minio/cmd/metacache-entries.go

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/*
* MinIO Cloud Storage, (C) 2020 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 (
"bytes"
"io"
"os"
"sort"
"strings"
)
// metaCacheEntry is an object or a directory within an unknown bucket.
type metaCacheEntry struct {
// name is the full name of the object including prefixes
name string
// Metadata. If none is present it is not an object but only a prefix.
// Entries without metadata will only be present in non-recursive scans.
metadata []byte
// cached contains the metadata if decoded.
cached *FileInfo
}
// isDir returns if the entry is representing a prefix directory.
func (e metaCacheEntry) isDir() bool {
return len(e.metadata) == 0
}
// isObject returns if the entry is representing an object.
func (e metaCacheEntry) isObject() bool {
return len(e.metadata) > 0
}
// hasPrefix returns whether an entry has a specific prefix
func (e metaCacheEntry) hasPrefix(s string) bool {
return strings.HasPrefix(e.name, s)
}
// likelyMatches returns if the entries match by comparing name and metadata length.
func (e *metaCacheEntry) likelyMatches(other *metaCacheEntry) bool {
// This should reject 99%
if len(e.metadata) != len(other.metadata) || e.name != other.name {
return false
}
return true
}
// matches returns if the entries match by comparing their latest version fileinfo.
func (e *metaCacheEntry) matches(other *metaCacheEntry, bucket string) bool {
if e == nil && other == nil {
return true
}
if e == nil || other == nil {
return false
}
// This should reject 99%
if len(e.metadata) != len(other.metadata) || e.name != other.name {
return false
}
eFi, eErr := e.fileInfo(bucket)
oFi, oErr := e.fileInfo(bucket)
if eErr != nil || oErr != nil {
return eErr == oErr
}
return eFi.ModTime.Equal(oFi.ModTime) && eFi.Size == oFi.Size && eFi.VersionID == oFi.VersionID
}
// isInDir returns whether the entry is in the dir when considering the separator.
func (e metaCacheEntry) isInDir(dir, separator string) bool {
if len(dir) == 0 {
// Root
idx := strings.Index(e.name, separator)
return idx == -1 || idx == len(e.name)-len(separator)
}
ext := strings.TrimPrefix(e.name, dir)
if len(ext) != len(e.name) {
idx := strings.Index(ext, separator)
// If separator is not found or is last entry, ok.
return idx == -1 || idx == len(ext)-len(separator)
}
return false
}
// isLatestDeletemarker returns whether the latest version is a delete marker.
// If metadata is NOT versioned false will always be returned.
// If v2 and UNABLE to load metadata true will be returned.
func (e *metaCacheEntry) isLatestDeletemarker() bool {
if e.cached != nil {
return e.cached.Deleted
}
if !isXL2V1Format(e.metadata) {
return false
}
var xlMeta xlMetaV2
if err := xlMeta.Load(e.metadata); err != nil || len(xlMeta.Versions) == 0 {
return true
}
return xlMeta.Versions[len(xlMeta.Versions)-1].Type == DeleteType
}
// fileInfo returns the decoded metadata.
// If entry is a directory it is returned as that.
// If versioned the latest version will be returned.
func (e *metaCacheEntry) fileInfo(bucket string) (*FileInfo, error) {
if e.isDir() {
return &FileInfo{
Volume: bucket,
Name: e.name,
Mode: uint32(os.ModeDir),
}, nil
}
if e.cached == nil {
fi, err := getFileInfo(e.metadata, bucket, e.name, "")
if err != nil {
return nil, err
}
e.cached = &fi
}
return e.cached, nil
}
// fileInfoVersions returns the metadata as FileInfoVersions.
