileNames returns all queued file names.
+func (f *fileScorer) fileNames() []string {
+	res := make([]string, 0, f.queue.Len())
+	e := f.queue.Front()
+	for e != nil {
+		res = append(res, e.Value.(queuedFile).name)
+		e = e.Next()
+	}
+	return res
+}
+
+func (f *fileScorer) reset() {
+	f.queue.Init()
+	f.queuedBytes = 0
+}
+
+func (f *fileScorer) queueString() string {
+	var res strings.Builder
+	e := f.queue.Front()
+	i := 0
+	for e != nil {
+		v := e.Value.(queuedFile)
+		if i > 0 {
+			res.WriteByte('\n')
+		}
+		res.WriteString(fmt.Sprintf("%03d: %s (score: %.3f, bytes: %d)", i, v.name, v.score, v.size))
+		i++
+		e = e.Next()
+	}
+	return res.String()
+}
+
+// bytesToClear() returns the number of bytes to clear to reach low watermark
+// w.r.t quota given disk total and free space, quota in % allocated to cache
+// and low watermark % w.r.t allowed quota.
+func bytesToClear(total, free int64, quotaPct, lowWatermark uint64) uint64 {
+	used := (total - free)
+	quotaAllowed := total * (int64)(quotaPct) / 100
+	lowWMUsage := (total * (int64)(lowWatermark*quotaPct) / (100 * 100))
+	return (uint64)(math.Min(float64(quotaAllowed), math.Max(0.0, float64(used-lowWMUsage))))
+}