// If entry is a directory it is returned as that.
func (e *metaCacheEntry) fileInfoVersions(bucket string) (FileInfoVersions, error) {
if e.isDir() {
return FileInfoVersions{
Volume: bucket,
Name: e.name,
Versions: []FileInfo{
{
Volume: bucket,
Name: e.name,
Mode: uint32(os.ModeDir),
},
},
}, nil
}
return getFileInfoVersions(e.metadata, bucket, e.name)
}
// metaCacheEntries is a slice of metacache entries.
type metaCacheEntries []metaCacheEntry
// less function for sorting.
func (m metaCacheEntries) less(i, j int) bool {
return m[i].name < m[j].name
}
// sort entries by name.
// m is sorted and a sorted metadata object is returned.
// Changes to m will also be reflected in the returned object.
func (m metaCacheEntries) sort() metaCacheEntriesSorted {
if m.isSorted() {
return metaCacheEntriesSorted{o: m}
}
sort.Slice(m, m.less)
return metaCacheEntriesSorted{o: m}
}
// isSorted returns whether the objects are sorted.
// This is usually orders of magnitude faster than actually sorting.
func (m metaCacheEntries) isSorted() bool {
return sort.SliceIsSorted(m, m.less)
}
// shallowClone will create a shallow clone of the array objects,
// but object metadata will not be cloned.
func (m metaCacheEntries) shallowClone() metaCacheEntries {
dst := make(metaCacheEntries, len(m))
copy(dst, m)
return dst
}
type metadataResolutionParams struct {
dirQuorum int // Number if disks needed for a directory to 'exist'.
objQuorum int // Number of disks needed for an object to 'exist'.
bucket string // Name of the bucket. Used for generating cached fileinfo.
}
func (m metaCacheEntries) resolve(r *metadataResolutionParams) (selected *metaCacheEntry, ok bool) {
if len(m) == 0 {
return nil, false
}
dirExists := 0
objExists := 0
var selFIV *FileInfo
for i := range m {
entry := &m[i]
if entry.name == "" {
continue
}
if entry.isDir() {
dirExists++
selected = entry
continue
}
// Get new entry metadata
objExists++
fiv, err := entry.fileInfo(r.bucket)
if err != nil {
continue
}
if selFIV == nil {
selected = entry
selFIV = fiv
continue
}
if selected.matches(entry, r.bucket) {
continue
}
// Select latest modtime.
if fiv.ModTime.After(selFIV.ModTime) {
selected = entry
selFIV = fiv
continue
}
}
// If directory, we need quorum.
if dirExists > 0 && dirExists < r.dirQuorum {
return nil, false
}
if objExists < r.objQuorum {
return nil, false
}
// Take the latest selected.
return selected, selected != nil
}
// firstFound returns the first found and the number of set entries.
func (m metaCacheEntries) firstFound() (first *metaCacheEntry, n int) {
for _, entry := range m {
if entry.name != "" {
n++
if first == nil {
first = &entry
}
}
}
return first, n
}
// names will return all names in order.
// Since this allocates it should not be used in critical functions.
func (m metaCacheEntries) names() []string {
res := make([]string, 0, len(m))
for _, obj := range m {
res = append(res, obj.name)
}
return res
}
// metaCacheEntriesSorted contains metacache entries that are sorted.
type metaCacheEntriesSorted struct {
o metaCacheEntries
// list id is not serialized
listID string
}
// writeTo will write all objects to the provided output.
func (m metaCacheEntriesSorted) writeTo(writer io.Writer) error {
w := newMetacacheWriter(writer, 1<<20)
if err := w.write(m.o...); err != nil {
w.Close()
return err
}
return w.Close()
}
// shallowClone will create a shallow clone of the array objects,
// but object metadata will not be cloned.
func (m metaCacheEntriesSorted) shallowClone() metaCacheEntriesSorted {
// We have value receiver so we already have a copy.
m.o = m.o.shallowClone()
return m
}
// iterate the entries in order.
// If the iterator function returns iterating stops.
func (m *metaCacheEntriesSorted) iterate(fn func(entry metaCacheEntry) (cont bool)) {
if m == nil {
return
}
for _, o := range m.o {
if !fn(o) {
return
}
}
}
// fileInfoVersions converts the metadata to FileInfoVersions where possible.
// Metadata that cannot be decoded is skipped.
func (m *metaCacheEntriesSorted) fileInfoVersions(bucket, prefix, delimiter, afterV string) (versions []ObjectInfo, commonPrefixes []string) {
versions = make([]ObjectInfo, 0, m.len())
prevPrefix := ""
for _, entry := range m.o {
if entry.isObject() {
if delimiter != "" {
idx := strings.Index(strings.TrimPrefix(entry.name, prefix), delimiter)
if idx >= 0 {
idx = len(prefix) + idx + len(delimiter)
currPrefix := entry.name[:idx]
if currPrefix == prevPrefix {
continue
}
prevPrefix = currPrefix
commonPrefixes = append(commonPrefixes, currPrefix)
continue
}
}
fiv, err := entry.fileInfoVersions(bucket)
if afterV != "" {
// Forward first entry to specified version
fiv.forwardPastVersion(afterV)
afterV = ""
}
if err == nil {
for _, version := range fiv.Versions {
versions = append(versions, version.ToObjectInfo(bucket, entry.name))
}
}
continue
}
if entry.isDir() {
if delimiter == "" {
continue
}
idx := strings.Index(strings.TrimPrefix(entry.name, prefix), delimiter)
if idx < 0 {
continue
}
idx = len(prefix) + idx + len(delimiter)
currPrefix := entry.name[:idx]
if currPrefix == prevPrefix {
continue
}
prevPrefix = currPrefix
commonPrefixes = append(commonPrefixes, currPrefix)
continue
}
}
return versions, commonPrefixes
}
// fileInfoVersions converts the metadata to FileInfoVersions where possible.
// Metadata that cannot be decoded is skipped.
func (m *metaCacheEntriesSorted) fileInfos(bucket, prefix, delimiter string) (objects []ObjectInfo, commonPrefixes []string) {
objects = make([]ObjectInfo, 0, m.len())
prevPrefix := ""
for _, entry := range m.o {
if entry.isObject() {
if delimiter != "" {
idx := strings.Index(strings.TrimPrefix(entry.name, prefix), delimiter)
if idx >= 0 {
idx = len(prefix) + idx + len(delimiter)
currPrefix := entry.name[:idx]
if currPrefix == prevPrefix {
continue
}
prevPrefix = currPrefix
commonPrefixes = append(commonPrefixes, currPrefix)
continue
}
}
fi, err := entry.fileInfo(bucket)
if err == nil {
objects = append(objects, fi.ToObjectInfo(bucket, entry.name))
}
continue
}
if entry.isDir() {
if delimiter == "" {
continue
}
idx := strings.Index(strings.TrimPrefix(entry.name, prefix), delimiter)
if idx < 0 {
continue
}
idx = len(prefix) + idx + len(delimiter)
currPrefix := entry.name[:idx]
if currPrefix == prevPrefix {
continue
}
prevPrefix = currPrefix
commonPrefixes = append(commonPrefixes, currPrefix)
continue
}
}
return objects, commonPrefixes
}
// forwardTo will truncate m so only entries that are s or after is in the list.
func (m *metaCacheEntriesSorted) forwardTo(s string) {
if s == "" {
return
}
idx := sort.Search(len(m.o), func(i int) bool {
return m.o[i].name >= s
})
m.o = m.o[idx:]
}
// merge will merge other into m.
// If the same entries exists in both and metadata matches only one is added,
// otherwise the entry from m will be placed first.
// Operation time is expected to be O(n+m).
func (m *metaCacheEntriesSorted) merge(other metaCacheEntriesSorted, limit int) {
merged := make(metaCacheEntries, 0, m.len()+other.len())
a := m.entries()
b := other.entries()
for len(a) > 0 && len(b) > 0 {
if a[0].name == b[0].name && bytes.Equal(a[0].metadata, b[0].metadata) {
// Same, discard one.
merged = append(merged, a[0])
a = a[1:]
b = b[1:]
} else if a[0].name < b[0].name {
merged = append(merged, a[0])
a = a[1:]
} else {
merged = append(merged, b[0])
b = b[1:]
}
if limit > 0 && len(merged) >= limit {
break
}
}
// Append anything left.
if limit < 0 || len(merged) < limit {
merged = append(merged, a...)
merged = append(merged, b...)
}
m.o = merged
}
// filter allows selective filtering with the provided function.
func (m *metaCacheEntriesSorted) filter(fn func(entry *metaCacheEntry) bool) {
dst := m.o[:0]
for _, o := range m.o {
if fn(&o) {
dst = append(dst, o)
}
}
m.o = dst
}
// filterPrefix will filter m to only contain entries with the specified prefix.
func (m *metaCacheEntriesSorted) filterPrefix(s string) {
if s == "" {
return
}
m.forwardTo(s)
for i, o := range m.o {
if !o.hasPrefix(s) {
m.o = m.o[:i]
break
}
}
}
// filterObjectsOnly will remove prefix directories.
// Order is preserved, but the underlying slice is modified.
func (m *metaCacheEntriesSorted) filterObjectsOnly() {
dst := m.o[:0]
for _, o := range m.o {
if !o.isDir() {
dst = append(dst, o)
}
}
m.o = dst
}
// filterPrefixesOnly will remove objects.
// Order is preserved, but the underlying slice is modified.
func (m *metaCacheEntriesSorted) filterPrefixesOnly() {
dst := m.o[:0]
for _, o := range m.o {
if o.isDir() {
dst = append(dst, o)
}
}
m.o = dst
}
// filterRecursiveEntries will keep entries only with the prefix that doesn't contain separator.
// This can be used to remove recursive listings.
// To return root elements only set prefix to an empty string.
// Order is preserved, but the underlying slice is modified.
func (m *metaCacheEntriesSorted) filterRecursiveEntries(prefix, separator string) {
dst := m.o[:0]
if prefix != "" {
m.forwardTo(prefix)
for _, o := range m.o {
ext := strings.TrimPrefix(o.name, prefix)
if len(ext) != len(o.name) {
if !strings.Contains(ext, separator) {
dst = append(dst, o)
}
}
}
} else {
// No prefix, simpler
for _, o := range m.o {
if !strings.Contains(o.name, separator) {
dst = append(dst, o)
}
}
}
m.o = dst
}
// truncate the number of entries to maximum n.
func (m *metaCacheEntriesSorted) truncate(n int) {
if m == nil {
return
}
if len(m.o) > n {
m.o = m.o[:n]
}
}
// len returns the number of objects and prefix dirs in m.
func (m *metaCacheEntriesSorted) len() int {
if m == nil {
return 0
}
return len(m.o)
}
// entries returns the underlying objects as is currently represented.
func (m *metaCacheEntriesSorted) entries() metaCacheEntries {
if m == nil {
return nil
}
return m.o
}
// deduplicate entries in the list.
// If compareMeta is set it will be used to resolve conflicts.
// The function should return whether the existing entry should be replaced with other.
// If no compareMeta is provided duplicates may be left.
// This is indicated by the returned boolean.
func (m *metaCacheEntriesSorted) deduplicate(compareMeta func(existing, other *metaCacheEntry) (replace bool)) (dupesLeft bool) {
dst := m.o[:0]
for j := range m.o {
found := false
obj := &m.o[j]
for i := len(dst) - 1; i >= 0; i++ {
existing := &dst[i]
if existing.name != obj.name {
break
}
// Use given resolution function first if any.
if compareMeta != nil {
if compareMeta(existing, obj) {
dst[i] = *obj
}
found = true
break
}
if obj.likelyMatches(existing) {
found = true
break
}
// Matches, move on.
dupesLeft = true
continue
}
if !found {
dst = append(dst, *obj)
}
}
m.o = dst
return dupesLeft
}